Research ArticleLongitudinal Reservoir Evaluation Technique for TightOil Reservoirs

Yutian Luo 123 Zhengming Yang 13 Zhenxing Tang4 Sibin Zhou5 Jinwei Wu5

and Qianhua Xiao 6

1University of Chinese Academy of Sciences Beijing 100049 China2Institute of Porous Flow and Fluid Mechanics Chinese Academy of Sciences Langfang 065007 China3Research Institute of Petroleum Exploration and Development Petrochina Langfang Hebei 065007 China4Exploration and Development Research Institute Jilin Oilfield Company Songyuan 138001 China5Exploration and Development Research Institute of Sinopec North China Branch Zhengzhou 450006 China6Chongqing University of Science and Technology Chongqing 401331 China

Correspondence should be addressed to Yutian Luo luoyutianpetrochinacomcn

Received 23 September 2018 Revised 3 November 2018 Accepted 5 December 2018 Published 6 January 2019

Guest Editor Jianchao Cai

Copyright copy 2019 Yutian Luo et al +is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Reservoir evaluation is a method for classifying reservoirs and the description of heterogeneity quantitatively In this studyaccording to the characteristics of longitudinal physical properties of tight oil reservoirs advanced experimental techniques suchas nuclear magnetic resonance high pressure mercury intrusion and X-ray diffraction were adopted the flow capacity reservoircapacity ability to build an effective displacement system and the ability to resist damage in reservoir reconstruction wereconsidered as evaluation indexes average throat radius percentage of movable fluid start-up pressure gradient and the content ofclay minerals were taken as the evaluation parameters On the above basis a longitudinal evaluation technique for tight oilreservoirs was established +e reservoir was divided into four categories by using this method +e reservoirs with a depth230654mndash236207m were mainly type I and II reservoirs and the reservoirs with a depth of 236207mndash239130m were mainlyreservoirs of type II and III +e most effective development was water injection in the upper section and gas injection in thelower section

1 Introduction

China has large reserves of tight oil and the tight oil reservesin the onshore basin are about 200 times 108 t which are mainlydistributed in the Ordos Songliao Junggar and Sichuanbasins [1ndash3] At the end of the ldquo12th Five-Year Planrdquo themajor oil fields have been explored for the large-scale de-velopment of tight oil reservoirs During the ldquo13th Five-YearPlanrdquo period the tight oil reservoirs will become an im-portant substitute energy source in China [4] +e primaryproblem that constrains the effective development of tightoil was how to accurately describe the heterogeneity of tightoil reservoirs +e physical properties of tight oil reservoirsin different oil fields in China were significantly differentand the reservoir porosity and permeability were extremelylow [5 6] In the evaluation of low-permeability and tight oil

reservoirs Chinese scholars have done a lot of researchYang et al and Zhang et al used a five-parameter method toevaluate the low-permeability reservoirs [7 8] Xiao used asix-parameter method to evaluate the tight oil reservoirs [9]Jia et al put forward 10 geological parameters to evaluate thetight oil reservoirs [10] Zou et al presented the six-propertymethod for the evaluation considering the geological andengineering factors of the reservoir [11] +e above researchstudies mainly focused on the differences among reservoirsin different oil fields or blocks+e evaluation parameters aregenerally calculated based on the mean values of reservoirphysical properties without taking the physical propertyparameter variations of the tight reservoirs in the longitu-dinal section into consideration +erefore the accuratedescription of the tight reservoirs can hardly be obtainedIn this study the multiparameters that reflect the most

HindawiAdvances in Materials Science and EngineeringVolume 2019 Article ID 7681760 8 pageshttpsdoiorg10115520197681760

significant longitudinal heterogeneity of the tight reservoirswere adopted to evaluate the tight reservoirs +e throatradius curve was plotted to describe the change of reservoirseepage capacity the percentage curve of the movable fluidwas plotted to show the change of fluid storage capacity thepressure gradient curve was used to present the variation ofreservoir displacement capacity and the clay percentagecurve was employed to explain the variation of difficulty inthe reservoir energy supplement Based on the compre-hensive reservoir evaluation result the development modewas determined and the development ldquosweet spotrdquo [12]areas in the tight reservoirs were preferred Different types ofreservoirs are suitable for different injection media Hence itis very important to study reservoir properties For exampleJia et al evaluated the effects of CO2 CH4 and N2 injectionon shale oil recovery [13]

2 Materials and Methods

21RockSamples In this study taking the tight sandstone ofK1q4 of Jilin Oilfield in Songliao Basin as the research objectthe rock cores were collected from the same layer of threeadjacent wells (namely No 1 well Qian262Well No 2 wellQian 246Well and No 3 well Qian21Well) with the coringdepth of 2309m 2321m and 2371m respectively Rocksamples have a porosity of 1314ndash1520 and a perme-ability of (039ndash186) times 10minus3 μm2 which was typical for thetight reservoir

22 Experimental Methodology Scanning electron micros-copy (SEM) was often used to capture high-resolutionimages that recognize rock structural features mineraltypes and reservoir spatial characteristics It can not onlyobserve the microscopic characteristics of rock samplesunder high magnification but can also qualitatively andsemiquantitatively analyze different components in thesample A Zeissbeam-540 FIB scanning electron microscope(Zeiss Germany) was employed to study the pore andmineral characteristics of tight rock samples with a mag-nification of 100 times Electron microscopy was used forvisual observation of pores

Pore distribution characteristics of tight rock sampleswere studied using an ASPE 730 rate-controlled mercuryintrusion instrument manufactured by US Coretest +esetests were conducted with a mercury-injection pressure of0ndash1000 psi (about 7MPa) a mercury-penetration speed of000005mLmin a contact angle of 140deg an interfacialtension factor of 485 dyncm and a physical size of ap-proximately 15 cm3 During rate-controlled mercury in-trusion mercury can be injected into pore volumes of rocksunder extremely low mercury-penetration speed(000005mlmin) without changing the surface tension orcontact angle to ensure quasistatic mercury intrusion pro-cesses [14 15] In accordance with changes in mercury-penetration pressures data related to pore structures couldbe acquired With the distribution of pore throats andquantities of pores known directly pore radius pore throatradius and other characteristic parameters of microscopic

pore structures in rocks could be obtained Rate-controlledmercury intrusion was used to quantitatively describe thesize of the pores

+e fluid distribution of pores in tight rocks was studiedusing the RecCore 2500 NMR instrument independentlydeveloped by the Institute of Porous Flow and Fluid Me-chanics Chinese Academy of Sciences +ese tests wereconducted with a resonance frequency of 238MHz an echotime of 03ms a recovery time of 6000ms an echo numberof 2048 and an experimental temperature of 25degC Since theoil or water was rich in hydrogen nuclei and had a nuclearmagnetic moment the nuclear magnetic moment wouldgenerate energy-level splitting in the applied static magneticfield If a specific radio frequency magnetic field was appliedthe nuclear magnetic moment would undergo an absorptiontransition resulting in a nuclear magnetic resonance phe-nomenon NMR was used to retrieve pore structure in-formation of tight reservoirs by testing T2 (transverserelaxation time) spectrum of saturated oil or water in rockcores We used a paramagnetic substance dissolved in waterto eliminate the water signal in NMR +is method coulddistinguish water and oil in tight reservoirs NMR was usedto describe the law of fluid occurrence in pores

3 Results and Discussion

31 Development Characteristics and Evaluation Difficul-ties of Tight Reservoirs Because tight oil reservoirs werecharacterized by source generation and source accumulationin situ and it had short-term migration the heterogeneity ofthe pore distribution was relatively strong [5 8 16] +eresults of the permeability test using different gases weresignificantly different [17] In keeping with the conventionaltest method in this paper the permeability was tested usingN2 According to the SEM images of tight rock cores (shownin Figure 1 the porosity and permeability were tested usingindustry standard methods) it was found that the lower theporosity of the core the more microscopic pores the rockcontains and the poorer the pore connectivity and the cementwas mainly composed of an illite-smectite mixed layer andwas mixed with a small amount of chlorite With the increasein permeability the core structure loosened increasingly largepores appeared gradually the number of pores increasedsignificantly and the connectivity became better

+e difference between reservoirs was relatively small inthe horizontal plane in the same depth+rough comparisonof the tight cores collected from different depths the dif-ference between reservoirs was significant in the longitu-dinal plane As shown in Table 1 the variation of rockporosity ranges from 033 to 252 with an average of132 the variation of permeability ranges from 714 to2796 with an average of 1639 As shown in Table 2 thevariation of rock porosity ranges from 1120 to 1327with an average of 1219 the variation of permeabilityranges from 6866 to 7903 with an average of 7311+e difference between tight reservoirs in the longitudinaldirection was much larger than that in the horizontal di-rection it was therefore inapplicable to evaluate the tightreservoir using porosity and permeability

2 Advances in Materials Science and Engineering

In order to study the pore distribution of the tight res-ervoir the core samples of Qian262 Well was continuouslycollected formercury intrusion experiments According to themercury intrusion test results the pore distribution curves atdierent scales were plotted as shown in Figure 2(a) and thepore size was divided into ve intervals using nuclear mag-netic and centrifugal methods in the literature [18] Namelythe rst was nanopores with radius less than 25nm whoseuid cannot be developed the second was nanopores withradius of 25ndash50 nm whose uid can be exploited by osmoticand displacement the third was nanopores with radius of50ndash100 nm whose uid can be mined by gas injection thefourth was submicron pores with radius of 01ndash1 μm whoseuid can be developed by a water injection-mixed surfactantand the fth was micropores with radius larger than 1 μmwhose uid can be exploited by water injection As seen fromFigure 2(a) the pore distribution of the tight reservoir variessharply the third type of pores with radius of 50ndash100 nmhas the largest variation with the lowest content of 15 and

the highest content of 446 the content of the rst type ofpores with radius less than 25nm accounts for 20ndash40the reservoir also contains considerable amounts of the fourthtype of pores with radius of 01ndash1 μm and there was anextremely small amount of the fth type of pores with radiuslarger than 1 μm

Nuclear magnetic resonance (NMR) tests were carriedout tomeasure the uid content in dierent sizes of the pores[19 20] e result is shown in Figure 2(b) It was observedthat the dierence in uid distribution in the reservoir wasalso obvious e uid in the nanopores accounts for about60 and it is as high as 90 in some depths In additionabout 10 of the uid exists in the micropores and 30 uidin the submicron pores It can be seen from Figure 2 that itwas dicult to describe accurately the distribution of poresand uids in tight reservoirs by a simple number Since theformation of tight reservoirs mainly depends on self-generation and self-storing or short-term migration [18]the physical properties of tight reservoirs were not as

Φ1314 K042mD Φ1336 K039mD

Φ1518 K141mDΦ1520 K186mDΦ1515 K134mD

Φ1348 K040mD

Φ1418 K065mD Φ1434 K061mD Φ1429 K071mD

2309

2321

2371

No 1 well No 2 well No 3 well

Dep

th (m

)

Figure 1 Scanning electron microscope images of tight reservoirs

Table 1 Variation of porosity and permeability of tight reservoirs in the horizontal direction

Depth (m) Horizontal porosityaverage (mD)

Horizontal porosityvariation ()

Horizontal permeabilityaverage (mD)

Horizontal permeabilityvariation ()

2309 1333 252 040 7142321 1427 112 066 14082371 1518 033 154 2796

Table 2 Variation of porosity and permeability of tight reservoirs in the longitudinal direction

Well no Longitudinal porosityaverage ()

Longitudinal porosityvariation ()

Longitudinal permeabilityaverage ()

Longitudinal permeabilityvariation ()

1 1416 1327 080 68662 1430 1211 095 79033 1432 1120 084 7163

Advances in Materials Science and Engineering 3

uniform as those of conventional sandstone reservoirscausing dramatic changes in reservoir pores and uiderefore multiparameter evaluation of tight reservoirswith dierent depths was necessary

32 Longitudinal Multiparameter Comprehensive Evaluationfor Tight Oil Reservoirs Four parameters were selected tocharacterize the longitudinal changes of reservoirs (1)Average throat radius whose distribution presents thechange of reservoir seepage capacity [16] (2) Percentage ofmovable uid whose distribution explains the change ofoccurrence characteristics of the reservoir uid and de-termines the development potential of the reservoirs [21ndash23] e movable uid of the tight reservoir corresponds tothe amount of uid measured by nuclear magnetic reso-nance at a centrifugal force of 417 psi (3) e start-uppressure gradient whose distribution characterizes thediculty degree in establishing an eective displacement

system for the reservoir [24 25] and (4) e content of claymineral whose distribution shows the reservoir damagesuered from water injection [26ndash28] In the reservoirevaluation in dierent blocks some scholars introducedparameters such as brittleness index and pressure coecientHowever for the same reservoir these parameters have littlechange in the longitudinal direction and cannot well reectthe physical properties of the tight reservoir erefore thisstudy did not consider these evaluation parameters

According to the test and analysis results of tightsandstone cores collected from K1q4 of the Songliao Basinthe classication evaluation intervals of each parameterwere divided into four categories as shown in Table 3 econventional reservoir evaluation methods only obtain theevaluation results based on the single parameter ignoringthe comprehensive evaluation and the inuence of variousparameters on the comprehensive evaluation results In thisstudy selecting the appropriate parameters [13] for eval-uation the comprehensive evaluation results were divided

Dep

th (m

)

0 20 40 60 80 10023072308231023112320232023212321232223232359236123622362236223702372238023832384238523862389239123912393

gt1μm01ndash1μm50ndash100nm

25ndash50nmlt25nm

(a)

Dep

th (m

)

0 20 40 60 80 1002322

2321

2311

2311

2311

2307

2311

2362

2402

2395

2395

2389

2357

2370

2385

2383

2394

2384

2311

2390

2389

gt1μm01ndash1μm50ndash100nm

25ndash50nmlt25nm

(b)

Figure 2 Pore distribution characteristics of tight reservoirs at dierent scales (a) Pore distribution at dierent scales (b) Fluid distributionin dierent pore spaces

4 Advances in Materials Science and Engineering

into four categories accordingly and a comprehensiveevaluation grading calculation formula was formed asfollows

D ln αlowastr0rsta 1113857lowast s0ssta 1113857

λ0λsta 1113857lowast m0msta 11138571113888 1113889 (1)

where D was the comprehensive evaluation result r0 wasthe average throat radius μm rsta was the evaluation limitof average throat radius μm s0 was the percentage of themovable fluid ssta was the evaluation limit of thepercentage of the movable fluid λ0 was the start-uppressure gradient MPam λsta was the evaluation limit ofthe start-up pressure gradient MPamm0 was the contentof clay mineral msta was the evaluation limit of thecontent of clay mineral and α was the reservoir in-fluence factor

In order to compare the changes of each parameter in thereservoir the graded evaluation results of each parameterwere normalized as shown in formulas (2) and (3)

When the evaluation parameters were positively cor-related with the comprehensive evaluation results

DN P0

Pmax minusPmin (2)

When the evaluation parameters were negatively cor-related with the comprehensive evaluation results

DN 1minusP0

Pmax minusPmin (3)

where DN was the normalized evaluation result of singleparameter P0 was the single parameter value Pmax was theupper limit of single parameter evaluation and Pmin was thelower limit of single parameter evaluation

+e classification results of the evaluation parameterswere placed in the same coordinate system to analyze thechanges between the parameters +e sampling cores werecollected from the tight sandstone of K1q4 of Jilin Oilfield inSongliao Basin with a depth of 23065ndash23913m andmercury intrusion test nuclear magnetic resonance testpercolation curve test and X-ray diffraction measurementwere carried out +e parameters that vary with reservoirdepth were obtained including the throat radius the per-centage of movable fluid the start-up pressure gradient andthe content of clay mineral Longitudinal subsection pa-rameter evaluation results and comprehensive evaluationresults of tight oil reservoirs were plotted according toformulas (1)ndash(3) as shown in Figure 3

It can be seen from Figure 3 that the throat radiusvalues in the longitudinal direction of the tight reservoir

were mainly categorized into type IV reservoir and thefluctuation range was small indicating that the reservoirwas relatively tight the pore throat was small and theseepage capacity was poor +e percentage values of themovable fluid were mainly categorized into type III typeII and type I reservoirs and the fluctuation range crossesthree intervals indicating that the occurrence differenceof the reservoir fluids was large +e start-up pressuregradient was dominated by type III II and I reservoirsindicating the difficulty degree of reservoir developmentwas relatively higher and attention should be paid towater channeling and gas channeling when replenishingenergy Clay mineral content was mainly dominated bytype III and type II reservoirs and attention should bepaid to reservoir damage during development +erewere five reservoir types (I-IV) in the longitudinalcomprehensive evaluation of the tight reservoir andthe fluctuation range was extremely large In the de-velopment of tight reservoirs a rational plan and thedevelopment modes should be made according to thelongitudinal comprehensive evaluation curve of thereservoir

33 Optimization of Development Modes Adopting Longitu-dinal Evaluation of Tight Oil Reservoirs +e longitudinaldistribution of tight oil reservoirs varies a lot +e re-covery of reservoirs with different evaluation results wasalso quite different using water injection or gas injectionas shown in Figure 4 Figure 4(a) shows the time-dependent recovery curve of four different types of res-ervoirs with water injection +e recovery of the fourtypes of reservoirs increased rapidly in the early stage butremained stable in the later period Type I reached thefinal recovery first and type IV was the slowestFigure 4(b) presents the time-dependent recovery curveof four different types of reservoirs with nitrogen in-jection +e evaluation results showed that the recoverydegree of the reservoirs with better evaluation resultsincreased rapidly in the early stage and then graduallyslowed down after a certain period of development In thelater period of development the recovery degree of poorreservoirs with poorer evaluation results was larger thanthat of the reservoirs with better evaluation results +etype IV reservoir had the highest recovery degree the typeI reservoir had the lowest recovery degree and type II andIII reservoirs were in the middle

It can be seen from Table 4 that the recovery ratios ofthe different types of reservoirs adopting different devel-opment modes vary significantly In the case of all reservoir

Table 3 Longitudinal evaluation interval of tight reservoirs

Classification interval +roat radius (μm) Movable fluidssaturation ()

Starting pressuregradient (MPam) Clay minerals () Comprehensive

evaluationI 06ndash08 60ndash75 0ndash03 0ndash50 gt50II 04ndash06 45ndash60 03ndash06 50ndash100 35ndash50III 02ndash04 30ndash45 06ndash09 100ndash150 15ndash35IV 0ndash02 15ndash30 09ndash12 150ndash200 0ndash15

Advances in Materials Science and Engineering 5

types involved type I reservoir was most suitable for waterinjection development and type IV reservoir was mostsuitable for gas injection development Taking the tight oilreservoir studied in this paper as an example the reservoirswith a depth of 230654ndash236207m were mainly domi-nated by type I and II reservoirs and the reservoirs with adepth of 236207ndash239130m were mainly dominated bytype II and III reservoirs rough comparison of waterinjection in the whole reservoir gas injection in the wholereservoir water injection in the upper reservoir and gasinjection in the lower reservoir and gas injection in theupper reservoir and water injection in the lower reservoirthe nal recovery ratio of the tight oil reservoir under

dierent development modes can be obtained according toformula (4) as shown in Table 5

ER sum4

i1ERi lowast hi (4)

where ER was the recovery of the tight oil reservoir ERiwas the recovery corresponding to type I type II type IIIand type IV reservoirs hi was the eective thicknesscorresponding to type I type II type III and type IV res-ervoirs m

In the case of all reservoir types involved the highestrecovery (7066) can be obtained under the development

00 02 04 06 08 10

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Grading intervals

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(a)

00 10 20 30 40 50 60 70

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Comprehensive evaluation

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(b)

Figure 3 Comprehensive evaluation results and longitudinal grading evaluation results of tight reservoirs

6 Advances in Materials Science and Engineering

mode of water injection in the upper reservoir and gasinjection in the lower reservoir the recovery was 6398using the water injection method and the recovery using thegas injection mode or gas injection in the upper reservoirand water injection in the lower reservoir were both lowerthan those of the previous two modes

4 Conclusions

Microscopic pore structure uid occurrence conditionsstart-up pressure gradient and the content of clay mineralsin the longitudinal direction of tight reservoirs were ana-lyzed in this study Each parameter represented a physicalproperty of the reservoir and these parameters were in-dependent of each other and did not aect each other so theevaluation results obtained in this way were objective elongitudinal evaluation method for tight reservoirs wasproposed and the optimal development mode was selectedaccording to reservoir evaluation results ree innovationsof this study are summarized as follows

(1) e longitudinal variations of the microscopic porestructure were bigger than the horizontal varia-tions e longitudinal variations of porosity and

permeability were 1219 and 7311 respectivelye horizontal variations of porosity and permeabilitywere 132 and 1639 respectively In tight oil res-ervoirs the nanopores dominate and control about60 of the ow space the submicron pores account forabout 30 of the ow space which is the main part inthe development and the micropores were few

(2) Four parameters including average throat radius thepercentage of movable uid start-up pressure gra-dient and the content of clay mineral were applied toevaluate the reservoir Seepage capacity developmentpotential of the reservoirs the diculty degree indevelopment and the reservoir damage suered fromwater injection and the four-parameter evaluationresults were normalized to obtain the inuence degreeof dierent factors on the reservoir physical propertye depth-dependent comprehensive evaluation re-sults and grading evaluation results were plotted

(3) e recovery of tight reservoirs under dierent de-velopment modes was compared According to thelongitudinal comprehensive evaluation curve andthe recovery the most appropriate developmentmethod for each type of reservoir would be chosen Itcan be known that the highest recovery was obtainedwhen the mode of water injection in the upperreservoir and gas injection reservoir was adopted

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conicts of interest

Acknowledgments

We gratefully acknowledge the nancial supports from theNational Science and Technology Major Project (No

Table 4 Recovery of dierent types of reservoirs

Developmentmode

TypeI ()

TypeII ()

TypeIII ()

TypeIV ()

Water injection 6923 5948 5615 5097Gas injection 4543 6717 8072 8616

Table 5 Recovery of reservoirs under dierent developmentmodes

Dierentdevelopmentmode

Waterinjection

Gasinjection

Upperwaterlower

gas

Upper gaslower water

Recovery ratio() 6398 5962 7066 5294

01020304050607080

0 5000 10000 15000 20000 25000 30000

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

(a)

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

0102030405060708090

0 5000 10000 15000 20000 25000 30000

(b)

FIGURE 4 Recovery curve of tight reservoirs with water injectiongas injection (a) Time-dependent recovery curve of tight reservoirs withwater injection (b) Time-dependent recovery curve of tight reservoirs with nitrogen injection

Advances in Materials Science and Engineering 7

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

In order to study the pore distribution of the tight res-ervoir the core samples of Qian262 Well was continuouslycollected formercury intrusion experiments According to themercury intrusion test results the pore distribution curves atdierent scales were plotted as shown in Figure 2(a) and thepore size was divided into ve intervals using nuclear mag-netic and centrifugal methods in the literature [18] Namelythe rst was nanopores with radius less than 25nm whoseuid cannot be developed the second was nanopores withradius of 25ndash50 nm whose uid can be exploited by osmoticand displacement the third was nanopores with radius of50ndash100 nm whose uid can be mined by gas injection thefourth was submicron pores with radius of 01ndash1 μm whoseuid can be developed by a water injection-mixed surfactantand the fth was micropores with radius larger than 1 μmwhose uid can be exploited by water injection As seen fromFigure 2(a) the pore distribution of the tight reservoir variessharply the third type of pores with radius of 50ndash100 nmhas the largest variation with the lowest content of 15 and

the highest content of 446 the content of the rst type ofpores with radius less than 25nm accounts for 20ndash40the reservoir also contains considerable amounts of the fourthtype of pores with radius of 01ndash1 μm and there was anextremely small amount of the fth type of pores with radiuslarger than 1 μm

Nuclear magnetic resonance (NMR) tests were carriedout tomeasure the uid content in dierent sizes of the pores[19 20] e result is shown in Figure 2(b) It was observedthat the dierence in uid distribution in the reservoir wasalso obvious e uid in the nanopores accounts for about60 and it is as high as 90 in some depths In additionabout 10 of the uid exists in the micropores and 30 uidin the submicron pores It can be seen from Figure 2 that itwas dicult to describe accurately the distribution of poresand uids in tight reservoirs by a simple number Since theformation of tight reservoirs mainly depends on self-generation and self-storing or short-term migration [18]the physical properties of tight reservoirs were not as

Φ1314 K042mD Φ1336 K039mD

Φ1518 K141mDΦ1520 K186mDΦ1515 K134mD

Φ1348 K040mD

Φ1418 K065mD Φ1434 K061mD Φ1429 K071mD

2309

2321

2371

No 1 well No 2 well No 3 well

Dep

th (m

)

Figure 1 Scanning electron microscope images of tight reservoirs

Table 1 Variation of porosity and permeability of tight reservoirs in the horizontal direction

Depth (m) Horizontal porosityaverage (mD)

Horizontal porosityvariation ()

Horizontal permeabilityaverage (mD)

Horizontal permeabilityvariation ()

2309 1333 252 040 7142321 1427 112 066 14082371 1518 033 154 2796

Table 2 Variation of porosity and permeability of tight reservoirs in the longitudinal direction

Well no Longitudinal porosityaverage ()

Longitudinal porosityvariation ()

Longitudinal permeabilityaverage ()

Longitudinal permeabilityvariation ()

1 1416 1327 080 68662 1430 1211 095 79033 1432 1120 084 7163

Advances in Materials Science and Engineering 3

uniform as those of conventional sandstone reservoirscausing dramatic changes in reservoir pores and uiderefore multiparameter evaluation of tight reservoirswith dierent depths was necessary

32 Longitudinal Multiparameter Comprehensive Evaluationfor Tight Oil Reservoirs Four parameters were selected tocharacterize the longitudinal changes of reservoirs (1)Average throat radius whose distribution presents thechange of reservoir seepage capacity [16] (2) Percentage ofmovable uid whose distribution explains the change ofoccurrence characteristics of the reservoir uid and de-termines the development potential of the reservoirs [21ndash23] e movable uid of the tight reservoir corresponds tothe amount of uid measured by nuclear magnetic reso-nance at a centrifugal force of 417 psi (3) e start-uppressure gradient whose distribution characterizes thediculty degree in establishing an eective displacement

system for the reservoir [24 25] and (4) e content of claymineral whose distribution shows the reservoir damagesuered from water injection [26ndash28] In the reservoirevaluation in dierent blocks some scholars introducedparameters such as brittleness index and pressure coecientHowever for the same reservoir these parameters have littlechange in the longitudinal direction and cannot well reectthe physical properties of the tight reservoir erefore thisstudy did not consider these evaluation parameters

According to the test and analysis results of tightsandstone cores collected from K1q4 of the Songliao Basinthe classication evaluation intervals of each parameterwere divided into four categories as shown in Table 3 econventional reservoir evaluation methods only obtain theevaluation results based on the single parameter ignoringthe comprehensive evaluation and the inuence of variousparameters on the comprehensive evaluation results In thisstudy selecting the appropriate parameters [13] for eval-uation the comprehensive evaluation results were divided

Dep

th (m

)

0 20 40 60 80 10023072308231023112320232023212321232223232359236123622362236223702372238023832384238523862389239123912393

gt1μm01ndash1μm50ndash100nm

25ndash50nmlt25nm

(a)

Dep

th (m

)

0 20 40 60 80 1002322

2321

2311

2311

2311

2307

2311

2362

2402

2395

2395

2389

2357

2370

2385

2383

2394

2384

2311

2390

2389

gt1μm01ndash1μm50ndash100nm

25ndash50nmlt25nm

(b)

Figure 2 Pore distribution characteristics of tight reservoirs at dierent scales (a) Pore distribution at dierent scales (b) Fluid distributionin dierent pore spaces

4 Advances in Materials Science and Engineering

into four categories accordingly and a comprehensiveevaluation grading calculation formula was formed asfollows

D ln αlowastr0rsta 1113857lowast s0ssta 1113857

λ0λsta 1113857lowast m0msta 11138571113888 1113889 (1)

where D was the comprehensive evaluation result r0 wasthe average throat radius μm rsta was the evaluation limitof average throat radius μm s0 was the percentage of themovable fluid ssta was the evaluation limit of thepercentage of the movable fluid λ0 was the start-uppressure gradient MPam λsta was the evaluation limit ofthe start-up pressure gradient MPamm0 was the contentof clay mineral msta was the evaluation limit of thecontent of clay mineral and α was the reservoir in-fluence factor

In order to compare the changes of each parameter in thereservoir the graded evaluation results of each parameterwere normalized as shown in formulas (2) and (3)

When the evaluation parameters were positively cor-related with the comprehensive evaluation results

DN P0

Pmax minusPmin (2)

When the evaluation parameters were negatively cor-related with the comprehensive evaluation results

DN 1minusP0

Pmax minusPmin (3)

where DN was the normalized evaluation result of singleparameter P0 was the single parameter value Pmax was theupper limit of single parameter evaluation and Pmin was thelower limit of single parameter evaluation

+e classification results of the evaluation parameterswere placed in the same coordinate system to analyze thechanges between the parameters +e sampling cores werecollected from the tight sandstone of K1q4 of Jilin Oilfield inSongliao Basin with a depth of 23065ndash23913m andmercury intrusion test nuclear magnetic resonance testpercolation curve test and X-ray diffraction measurementwere carried out +e parameters that vary with reservoirdepth were obtained including the throat radius the per-centage of movable fluid the start-up pressure gradient andthe content of clay mineral Longitudinal subsection pa-rameter evaluation results and comprehensive evaluationresults of tight oil reservoirs were plotted according toformulas (1)ndash(3) as shown in Figure 3

It can be seen from Figure 3 that the throat radiusvalues in the longitudinal direction of the tight reservoir

were mainly categorized into type IV reservoir and thefluctuation range was small indicating that the reservoirwas relatively tight the pore throat was small and theseepage capacity was poor +e percentage values of themovable fluid were mainly categorized into type III typeII and type I reservoirs and the fluctuation range crossesthree intervals indicating that the occurrence differenceof the reservoir fluids was large +e start-up pressuregradient was dominated by type III II and I reservoirsindicating the difficulty degree of reservoir developmentwas relatively higher and attention should be paid towater channeling and gas channeling when replenishingenergy Clay mineral content was mainly dominated bytype III and type II reservoirs and attention should bepaid to reservoir damage during development +erewere five reservoir types (I-IV) in the longitudinalcomprehensive evaluation of the tight reservoir andthe fluctuation range was extremely large In the de-velopment of tight reservoirs a rational plan and thedevelopment modes should be made according to thelongitudinal comprehensive evaluation curve of thereservoir

33 Optimization of Development Modes Adopting Longitu-dinal Evaluation of Tight Oil Reservoirs +e longitudinaldistribution of tight oil reservoirs varies a lot +e re-covery of reservoirs with different evaluation results wasalso quite different using water injection or gas injectionas shown in Figure 4 Figure 4(a) shows the time-dependent recovery curve of four different types of res-ervoirs with water injection +e recovery of the fourtypes of reservoirs increased rapidly in the early stage butremained stable in the later period Type I reached thefinal recovery first and type IV was the slowestFigure 4(b) presents the time-dependent recovery curveof four different types of reservoirs with nitrogen in-jection +e evaluation results showed that the recoverydegree of the reservoirs with better evaluation resultsincreased rapidly in the early stage and then graduallyslowed down after a certain period of development In thelater period of development the recovery degree of poorreservoirs with poorer evaluation results was larger thanthat of the reservoirs with better evaluation results +etype IV reservoir had the highest recovery degree the typeI reservoir had the lowest recovery degree and type II andIII reservoirs were in the middle

It can be seen from Table 4 that the recovery ratios ofthe different types of reservoirs adopting different devel-opment modes vary significantly In the case of all reservoir

Table 3 Longitudinal evaluation interval of tight reservoirs

Classification interval +roat radius (μm) Movable fluidssaturation ()

Starting pressuregradient (MPam) Clay minerals () Comprehensive

evaluationI 06ndash08 60ndash75 0ndash03 0ndash50 gt50II 04ndash06 45ndash60 03ndash06 50ndash100 35ndash50III 02ndash04 30ndash45 06ndash09 100ndash150 15ndash35IV 0ndash02 15ndash30 09ndash12 150ndash200 0ndash15

Advances in Materials Science and Engineering 5

types involved type I reservoir was most suitable for waterinjection development and type IV reservoir was mostsuitable for gas injection development Taking the tight oilreservoir studied in this paper as an example the reservoirswith a depth of 230654ndash236207m were mainly domi-nated by type I and II reservoirs and the reservoirs with adepth of 236207ndash239130m were mainly dominated bytype II and III reservoirs rough comparison of waterinjection in the whole reservoir gas injection in the wholereservoir water injection in the upper reservoir and gasinjection in the lower reservoir and gas injection in theupper reservoir and water injection in the lower reservoirthe nal recovery ratio of the tight oil reservoir under

dierent development modes can be obtained according toformula (4) as shown in Table 5

ER sum4

i1ERi lowast hi (4)

where ER was the recovery of the tight oil reservoir ERiwas the recovery corresponding to type I type II type IIIand type IV reservoirs hi was the eective thicknesscorresponding to type I type II type III and type IV res-ervoirs m

In the case of all reservoir types involved the highestrecovery (7066) can be obtained under the development

00 02 04 06 08 10

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Grading intervals

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(a)

00 10 20 30 40 50 60 70

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Comprehensive evaluation

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(b)

Figure 3 Comprehensive evaluation results and longitudinal grading evaluation results of tight reservoirs

6 Advances in Materials Science and Engineering

mode of water injection in the upper reservoir and gasinjection in the lower reservoir the recovery was 6398using the water injection method and the recovery using thegas injection mode or gas injection in the upper reservoirand water injection in the lower reservoir were both lowerthan those of the previous two modes

4 Conclusions

Microscopic pore structure uid occurrence conditionsstart-up pressure gradient and the content of clay mineralsin the longitudinal direction of tight reservoirs were ana-lyzed in this study Each parameter represented a physicalproperty of the reservoir and these parameters were in-dependent of each other and did not aect each other so theevaluation results obtained in this way were objective elongitudinal evaluation method for tight reservoirs wasproposed and the optimal development mode was selectedaccording to reservoir evaluation results ree innovationsof this study are summarized as follows

(1) e longitudinal variations of the microscopic porestructure were bigger than the horizontal varia-tions e longitudinal variations of porosity and

permeability were 1219 and 7311 respectivelye horizontal variations of porosity and permeabilitywere 132 and 1639 respectively In tight oil res-ervoirs the nanopores dominate and control about60 of the ow space the submicron pores account forabout 30 of the ow space which is the main part inthe development and the micropores were few

(2) Four parameters including average throat radius thepercentage of movable uid start-up pressure gra-dient and the content of clay mineral were applied toevaluate the reservoir Seepage capacity developmentpotential of the reservoirs the diculty degree indevelopment and the reservoir damage suered fromwater injection and the four-parameter evaluationresults were normalized to obtain the inuence degreeof dierent factors on the reservoir physical propertye depth-dependent comprehensive evaluation re-sults and grading evaluation results were plotted

(3) e recovery of tight reservoirs under dierent de-velopment modes was compared According to thelongitudinal comprehensive evaluation curve andthe recovery the most appropriate developmentmethod for each type of reservoir would be chosen Itcan be known that the highest recovery was obtainedwhen the mode of water injection in the upperreservoir and gas injection reservoir was adopted

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conicts of interest

Acknowledgments

We gratefully acknowledge the nancial supports from theNational Science and Technology Major Project (No

Table 4 Recovery of dierent types of reservoirs

Developmentmode

TypeI ()

TypeII ()

TypeIII ()

TypeIV ()

Water injection 6923 5948 5615 5097Gas injection 4543 6717 8072 8616

Table 5 Recovery of reservoirs under dierent developmentmodes

Dierentdevelopmentmode

Waterinjection

Gasinjection

Upperwaterlower

gas

Upper gaslower water

Recovery ratio() 6398 5962 7066 5294

01020304050607080

0 5000 10000 15000 20000 25000 30000

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

(a)

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

0102030405060708090

0 5000 10000 15000 20000 25000 30000

(b)

FIGURE 4 Recovery curve of tight reservoirs with water injectiongas injection (a) Time-dependent recovery curve of tight reservoirs withwater injection (b) Time-dependent recovery curve of tight reservoirs with nitrogen injection

Advances in Materials Science and Engineering 7

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

uniform as those of conventional sandstone reservoirscausing dramatic changes in reservoir pores and uiderefore multiparameter evaluation of tight reservoirswith dierent depths was necessary

32 Longitudinal Multiparameter Comprehensive Evaluationfor Tight Oil Reservoirs Four parameters were selected tocharacterize the longitudinal changes of reservoirs (1)Average throat radius whose distribution presents thechange of reservoir seepage capacity [16] (2) Percentage ofmovable uid whose distribution explains the change ofoccurrence characteristics of the reservoir uid and de-termines the development potential of the reservoirs [21ndash23] e movable uid of the tight reservoir corresponds tothe amount of uid measured by nuclear magnetic reso-nance at a centrifugal force of 417 psi (3) e start-uppressure gradient whose distribution characterizes thediculty degree in establishing an eective displacement

system for the reservoir [24 25] and (4) e content of claymineral whose distribution shows the reservoir damagesuered from water injection [26ndash28] In the reservoirevaluation in dierent blocks some scholars introducedparameters such as brittleness index and pressure coecientHowever for the same reservoir these parameters have littlechange in the longitudinal direction and cannot well reectthe physical properties of the tight reservoir erefore thisstudy did not consider these evaluation parameters

According to the test and analysis results of tightsandstone cores collected from K1q4 of the Songliao Basinthe classication evaluation intervals of each parameterwere divided into four categories as shown in Table 3 econventional reservoir evaluation methods only obtain theevaluation results based on the single parameter ignoringthe comprehensive evaluation and the inuence of variousparameters on the comprehensive evaluation results In thisstudy selecting the appropriate parameters [13] for eval-uation the comprehensive evaluation results were divided

Dep

th (m

)

0 20 40 60 80 10023072308231023112320232023212321232223232359236123622362236223702372238023832384238523862389239123912393

gt1μm01ndash1μm50ndash100nm

25ndash50nmlt25nm

(a)

Dep

th (m

)

0 20 40 60 80 1002322

2321

2311

2311

2311

2307

2311

2362

2402

2395

2395

2389

2357

2370

2385

2383

2394

2384

2311

2390

2389

gt1μm01ndash1μm50ndash100nm

25ndash50nmlt25nm

(b)

Figure 2 Pore distribution characteristics of tight reservoirs at dierent scales (a) Pore distribution at dierent scales (b) Fluid distributionin dierent pore spaces

4 Advances in Materials Science and Engineering

into four categories accordingly and a comprehensiveevaluation grading calculation formula was formed asfollows

D ln αlowastr0rsta 1113857lowast s0ssta 1113857

λ0λsta 1113857lowast m0msta 11138571113888 1113889 (1)

where D was the comprehensive evaluation result r0 wasthe average throat radius μm rsta was the evaluation limitof average throat radius μm s0 was the percentage of themovable fluid ssta was the evaluation limit of thepercentage of the movable fluid λ0 was the start-uppressure gradient MPam λsta was the evaluation limit ofthe start-up pressure gradient MPamm0 was the contentof clay mineral msta was the evaluation limit of thecontent of clay mineral and α was the reservoir in-fluence factor

In order to compare the changes of each parameter in thereservoir the graded evaluation results of each parameterwere normalized as shown in formulas (2) and (3)

When the evaluation parameters were positively cor-related with the comprehensive evaluation results

DN P0

Pmax minusPmin (2)

When the evaluation parameters were negatively cor-related with the comprehensive evaluation results

DN 1minusP0

Pmax minusPmin (3)

where DN was the normalized evaluation result of singleparameter P0 was the single parameter value Pmax was theupper limit of single parameter evaluation and Pmin was thelower limit of single parameter evaluation

+e classification results of the evaluation parameterswere placed in the same coordinate system to analyze thechanges between the parameters +e sampling cores werecollected from the tight sandstone of K1q4 of Jilin Oilfield inSongliao Basin with a depth of 23065ndash23913m andmercury intrusion test nuclear magnetic resonance testpercolation curve test and X-ray diffraction measurementwere carried out +e parameters that vary with reservoirdepth were obtained including the throat radius the per-centage of movable fluid the start-up pressure gradient andthe content of clay mineral Longitudinal subsection pa-rameter evaluation results and comprehensive evaluationresults of tight oil reservoirs were plotted according toformulas (1)ndash(3) as shown in Figure 3

It can be seen from Figure 3 that the throat radiusvalues in the longitudinal direction of the tight reservoir

were mainly categorized into type IV reservoir and thefluctuation range was small indicating that the reservoirwas relatively tight the pore throat was small and theseepage capacity was poor +e percentage values of themovable fluid were mainly categorized into type III typeII and type I reservoirs and the fluctuation range crossesthree intervals indicating that the occurrence differenceof the reservoir fluids was large +e start-up pressuregradient was dominated by type III II and I reservoirsindicating the difficulty degree of reservoir developmentwas relatively higher and attention should be paid towater channeling and gas channeling when replenishingenergy Clay mineral content was mainly dominated bytype III and type II reservoirs and attention should bepaid to reservoir damage during development +erewere five reservoir types (I-IV) in the longitudinalcomprehensive evaluation of the tight reservoir andthe fluctuation range was extremely large In the de-velopment of tight reservoirs a rational plan and thedevelopment modes should be made according to thelongitudinal comprehensive evaluation curve of thereservoir

33 Optimization of Development Modes Adopting Longitu-dinal Evaluation of Tight Oil Reservoirs +e longitudinaldistribution of tight oil reservoirs varies a lot +e re-covery of reservoirs with different evaluation results wasalso quite different using water injection or gas injectionas shown in Figure 4 Figure 4(a) shows the time-dependent recovery curve of four different types of res-ervoirs with water injection +e recovery of the fourtypes of reservoirs increased rapidly in the early stage butremained stable in the later period Type I reached thefinal recovery first and type IV was the slowestFigure 4(b) presents the time-dependent recovery curveof four different types of reservoirs with nitrogen in-jection +e evaluation results showed that the recoverydegree of the reservoirs with better evaluation resultsincreased rapidly in the early stage and then graduallyslowed down after a certain period of development In thelater period of development the recovery degree of poorreservoirs with poorer evaluation results was larger thanthat of the reservoirs with better evaluation results +etype IV reservoir had the highest recovery degree the typeI reservoir had the lowest recovery degree and type II andIII reservoirs were in the middle

It can be seen from Table 4 that the recovery ratios ofthe different types of reservoirs adopting different devel-opment modes vary significantly In the case of all reservoir

Table 3 Longitudinal evaluation interval of tight reservoirs

Classification interval +roat radius (μm) Movable fluidssaturation ()

Starting pressuregradient (MPam) Clay minerals () Comprehensive

evaluationI 06ndash08 60ndash75 0ndash03 0ndash50 gt50II 04ndash06 45ndash60 03ndash06 50ndash100 35ndash50III 02ndash04 30ndash45 06ndash09 100ndash150 15ndash35IV 0ndash02 15ndash30 09ndash12 150ndash200 0ndash15

Advances in Materials Science and Engineering 5

types involved type I reservoir was most suitable for waterinjection development and type IV reservoir was mostsuitable for gas injection development Taking the tight oilreservoir studied in this paper as an example the reservoirswith a depth of 230654ndash236207m were mainly domi-nated by type I and II reservoirs and the reservoirs with adepth of 236207ndash239130m were mainly dominated bytype II and III reservoirs rough comparison of waterinjection in the whole reservoir gas injection in the wholereservoir water injection in the upper reservoir and gasinjection in the lower reservoir and gas injection in theupper reservoir and water injection in the lower reservoirthe nal recovery ratio of the tight oil reservoir under

dierent development modes can be obtained according toformula (4) as shown in Table 5

ER sum4

i1ERi lowast hi (4)

where ER was the recovery of the tight oil reservoir ERiwas the recovery corresponding to type I type II type IIIand type IV reservoirs hi was the eective thicknesscorresponding to type I type II type III and type IV res-ervoirs m

In the case of all reservoir types involved the highestrecovery (7066) can be obtained under the development

00 02 04 06 08 10

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Grading intervals

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(a)

00 10 20 30 40 50 60 70

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Comprehensive evaluation

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(b)

Figure 3 Comprehensive evaluation results and longitudinal grading evaluation results of tight reservoirs

6 Advances in Materials Science and Engineering

mode of water injection in the upper reservoir and gasinjection in the lower reservoir the recovery was 6398using the water injection method and the recovery using thegas injection mode or gas injection in the upper reservoirand water injection in the lower reservoir were both lowerthan those of the previous two modes

4 Conclusions

Microscopic pore structure uid occurrence conditionsstart-up pressure gradient and the content of clay mineralsin the longitudinal direction of tight reservoirs were ana-lyzed in this study Each parameter represented a physicalproperty of the reservoir and these parameters were in-dependent of each other and did not aect each other so theevaluation results obtained in this way were objective elongitudinal evaluation method for tight reservoirs wasproposed and the optimal development mode was selectedaccording to reservoir evaluation results ree innovationsof this study are summarized as follows

(1) e longitudinal variations of the microscopic porestructure were bigger than the horizontal varia-tions e longitudinal variations of porosity and

permeability were 1219 and 7311 respectivelye horizontal variations of porosity and permeabilitywere 132 and 1639 respectively In tight oil res-ervoirs the nanopores dominate and control about60 of the ow space the submicron pores account forabout 30 of the ow space which is the main part inthe development and the micropores were few

(2) Four parameters including average throat radius thepercentage of movable uid start-up pressure gra-dient and the content of clay mineral were applied toevaluate the reservoir Seepage capacity developmentpotential of the reservoirs the diculty degree indevelopment and the reservoir damage suered fromwater injection and the four-parameter evaluationresults were normalized to obtain the inuence degreeof dierent factors on the reservoir physical propertye depth-dependent comprehensive evaluation re-sults and grading evaluation results were plotted

(3) e recovery of tight reservoirs under dierent de-velopment modes was compared According to thelongitudinal comprehensive evaluation curve andthe recovery the most appropriate developmentmethod for each type of reservoir would be chosen Itcan be known that the highest recovery was obtainedwhen the mode of water injection in the upperreservoir and gas injection reservoir was adopted

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conicts of interest

Acknowledgments

We gratefully acknowledge the nancial supports from theNational Science and Technology Major Project (No

Table 4 Recovery of dierent types of reservoirs

Developmentmode

TypeI ()

TypeII ()

TypeIII ()

TypeIV ()

Water injection 6923 5948 5615 5097Gas injection 4543 6717 8072 8616

Table 5 Recovery of reservoirs under dierent developmentmodes

Dierentdevelopmentmode

Waterinjection

Gasinjection

Upperwaterlower

gas

Upper gaslower water

Recovery ratio() 6398 5962 7066 5294

01020304050607080

0 5000 10000 15000 20000 25000 30000

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

(a)

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

0102030405060708090

0 5000 10000 15000 20000 25000 30000

(b)

FIGURE 4 Recovery curve of tight reservoirs with water injectiongas injection (a) Time-dependent recovery curve of tight reservoirs withwater injection (b) Time-dependent recovery curve of tight reservoirs with nitrogen injection

Advances in Materials Science and Engineering 7

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

into four categories accordingly and a comprehensiveevaluation grading calculation formula was formed asfollows

D ln αlowastr0rsta 1113857lowast s0ssta 1113857

λ0λsta 1113857lowast m0msta 11138571113888 1113889 (1)

where D was the comprehensive evaluation result r0 wasthe average throat radius μm rsta was the evaluation limitof average throat radius μm s0 was the percentage of themovable fluid ssta was the evaluation limit of thepercentage of the movable fluid λ0 was the start-uppressure gradient MPam λsta was the evaluation limit ofthe start-up pressure gradient MPamm0 was the contentof clay mineral msta was the evaluation limit of thecontent of clay mineral and α was the reservoir in-fluence factor

In order to compare the changes of each parameter in thereservoir the graded evaluation results of each parameterwere normalized as shown in formulas (2) and (3)

When the evaluation parameters were positively cor-related with the comprehensive evaluation results

DN P0

Pmax minusPmin (2)

When the evaluation parameters were negatively cor-related with the comprehensive evaluation results

DN 1minusP0

Pmax minusPmin (3)

where DN was the normalized evaluation result of singleparameter P0 was the single parameter value Pmax was theupper limit of single parameter evaluation and Pmin was thelower limit of single parameter evaluation

+e classification results of the evaluation parameterswere placed in the same coordinate system to analyze thechanges between the parameters +e sampling cores werecollected from the tight sandstone of K1q4 of Jilin Oilfield inSongliao Basin with a depth of 23065ndash23913m andmercury intrusion test nuclear magnetic resonance testpercolation curve test and X-ray diffraction measurementwere carried out +e parameters that vary with reservoirdepth were obtained including the throat radius the per-centage of movable fluid the start-up pressure gradient andthe content of clay mineral Longitudinal subsection pa-rameter evaluation results and comprehensive evaluationresults of tight oil reservoirs were plotted according toformulas (1)ndash(3) as shown in Figure 3

It can be seen from Figure 3 that the throat radiusvalues in the longitudinal direction of the tight reservoir

were mainly categorized into type IV reservoir and thefluctuation range was small indicating that the reservoirwas relatively tight the pore throat was small and theseepage capacity was poor +e percentage values of themovable fluid were mainly categorized into type III typeII and type I reservoirs and the fluctuation range crossesthree intervals indicating that the occurrence differenceof the reservoir fluids was large +e start-up pressuregradient was dominated by type III II and I reservoirsindicating the difficulty degree of reservoir developmentwas relatively higher and attention should be paid towater channeling and gas channeling when replenishingenergy Clay mineral content was mainly dominated bytype III and type II reservoirs and attention should bepaid to reservoir damage during development +erewere five reservoir types (I-IV) in the longitudinalcomprehensive evaluation of the tight reservoir andthe fluctuation range was extremely large In the de-velopment of tight reservoirs a rational plan and thedevelopment modes should be made according to thelongitudinal comprehensive evaluation curve of thereservoir

33 Optimization of Development Modes Adopting Longitu-dinal Evaluation of Tight Oil Reservoirs +e longitudinaldistribution of tight oil reservoirs varies a lot +e re-covery of reservoirs with different evaluation results wasalso quite different using water injection or gas injectionas shown in Figure 4 Figure 4(a) shows the time-dependent recovery curve of four different types of res-ervoirs with water injection +e recovery of the fourtypes of reservoirs increased rapidly in the early stage butremained stable in the later period Type I reached thefinal recovery first and type IV was the slowestFigure 4(b) presents the time-dependent recovery curveof four different types of reservoirs with nitrogen in-jection +e evaluation results showed that the recoverydegree of the reservoirs with better evaluation resultsincreased rapidly in the early stage and then graduallyslowed down after a certain period of development In thelater period of development the recovery degree of poorreservoirs with poorer evaluation results was larger thanthat of the reservoirs with better evaluation results +etype IV reservoir had the highest recovery degree the typeI reservoir had the lowest recovery degree and type II andIII reservoirs were in the middle

It can be seen from Table 4 that the recovery ratios ofthe different types of reservoirs adopting different devel-opment modes vary significantly In the case of all reservoir

Table 3 Longitudinal evaluation interval of tight reservoirs

Classification interval +roat radius (μm) Movable fluidssaturation ()

Starting pressuregradient (MPam) Clay minerals () Comprehensive

evaluationI 06ndash08 60ndash75 0ndash03 0ndash50 gt50II 04ndash06 45ndash60 03ndash06 50ndash100 35ndash50III 02ndash04 30ndash45 06ndash09 100ndash150 15ndash35IV 0ndash02 15ndash30 09ndash12 150ndash200 0ndash15

Advances in Materials Science and Engineering 5

types involved type I reservoir was most suitable for waterinjection development and type IV reservoir was mostsuitable for gas injection development Taking the tight oilreservoir studied in this paper as an example the reservoirswith a depth of 230654ndash236207m were mainly domi-nated by type I and II reservoirs and the reservoirs with adepth of 236207ndash239130m were mainly dominated bytype II and III reservoirs rough comparison of waterinjection in the whole reservoir gas injection in the wholereservoir water injection in the upper reservoir and gasinjection in the lower reservoir and gas injection in theupper reservoir and water injection in the lower reservoirthe nal recovery ratio of the tight oil reservoir under

dierent development modes can be obtained according toformula (4) as shown in Table 5

ER sum4

i1ERi lowast hi (4)

where ER was the recovery of the tight oil reservoir ERiwas the recovery corresponding to type I type II type IIIand type IV reservoirs hi was the eective thicknesscorresponding to type I type II type III and type IV res-ervoirs m

In the case of all reservoir types involved the highestrecovery (7066) can be obtained under the development

00 02 04 06 08 10

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Grading intervals

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(a)

00 10 20 30 40 50 60 70

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Comprehensive evaluation

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(b)

Figure 3 Comprehensive evaluation results and longitudinal grading evaluation results of tight reservoirs

6 Advances in Materials Science and Engineering

mode of water injection in the upper reservoir and gasinjection in the lower reservoir the recovery was 6398using the water injection method and the recovery using thegas injection mode or gas injection in the upper reservoirand water injection in the lower reservoir were both lowerthan those of the previous two modes

4 Conclusions

Microscopic pore structure uid occurrence conditionsstart-up pressure gradient and the content of clay mineralsin the longitudinal direction of tight reservoirs were ana-lyzed in this study Each parameter represented a physicalproperty of the reservoir and these parameters were in-dependent of each other and did not aect each other so theevaluation results obtained in this way were objective elongitudinal evaluation method for tight reservoirs wasproposed and the optimal development mode was selectedaccording to reservoir evaluation results ree innovationsof this study are summarized as follows

(1) e longitudinal variations of the microscopic porestructure were bigger than the horizontal varia-tions e longitudinal variations of porosity and

permeability were 1219 and 7311 respectivelye horizontal variations of porosity and permeabilitywere 132 and 1639 respectively In tight oil res-ervoirs the nanopores dominate and control about60 of the ow space the submicron pores account forabout 30 of the ow space which is the main part inthe development and the micropores were few

(2) Four parameters including average throat radius thepercentage of movable uid start-up pressure gra-dient and the content of clay mineral were applied toevaluate the reservoir Seepage capacity developmentpotential of the reservoirs the diculty degree indevelopment and the reservoir damage suered fromwater injection and the four-parameter evaluationresults were normalized to obtain the inuence degreeof dierent factors on the reservoir physical propertye depth-dependent comprehensive evaluation re-sults and grading evaluation results were plotted

(3) e recovery of tight reservoirs under dierent de-velopment modes was compared According to thelongitudinal comprehensive evaluation curve andthe recovery the most appropriate developmentmethod for each type of reservoir would be chosen Itcan be known that the highest recovery was obtainedwhen the mode of water injection in the upperreservoir and gas injection reservoir was adopted

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conicts of interest

Acknowledgments

We gratefully acknowledge the nancial supports from theNational Science and Technology Major Project (No

Table 4 Recovery of dierent types of reservoirs

Developmentmode

TypeI ()

TypeII ()

TypeIII ()

TypeIV ()

Water injection 6923 5948 5615 5097Gas injection 4543 6717 8072 8616

Table 5 Recovery of reservoirs under dierent developmentmodes

Dierentdevelopmentmode

Waterinjection

Gasinjection

Upperwaterlower

gas

Upper gaslower water

Recovery ratio() 6398 5962 7066 5294

01020304050607080

0 5000 10000 15000 20000 25000 30000

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

(a)

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

0102030405060708090

0 5000 10000 15000 20000 25000 30000

(b)

FIGURE 4 Recovery curve of tight reservoirs with water injectiongas injection (a) Time-dependent recovery curve of tight reservoirs withwater injection (b) Time-dependent recovery curve of tight reservoirs with nitrogen injection

Advances in Materials Science and Engineering 7

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

types involved type I reservoir was most suitable for waterinjection development and type IV reservoir was mostsuitable for gas injection development Taking the tight oilreservoir studied in this paper as an example the reservoirswith a depth of 230654ndash236207m were mainly domi-nated by type I and II reservoirs and the reservoirs with adepth of 236207ndash239130m were mainly dominated bytype II and III reservoirs rough comparison of waterinjection in the whole reservoir gas injection in the wholereservoir water injection in the upper reservoir and gasinjection in the lower reservoir and gas injection in theupper reservoir and water injection in the lower reservoirthe nal recovery ratio of the tight oil reservoir under

dierent development modes can be obtained according toformula (4) as shown in Table 5

ER sum4

i1ERi lowast hi (4)

where ER was the recovery of the tight oil reservoir ERiwas the recovery corresponding to type I type II type IIIand type IV reservoirs hi was the eective thicknesscorresponding to type I type II type III and type IV res-ervoirs m

In the case of all reservoir types involved the highestrecovery (7066) can be obtained under the development

00 02 04 06 08 10

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Grading intervals

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(a)

00 10 20 30 40 50 60 70

23065

23082

23096

23111

23199

23203

23207

23211

23217

23226

23593

23606

23617

23621

23623

23701

23719

23798

23830

23843

23847

23856

23889

23907

23913

Dep

th (m

)

Comprehensive evaluation

Throat radius Movable fluid saturation Starting pressure gradientClay mineralsComprehensive evaluation

IV III II I

(b)

Figure 3 Comprehensive evaluation results and longitudinal grading evaluation results of tight reservoirs

6 Advances in Materials Science and Engineering

mode of water injection in the upper reservoir and gasinjection in the lower reservoir the recovery was 6398using the water injection method and the recovery using thegas injection mode or gas injection in the upper reservoirand water injection in the lower reservoir were both lowerthan those of the previous two modes

4 Conclusions

Microscopic pore structure uid occurrence conditionsstart-up pressure gradient and the content of clay mineralsin the longitudinal direction of tight reservoirs were ana-lyzed in this study Each parameter represented a physicalproperty of the reservoir and these parameters were in-dependent of each other and did not aect each other so theevaluation results obtained in this way were objective elongitudinal evaluation method for tight reservoirs wasproposed and the optimal development mode was selectedaccording to reservoir evaluation results ree innovationsof this study are summarized as follows

(1) e longitudinal variations of the microscopic porestructure were bigger than the horizontal varia-tions e longitudinal variations of porosity and

permeability were 1219 and 7311 respectivelye horizontal variations of porosity and permeabilitywere 132 and 1639 respectively In tight oil res-ervoirs the nanopores dominate and control about60 of the ow space the submicron pores account forabout 30 of the ow space which is the main part inthe development and the micropores were few

(2) Four parameters including average throat radius thepercentage of movable uid start-up pressure gra-dient and the content of clay mineral were applied toevaluate the reservoir Seepage capacity developmentpotential of the reservoirs the diculty degree indevelopment and the reservoir damage suered fromwater injection and the four-parameter evaluationresults were normalized to obtain the inuence degreeof dierent factors on the reservoir physical propertye depth-dependent comprehensive evaluation re-sults and grading evaluation results were plotted

(3) e recovery of tight reservoirs under dierent de-velopment modes was compared According to thelongitudinal comprehensive evaluation curve andthe recovery the most appropriate developmentmethod for each type of reservoir would be chosen Itcan be known that the highest recovery was obtainedwhen the mode of water injection in the upperreservoir and gas injection reservoir was adopted

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conicts of interest

Acknowledgments

We gratefully acknowledge the nancial supports from theNational Science and Technology Major Project (No

Table 4 Recovery of dierent types of reservoirs

Developmentmode

TypeI ()

TypeII ()

TypeIII ()

TypeIV ()

Water injection 6923 5948 5615 5097Gas injection 4543 6717 8072 8616

Table 5 Recovery of reservoirs under dierent developmentmodes

Dierentdevelopmentmode

Waterinjection

Gasinjection

Upperwaterlower

gas

Upper gaslower water

Recovery ratio() 6398 5962 7066 5294

01020304050607080

0 5000 10000 15000 20000 25000 30000

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

(a)

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

0102030405060708090

0 5000 10000 15000 20000 25000 30000

(b)

FIGURE 4 Recovery curve of tight reservoirs with water injectiongas injection (a) Time-dependent recovery curve of tight reservoirs withwater injection (b) Time-dependent recovery curve of tight reservoirs with nitrogen injection

Advances in Materials Science and Engineering 7

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

mode of water injection in the upper reservoir and gasinjection in the lower reservoir the recovery was 6398using the water injection method and the recovery using thegas injection mode or gas injection in the upper reservoirand water injection in the lower reservoir were both lowerthan those of the previous two modes

4 Conclusions

Microscopic pore structure uid occurrence conditionsstart-up pressure gradient and the content of clay mineralsin the longitudinal direction of tight reservoirs were ana-lyzed in this study Each parameter represented a physicalproperty of the reservoir and these parameters were in-dependent of each other and did not aect each other so theevaluation results obtained in this way were objective elongitudinal evaluation method for tight reservoirs wasproposed and the optimal development mode was selectedaccording to reservoir evaluation results ree innovationsof this study are summarized as follows

(1) e longitudinal variations of the microscopic porestructure were bigger than the horizontal varia-tions e longitudinal variations of porosity and

permeability were 1219 and 7311 respectivelye horizontal variations of porosity and permeabilitywere 132 and 1639 respectively In tight oil res-ervoirs the nanopores dominate and control about60 of the ow space the submicron pores account forabout 30 of the ow space which is the main part inthe development and the micropores were few

(2) Four parameters including average throat radius thepercentage of movable uid start-up pressure gra-dient and the content of clay mineral were applied toevaluate the reservoir Seepage capacity developmentpotential of the reservoirs the diculty degree indevelopment and the reservoir damage suered fromwater injection and the four-parameter evaluationresults were normalized to obtain the inuence degreeof dierent factors on the reservoir physical propertye depth-dependent comprehensive evaluation re-sults and grading evaluation results were plotted

(3) e recovery of tight reservoirs under dierent de-velopment modes was compared According to thelongitudinal comprehensive evaluation curve andthe recovery the most appropriate developmentmethod for each type of reservoir would be chosen Itcan be known that the highest recovery was obtainedwhen the mode of water injection in the upperreservoir and gas injection reservoir was adopted

Data Availability

e data used to support the ndings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conicts of interest

Acknowledgments

We gratefully acknowledge the nancial supports from theNational Science and Technology Major Project (No

Table 4 Recovery of dierent types of reservoirs

Developmentmode

TypeI ()

TypeII ()

TypeIII ()

TypeIV ()

Water injection 6923 5948 5615 5097Gas injection 4543 6717 8072 8616

Table 5 Recovery of reservoirs under dierent developmentmodes

Dierentdevelopmentmode

Waterinjection

Gasinjection

Upperwaterlower

gas

Upper gaslower water

Recovery ratio() 6398 5962 7066 5294

01020304050607080

0 5000 10000 15000 20000 25000 30000

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

(a)

Reco

very

ratio

()

Time (s)

Type I reservoirType II reservoir

Type III reservoirType IVreservoir

0102030405060708090

0 5000 10000 15000 20000 25000 30000

(b)

FIGURE 4 Recovery curve of tight reservoirs with water injectiongas injection (a) Time-dependent recovery curve of tight reservoirs withwater injection (b) Time-dependent recovery curve of tight reservoirs with nitrogen injection

Advances in Materials Science and Engineering 7

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

2016ZX05048-001) the National Science and TechnologyMajor Project (No 2017ZX05069-003) and the NationalNatural Science Foundation of China (grant 51604053)

References

[1] S Y Hu R K Zhu S TWu et al ldquoProfitable exploration anddevelopment of continental tight oil in Chinardquo PetroleumExploration and Development vol 45 no 4 pp 737ndash7482018

[2] S J Wang R J Wei Q L Guo et al ldquoNew advance inresource evaluation of tight oilrdquo Acta Petrolei Sinica vol 35no 6 pp 1095ndash1105 2014

[3] J H Du H Q He J Z Li et al ldquoProgress in Chinarsquos tight oilexploration and challengesrdquo China Petroleum Explorationvol 19 no 1 pp 1ndash9 2014

[4] G G Wu H Fang Z Han et al ldquoGrowth features ofmeasured oil initially in place amp gas initially in place duringthe 12th five-year plan and its outlook for the 13th five-yearplan in Chinardquo Acta Petrolei Sinica vol 37 no 9pp 1145ndash1151 2016

[5] Y T Luo Z M Yang Y He et al ldquo+e research of lithologycharacteristics and effective development in tight oil reser-voirrdquo Unconventional Oil and Gas vol 1 no 1 pp 47ndash542014

[6] H Cander What are Unconventional Resources AAPG An-nual Convention and Exhibition Long Beach CA USA 2012

[7] Z M Yang Y Z Zhang M Q Hao et al ldquoComprehensiveevaluation of reservoir in low permeability oilfieldsrdquo ActaPetrolei Sinica vol 27 no 2 pp 64ndash67 2006

[8] Z H Zhang Z M Yang X G Liu et al ldquoA grading eval-uation method for low-permeability reservoirs and its ap-plicationrdquo Acta Petrolei Sinica vol 33 no 3 pp 437ndash4412012

[9] Q H Xiao Be Reservoir Evaluation and Porous FlowMechanism for Typical Tight Oil Fields Institute of PorousFlow and Fluid Mechanics University of Chinese Academy ofSciences Langfang China 2015

[10] C Z Jia C N Zou J Z Li et al ldquoAssessment criteria maintypes basic features and resource prospects of the tight oil inChinardquo Acta Petrolei Sinica vol 33 no 3 pp 343ndash350 2012

[11] C N Zou R K Zhu S T Wu et al ldquoType characteristicsgenesis and prospects of conventional and unconventionalhydrocarbon accumulations taking tight oil and tight gas inChina as an instancerdquo Acta Petrolei Sinica vol 33 no 2pp 173ndash187 2012

[12] Z Yang L H Hou S Z Tao et al ldquoFormation conditions andldquosweet spotrdquoevaluation of tight oil and shale oilrdquo PetroleumExploration and Development vol 42 no 5 pp 555ndash5652015

[13] B Jia J S Tsau and R Barati ldquoA review of the currentprogress of CO2 injection EOR and carbon storage in shale oilreservoirsrdquo Fuel vol 236 pp 404ndash427 2019

[14] W R Purcell ldquoCapillary pressuresmdashtheir measurement usingmercury and the calculation of permeability therefromrdquoJournal of Petroleum Technology vol 1 no 2 pp 39ndash48 2013

[15] B F Swanson and B F Swanson ldquoA simple correlationbetween permeabilities and mercury capillary pressuresrdquoJournal of Petroleum Technology vol 33 no 12 pp 2498ndash2504 2013

[16] A Hakami A Al-Mubarak K Al-Ramadan C Kurison andI Leyva ldquoCharacterization of carbonate mudrocks of thejurassic tuwaiq mountain formation jafurah basin Saudiarabia implications for unconventional reservoir potential

evaluationrdquo Journal of Natural Gas Science and Engineeringvol 33 pp 1149ndash1168 2016

[17] B Jia J S Tsau and R Barati ldquoDifferent flow behaviors oflow-pressure and high-pressure carbon dioxide in shalesrdquoSPE Journal vol 23 no 4 pp 1452ndash1468 2018

[18] Z M Yang R Z Yu Z X Su et al ldquoNumerical simulation ofthe nonlinear flow in ultra-low permeability reservoirsrdquo Pe-troleum Exploration and Development vol 37 no 1pp 94ndash98 2010

[19] D P LiBe Development of the Low Permeability SandstoneOil Field Petroleum Industry Press Beijing China 1997

[20] Z M Yang Y T Luo Y He et al ldquoStudy on occurrencefeature of fluid and effective development in tight sandstoneoil reservoirrdquo Journal of Southwest Petroleum University(Science amp Technology Edition) vol 37 no 3 pp 85ndash92 2015

[21] W M Wang H K Guo and Z H Ye ldquo+e Evaluation ofdevelopment potential in low permeability oilfield by the aidof NMR movable fluid detecting technologyrdquo Acta PetroleiSinica vol 22 no 6 pp 40ndash44 2001

[22] D O Seevers ldquoA nuelear magnetic method for determiningthe permeability of sandstonesrdquo in Proceedings of AnnualLogging SymPosium Transaetions Soeiety of Professional WellLog Analysts Tulsa OK USA May 1966

[23] R J S Brown and I Fatt ldquoMeasurement of fraetional wet-tability of oil fieldsrsquo rocks by the nuclear magnetic relaxationmethodrdquo in Proceedings of Fall Meeting of the PetroleumBranch of AIME SPE-743-G Soeiety of Petroleum EngineersLos Angeles CA USA October 1956

[24] Y Shi Z M Yang and Y Z Huang ldquoStudy on non-linearseepage flow model for low-permeability reservoirrdquo ActaPetrolei Sinica vol 30 no 5 pp 731ndash734 2009

[25] C Dabbouk A Liaqat G Williams and G Beattie ldquoWa-terflood in vuggy layer of a middle east reservoir-displacementphysics understoodrdquo in Proceedings of Abu Dhabi In-ternational Petroleum Exhibition and Conference Abu DhabiUAE October 2002

[26] S B Peng X Yin J C Zhang et al ldquoEvolutionary pattern ofclay mineral and rock sensitivity in water-flooding reservoirrdquoActa Petrolei Sinica vol 27 no 4 pp 71ndash75 2006

[27] Y T Luo and Z Yang ldquoAdvantageous reservoir character-ization technology in extra low permeability oil reservoirsrdquoJournal of Engineering vol 2017 Article ID 6705263 9 pages2017

[28] H Karimaie and O Torsaeligter ldquoEffect of injection rate initialwater saturation and gravity on water injection in slightlywater-wet fractured porous mediardquo Journal of PetroleumScience and Engineering vol 58 no 1-2 pp 293ndash308 2007

8 Advances in Materials Science and Engineering

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Analytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Advances in Condensed Matter Physics

Hindawiwwwhindawicom Volume 2018

International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Hindawiwwwhindawicom Volume 2018

High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

ChemistryAdvances in

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom Volume 2018

BioMed Research InternationalMaterials

Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom