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Research ArticleGenetic Types and Source of the Upper Paleozoic Tight Gas inthe Hangjinqi Area Northern Ordos Basin China

Xiaoqi Wu1 Chunhua Ni1 Quanyou Liu23 Guangxiang Liu1

Jianhui Zhu1 and Yingbin Chen1

1Wuxi Research Institute of Petroleum Geology Petroleum Exploration and Production Research Institute SINOPEC WuxiJiangsu 214126 China2State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development Beijing 100083 China3Petroleum Exploration and Production Research Institute SINOPEC Beijing 100083 China

Correspondence should be addressed to Quanyou Liu qyouliusohucom

Received 21 December 2016 Accepted 24 April 2017 Published 29 May 2017

Academic Editor Xiaorong Luo

Copyright copy 2017 Xiaoqi Wu et al This 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

The molecular and stable isotopic compositions of the Upper Paleozoic tight gas in the Hangjinqi area in northern Ordos Basinwere investigated to study the geochemical characteristics The tight gas is mainly wet with the dryness coefficient (C1C1ndash5) of0853ndash0951 and 12057513C1 and 120575

2H-C1 values are ranging from minus362permil to minus320permil and from minus199permil to minus174permil respectively withgenerally positive carbon and hydrogen isotopic series Identification of gas origin indicates that tight gas is mainly coal-typegas and it has been affected by mixing of oil-type gas in the wells from the Shilijiahan and Gongkahan zones adjacent to theWulanjilinmiao and Borjianghaizi faults Gas-source correlation indicates that coal-type gas in the Shiguhao zone displays distal-source accumulation It was mainly derived from the coal-measure source rocks in the Upper Carboniferous Taiyuan Formation(C3t) and Lower Permian Shanxi Formation (P1s) probablywith aminor contribution fromP1s coalmeasures from in situ Shiguhaozone Natural gas in the Shilijiahan and Gongkahan zones mainly displays near-source accumulationThe coal-type gas componentwas derived from in situ C3t-P1s source rocks whereas the oil-type gas component might be derived from the carbonate rocks inthe Lower Ordovician Majiagou Formation (O1m)

1 Introduction

Geochemical characteristics of natural gas are fundamentalto the study on the origin migration accumulation andalteration of natural gas and have played an important rolein revealing the organic type thermal evolution degreeand sedimentary environment of source rocks of naturalgas [1ndash8] The studies on the origin and source of naturalgas especially unconventional gas in China have achievedsignificant progress in recent years [9ndash15] Tight gas hasmadethemost contribution to the rapid increase of unconventionalgas output and reserves in China and the reserves and annualproduction of tight gas in China at the end of 2010 accountedfor 392 and 246 of the total natural gas respectively[16] Therefore tight gas has been considered in priority inthe exploration and exploitation of unconventional gas in

China [16] There were 16 tight gas fields in the 48 large gasfields discovered in China by the end of 2011 suggesting thecrucial importance of this type of reservoirs in ChinaThe gasproduction of these 16 large tight gas fields in 2011 was 26799times 109m3 accounting for 261 of the total gas production inChina [17]

The Ordos Basin a petroliferous basin located in cen-tral China is the most productive basin with the highestannual gas output in China [18] The exploration targetsfor natural gas in the Ordos Basin mainly consist of theUpper Paleozoic Carboniferous-Permian tight sandstoneand the Lower Paleozoic Ordovician carbonate reservoirsSeveral giant Upper Paleozoic tight gas fields with provenreserves over 100 times 109m3 have been discovered in theCarboniferous-Permian tight sandstone for example Sulige

HindawiGeofluidsVolume 2017 Article ID 4596273 14 pageshttpsdoiorg10115520174596273

2 Geofluids

Yulin Daniudi Wushenqi and Zizhou The Upper Paleozoicnatural gas is commonly considered as coal-type gas fromthe Carboniferous-Permian coal-measure source rocks [19ndash26] However the Lower Paleozoic natural gas was generallybelieved to be mixed by both coal-type gas from the UpperPaleozoic coal measures and oil-type gas from the marinesource rocks [27ndash29]

The Hangjinqi area is located in northern Ordos Basinand the gas exploration has achieved continuous break-throughs in recent years Natural gas is mainly enrichedin the Upper Paleozoic tight sandstone reservoirs with fewdiscoveries in the Mesoproterozoic strata such as wells J3and J13 [30] The geological reserves of tight gas in theHangjinqi area are higher than 700 times 109m3 and theUpper Paleozoic tight gas reservoirs are characterized by thelithological traps large gas-bearing area and low abundanceof reserves [31] Previous studies have been conducted onthe Mesozoic tectonic evolution [32] segmentation of thefaults [33] geochemical characteristics of the source rocks[34 35] and the origin of natural gas [36] Moreover Haoet al [31] demonstrated the forming conditions of the gasreservoirs and Wang et al [37] proposed the accumulatingmechanism of natural gas based on the analysis of trapconditions However there is no consensus on the sourceand accumulating pattern of natural gas Although the UpperPaleozoic tight gas in the Hangjinqi area was commonlybelieved to be sourced from the Carboniferous-Permian coalmeasures it is still controversial whether the gas was derivedfrom the source rocks in in situ Hangjinqi area [34 35] or theWushenqi area in central Ordos Basin [37] Wang et al [37]proposed that advantageous sandbody unconformity faultsand fissures constituted favorable migration pathways for thenorthwardmigration natural gas Nevertheless Xue et al [34]considered that the strata in the Ordos Basin were gentlewith a low dip angle and the conditions for large-scale lateralmigration were undeveloped in consideration of the UpperPaleozoic tight sandstone reservoirs Hao et al [31] and Chenet al [36] demonstrated that the Upper Paleozoic natural gasto the south and north of the Sanyanjing-Wulanjilinmiao-Borjianghaizi fault zones displayed near-source and distal-source accumulation respectively However Xue et al [34]proposed that the Upper Paleozoic natural gas in theHangjinqi area displayed near-source accumulation and wasderived from in situ Upper Paleozoic coal-measure sourcerocks

The above controversy is mainly derived from the dif-ferent understandings on the geological conditions of tightgas in the Hangjinqi area and geochemical characteristicsof tight gas in the area have been weakly studied with afew confusions Chen et al [36] demonstrated that naturalgas in the Shiguhao zone in northern Hangjinqi area waspartially derived from source rocks in the Shilijiahan areato the south of the Borjianghaizi fault and the gas hadbeen affected by compositional geochromatographic effectand carbon isotopic fractionation However natural gas inthe Shiguhao zone displayed obviously higher 12057513C1 valuesand C1C1ndash5 ratios than those in the Shilijiahan zone [36]suggesting higher maturity rather than the migration effect

The generation and alteration processes of natural gas can berevealed by the study of genetic and postgenetic molecularand isotopic fractionations based on the gas geochemicalcharacteristics [2 38] Therefore the authors intend to docu-ment the geochemical characteristics of the Upper Paleozoictight gas based on the analyses of molecular and stableisotopic compositions in this study We further demonstratethe origin source and possible postgenetic processes oftight gas in comparison with the Lower Paleozoic gas in theJingbian gas field This would provide valuable informationfor the accumulation and resource evaluation of natural gasin the Ordos Basin

2 Geological Setting

The Ordos Basin is a multicycle cratonic basin with stablesubsidence and located at the western margin of the NorthChina Block covering an area of 37 times 104 km2 [44] Based onthe basement property and the present tectonic morphologyand characteristics the Ordos Basin can be divided into 6tectonic units (Figure 1) that is YimengUpliftWeibei UpliftJinxi Fault-fold Belt Yishan Slope TianhuanDepression andWest MarginThrust Belt [24 45]

The Hangjinqi area is located tectonically in the YimengUplift and northern Yishan Slope covering an area of9825 km2 It can be subdivided into 5 secondary struc-tural units according to the fluctuation characteristics andstructural configuration of the top surface of the basementthat is Wulangeer uplift Gongkahan uplift Hangjinqi faultterrace northern Yishan Slope and the northeastern cornerof the Tianhuan Depression (Figure 1) Three main faultsare distributed in the Hangjinqi area from west to east inwhich the Sanyanjing and Wulanjilinmiao faults are south-dipping normal faults whereas the Borjianghaizi fault isnorth-dipping thrust fault (Figure 1) Seven gas zones thatis Haoraozhao Shiguhao Shilijiahan Azhen GongkahanWulanjilinmiao and Xinzhao are classified according tothe fault distribution (Figure 1) The Hangjinqi area wastopographically a long-term inherited paleohigh in northernOrdos Basin and was considered as the favorable orientedregion for oil and gasmigration [46] Gas reservoirs are foundmainly in the Shiguhao and Shilijiahan zones

The Upper Paleozoic strata in the Hangjinqi area uncon-formably overlie the Lower Ordovician Majiagou Formation(O1m) or Meso-Neoproterozoic strata (Pt2-Pt3) and theyconsist upward of the Upper Carboniferous Taiyuan Fm(C3t) Lower Permian Shanxi Fm (P1s) and Lower Shi-hezi Fm (P1x) as well as Upper Permian Upper ShiheziFm (P2sh) and Shiqianfeng Fm (P2s) (Figure 2) Naturalgas is mainly reservoired in the P1x tight sandstone withonly a few discoveries in the P1s and C3t sandstones andthese sandstone reservoirs are generally characterized bylow porosity and permeability [37] The P2sh and P2s strataare mainly composed of thick-layer lacustrine mudstoneinterbedded with sandstone and the mudstone is widelyand stably distributed with the thickness of 130mndash160mconstituting the regional caprock for the underlying P1x andP1s tight gas reservoirs [31] Moreover natural gas has also

Geofluids 3

OrdosChina

N

Yishan Slope

Yimeng Upli

Tian

huan

Dep

ress

ion

Wes

t Mar

gin

ru

st Be

lt

Jinxi

Fau

lt-fo

ld B

elt

Weibei Upli

Wuqi

EtuokeqiSulige

Jingbian

Yinchuan

Qingyang

Tongchuan

Yanrsquoan

Lishi

0 8040

Basin

Hangjinqi areaFigure 1(b)

Wushenqi

Beijing

(km)

(a)

J55

Wuqi

Fault

Boundary of rst-order tectonic units

Work area

City

Gas well

Upper Paleozoic gas reservoir

Boundary of secondary tectonic units

Lower Paleozoic gas reservoir

Boundary of gas zone

15

0 2010 30 40 N

J101J110

J58P13HJ98

J111 J99

J55 J77

J66P9H

J66P8HJPH-13

J26J11YS1

J66P5H

J66J3

J13

J58 J56

J6J54

Y19

J34

J43

J14

J39

J10

JP1

fault

Xinzhao zone

Gongkahan zone

Haoraozhao zone

Azhen zone

Shilijiahan zone

Wulanjilinmiao zone

zone

ShiguhaoHangjinqi

Yijinhuoluoqi

Shiguhao

Xinzhao

Wujiamiaosag

Gongkahanupli

Tian

huan

Depr

essio

n

Yishan

Slope

Wulangeer upli

Hangjinqifau

ltterr

ace

Sanyanjing fault

Wulanjilinmiao

Borjianghaizifault 11

1315

19A

07

09

(km)

17

Isoline of Ro () for P1s source rocks

A㰀

(b)

Figure 1 (a) Locationmap of theHangjinqi area and the distribution of tectonic units in the Ordos Basin (b) distributionmap of the tectonicunits gas zones and gas wells in the Hangjinqi area The isolines of 119877o () are modified after Ji et al [35]

been discovered in the Mesoproterozoic strata (Pt2) in only afew wells with low gas production [30]

The C3t and P1s coal measures are the main UpperPaleozoic source rocks and composed of coal seam and darkmudstone with the average TOC contents of 5692 and301 respectively [31] The thickness of the C3t-P1s sourcerocks decreases gradually from southeast to northwest andthe P1s source rocks are distributed all over the Hangjinqiarea however the C3t source rocks display the largestthickness of 20m to the south of the Borjianghaizi fault andare generally undeveloped to the north of the fault [47] TheC3t-P1s coal-measure source rocks in the Hangjinqi area aremainly gas-prone with kerogen type III and the thermalmaturity increases from north to south and is mainly inthe range of 08ndash17 and the vitrinite reflectance (119877o)values are generally higher and lower than 11 to the southand north of the Borjianghaizi fault (Figure 1) respectively[34 35] The gas generation intensity of the C3t-P1s coal-measure source rocks is mainly (15ndash30) times 108m3km2 to thesouth of the Sanyanjing-Wulanjilinmiao-Borjianghaizi faultsand is 0ndash10 times 108m3km2 in the Shiguhao zone to the northof the Borjianghaizi fault [31] The gas generation intensity is(5ndash10) times 108m3km2 on the north side near the Sanyanjing-Wulanjilinmiao faults however theUpper Paleozoic strata faraway from and to the north of the fault zones have little gasgeneration capacity as a result of the undevelopment of thesource rocks [31]

3 Analytical Methods

16 gas samples from the Upper Paleozoic (P1s-P1x) tightsandstone reservoirs in theHangjinqi area in northernOrdosBasin were collected from the wellheads after first flushingthe lines for 15ndash20min to remove air contamination and1 gas sample from the Mesoproterozoic stratum was alsocollected for comparative analysis The gas samples werecollected using 5 cm radius stainless steel cylinders withdouble valves and analyzed at Wuxi Research Institute ofPetroleum Geology Petroleum Exploration and ProductionResearch Institute (PEPRIS) of SINOPEC

The chemical composition of gas samples was determinedusing an Agilent 7890A gas chromatograph (GC) equippedwith a flame ionization detector and a thermal conductivitydetector Individual alkane gas components were separatedusing a capillary column (PLOT Al2O3 50m times 053mm)The GC oven temperature was initially set at 40∘C for 5minheating at a rate of 10∘Cmin to a final temperature of 180∘Cwhich was held for 20min

Stable carbon isotopic composition of the natural gaswas measured on a Finnigan MAT-253 mass spectrometerThe alkane gas components were initially separated usinga fused silica capillary column (PLOT Q 30m times 032mm)with helium carrier gas The oven temperature was rampedfrom 40 to 180∘C at a heating rate of 10∘Cmin and thefinal temperature was held for 10min Each gas sample wasmeasured in triplicate Stable carbon isotopic values are

4 Geofluids

Perm

ian

Lithologyickness (m)Strata Lithological description Gas

zone

Coarse sandstone

Medium sandstone

Fine sandstone

Dolomite

Coal bed

Gas zone

Mudstone

Limestone

0~325 ick-layer brown mudstone interbedded with thin-layer ne sandstone with medium-ne sandstone at the bottomP2sh

60~130

Grey greenish mudstone interbedded with thin-layer medium-ne sandstone at the upper and middle section thick-layer grey coarse sandstone interbedded with dark grey mudstone at the lower section

P1x

43~72Dark mudstone interbedded with thin-layer ne sandstone at the upper section dark mudstone interbedded with coal seam at the lower section

P1s

Carboniferous 0~50Dark mudstone interbedded with coal seam at the upper section dark mudstone interbedded with medium-ne sandstone at the middle-lower section

C3t

Ordovician Limestone interbedded with dolomite

UpperShihezi

LowerShihezi

Shanxi

Taiyuan

Majiagou 0~30O1m

Meso-NeoproterozoicFine sandstone interbedded with thin-layer grey

greenish mudstone10~20Pt2-Pt3

Figure 2 Stratigraphic column of the Hangjinqi area in the Ordos Basin

reported in the 120575 notation in permil (permil) relative to VPDBand the measurement precision is estimated to be plusmn05permil for12057513C

Stable hydrogen isotopic composition of alkane gases wasmeasured on a Thermo Scientific Delta V Advantage massspectrometer (GCTCIRMS) The alkane gas componentswere separated on a HP-PLOT Q column (30m times 032mmtimes 20120583m) with helium carrier gas at 15mlminThe GC ovenwas initially held at 30∘C for 5min and then programmedto 80∘C at 8∘Cmin and then heated to 260∘C at 4∘Cminwhere it was held for 10min Each gas sample was measuredin triplicate and the results were averaged The measurementprecision is estimated to be plusmn3permil for 1205752H with respect toVSMOW

4 Results

Themolecular and stable isotopic compositions of the UpperPaleozoic tight gas from the Hangjinqi area are listed inTable 1

41 Chemical Composition of Natural Gas The P1s-P1x tightgas in the Hangjinqi area in northern Ordos Basin is domi-nated by methane with CH4 and C2ndash5 contents in the rangesof 8348ndash9372 and 481ndash1449 respectively The gas isgenerally wet with dryness coefficient (C1C1ndash5) in the rangeof 0853ndash0951 which is mainly lower than 095 (Table 1) andCH4 content is positively correlated with the C1C1ndash5 ratio(Figure 3(a))The Pt2 gas sample fromWell J101 displays CH4

Geofluids 5

Table1Molecular

andsta

bleisotopicc

ompo

sitions

ofnaturalgas

from

theH

angjinqi

area

intheO

rdos

Basin

Gas

zone

Gas

well

Strata

Chem

icalcompo

sition(

)C 1

C1ndash512057513C(permil

VPD

B)1205752H(permil

VSM

OW)119877o(

)A119877o(

)BCH4

C 2H6

C 3H8119894C4H10119899C 4

H10119894C5H12119899C 5

H12

N2

CO2

12057513C 112057513C 212057513C 31205752H-C11205752H-C21205752H-C3

Shiguh

ao

J11P 1x

9347

362

084

012

018

005

005

136

030

0950minus322minus249minus245minus174minus153minus139

143

050

J26

P 1x

9366

359

081

011

019

006

005

116

035


148

052

J66P

5HP 1x

9322

433

094

011

021

005

007

084

021


128

045

J66P

8HP 1x

8435

832

328

068

112

056

053

025

000


132

046

J66P

9HP 1x

8704

779

250

045

072

034

030

039

000


141

049

JPH-13

P 1x

8728

736

252

043

070

034

031

027

000

0882minus327minus266minus230minus191minus148

13

2046

YS1

P 1x

9004

649

192

031

050

026

022

024

000


132

046

J66

P 1x

8827

728

236

041

061

027

022

018

000


138

048

Shilijiahan

J77

P 1x

8947

618

203

033

048

016

01

077

045


095

033

J55

P 1s

8348

714

186

018

038

008

007

676

003

0896minus362minus248minus264

074

026

J111

P 1x

9088

547

157

029

046

027

023

042

000


138

048

J58P

13H

P 1x

9372

377

105

022

033

017

014

046

000


13

0045

J98

P 1x

9267

463

118

024

035

021

017

016

000


130

045

J58

P 1x

9002

531

152

035

053

025

022

110

000


13

4047

J99

P 1x

9097

569

152

032

048

030

026

035

000


130

045

Gon

gkahan

J110

P 1x

8734

679

271

066

086

041

032

019

000


138

048

J101

Pt2

8275

502

270

046

084

028

028

710

000

0896minus345minus301minus311minus173

098

034

Note119877

o(

)(AB

)valuesw

erec

alculatedaccordingto

the12057513C 1

-119877oem

piric

alequatio

nsforc

oal-typeg

asprop

osed

byDaiandQi[48]a

ndStahl[49]respectiv

elyldquordquoindicatesn

odata

6 Geofluids

CH4 ()95908580

085

090

095

100

C1C

1minus5

P1x ShiguhaoP1x + P1s Shilijiahan

P1x GongkahanPt2 Gongkahan

(a)

085

090

095

100

C1C

1minus5

minus36 minus34 minus32 minus30minus38

훿13C1 (permil)



(b)

Figure 3 Correlation diagrams of dryness coefficient (C1C1ndash5) versus CH4 (a) and C1C1ndash5 ratio versus 12057513C1 value (b) of tight gas fromthe Hangjinqi area in the Ordos Basin

content of 8275 which is lower than the P1s-P1x tight gasand it is also wet gas with C1C1ndash5 ratio of 0896 (Table 1Figure 3(a))

The P1s-P1x tight gas in the Hangjinqi area containsfew amount of CO2 with the content of 0ndash045 and thenonhydrocarbon component is mainly N2 with the contentmainly in the range of 016ndash136 (Table 1) Only onesample (J55) has N2 content of 676 which is similar tothe Pt2 gas sample from Well J101 (Table 1) This might becaused by the application of the technology of nitrogen gas-lift recovery which would not affect the carbon and hydrogenisotopic compositions of alkane gas Therefore the carbonand hydrogen isotopic compositions of the gas samples couldbe used to identify the gas origin

42 Carbon Isotopic Composition 12057513C1 value of the alkanesin the P1s-P1x tight gas in the Hangjinqi area is from minus362permilto minus320permil and it is uncorrelated with the dryness coefficient(C1C1ndash5) (Table 1 Figure 3(b)) The P1s-P1x alkane gasdisplays variable C1C1ndash5 ratio and nearly constant 12057513C1value (from minus329permil to minus320permil) except two gas samples (J55J77) (Table 1 Figure 3(b)) 12057513C1 value of the Pt2 gas samplefrom Well J101 is minus345permil which is slightly lower than themain value of the P1s-P1x gas (Table 1 Figure 3(b))12057513C2 and 120575

13C3 values of the P1s-P1x alkane gas arefrom minus289permil to minus245permil and from minus266permil to minus195permilrespectively whereas those of the Pt2 gas sample are minus300permiland minus311permil respectively (Table 1 Figure 4) The P1s-P1xalkane gas generally displays positive carbon isotopic series(12057513C1 lt 120575

13C2 lt 12057513C3) with only two gas samples (J55 J77)

displaying partial reversal between C2H6 and C3H8 carbonisotopes (12057513C2 gt 120575

13C3) which are consistent with the Pt2gas sample fromWell J101 (Figure 4)

1Cn

13 12 1



minus40

minus35

minus30

minus25

minus20

minus15

훿13C

(permil)

Figure 4 Carbon isotopic series of alkane gas in the Hangjinqi areain the Ordos Basin

43 Hydrogen Isotopic Composition 1205752H-C1 value of the P1s-P1x alkane gas in the Hangjinqi area is from minus199permil tominus174permil whereas that of the Pt2 gas sample from Well J101 isminus173permil and it is slightly higher than that of the P1s-P1x gas(Table 1 Figure 5) 1205752H-C2 and 120575

2H-C3 values of the P1s-P1xalkane gas are from minus171permil to minus129permil and from minus176permil tominus100permil respectively The alkane gas generally displays posi-tive hydrogen isotopic series (1205752H-C1 lt 120575

2H-C2 lt 1205752H-C3)

with only one gas sample (J77) being partially reversedbetween C2H6 and C3H8 hydrogen isotopes (120575

2H-C2 gt 1205752H-

C3) (Table 1 Figure 5)

Geofluids 7

1Cn

13 12 1

P1x ShiguhaoP1x + P1s ShilijiahanP1x Gongkahan

minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)

Figure 5 Hydrogen isotopic series of alkane gas from theHangjinqiarea in the Ordos Basin

5 Discussion

51 Origin of Tight Gas The Upper Paleozoic (P1s-P1x)alkane gas in the Hangjinqi area in northern Ordos Basinmainly displays positive carbon and hydrogen isotopic series(Figures 4 and 5) with 12057513C1 value higher than minus30permil(Figure 3(b)) suggesting the typically biogenic gas ratherthan the abiogenic one [50] The biogenic gas can be dividedinto bacterial gas and thermogenic gas in which the bacterialgas is dominated by CH4 and extremely dry with C1C1ndash5ratio higher than 099 and 12057513C1 value lower than minus55permilwhereas thermogenic gas generally displays 12057513C1 valuehigher than minus50permil [4 50] The P1s-P1x and Pt2 gases in theHangjinqi area display 12057513C1 value and dryness coefficientranging from minus362permil to minus320permil and from 0853 to 0951respectively (Figure 3(b)) They are significantly differentfrom the bacterial gas and they follow the maturity trendrather than the biodegradation trend in correlation diagrambetween C2C3 and C2iC4 (Figure 6)

The P1s-P1x and Pt2 gases in the Hangjinqi area displaytypical characteristics of thermogenic gas in the modifiedBernard diagram (Figure 7) Thermogenic gas can be gen-erally divided into coal-type gas from humic organic matterand oil-type gas from sapropelic organic matter [3 50] TheUpper Paleozoic tight gas in the Hangjinqi area follows thetrend of natural gas from type III kerogen suggesting theorigin of coal-type gas (Figure 7) However the O1m gas inthe Jingbian gas field lies in the mixing or transitional zonebetween gases from types II and III kerogens which mayindicate the trend of mixing between oil-type and coal-typegases (Figure 7) The P1s-P1x tight gas in the Hangjinqi areamainly displays a wide range of C1C2+3 ratio (727ndash2130)with nearly constant 12057513C1 value (from minus329permil to minus320permil)indicating certain migration trend (Figure 7)

Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3

Figure 6 Correlation diagram between C2C3 and C2iC4 valuesof tight gas from the Hangjinqi area (modified after Prinzhofer andBattani [39])

Migration

MigrationOxidationermogenic

Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity


Pt2 GongkahanO1m Jingbian

C1C

2+3

100

101

102

103

훿13C1 (permil)

minus20minus30minus40minus50minus60

Figure 7ModifiedBernard diagramof tight gas from theHangjinqiarea (modified after Bernard et al [40]) Data of the O1m gas in theJingbian gas fields are from Dai [18]

Since coal-type gas sourced from humic organic matterhas relatively higher 12057513C2 value than oil-type gas from sapro-pelic organic matter with similar 12057513C1 value they followdifferent evolution trends in correlation diagram between12057513C1 and 120575

13C2 values [3] The P1s-P1x gas in the Hangjinqiarea generally follows the trends of gases derived from typeIII kerogen in the Niger Delta [3] and Sacramento Bain [41]indicating the genetic type of coal-type gas (Figure 8(a))Several P1x gas samples are distributed in the transitionalzone between gases from types II and III kerogens andthey display the characteristics of gas mixed by oil-type and

8 Geofluids

Type III Niger Delta(Rooney et al 1995)

Type III Sacramento Basin(Jenden et al 1988)

Type II DelwareVal VerdeBasin (Rooney et al 1995)


훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33

minus30 minus28 minus26 minus24 minus22minus32

훿13C2 (permil)



(b)

Figure 8 Cross-plots of 12057513C2 versus 12057513C1 (a) and 120575

13C3 versus 12057513C2 (b) of tight gas from the Hangjinqi areaThe trend lines for gases from

kerogen type III of Niger Delta and kerogen type II of DelawareVal Verde Basin are from Rooney et al [3] and the trend lines for gas fromkerogen type III of Sacramento Basin are from Jenden et al [41] 12057513C2 and 120575

13C3 ranges for coal-type and oil-type gases in (b) are from Dai[42] Data of the O1m gas in the Jingbian gas fields are from Dai [18]

coal-type gases which are similar to the O1m gas in theJingbian gas field (Figure 8(a)) The Pt2 gas sample from theGongkahan zone follows the trend of gas derived from type IIkerogen in the DelawareVal Verde Basin [3] indicating thecharacteristics of oil-type gas (Figure 8(a))

The carbon isotopes of ethane and propane generallyinherited those of original organic matter and were effectiveindexes to identify the coal-type and oil-type gases [50]Empirical observations indicated that 12057513C2 and 120575

13C3 valuesof coal-type gas were generally higher than minus275permil andminus255permil respectively whereas those of oil-type gas werelower than minus290permil and minus270permil respectively [42] The Pt2gas in the Gongkahan zone displays the characteristics of oil-type gas with low 12057513C2 and 120575

13C3 values (Figure 8(b)) TheP1s-P1x tight gas in the Hangjinqi area mainly displays thecharacteristics of coal-type gas with several P1x gas samplesfrom the Shilijiahan and Gongkahan zones displaying thetrend of mixing with oil-type gas and the proportion of oil-type gas seems generally lower than that in the O1m gas inthe Jingbian gas field (Figure 8(b))

The hydrogen isotopic composition of natural gas iscontrolled by the type of organic matter thermal maturityand the environmental condition of the aqueous mediumand has been effectively used to identify the gas origin [150ndash52] The coal-type and oil-type gases display differentdistribution trends in correlation diagrams of both 1205752H-C1 versus 120575

13C1 and 1205752H-C1 versus 120575

13C2 [13] The P1s-P1x gas in the Hangjinqi area displays the characteristicsof gases from humic organic matter and generally followsthe maturity trend in correlation diagram of 1205752H-C1 versus12057513C1 (Figure 9(a)) suggesting the genetic type of coal-type

gas The O1m gas in the Jingbian gas field also displays thecharacteristics of gases from humic organic matter whichindicates that the gas is dominated by coal-type gas andthis is consistent with the conclusions of previous studies[19 53] The Pt2 gas from the Gongkahan zone is plotted inthe mixing or transitional zone and it is adjacent to the zoneof humic gases in correlation diagramof 1205752H-C1 versus 120575

13C1(Figure 9(a)) which indicates that the Pt2 gas is dominated bycoal-type gas and has been mixed by a small amount of oil-type gas

In correlation diagram of 1205752H-C1 versus 12057513C2 (Fig-

ure 9(b)) the P1x tight gas from the Shiguhao zone mainlydisplays the characteristics of coal-type gas whereas the P1s-P1x gas in the Shilijiahan and Gongkahan zones generallyfollows the trend of mixing with oil-type gas although it isadjacent to the range of coal-type gas The O1m gas in theJingbian gas field also displays themixing trend (Figure 9(b))which is consistent with previous studies [28 54] Howeverit is generally closer to the range of oil-type gas than the P1s-P1x tight gas in the Shilijiahan and Gongkahan zones andthis indicates that the proportion of oil-type gas in the O1mgas in the Jingbian gas field is probably higher (Figure 9(b))

Therefore the Upper Paleozoic tight gas in the Hangjinqiarea in northern Ordos Basin is mainly composed of coal-type gas 12057513C2 and 120575

13C3 values indicate that tight gas in theShilijiahan and Gongkahan zones has been generally mixedby oil-type gas and it displays similar characteristics withthe Pt2 gas from the Gongkahan zone and the O1m gas inthe Jingbian gas field The proportion of oil-type gas in theUpper Paleozoic gas in the Shilijiahan and Gongkahan zonesis slightly lower than that in the O1m gas in the Jingbian gasfield

Geofluids 9

Gases from sapropelic

Gases from humicorganic matter

organic matter

Maturity

Maturity

Mixing ortransitional

minus25minus35 minus30minus40minus45

훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)

Gases fromhumic organic

matter

Gases from sapropelicorganic matter

Mixing withoil-type gases

Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)

minus25 minus20minus30minus35

훿13C2 (permil)



minus40

(b)

Figure 9 Correlation diagrams of 1205752H-C1 versus 12057513C1 (a) and 120575

2H-C1 versus 12057513C2 (b) of tight gas from the Hangjinqi area (modified after

Wang et al [13]) Data of the O1m gas in the Jingbian gas fields are from Dai [18]

52 Source of Tight Gas TheUpper Paleozoic coal-type gas inthe Ordos Basin has been commonly accepted to be derivedfrom the C3t-P1s coal-measure source rocks [19ndash26] Only aset of humic source rocks that is the C3t-P1s coal measuresis developed in the Hangjinqi area in northern Ordos BasinIt is believed to be the source of the Upper Paleozoic coal-type gas in this area However it is controversial whether thegas was generated from in situ source rocks in the Hangjinqiarea [34 35] or had been contributed by source rocks in theWushenqi area in centralOrdosBasin [37] Since theC3t coal-measure source rocks are undeveloped to the north of theBorjianghaizi fault [47] there is no consensus on whetherthe C3t-P1s coal measures to the south of the fault havecontributed to the P1s-P1x tight gas in the Shiguhao zone tothe north of the Borjianghaizi fault [31 34ndash36]

The C3t-P1s coal-measure source rocks in the Hangjinqiarea are gas-prone with kerogen type III however thedevelopment of the C3t-P1s source rocks to the south andnorth of the Borjianghaizi fault is significantly different Onlythe P1s coal-measure source rocks are generally developed inthe Shiguhao zone to the north of the Borjianghaizi fault withthe thickness and119877o value generally lower than 30m and 11(Figure 1) respectively and the cumulative gas generationintensity is in the range of 0ndash10 times 108m3km2 [31 35]However both the C3t and P1s source rocks are developedin the Shilijiahan zone to the south of the Borjianghaizifault with the thickness and 119877o value generally higher than30m and 11 (Figure 1) respectively The cumulative gasgeneration intensity is mainly in the range of (15ndash30) times108m3km2 [31 35] The exploration in recent years indicatesthat the gas production and reserves in the Shiguhao zone tothe north of the Borjianghaizi fault with relatively poor sourcecondition are commonly higher than those in the Shilijiahan

zone to the south of the fault with favorable source conditionrespectively [31]

Thermal maturity of the source rocks could be indicatedby 12057513C1 value of the natural gas and the comparisonbetween the measured 119877o values of source rocks and thecalculated 119877o values based on 12057513C1 values provides animportant approach for gas-source correlationThe 12057513C1-119877oempirical equation for coal-type gas proposed by Stahl [49]was based on the coal gas from the NWGermany and it wassuitable for the instantaneous gas generation in high-maturestage [55 56] The 12057513C1-119877o empirical equation for coal-typegas proposed by Dai andQi [48] was based on the statistics ofcoal-type gases from main Chinese petroliferous basins andhas been widely and effectively applied in China and it wasappropriate for the continuous and cumulative gas generation[55 56]

The burial history in the Hangjinqi area indicated thatthe P1s coal-measure source rocks in the Shiguhao zone hadjust entered the threshold of the hydrocarbon generationand had been uplifted in the Late Jurassic and they hadbeen continuously buried and gradually entered the maturestage in the Early Cretaceous (Figure 10(a)) The C3t-P1scoal-measure source rocks in the Shilijiahan zone had beencontinuously buried from the deposition to the end of theEarly Cretaceous and continuously generated hydrocarbonsfrom the Early Jurassic to the Early Cretaceous (Figure 10(b))Both the Shiguhao and Shilijiahan zones have been upliftedsince the Late Cretaceous with the stagnation of the hydro-carbon generation of the source rocks (Figure 10) Thereforethe hydrocarbon generation history of the C3t-P1s coal-measure source rocks in the Hangjinqi area is similar to thecumulative model proposed by Dai and Qi [48] rather thanthe instantaneous model in high-mature stage proposed by

10 Geofluids

StrataO1 C P T J K1 K2-QK-Q

JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)

Figure 10 Burial and thermal evolution histories of the major stratigraphic intervals at the locations of Well JP1 in the Shiguhao gas zone (a)and Well J10 in the Shilijiahan gas zone (b) in the Hangjinqi area (modified after Hao et al [31])

Stahl [49] The calculation results indicate that the calculated119877o value according to Stahlrsquos equation is generally lowerthan 05 (Table 1) which is significantly different from themain measured 119877o value of 08ndash17 of the source rockstherefore Stahlrsquos equation is unsuitable for tight gas in theHangjinqi area

The calculated 119877o values of natural gas from the Shilijia-han and Gongkahan zones based on the 12057513C1-119877o empiricalequation for coal-type gas proposed by Dai and Qi [48]are in the ranges of 074ndash138 and 098ndash138 withthe average values of 119 and 118 respectively (Table 1)These calculated 119877o values are mainly higher than 11 andconsistent with the measured 119877o values of the C3t-P1s sourcerocks to the south of the Borjianghaizi fault (Figure 1) whichindicates that the coal-type gas from the Shilijiahan andGongkahan zones is mainly derived from in situ C3t-P1ssource rocks The calculated 119877o value of natural gas fromthe Shiguhao zone based on the 12057513C1-119877o empirical equationfor coal-type gas proposed by Dai and Qi [48] is in therange of 128ndash148 with an average of 137 which issignificantly higher than the measured 119877o value (lt11) of insitu P1s source rocks (Figure 1) This indicates that the UpperPaleozoic tight gas in the Shiguhao zone was mainly derivedfrom the coal-measure source rocks with highmaturity to thesouth of the Borjianghaizi fault rather than in situ P1s sourcerocks

Although the source rocks in theWushenqi area had beenconsidered to contribute to the natural gas in the Hangjinqi

area [37] the measured 119877o value of the C3t-P1s source rocksin the Wushenqi area is generally in the range of 16ndash18[19] It is obviously higher than both the measured 119877o valueof the source rocks (Figure 1) and the calculated 119877o valueof natural gas in the Hangjinqi area Since the strata in theOrdos Basin are generally flat with a low dip angle andthe Upper Paleozoic reservoirs are mainly tight sandstonewith low porosity and permeability the conditions for large-scale lateral migration were undeveloped [25 34] Thereforenatural gas generated by the coal-measure source rocks inthe Wushenqi area seems unlikely to migrate laterally to theWushenqi area by a long distance of nearly one hundredkilometers Moreover the Upper Paleozoic tight gas in theHangjinqi area is generally wet with the average C1C1ndash5 ratioand 12057513C1 value of 0910 and minus329permil respectively (Table 1Figure 3(b)) However the Upper Paleozoic tight gas in theWushenqi area is mainly dry with the average C1C1ndash5 ratioand 12057513C1 value of 0952 andminus327permil respectively [18] whichare both slightly higher indicating the maturity differencerather than the migration fractionation [38]Therefore thereis little contribution from the source rocks in the Wushenqiarea in central Ordos Basin to the Upper Paleozoic tight gasin the Hangjinqi area in northern Ordos Basin

The calculated 119877o value of coal-type gas from theShiguhao zone based on the 12057513C1-119877o empirical equation forcoal-type gas proposed by Dai and Qi [48] is in the range of128ndash148 It is consistent with the thermal maturity of theC3t-P1s coal measures (Figure 1) in the northern margin of

Geofluids 11

the Yishan Slope to the south of the Borjianghaizi such as theShilijiahan zoneTherefore the coal-type gas in the Shiguhaozone was mainly derived from the C3t-P1s coal measures tothe south of the Borjianghaizi zone such as the Shilijiahanzone with probably a small amount of contribution by in situP1s coal measures in the Shiguhao zone

Although several tight gas samples (J58 J58P13H J98 J99and J111) from the Shilijiahan zone are mainly coal-type gasthey display significant mixing by oil-type gas as indicatedby low 12057513C2 value (minus287permilsimminus263permil) (Figures 8(a) and9(b)) The P1x (J110) and Pt2 (J101) tight gas samples fromthe Gongkahan zone also display similar characteristics with12057513C2 values of minus289permil and minus301permil respectively These gassamples were all collected from the wells located adjacent tothe Wulanjilinmiao and Borjianghaizi faults Those tight gassamples collected from the wells (J55 J77) in the Shilijiahanzone away from the faults are typically coal-type gas withrelatively higher 12057513C2 values (minus248permil minus247permil) and theyhave not been mixed by the oil-type gas (Figures 8(a) and9(b))

The Paleozoic oil-type gas is mainly distributed in theO1m carbonate reservoirs and it is believed to be derivedfrom the O1m carbonate rocks [27 29 57] or C3t limestone[19 20 58] The C3t limestone is mainly distributed incentral Ordos Basin such as the Jingbian area and has beenconsidered to contribute to the Lower Paleozoic gas in theJingbian gas field however the C3t limestone is undevelopedin northern Ordos Basin such as the Hangjinqi area [19]Although theO1mcarbonate rocks in theOrdos Basinmainlyhave not reached the standard of hydrocarbon generationdue to the low TOC content [20] they display certain hydro-carbon generation potential for example the self-generatedand self-reservoired oil-type gas has been discovered in thepresalt O1m reservoirs in central-eastern Ordos Basin Thepresalt O1m source rocks display an average TOC content of03 with kerogen type I and the O1m source rocks couldgenerate a certain amount of oil-type gas since the sampleswith TOC content higher than 04 account for 282 of thetotal [59] Therefore the oil-type gas component in tight gasfrom the Gongkahan and Shilijiahan zones in the Hangjinqiarea is inferred to be derived from the O1m carbonaterocks and it migrated upwards along theWulanjilinmiao andBorjianghaizi faults

Moreover the Pt2 gas sample (J101) from the Hangjinqiarea also displays the mixing characteristics of coal-typegas and oil-type gas and relatively low 12057513C2 and 120575

13C3values indicate that the proportion of oil-type gas is slightlyhigher than that in the Upper Paleozoic tight gas This mayexplain the reason why the calculated 119877o value (098) ofthe Pt2 gas sample according to the 12057513C1-119877o empiricalequation for coal-type gas proposed by Dai and Qi [48]is significantly lower than that of the P1s-P1x tight gasThe Proterozoic mudstone in the Hangjinqi area has certainhydrocarbon generation potential with mainly kerogen typeIII and the distribution range and thickness are both limited[30] Since only a small amount of the Pt2 gas has beendiscovered in Wells J3 J13 and J101 it is inferred that thePt2 gas was mainly derived from the mixing of coal-type

gas from the Pt2 mudstone and oil-type gas from the O1mcarbonate rocks The Pt2 mudstone or O1m carbonate coresamples have not been obtained in the Hangjinqi area tillnow Therefore further study needs to be conducted on thegeochemical characteristics and hydrocarbon potential of thePt2 mudstone and O1m carbonate source rocks

53 Filling Patterns of Tight Gas The accumulation anddistribution of the Upper Paleozoic tight gas in the Hangjinqiarea were controlled by the Borjianghaizi fault It experiencedthree obvious peaks of activity in the evolution history thatis the Caledonian to the Early Hercynian fracture period theIndosinian to the Early Yanshanian squeezing thrust activityperiod and the Middle-Late Yanshanian strike-slip tearingactivity period [43] The studies on the homogenization tem-perature of the fluid inclusions and the accumulation historyindicated that two periods of gas filling occurred to theUpper Paleozoic strata in the Hangjinqi area in the Middle-Late Jurassic and the Early Cretaceous respectively [43 46]The C3t-P1s coal-measure source rocks in the Shilijiahanand Shiguhao zones entered the peak stage (119877o gt 08) ofhydrocarbon generation in the early and middle periods ofthe Early Cretaceous respectively that is both the C3t-P1ssource rocks in these two zones started to generate a largeamount of natural gas in the Early Cretaceous (Figure 10)Therefore the strike-slip activity of the Borjianghaizi faultin the Middle-Late Yanshanian effectively matched with themain gas filling period in the Early Cretaceous and theintensive fault activity in the gas filling period was favorablefor the effective expulsion of hydrocarbons from the sourcerocks and migration and accumulation of natural gas [43]

The study on the fault sealing ability indicated that thefault plane of the Borjianghaizi fault was vertically sealedin the P2sh and P2s strata with the fault sealing coefficientsalmost less than 10 whereas the fault plane was verticallyopen in the P1s and P1x strata with the fault sealing coef-ficients mostly ranging from 40 to 100 [43] Moreover theP2sh and P2s mudstones constituted the favorable regionalcaprock since they display a large thickness and stable lateraldistribution Therefore the large amount of natural gasgenerated by the C3t-P1s coal-measure source rocks to thesouth of the Borjianghaizi fault firstly migrated verticallyalong the fault and then migrated laterally across the faultto the north along the P1x stripped sand bodies (Figure 11)It finally accumulated in the favorable traps during themigration (Figure 11) that is natural gas in the Shiguhao zoneto the north of the Borjianghaizi faultmainly displayed distal-source accumulation

Molecular fractionation of natural gas occurs duringthe migration process Since the diffusion coefficient of thehydrocarbon decreases with the increase of the molecularweight [60] the diffusive gas is enriched in CH4 and displayshigher C1C1ndash5 ratio As indicated from the section A-A1015840(Figure 11) the P1s gas sample from Well J55 to the southof the Borjianghaizi fault displays C1C1ndash5 ratio of 0896whereas the P1x gas samples from Wells J66P5H YS1 J11and J26 to the north of the fault display C1C1ndash5 ratios higherthan 0900 (Figure 11) This suggests that the P1x gas in the

12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500

J14J26J11YS1J39J43J34J66P5HY19J54J6J55J56Strata

Gas layerCoal bedSandstone

Sampling positionMigration directionWell position and projection

Elevation(m)

A㰀

Figure 11 Gas fillingmodel of the Upper Paleozoic tight gas in the Hangjinqi area and the position of the section A-A1015840 is indicated in Figure 1(modified after Li et al [43])

reservoirs to the north of the fault has beenmigrated from theC3t-P1s coal-measure source rocks to the south of the fault

As to the Shilijiahan zone to the south of the Borjianghaizifault since the strata dipped to the south due to the effectof the thrusting in the Late Jurassic natural gas which hadmigrated upwards along the fault seemed unfavorable to fillinto in situ P1s and P1x sand bodies (Figure 11) Thereforenatural gas in the Shilijiahan zone was mainly derived fromin situ C3t and P1s source rocks The migration pathwayswere mainly the sand bodies and fissures with the drivingforce of the pressure difference between source rocks and thereservoirs which affected the degree of gas accumulationConsequently tight gas in the Shilijiahan and Gongkahanzonesmainly displayed near-source accumulationMoreoverthe gas samples which had been mixed by the oil-type gaswere all collected from the wells adjacent to the Borjianghaiziand Wulanjilinmiao faults and the oil-type gas componentwas inferred to be derived from the O1mcarbonate rocks andmigrate upwards along the two faults

6 Conclusions

(1) The Upper Paleozoic tight gas in the Hangjinqi area innorthernOrdosBasin ismainlywet gaswith the dryness coef-ficient (C1C1ndash5) of 0853ndash0951 which is positively correlatedwith the CH4 contentThe 12057513C1 120575

13C2 and 12057513C3 values are

ranging from minus362permil to minus320permil from minus289permil to minus245permiland from minus266permil to minus195permil respectively with the 1205752H-C1 values from minus199permil to minus174permil The alkane gas generallydisplays positive carbon and hydrogen isotopic series withonly a few gas samples being partially reversed between C2H6and C3H8

(2) Integrated analysis on geochemical characteristicsfrom the alkane carbon and hydrogen isotopes demonstratesthat the Upper Paleozoic tight gas in the Hangjinqi area ismainly coal-type gas The carbon isotopic compositions ofethane and propane indicate that tight gas from the wellsin the Shilijiahan and Gongkahan zones adjacent to theWulanjilinmiao and Borjianghaizi faults has been affected bythemixing of oil-type gas and it displays similar geochemicalcharacteristics with the O1m gas in the Jingbian gas fieldHowever the proportion of oil-type gas in the Upper Pale-ozoic gas in the Shilijiahan and Gongkahan zones is slightlylower than that in the O1m gas in the Jingbian gas field

(3)Gas-source correlation indicated that the coal-type gasin the Shiguhao zone displayed distal-source accumulationand it was mainly derived from the C3t-P1s coal-measuresource rocks probably with a minor contribution fromthe P1s coal measures in in situ Shiguhao zone Tight gasin the Shilijiahan and Gongkahan zones mainly displayednear-source accumulationThe coal-type gas component wasderived from in situ C3t-P1s source rocks whereas the oil-type gas component might be derived from the O1m carbon-ate rocks and it migrated upwards along the Wulanjilinmiaoand Borjianghaizi faults

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

The authors would like to thank Professor Jinxing Dai andDeliang Liu for generous guidance and assistance the North

Geofluids 13

China Branch Company of SINOPEC for sample collectionand technical support and Key Laboratory for Hydrocar-bon Accumulation Mechanism of SINOPEC for chemicalanalyses of natural gas This work was supported by theNational Natural Science Foundation of China (Grants nos41625009 U1663201 and 41302118) and the National Scienceamp Technology Special Project (Grant no 2016ZX05002-006)

References

[1] M Schoell ldquoThe hydrogen and carbon isotopic composition ofmethane from natural gases of various originsrdquo Geochimica etCosmochimica Acta vol 44 no 5 pp 649ndash661 1980

[2] A A Prinzhofer and A Y Huc ldquoGenetic and post-geneticmolecular and isotopic fractionations in natural gasesrdquo Chemi-cal Geology vol 126 no 3-4 pp 281ndash290 1995

[3] M A Rooney G E Claypool and HMoses Chung ldquoModelingthermogenic gas generation using carbon isotope ratios ofnatural gas hydrocarbonsrdquo Chemical Geology vol 126 no 3-4pp 219ndash232 1995

[4] M J Whiticar ldquoCarbon and hydrogen isotope systematicsof bacterial formation and oxidation of methanerdquo ChemicalGeology vol 161 no 1 pp 291ndash314 1999

[5] Y Tang J K Perry P D Jenden andM Schoell ldquoMathematicalmodeling of stable carbon isotope ratios in natural gasesrdquoGeochimica et CosmochimicaActa vol 64 no 15 pp 2673ndash26872000

[6] Y Ni Q Ma G S Ellis et al ldquoFundamental studies on kineticisotope effect (KIE) of hydrogen isotope fractionation in naturalgas systemsrdquo Geochimica et Cosmochimica Acta vol 75 no 10pp 2696ndash2707 2011

[7] Q Y Liu R H Worden Z J Jin et al ldquoTSR versus non-TSRprocesses and their impact on gas geochemistry and carbonstable isotopes in carboniferous permian and lower triassicmarine carbonate gas reservoirs in the Eastern Sichuan BasinChinardquo Geochimica et Cosmochimica Acta vol 100 no 1 pp96ndash115 2013

[8] Q Y Liu R H Worden Z J Jin et al ldquoThermochemicalsulphate reduction (TSR) versusmaturation and their effects onhydrogen stable isotopes of very dry alkane gasesrdquo Geochimicaet Cosmochimica Acta vol 137 no 0 pp 208ndash220 2014

[9] Q Liu J Dai Z Jin et al ldquoAbnormal carbon and hydrogenisotopes of alkane gases from the Qingshen gas field SongliaoBasin China suggesting abiogenic alkanesrdquo Journal of AsianEarth Sciences vol 115 no 1 pp 285ndash297 2016

[10] Q Liu Z Jin J Li A Hu and C Bi ldquoOrigin of marine sournatural gas and gas-filling model for the wolonghe gas fieldSichuan Basin Chinardquo Journal of Asian Earth Sciences vol 58pp 24ndash37 2012

[11] F Hao X Zhang C Wang et al ldquoThe fate of CO2 derived

from thermochemical sulfate reduction (TSR) and effect of TSRon carbonate porosity and permeability Sichuan Basin ChinardquoEarth-Science Reviews vol 141 pp 154ndash177 2015

[12] Y Ni J Dai C Zou F Liao Y Shuai and Y Zhang ldquoGeochem-ical characteristics of biogenic gases in Chinardquo InternationalJournal of Coal Geology vol 113 pp 76ndash87 2013

[13] X Wang W Liu B Shi Z Zhang Y Xu and J ZhengldquoHydrogen isotope characteristics of thermogenic methane inchinese sedimentary basinsrdquo Organic Geochemistry vol 83-84no 1 pp 178ndash189 2015

[14] F Hao and H Zou ldquoCause of shale gas geochemical anomaliesand mechanisms for gas enrichment and depletion in high-maturity shalesrdquoMarine and Petroleum Geology vol 44 pp 1ndash12 2013

[15] J Dai C Zou D Dong et al ldquoGeochemical characteristicsof marine and terrestrial shale gas in Chinardquo Marine andPetroleum Geology vol 76 pp 444ndash463 2016

[16] J Dai Y Ni and XWu ldquoTight gas in China and its significancein exploration and exploitationrdquo Petroleum Exploration andDevelopment vol 39 no 3 pp 277ndash284 2012

[17] J Dai C Yu S Huang et al ldquoGeological and geochemical char-acteristics of large gas fields in Chinardquo Petroleum Explorationand Development vol 41 no 1 pp 1ndash13 2014

[18] J Dai Giant Coal-Derived Gas Fields and the Source in ChinaScience Press Beijing China 2014

[19] J Dai J Li X Luo et al ldquoStable carbon isotope compositionsand source rock geochemistry of the giant gas accumulations inthe Ordos Basin Chinardquo Organic Geochemistry vol 36 no 12pp 1617ndash1635 2005

[20] A Hu J Li W Zhang Z Li L Hou and Q Liu ldquoGeochemicalcharacteristics and origin of gases from the Upper LowerPaleozoic and the Mesozoic reservoirs in the Ordos BasinChinardquo Science in China Series D Earth Sciences vol 51supplement I pp 183ndash194 2008

[21] H Yang J Fu X Liu and P Meng ldquoAccumulation conditionsand exploration and development of tight gas in the UpperPaleozoic of the Ordos Basinrdquo Petroleum Exploration andDevelopment vol 39 no 3 pp 295ndash303 2012

[22] G Hu J Li X Shan and Z Han ldquoThe origin of natural gas andthe hydrocarbon charging history of the Yulin gas field in theOrdos Basin Chinardquo International Journal of Coal Geology vol81 no 4 pp 381ndash391 2010

[23] S Huang X Fang D Liu C Fang and T Huang ldquoNatural gasgenesis and sources in the Zizhou gas fieldOrdos Basin ChinardquoInternational Journal of Coal Geology vol 152 part A pp 132ndash143 2015

[24] H Yang J Fu X Wei and X Liu ldquoSulige field in theOrdos Basin geological setting field discovery and tight gasreservoirsrdquoMarine and Petroleum Geology vol 25 no 4-5 pp387ndash400 2008

[25] C N Zou Z Yang S Z Tao et al ldquoContinuous hydrocarbonaccumulation over a large area as a distinguishing characteristicof unconventional petroleum the Ordos Basin North-CentralChinardquo Earth-Science Reviews vol 126 pp 358ndash369 2013

[26] Q Liu Z Jin Q Meng X Wu and H Jia ldquoGenetic typesof natural gas and filling patterns in Daniudi gas field OrdosBasin Chinardquo Journal of Asian Earth Sciences vol 107 pp 1ndash112015

[27] Q Y Liu Z J Jin YWang et al ldquoGas filling pattern in Paleozoicmarine carbonate reservoir of Ordos Basinrdquo Acta PetrologicaSinica vol 28 no 3 pp 847ndash858 2012

[28] C Cai G Hu H He J Li J Li and Y Wu ldquoGeochemicalcharacteristics and origin of natural gas and thermochemicalsulphate reduction in Ordovician carbonates in the OrdosBasin Chinardquo Journal of Petroleum Science and Engineering vol48 no 3-4 pp 209ndash226 2005

[29] Q Liu M Chen W Liu J Li P Han and Y Guo ldquoOrigin ofnatural gas from the Ordovician paleo-weathering crust andgas-filling model in Jingbian gas field Ordos Basin ChinardquoJournal of Asian Earth Sciences vol 35 no 1 pp 74ndash88 2009

14 Geofluids

[30] S Peng The Analyzation of Middle-Late Proterozoic Hydrocar-bon Geologic Feature and Exploration Potential in HangjinqiArea Northwest University Xirsquoan China 2009

[31] S Hao L Li W Zhang R Qi C Ma and J Chen ldquoFormingconditions of large-scale gas fields in Permo-Carboniferous inthe northern Ordos Basinrdquo Oil and Gas Geology vol 37 no 2pp 149ndash154 2016

[32] M Yang L Li J Zhou et al ldquoMesozoic structural evolution ofthe Hangjinqi area in the northern Ordos Basin North ChinardquoMarine and Petroleum Geology vol 66 pp 695ndash710 2015

[33] M Yang L Li J Zhou X Qu and D Zhou ldquoSegmentation andinversion of theHangjinqi fault zone theNorthernOrdos Basin(North China)rdquo Journal of Asian Earth Sciences vol 70-71 no1 pp 64ndash78 2013

[34] H Xue J-C Zhang B Xu YWang and X-P Mao ldquoEvaluationof Upper Paleozoic source rocks of the Hangjinqi block in thenorthern Ordos Basin Chinardquo Journal of Chengdu University ofTechnology (Science and Technology Edition) vol 37 no 1 pp21ndash28 2010

[35] W-M Ji W-L Li Z Liu and T Lei ldquoResearch on the UpperPaleozoic gas source of the Hangjinqi block in the northernOrdos Basinrdquo Natural Gas Geoscience vol 24 no 5 pp 905ndash914 2013

[36] J Chen H Jia Y Li C AnW Li and S Liu ldquoOrigin and sourceof natural gas in the Upper Paleozoic of the Yimeng UpliftOrdos Basinrdquo Oil and Gas Geology vol 37 no 2 pp 205ndash2092016

[37] M Wang D He H Bao R Lu and B Gui ldquoUpper Palaeo-zoic gas accumulations of the Yimeng Uplift Ordos BasinrdquoPetroleum Exploration and Development vol 38 no 1 pp 30ndash39 2011

[38] A Prinzhofer and E Pernaton ldquoIsotopically light methanein natural gas bacterial imprint or diffusive fractionationrdquoChemical Geology vol 142 no 3-4 pp 193ndash200 1997

[39] A Prinzhofer and A Battani ldquoGas isotopes tracing An impor-tant tool for hydrocarbons explorationrdquoOil andGas Science andTechnology vol 58 no 2 pp 299ndash311 2003

[40] B B Bernard J M Brooks and W M Sackett ldquoNatural gasseepage in the Gulf of Mexicordquo Earth and Planetary ScienceLetters vol 31 no 1 pp 48ndash54 1976

[41] P D Jenden I R Kaplan R Poreda and H Craig ldquoOriginof nitrogen-rich natural gases in the California Great Valleyevidence from helium carbon and nitrogen isotope ratiosrdquoGeochimica et Cosmochimica Acta vol 52 no 4 pp 851ndash8611988

[42] J Dai ldquoSignificant advancement in research on coal-derived gasin Chinardquo Petroleum Exploration and Development vol 26 no3 pp 1ndash10 1999

[43] W Li W Ji and Z Liu ldquoControl of Boerjianghaizi fault ongas accumulation of Upper Paleozoic in northern Ordos BasinrdquoGeoscience vol 29 no 3 pp 584ndash590 2015

[44] J Yang and X Pei Natural Gas Geology in China vol 4Petroleum Industry Press Beijing China 1996

[45] Y YangW Li and LMa ldquoTectonic and stratigraphic controls ofhydrocarbon systems in the Ordos Basin a multicycle cratonicbasin in central Chinardquo AAPG Bulletin vol 89 no 2 pp 255ndash269 2005

[46] H Xue Y Wang and X Mao ldquoThe timing of gas pooling in theUpper Paleozoic in the northern Ordos Basin A case study ofthe Hangjinqi Blockrdquo Natural Gas Industry vol 29 no 12 pp9ndash12 2009

[47] B Xu H Nie and M Wang ldquoA study of hydrocarbon-generating potential of Hangjinqi prospect area in ordos basinrdquoPetroleumGeology and Recovery Efficiency vol 16 no 4 pp 38-39 2009

[48] J Dai and H Qi ldquoThe 12057513C-Ro relationship of coal-derivedalkane gases in Chinardquo Chinese Science Bulletin vol 34 no 9pp 690ndash692 1989

[49] W J Stahl ldquoCarbon and nitrogen isotopes in hydrocarbonresearch and explorationrdquo Chemical Geology vol 20 no C pp121ndash149 1977

[50] J Dai X Pei and H Qi Natural Gas Geology in China vol 1Petroleum Industry Press Beijing China 1992

[51] Q Liu JDai J Li andQZhou ldquoHydrogen isotope compositionof natural gases from the Tarim Basin and its indication ofdepositional environments of the source rocksrdquo Science inChina Series D Earth Sciences vol 51 no 2 pp 300ndash311 2008

[52] J Dai Y Ni and C Zou ldquoStable carbon and hydrogen isotopesof natural gases sourced from the Xujiahe Formation in theSichuan Basin Chinardquo Organic Geochemistry vol 43 no 1 pp103ndash111 2012

[53] G Hu and S Zhang ldquoCharacterization of lowmolecular weighthydrocarbons in Jingbian gas field and its application to gassources identificationrdquo Energy Exploration and Exploitationvol 29 no 6 pp 777ndash796 2011

[54] Y-R Zou Y Cai C Zhang X Zhang and P Peng ldquoVari-ations of natural gas carbon isotope-type curves and theirinterpretationmdasha case studyrdquoOrganic Geochemistry vol 38 no8 pp 1398ndash1415 2007

[55] W Liu and Y Xu ldquoA two-stage model of carbon isotopicfractionation in coal-gasrdquo Geochimica vol 28 no 4 pp 359ndash365 1999

[56] E M Galimov ldquoIsotope organic geochemistryrdquo Organic Geo-chemistry vol 37 no 10 pp 1200ndash1262 2006

[57] S Hao Y Gao and Z Huang ldquoCharacteristics of dynamicequilibrium for natural gas migration and accumulation of thegas field in the center of the Ordos Basinrdquo Science in ChinaSeries D Earth Sciences vol 40 no 1 pp 11ndash15 1997

[58] X Xia L Zhao W Zhang and J Li ldquoGeochemical character-istics and source rock of Ordovician gas reservoir ChangqingGasfieldrdquoChinese Science Bulletin vol 44 no 20 pp 1917ndash19201999

[59] D Liu W Zhang Q Kong Z Feng C Fang and W PengldquoLower Paleozoic source rocks and natural gas origins in OrdosBasin NW Chinardquo Petroleum Exploration and Developmentvol 43 no 4 pp 591ndash601 2016

[60] BM Krooss andD Leythaeuser ldquoExperimental measurementsof the diffusion parameters of light hydrocarbons in water-saturated sedimentary rocks-II Results and geochemical signif-icancerdquo Organic Geochemistry vol 12 no 2 pp 91ndash108 1988

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

ClimatologyJournal of

EcologyInternational Journal of


EarthquakesJournal of


Mining


Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal of

OceanographyInternational Journal of


Journal of Computational Environmental SciencesHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering


GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Atmospheric SciencesInternational Journal of


OceanographyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in


MineralogyInternational Journal of


MeteorologyAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Paleontology JournalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Geological ResearchJournal of


Geology Advances in

2 Geofluids

Yulin Daniudi Wushenqi and Zizhou The Upper Paleozoicnatural gas is commonly considered as coal-type gas fromthe Carboniferous-Permian coal-measure source rocks [19ndash26] However the Lower Paleozoic natural gas was generallybelieved to be mixed by both coal-type gas from the UpperPaleozoic coal measures and oil-type gas from the marinesource rocks [27ndash29]

The Hangjinqi area is located in northern Ordos Basinand the gas exploration has achieved continuous break-throughs in recent years Natural gas is mainly enrichedin the Upper Paleozoic tight sandstone reservoirs with fewdiscoveries in the Mesoproterozoic strata such as wells J3and J13 [30] The geological reserves of tight gas in theHangjinqi area are higher than 700 times 109m3 and theUpper Paleozoic tight gas reservoirs are characterized by thelithological traps large gas-bearing area and low abundanceof reserves [31] Previous studies have been conducted onthe Mesozoic tectonic evolution [32] segmentation of thefaults [33] geochemical characteristics of the source rocks[34 35] and the origin of natural gas [36] Moreover Haoet al [31] demonstrated the forming conditions of the gasreservoirs and Wang et al [37] proposed the accumulatingmechanism of natural gas based on the analysis of trapconditions However there is no consensus on the sourceand accumulating pattern of natural gas Although the UpperPaleozoic tight gas in the Hangjinqi area was commonlybelieved to be sourced from the Carboniferous-Permian coalmeasures it is still controversial whether the gas was derivedfrom the source rocks in in situ Hangjinqi area [34 35] or theWushenqi area in central Ordos Basin [37] Wang et al [37]proposed that advantageous sandbody unconformity faultsand fissures constituted favorable migration pathways for thenorthwardmigration natural gas Nevertheless Xue et al [34]considered that the strata in the Ordos Basin were gentlewith a low dip angle and the conditions for large-scale lateralmigration were undeveloped in consideration of the UpperPaleozoic tight sandstone reservoirs Hao et al [31] and Chenet al [36] demonstrated that the Upper Paleozoic natural gasto the south and north of the Sanyanjing-Wulanjilinmiao-Borjianghaizi fault zones displayed near-source and distal-source accumulation respectively However Xue et al [34]proposed that the Upper Paleozoic natural gas in theHangjinqi area displayed near-source accumulation and wasderived from in situ Upper Paleozoic coal-measure sourcerocks

The above controversy is mainly derived from the dif-ferent understandings on the geological conditions of tightgas in the Hangjinqi area and geochemical characteristicsof tight gas in the area have been weakly studied with afew confusions Chen et al [36] demonstrated that naturalgas in the Shiguhao zone in northern Hangjinqi area waspartially derived from source rocks in the Shilijiahan areato the south of the Borjianghaizi fault and the gas hadbeen affected by compositional geochromatographic effectand carbon isotopic fractionation However natural gas inthe Shiguhao zone displayed obviously higher 12057513C1 valuesand C1C1ndash5 ratios than those in the Shilijiahan zone [36]suggesting higher maturity rather than the migration effect

The generation and alteration processes of natural gas can berevealed by the study of genetic and postgenetic molecularand isotopic fractionations based on the gas geochemicalcharacteristics [2 38] Therefore the authors intend to docu-ment the geochemical characteristics of the Upper Paleozoictight gas based on the analyses of molecular and stableisotopic compositions in this study We further demonstratethe origin source and possible postgenetic processes oftight gas in comparison with the Lower Paleozoic gas in theJingbian gas field This would provide valuable informationfor the accumulation and resource evaluation of natural gasin the Ordos Basin

2 Geological Setting

The Ordos Basin is a multicycle cratonic basin with stablesubsidence and located at the western margin of the NorthChina Block covering an area of 37 times 104 km2 [44] Based onthe basement property and the present tectonic morphologyand characteristics the Ordos Basin can be divided into 6tectonic units (Figure 1) that is YimengUpliftWeibei UpliftJinxi Fault-fold Belt Yishan Slope TianhuanDepression andWest MarginThrust Belt [24 45]

The Hangjinqi area is located tectonically in the YimengUplift and northern Yishan Slope covering an area of9825 km2 It can be subdivided into 5 secondary struc-tural units according to the fluctuation characteristics andstructural configuration of the top surface of the basementthat is Wulangeer uplift Gongkahan uplift Hangjinqi faultterrace northern Yishan Slope and the northeastern cornerof the Tianhuan Depression (Figure 1) Three main faultsare distributed in the Hangjinqi area from west to east inwhich the Sanyanjing and Wulanjilinmiao faults are south-dipping normal faults whereas the Borjianghaizi fault isnorth-dipping thrust fault (Figure 1) Seven gas zones thatis Haoraozhao Shiguhao Shilijiahan Azhen GongkahanWulanjilinmiao and Xinzhao are classified according tothe fault distribution (Figure 1) The Hangjinqi area wastopographically a long-term inherited paleohigh in northernOrdos Basin and was considered as the favorable orientedregion for oil and gasmigration [46] Gas reservoirs are foundmainly in the Shiguhao and Shilijiahan zones

The Upper Paleozoic strata in the Hangjinqi area uncon-formably overlie the Lower Ordovician Majiagou Formation(O1m) or Meso-Neoproterozoic strata (Pt2-Pt3) and theyconsist upward of the Upper Carboniferous Taiyuan Fm(C3t) Lower Permian Shanxi Fm (P1s) and Lower Shi-hezi Fm (P1x) as well as Upper Permian Upper ShiheziFm (P2sh) and Shiqianfeng Fm (P2s) (Figure 2) Naturalgas is mainly reservoired in the P1x tight sandstone withonly a few discoveries in the P1s and C3t sandstones andthese sandstone reservoirs are generally characterized bylow porosity and permeability [37] The P2sh and P2s strataare mainly composed of thick-layer lacustrine mudstoneinterbedded with sandstone and the mudstone is widelyand stably distributed with the thickness of 130mndash160mconstituting the regional caprock for the underlying P1x andP1s tight gas reservoirs [31] Moreover natural gas has also

Geofluids 3

OrdosChina

N

Yishan Slope

Yimeng Upli

Tian

huan

Dep

ress

ion

Wes

t Mar

gin

ru

st Be

lt

Jinxi

Fau

lt-fo

ld B

elt

Weibei Upli

Wuqi

EtuokeqiSulige

Jingbian

Yinchuan

Qingyang

Tongchuan

Yanrsquoan

Lishi

0 8040

Basin


Wushenqi

Beijing

(km)

(a)

J55

Wuqi

Fault


Work area

City

Gas well





15

0 2010 30 40 N

J101J110

J58P13HJ98

J111 J99

J55 J77

J66P9H

J66P8HJPH-13

J26J11YS1

J66P5H

J66J3

J13

J58 J56

J6J54

Y19

J34

J43

J14

J39

J10

JP1

fault

Xinzhao zone

Gongkahan zone

Haoraozhao zone

Azhen zone

Shilijiahan zone

Wulanjilinmiao zone

zone

ShiguhaoHangjinqi

Yijinhuoluoqi

Shiguhao

Xinzhao

Wujiamiaosag

Gongkahanupli

Tian

huan

Depr

essio

n

Yishan

Slope

Wulangeer upli

Hangjinqifau

ltterr

ace

Sanyanjing fault

Wulanjilinmiao


1315

19A

07

09

(km)

17


A㰀

(b)








4 Geofluids

Perm

ian


zone

Coarse sandstone

Medium sandstone

Fine sandstone

Dolomite

Coal bed

Gas zone

Mudstone

Limestone


60~130


P1x


P1s


C3t


UpperShihezi

LowerShihezi

Shanxi

Taiyuan

Majiagou 0~30O1m






4 Results



Geofluids 5

Table1Molecular

andsta

bleisotopicc

ompo

sitions

ofnaturalgas

from

theH

angjinqi

area

intheO

rdos

Basin

Gas

zone

Gas

well

Strata

Chem

icalcompo

sition(

)C 1


VPD

B)1205752H(permil

VSM

OW)119877o(

)A119877o(

)BCH4

C 2H6

C 3H8119894C4H10119899C 4

H10119894C5H12119899C 5

H12

N2

CO2

12057513C 112057513C 212057513C 31205752H-C11205752H-C21205752H-C3

Shiguh

ao

J11P 1x

9347

362

084

012

018

005

005

136

030


143

050

J26

P 1x

9366

359

081

011

019

006

005

116

035


148

052

J66P

5HP 1x

9322

433

094

011

021

005

007

084

021


128

045

J66P

8HP 1x

8435

832

328

068

112

056

053

025

000


132

046

J66P

9HP 1x

8704

779

250

045

072

034

030

039

000


141

049

JPH-13

P 1x

8728

736

252

043

070

034

031

027

000


13

2046

YS1

P 1x

9004

649

192

031

050

026

022

024

000


132

046

J66

P 1x

8827

728

236

041

061

027

022

018

000


138

048

Shilijiahan

J77

P 1x

8947

618

203

033

048

016

01

077

045


095

033

J55

P 1s

8348

714

186

018

038

008

007

676

003


074

026

J111

P 1x

9088

547

157

029

046

027

023

042

000


138

048

J58P

13H

P 1x

9372

377

105

022

033

017

014

046

000


13

0045

J98

P 1x

9267

463

118

024

035

021

017

016

000


130

045

J58

P 1x

9002

531

152

035

053

025

022

110

000


13

4047

J99

P 1x

9097

569

152

032

048

030

026

035

000


130

045

Gon

gkahan

J110

P 1x

8734

679

271

066

086

041

032

019

000


138

048

J101

Pt2

8275

502

270

046

084

028

028

710

000


098

034

Note119877

o(

)(AB

)valuesw

erec


the12057513C 1

-119877oem

piric

alequatio

nsforc

oal-typeg

asprop

osed

byDaiandQi[48]a



odata

6 Geofluids

CH4 ()95908580

085

090

095

100

C1C

1minus5



(a)

085

090

095

100

C1C

1minus5


훿13C1 (permil)



(b)









1Cn

13 12 1



minus40

minus35

minus30

minus25

minus20

minus15

훿13C

(permil)




2H-C2 lt 1205752H-C3)


2H-C2 gt 1205752H-


Geofluids 7

1Cn

13 12 1


minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)


5 Discussion



Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3


Migration


Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity



C1C

2+3

100

101

102

103

훿13C1 (permil)





8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

Geofluids 3

OrdosChina

N

Yishan Slope

Yimeng Upli

Tian

huan

Dep

ress

ion

Wes

t Mar

gin

ru

st Be

lt

Jinxi

Fau

lt-fo

ld B

elt

Weibei Upli

Wuqi

EtuokeqiSulige

Jingbian

Yinchuan

Qingyang

Tongchuan

Yanrsquoan

Lishi

0 8040

Basin


Wushenqi

Beijing

(km)

(a)

J55

Wuqi

Fault


Work area

City

Gas well





15

0 2010 30 40 N

J101J110

J58P13HJ98

J111 J99

J55 J77

J66P9H

J66P8HJPH-13

J26J11YS1

J66P5H

J66J3

J13

J58 J56

J6J54

Y19

J34

J43

J14

J39

J10

JP1

fault

Xinzhao zone

Gongkahan zone

Haoraozhao zone

Azhen zone

Shilijiahan zone

Wulanjilinmiao zone

zone

ShiguhaoHangjinqi

Yijinhuoluoqi

Shiguhao

Xinzhao

Wujiamiaosag

Gongkahanupli

Tian

huan

Depr

essio

n

Yishan

Slope

Wulangeer upli

Hangjinqifau

ltterr

ace

Sanyanjing fault

Wulanjilinmiao


1315

19A

07

09

(km)

17


A㰀

(b)








4 Geofluids

Perm

ian


zone

Coarse sandstone

Medium sandstone

Fine sandstone

Dolomite

Coal bed

Gas zone

Mudstone

Limestone


60~130


P1x


P1s


C3t


UpperShihezi

LowerShihezi

Shanxi

Taiyuan

Majiagou 0~30O1m






4 Results



Geofluids 5

Table1Molecular

andsta

bleisotopicc

ompo

sitions

ofnaturalgas

from

theH

angjinqi

area

intheO

rdos

Basin

Gas

zone

Gas

well

Strata

Chem

icalcompo

sition(

)C 1


VPD

B)1205752H(permil

VSM

OW)119877o(

)A119877o(

)BCH4

C 2H6

C 3H8119894C4H10119899C 4

H10119894C5H12119899C 5

H12

N2

CO2

12057513C 112057513C 212057513C 31205752H-C11205752H-C21205752H-C3

Shiguh

ao

J11P 1x

9347

362

084

012

018

005

005

136

030


143

050

J26

P 1x

9366

359

081

011

019

006

005

116

035


148

052

J66P

5HP 1x

9322

433

094

011

021

005

007

084

021


128

045

J66P

8HP 1x

8435

832

328

068

112

056

053

025

000


132

046

J66P

9HP 1x

8704

779

250

045

072

034

030

039

000


141

049

JPH-13

P 1x

8728

736

252

043

070

034

031

027

000


13

2046

YS1

P 1x

9004

649

192

031

050

026

022

024

000


132

046

J66

P 1x

8827

728

236

041

061

027

022

018

000


138

048

Shilijiahan

J77

P 1x

8947

618

203

033

048

016

01

077

045


095

033

J55

P 1s

8348

714

186

018

038

008

007

676

003


074

026

J111

P 1x

9088

547

157

029

046

027

023

042

000


138

048

J58P

13H

P 1x

9372

377

105

022

033

017

014

046

000


13

0045

J98

P 1x

9267

463

118

024

035

021

017

016

000


130

045

J58

P 1x

9002

531

152

035

053

025

022

110

000


13

4047

J99

P 1x

9097

569

152

032

048

030

026

035

000


130

045

Gon

gkahan

J110

P 1x

8734

679

271

066

086

041

032

019

000


138

048

J101

Pt2

8275

502

270

046

084

028

028

710

000


098

034

Note119877

o(

)(AB

)valuesw

erec


the12057513C 1

-119877oem

piric

alequatio

nsforc

oal-typeg

asprop

osed

byDaiandQi[48]a



odata

6 Geofluids

CH4 ()95908580

085

090

095

100

C1C

1minus5



(a)

085

090

095

100

C1C

1minus5


훿13C1 (permil)



(b)









1Cn

13 12 1



minus40

minus35

minus30

minus25

minus20

minus15

훿13C

(permil)




2H-C2 lt 1205752H-C3)


2H-C2 gt 1205752H-


Geofluids 7

1Cn

13 12 1


minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)


5 Discussion



Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3


Migration


Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity



C1C

2+3

100

101

102

103

훿13C1 (permil)





8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

4 Geofluids

Perm

ian


zone

Coarse sandstone

Medium sandstone

Fine sandstone

Dolomite

Coal bed

Gas zone

Mudstone

Limestone


60~130


P1x


P1s


C3t


UpperShihezi

LowerShihezi

Shanxi

Taiyuan

Majiagou 0~30O1m






4 Results



Geofluids 5

Table1Molecular

andsta

bleisotopicc

ompo

sitions

ofnaturalgas

from

theH

angjinqi

area

intheO

rdos

Basin

Gas

zone

Gas

well

Strata

Chem

icalcompo

sition(

)C 1


VPD

B)1205752H(permil

VSM

OW)119877o(

)A119877o(

)BCH4

C 2H6

C 3H8119894C4H10119899C 4

H10119894C5H12119899C 5

H12

N2

CO2

12057513C 112057513C 212057513C 31205752H-C11205752H-C21205752H-C3

Shiguh

ao

J11P 1x

9347

362

084

012

018

005

005

136

030


143

050

J26

P 1x

9366

359

081

011

019

006

005

116

035


148

052

J66P

5HP 1x

9322

433

094

011

021

005

007

084

021


128

045

J66P

8HP 1x

8435

832

328

068

112

056

053

025

000


132

046

J66P

9HP 1x

8704

779

250

045

072

034

030

039

000


141

049

JPH-13

P 1x

8728

736

252

043

070

034

031

027

000


13

2046

YS1

P 1x

9004

649

192

031

050

026

022

024

000


132

046

J66

P 1x

8827

728

236

041

061

027

022

018

000


138

048

Shilijiahan

J77

P 1x

8947

618

203

033

048

016

01

077

045


095

033

J55

P 1s

8348

714

186

018

038

008

007

676

003


074

026

J111

P 1x

9088

547

157

029

046

027

023

042

000


138

048

J58P

13H

P 1x

9372

377

105

022

033

017

014

046

000


13

0045

J98

P 1x

9267

463

118

024

035

021

017

016

000


130

045

J58

P 1x

9002

531

152

035

053

025

022

110

000


13

4047

J99

P 1x

9097

569

152

032

048

030

026

035

000


130

045

Gon

gkahan

J110

P 1x

8734

679

271

066

086

041

032

019

000


138

048

J101

Pt2

8275

502

270

046

084

028

028

710

000


098

034

Note119877

o(

)(AB

)valuesw

erec


the12057513C 1

-119877oem

piric

alequatio

nsforc

oal-typeg

asprop

osed

byDaiandQi[48]a



odata

6 Geofluids

CH4 ()95908580

085

090

095

100

C1C

1minus5



(a)

085

090

095

100

C1C

1minus5


훿13C1 (permil)



(b)









1Cn

13 12 1



minus40

minus35

minus30

minus25

minus20

minus15

훿13C

(permil)




2H-C2 lt 1205752H-C3)


2H-C2 gt 1205752H-


Geofluids 7

1Cn

13 12 1


minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)


5 Discussion



Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3


Migration


Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity



C1C

2+3

100

101

102

103

훿13C1 (permil)





8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

Geofluids 5

Table1Molecular

andsta

bleisotopicc

ompo

sitions

ofnaturalgas

from

theH

angjinqi

area

intheO

rdos

Basin

Gas

zone

Gas

well

Strata

Chem

icalcompo

sition(

)C 1


VPD

B)1205752H(permil

VSM

OW)119877o(

)A119877o(

)BCH4

C 2H6

C 3H8119894C4H10119899C 4

H10119894C5H12119899C 5

H12

N2

CO2

12057513C 112057513C 212057513C 31205752H-C11205752H-C21205752H-C3

Shiguh

ao

J11P 1x

9347

362

084

012

018

005

005

136

030


143

050

J26

P 1x

9366

359

081

011

019

006

005

116

035


148

052

J66P

5HP 1x

9322

433

094

011

021

005

007

084

021


128

045

J66P

8HP 1x

8435

832

328

068

112

056

053

025

000


132

046

J66P

9HP 1x

8704

779

250

045

072

034

030

039

000


141

049

JPH-13

P 1x

8728

736

252

043

070

034

031

027

000


13

2046

YS1

P 1x

9004

649

192

031

050

026

022

024

000


132

046

J66

P 1x

8827

728

236

041

061

027

022

018

000


138

048

Shilijiahan

J77

P 1x

8947

618

203

033

048

016

01

077

045


095

033

J55

P 1s

8348

714

186

018

038

008

007

676

003


074

026

J111

P 1x

9088

547

157

029

046

027

023

042

000


138

048

J58P

13H

P 1x

9372

377

105

022

033

017

014

046

000


13

0045

J98

P 1x

9267

463

118

024

035

021

017

016

000


130

045

J58

P 1x

9002

531

152

035

053

025

022

110

000


13

4047

J99

P 1x

9097

569

152

032

048

030

026

035

000


130

045

Gon

gkahan

J110

P 1x

8734

679

271

066

086

041

032

019

000


138

048

J101

Pt2

8275

502

270

046

084

028

028

710

000


098

034

Note119877

o(

)(AB

)valuesw

erec


the12057513C 1

-119877oem

piric

alequatio

nsforc

oal-typeg

asprop

osed

byDaiandQi[48]a



odata

6 Geofluids

CH4 ()95908580

085

090

095

100

C1C

1minus5



(a)

085

090

095

100

C1C

1minus5


훿13C1 (permil)



(b)









1Cn

13 12 1



minus40

minus35

minus30

minus25

minus20

minus15

훿13C

(permil)




2H-C2 lt 1205752H-C3)


2H-C2 gt 1205752H-


Geofluids 7

1Cn

13 12 1


minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)


5 Discussion



Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3


Migration


Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity



C1C

2+3

100

101

102

103

훿13C1 (permil)





8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

6 Geofluids

CH4 ()95908580

085

090

095

100

C1C

1minus5



(a)

085

090

095

100

C1C

1minus5


훿13C1 (permil)



(b)









1Cn

13 12 1



minus40

minus35

minus30

minus25

minus20

minus15

훿13C

(permil)




2H-C2 lt 1205752H-C3)


2H-C2 gt 1205752H-


Geofluids 7

1Cn

13 12 1


minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)


5 Discussion



Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3


Migration


Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity



C1C

2+3

100

101

102

103

훿13C1 (permil)





8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

Geofluids 7

1Cn

13 12 1


minus220

minus200

minus180

minus160

minus140

minus120

minus100

훿2H

(permil)


5 Discussion



Biodegradation

Maturity

C2iC4

150100500



0

5

10

15

20

C2C

3


Migration


Kero

gen t

ype I

I

Keroge

n typ

e III

Maturity



C1C

2+3

100

101

102

103

훿13C1 (permil)





8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

8 Geofluids





훿13C1 (permil)

minus40

minus35

minus30

minus25

minus20

훿13C

2(permil

)



(a)

Coal-type gas

Oil-typegas

Mixing trend

훿13C

3(permil

)

minus18

minus21

minus24

minus27

minus30

minus33


훿13C2 (permil)



(b)










13C1 and 1205752H-C1 versus 120575








Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

Geofluids 9



organic matter

Maturity

Maturity



훿13C1 (permil)

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)



(a)


matter



Maturity

Matu

rity

minus220

minus200

minus180

minus160

minus140

minus120

훿2H

-C1

(permil)


훿13C2 (permil)



minus40

(b)









10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

10 Geofluids


JT2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

1109

0705Ro =

Ro =Ro =

Ro =

(a)

Strata

O1

O1 C P T J K1 K2-Q

K-Q

J

T2

T1

P2

P1C3

4

3

2

1

0

Buria

l dep

th (k

m)

050709

1113

Ro =Ro =Ro =

Ro =Ro =

(b)







Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

Geofluids 11










12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

12 Geofluids

NA

C1C1minus5 = 0951

C1C1minus5 = 0950

C1C1minus5 = 0903

C1C1minus5 = 0942

C1C1minus5 = 0896

P2sh

2s-P

P1x

P1s

O1mC3t

minus1000

minus1100

minus1200

minus1300

minus1400

minus1500




Elevation(m)

A㰀




6 Conclusions








Acknowledgments


Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

Geofluids 13


References































14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in

14 Geofluids







































Mining


Journal of









Journal of




Advances in











Geology Advances in








Mining


Journal of









Journal of




Advances in











Geology Advances in

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Genetic Types and Source of the Upper Paleozoic Tight Gas ...downloads.hindawi.com/journals/geofluids/2017/4596273.pdf · Upper Paleozoic Carboniferous-Permian tight sandstone and