050607Formation Evaluation-tight gas.pdf

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Formation Evaluation Formation Evaluation Challenges in Unconventional Challenges in Unconventional Tight Hydrocarbon ReservoirsTight Hydrocarbon Reservoirs

Mauro GonfaliniMauro GonfaliniSPE Italian SectionSPE Italian Section

June 7June 7thth, 2005, 2005

SPE Italian Section SPE Italian Section -- FE challenges in Unconventional Hydrocarbon Reservoir FE challenges in Unconventional Hydrocarbon Reservoir –– slide # slide # 22

Outline of the lectureOutline of the lecture

IntroductionIntroductionDefinitionsDefinitionsGas from Tight Reservoirs Gas from Tight Reservoirs (mainly(mainly sandstones)sandstones)

Gas from Gas from ShalesShalesGas from CoalGas from CoalConclusionsConclusions

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Global economy is strongly Global economy is strongly based on Fossil Fuels based on Fossil Fuels representing 90% of the representing 90% of the primary energy produced in primary energy produced in the world.the world.Fossil FuelsFossil Fuels, by definition, , by definition, are not renewable sourcesare not renewable sourcesof energy, and their amount of energy, and their amount is limited.is limited.Oil, by itself, represents Oil, by itself, represents about 40% of the Fossil about 40% of the Fossil Fuels used worldwide.Fuels used worldwide.Oil production peak is close!Oil production peak is close!

THE GROWING GAPRegular Oil

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Future Discovery

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Past discovery based on ExxonMobil (2002).Revisions backdated

Why do we need to discuss about Why do we need to discuss about Unconventional Hydrocarbon Reservoirs?Unconventional Hydrocarbon Reservoirs?

Newsletter ASPO n° 49 - January 2005


The resource TriangleThe resource Triangle

Mr Holditch Mr Holditch vision about vision about fossil fossil hydrocarbon hydrocarbon resourcesresources..

Unconventional sources are Next on the E&P Radar -Drilling Contractor - November/December 2004

Past

Present

Future

Conventional reservoirssmall volume, easy to develop

Unconventional Reservoirs

Large Volumes,difficult todevelop

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The resource triangle modifiedThe resource triangle modified

The resource The resource triangle is here triangle is here modified in modified in order to better order to better define the define the focus focus of this lectureof this lecture..

Gas shales

Resource Triangle modified

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Focus of the lectureFocus of the lecture

SPE 90242SPE 90242 -- Is Is BBitumen a Petroleum Reserveitumen a Petroleum Reserve??J. R. Etherington et al., 2004J. R. Etherington et al., 2004


Conventional vs Unconventional Conventional vs Unconventional Hydrocarbon ReservoirsHydrocarbon Reservoirs

The increasing role of UnconventionalThe increasing role of UnconventionalReservoirs in the Future of the Oil and GasReservoirs in the Future of the Oil and Gas

Business Business --SPE Lecture 2001 SPE Lecture 2001 -- S. A. HolditchS. A. Holditch

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Expected decarbonization trendExpected decarbonization trend

Due to Due to environmental environmental issues and issues and availability of availability of fossil energy fossil energy sources, we see sources, we see in the industry a in the industry a trend toward trend toward decarbonization decarbonization of fossil fuelsof fossil fuels

The Increasing Role of UnconventionalThe Increasing Role of UnconventionalReservoirs in the Future of the Oil and Gas BusinessReservoirs in the Future of the Oil and Gas Business

SPE Lecture 2001 SPE Lecture 2001 -- S. A. S. A. HolditchHolditch


The Golden Age of Natural GasThe Golden Age of Natural Gas

The Schlumberger Natural Gas Strategies 2004The Schlumberger Natural Gas Strategies 2004

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Is this really true?Is this really true?

bp statistical review of world energy bp statistical review of world energy June 2004June 2004

CoalCoalHydroelectricityHydroelectricityNuclear energyNuclear energyNatural GasNatural GasOilOil

Primary EnergyPrimary Energy


Unconventional Reservoirs: Unconventional Reservoirs: some example of the growing interest in the industrysome example of the growing interest in the industry

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Formation EvaluationFormation EvaluationFormation EvaluationFormation Evaluation is the is the analysis and interpretation of well log analysis and interpretation of well log data, drill stem tests, etc. in terms of data, drill stem tests, etc. in terms of the nature of the formations and their the nature of the formations and their fluid content. fluid content. The The objectivesobjectives of of Formation Formation EvaluationEvaluation are:are:

to ascertain if commercially to ascertain if commercially producible hydrocarbons are present, producible hydrocarbons are present, to determine the best means for their to determine the best means for their recovery,recovery,to derive lithology and other to derive lithology and other information on formation information on formation characteristics for use in further characteristics for use in further exploration and developmentexploration and development..

From SPWLA GlossaryFrom SPWLA Glossary


Formation Evaluation and E&P processFormation Evaluation and E&P process

FE TechnologiesFE Technologies•• Surface LoggingSurface Logging•• Well LoggingWell Logging•• CoringCoring•• Formation Testing Formation Testing •• Well TestingWell Testing

DisciplinesDisciplines•• GeosciencesGeosciences•• DrillingDrilling•• Production (feasibility)Production (feasibility)•• Reserve evaluationReserve evaluation

FE TechnologiesFE Technologies•• Surface LoggingSurface Logging•• Well LoggingWell Logging•• CoringCoring•• Formation Testing Formation Testing •• Well TestingWell Testing

DisciplinesDisciplines•• GeosciencesGeosciences•• DrillingDrilling•• Reservoir EngineeringReservoir Engineering•• Production (design)Production (design)•• Reserve certificationReserve certification

FE TechnologiesFE Technologies•• CH LoggingCH Logging•• Reservoir Monitoring & Reservoir Monitoring &

SurveillanceSurveillance

DisciplinesDisciplines•• GeosciencesGeosciences•• DrillingDrilling•• Reservoir EngineeringReservoir Engineering•• Production (optimization)Production (optimization)

Exploration & Exploration & Discovery EvaluationDiscovery Evaluation AppraisalAppraisal

Development & Development & Production Production

OptimizationOptimization

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The importance of Tight Gas ReservoirsThe importance of Tight Gas Reservoirs

Unconventional resources are probably very large, Unconventional resources are probably very large, but their character and distribution are not yet well but their character and distribution are not yet well understood.understood.Tight GasTight Gas sands in the sands in the U.S.U.S. comprise comprise 69%69% of gas of gas production from all unconventional gas resources production from all unconventional gas resources and already account for and already account for 19%19% of the total gas of the total gas production from conventional and unconventional production from conventional and unconventional sources. sources. Total Gas In PlaceTotal Gas In Place related to related to Tight GasTight Gas sands in sands in the the U.S.U.S. is estimated between is estimated between 100 & 400100 & 400 TmTm33..Other countries: Canada, Australia, Argentina, Other countries: Canada, Australia, Argentina, Venezuela, Egypt, Algeria and … ?Venezuela, Egypt, Algeria and … ?


Gas production from Tight ReservoirsGas production from Tight Reservoirs

Tight hydrocarbon reservoirs are the ones Tight hydrocarbon reservoirs are the ones characterized by characterized by low qualitylow quality due to due to low low permeabilitiespermeabilities, generally in the range between , generally in the range between a a mDmD and aand a µµDD (a millionth of a Darcy!).(a millionth of a Darcy!).Tight reservoirs can be of any kind:Tight reservoirs can be of any kind:clasticsclastics, , carbonates carbonates and and igneous rocksigneous rocks..

Higher Quality Tight Hydrocarbon reservoirs Higher Quality Tight Hydrocarbon reservoirs are already in production from years, but new are already in production from years, but new E&P technologies and methodologies will E&P technologies and methodologies will lower the cost to drill, characterize, complete lower the cost to drill, characterize, complete and produce hydrocarbons from and produce hydrocarbons from highly tight highly tight formationsformations..

Each one of these reservoir types requires Each one of these reservoir types requires specific E&P strategies and adequate specific E&P strategies and adequate Formation EvaluationFormation Evaluation Techniques.Techniques.

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What makes a reservoir tight?What makes a reservoir tight?Effective porosity, viscosity, fluid Effective porosity, viscosity, fluid saturation, the capillary pressure are saturation, the capillary pressure are some of the import parameter some of the import parameter controlling the effective permeability controlling the effective permeability of a reservoir.of a reservoir.Rock parameters are controlled by Rock parameters are controlled by depositional and postdepositional and post--depositional depositional environments:environments:

deep deep basinalbasinal or overor over--bank levees in flood bank levees in flood plains areas (deposition of very fine sand to plains areas (deposition of very fine sand to silt and clays, which form poor reservoirs on silt and clays, which form poor reservoirs on lithificationlithification););highhigh--energy clean sandstones (energy clean sandstones (intergranularintergranularpores occluded by pores occluded by authigenicauthigenic clay minerals & clay minerals & cements);cements);postpost--depositional depositional diageneticdiagenetic events act many events act many times negatively, reduce the effective porosity times negatively, reduce the effective porosity and thereby make the rock less permeable.and thereby make the rock less permeable.

Conventional Gas SandConventional Gas Sand

Tight Gas Tight Gas SandSand

G. C. Naik, 2003G. C. Naik, 2003


Petrophysical attributes of Petrophysical attributes of lowlow--permeability Reservoirspermeability Reservoirs

The lowThe low--permeability structure permeability structure and the response to overburden and the response to overburden stress have a strong impact on stress have a strong impact on the lowthe low--permeability structure permeability structure and the relative permeability and the relative permeability relationships.relationships.In lowIn low--permeability reservoirs permeability reservoirs there can be a broad range of there can be a broad range of water saturations in which water saturations in which neither gas nor water can flow. neither gas nor water can flow. In some very lowIn some very low--permeability permeability reservoir, there is virtually no reservoir, there is virtually no mobile water phase even at very mobile water phase even at very high water saturations.high water saturations. G. C. Naik, 2003G. C. Naik, 2003

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Key F. E. technologiesKey F. E. technologies

Tight gas sands often exhibit unique gas storage Tight gas sands often exhibit unique gas storage and producing characteristics that requireand producing characteristics that require::

improved knowledge of the nature, geometry and improved knowledge of the nature, geometry and distribution of petrophysical properties,distribution of petrophysical properties,more dense well spacing,more dense well spacing,adequate Stimulation & Production techniques.adequate Stimulation & Production techniques.

PetrophysicsPetrophysics is a critical technology required for is a critical technology required for understanding lowunderstanding low--permeability reservoirs.permeability reservoirs.GeomechanicsGeomechanics is also very important for the is also very important for the correct implementation of advanced Drilling correct implementation of advanced Drilling technologies and of adequate stimulation and technologies and of adequate stimulation and production strategies.production strategies.


Data Acquisition & Formation EvaluationData Acquisition & Formation Evaluation

The objective of the reservoir description program is The objective of the reservoir description program is to provide sufficient data to accurately describe the to provide sufficient data to accurately describe the resource in place and reserve potential.resource in place and reserve potential.

Surface LoggingSurface LoggingCoringCoringWell Logging Well Logging Formation testingFormation testingProduction Logging & Reservoir SurveillanceProduction Logging & Reservoir Surveillance

ApplicationsApplicationsReservoir CharacterizationReservoir CharacterizationReservoir ModelingReservoir ModelingDrilling & CompletionDrilling & CompletionWell Stimulation & Production OptimizationWell Stimulation & Production Optimization

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Reservoir CharacterizationReservoir Characterization

The objective of the The objective of the reservoir reservoir characterizationcharacterization program is to program is to acquire data to identify and acquire data to identify and characterize the mechanisms characterize the mechanisms controlling production and controlling production and optimum development.optimum development.


Reservoir ModelingReservoir Modeling

The ultimate goal of The ultimate goal of reservoir reservoir modelingmodeling is to validate the reservoir is to validate the reservoir description and characterization description and characterization programs and to develop realistic 3D programs and to develop realistic 3D well bore and reservoir models that well bore and reservoir models that can be used to predict future can be used to predict future performances:performances:

increase in model complexity with increase in model complexity with timetimestochastic modelsstochastic modelsdeterministic modelsdeterministic modelsmodel integrationmodel integration

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Reservoir Monitoring and SurveillanceReservoir Monitoring and Surveillance

The objective of The objective of reservoir monitoring and reservoir monitoring and surveillancesurveillance is; is; a)a) continuously monitor well continuously monitor well production performance, production performance, b)b) obtain data required to obtain data required to quantify any anomalous behavior and quantify any anomalous behavior and c)c) update the update the reservoir models. reservoir models. Dynamic reservoir characterization data are critical Dynamic reservoir characterization data are critical for evaluating production performancefor evaluating production performance (Pressure (Pressure WD, CH Testing, WD, CH Testing, PLT’sPLT’s & Permanent Sensors, etc.).& Permanent Sensors, etc.).

SPE ACTE 2004SPE ACTE 2004


Drilling & CompletionDrilling & CompletionEconomically producing gas from Economically producing gas from the unconventional sources is a the unconventional sources is a great challenge today and tight gas great challenge today and tight gas reservoirs require advanced reservoirs require advanced techniques to enable migration techniques to enable migration distances from formation to well to distances from formation to well to be reduced. be reduced. Therefore modern technologies for Therefore modern technologies for the production of tight gas the production of tight gas reservoirs are horizontal and reservoirs are horizontal and multilateral wells, as well as undermultilateral wells, as well as under--balanced drilling. balanced drilling. Stimulation and cementing technoStimulation and cementing techno--logieslogies are proving very significant are proving very significant for improved economic production.for improved economic production.

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Importance of Surface logging dataImportance of Surface logging data

C. C. CarugoCarugo, V. , V. CheliniChelini, S. El , S. El ManaaManaa, EAGE, Tunis, 2002, EAGE, Tunis, 2002


Formation TestingFormation Testing

The low permeability of these The low permeability of these reservoirs slows down their response reservoirs slows down their response to pressure transient testing so it is to pressure transient testing so it is difficult to obtain dynamic reservoir difficult to obtain dynamic reservoir properties and, therefore, to properties and, therefore, to characterize gas reserves. characterize gas reserves. Moreover, the determination of real Moreover, the determination of real composition of fluids trapped in tight composition of fluids trapped in tight reservoirs is very challenging, since reservoirs is very challenging, since recovered fluid often reflects the recovered fluid often reflects the composition of the ones related to composition of the ones related to largest pores, interstices and largest pores, interstices and invaded zone.invaded zone. RCI RCI –– Baker AtlasBaker Atlas

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Well logging in Tight ReservoirsWell logging in Tight Reservoirs

High porosity/low permeabilityHigh porosity/low permeability(Sandstones, carbonates & volcanic)(Sandstones, carbonates & volcanic)

Strong diagenetic effects and clay filling by chlorite Strong diagenetic effects and clay filling by chlorite and illite need to be studied by means of ad hoc and illite need to be studied by means of ad hoc petrophysicalpetrophysical models and specialized models and specialized lithologylithology logslogsLow Resistivity contrasts affect Water Saturation Low Resistivity contrasts affect Water Saturation evaluationevaluationGood total porosity determination using Density, Good total porosity determination using Density, Neutron & SonicNeutron & SonicNMR logging: good NMR logging: good ΦΦ estimation, poor K estimationestimation, poor K estimationExtensive laboratory analysis for Archie parameters Extensive laboratory analysis for Archie parameters ((especially “n”especially “n”) are required.) are required.


Low porosity/low permeabilityLow porosity/low permeability(Sandstones & carbonates)(Sandstones & carbonates)

Very high Very high ResistivityResistivity contrasts, anisotropy and contrasts, anisotropy and dipping effects require dipping effects require ResistivityResistivity modelingmodelingLack of accuracy for all porosity logs (Lack of accuracy for all porosity logs (Density, Density, Neutron, Sonic and NMRNeutron, Sonic and NMR))Extensive laboratory analysis for Archie parameters Extensive laboratory analysis for Archie parameters ((especially “m” and especially “m” and RwRw))Need for image log acquisition and interpretation Need for image log acquisition and interpretation ((geology and formation/stress anisotropygeology and formation/stress anisotropy))Need for acoustic anisotropy acquisition and Need for acoustic anisotropy acquisition and interpretation (interpretation (to improve seismic interpretation and to improve seismic interpretation and better characterize in situ stress anisotropybetter characterize in situ stress anisotropy))

Well logging in Tight ReservoirsWell logging in Tight Reservoirs

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Log interpretation uncertainties Log interpretation uncertainties in a tight gas bearing sandstonein a tight gas bearing sandstone

5 ohmm

0.3 – 0.4 ohmm

Uncertainties on Uncertainties on ResistivityResistivity measurements and measurements and petrophysicalpetrophysical modelsmodels

P. P. F.F. WorthingtonWorthington, 2000, 2000



Uncertainties on Archie parameters and log derived porositiesUncertainties on Archie parameters and log derived porosities

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Uncertainties on Uncertainties on on fluid contactson fluid contacts

(CPI vs RFT)(CPI vs RFT)

Supercharge effectSupercharge effecton WFT dataon WFT data

GWC RFT

GWC LOG

Schlumberger WEC AlgeriaSchlumberger WEC Algeria


Uncertainty reduction by integrationUncertainty reduction by integrationTo reduce the uncertainty in the To reduce the uncertainty in the estimation of hydrocarbon inestimation of hydrocarbon inplace and fluid contact in tight gas place and fluid contact in tight gas reservoirs, it is essential toreservoirs, it is essential tointegrate core data and log analysis integrate core data and log analysis (i.e. saturation height functions)(i.e. saturation height functions) to to better define better define petrophysicalpetrophysicalproperties such as properties such as SwSw and FWL.and FWL.(SPE 84390).(SPE 84390).

This implies that the This implies that the Well Data Well Data AcquisitionAcquisition program is defined with program is defined with the strong collaboration among all the strong collaboration among all the different specialists involvedthe different specialists involved(Eni & Total WDA (Eni & Total WDA –– SPE 63284)SPE 63284)

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New Logging technologies: New Logging technologies: Array Acoustic measurementsArray Acoustic measurements

Wire Line technologyWire Line technologyImproved Improved petrophysicalpetrophysicalanalysisanalysisSeismic calibration & AVOSeismic calibration & AVOStoneleyStoneley permeability permeability In situ stress anisotropyIn situ stress anisotropyFracture location (OH/CH)Fracture location (OH/CH)Rock MechanicsRock Mechanics

While DrillingWhile DrillingRealReal--time applications:time applications:

Pressure ManagementPressure ManagementSeismic TimeSeismic Time--Depth TieDepth Tie--In In GeosteeringGeosteeringWell bore instability Well bore instability analysisanalysisFormation EvaluationFormation Evaluation

PostPost--well applications:well applications:Detailed Detailed petrophysicspetrophysicsSeismic calibration & AVOSeismic calibration & AVORock Mechanics. Rock Mechanics.


New Logging technologies: New Logging technologies: Nuclear Magnetic ResonanceNuclear Magnetic Resonance

There are strong limits to the There are strong limits to the application of NMR logging in application of NMR logging in low porosity, low permeability low porosity, low permeability gas bearing formation.gas bearing formation.New tools can better cope with New tools can better cope with these conditions provided that these conditions provided that pre job/post job modeling and pre job/post job modeling and strong integration with all the strong integration with all the available well data (core, available well data (core, pressure data and fluid pressure data and fluid samples, logs, etc.) are samples, logs, etc.) are performed by well trained performed by well trained experts.experts.

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Fracture network characterizationFracture network characterizationTight reservoirs are prone to intense Tight reservoirs are prone to intense fracturing and fracturing and fractures have a strong fractures have a strong impact on drilling, exploration & impact on drilling, exploration & production activitiesproduction activities..The correct knowledge of the The correct knowledge of the relationships between the in situ stress relationships between the in situ stress and the natural fractureand the natural fracture system is of system is of primary importance for:primary importance for:

minimizing drilling risks,minimizing drilling risks,maximizing hydrocarbon production maximizing hydrocarbon production minimizing operational costs.minimizing operational costs.

To achieve these goals, a To achieve these goals, a very strong very strong integration among different disciplinesintegration among different disciplines(i.e. Geosciences, Reservoir Engineering, (i.e. Geosciences, Reservoir Engineering, GeomechanicsGeomechanics, etc.) , etc.) is mandatory!is mandatory!


Fracture network characterizationFracture network characterization

Distribution, orientation and density of Distribution, orientation and density of natural fractures need to be studied but, natural fractures need to be studied but, reservoir engineers also need detailed reservoir engineers also need detailed analyses of the effects of interstitial analyses of the effects of interstitial clays and fluids.clays and fluids.Conventional methods of producing gas Conventional methods of producing gas from tight reservoirs usually requires from tight reservoirs usually requires some form of artificial stimulation (such some form of artificial stimulation (such as hydraulic fracturing) and/or other ad as hydraulic fracturing) and/or other ad hoc completion and production hoc completion and production strategies that are strongly dependant strategies that are strongly dependant on correct characterization of the on correct characterization of the natural fracture systems and in situ natural fracture systems and in situ stress conditions.stress conditions.

SH max directionfrom Image Logs

R. Nelson R. Nelson –– SPE ACTE 2004SPE ACTE 2004

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Fracture Fracture ccharacterization by imaging logsharacterization by imaging logs

Courtesy of SchlumbergerCourtesy of Schlumberger

Open vs drillinginduced fractures

Open vs drillingOpen vs drillinginduced fracturesinduced fractures

Monitoring ofinduced fractures

Monitoring ofMonitoring ofinduced fracturesinduced fractures

In situ stress & fractures

relationships

In situ stress & In situ stress & fracturesfractures

relationshipsrelationships


Well information & well bore stabilityWell information & well bore stability

Courtesy of Baker AtlasCourtesy of Baker Atlas

Importance of OH & CH Importance of OH & CH Shear Wave anisotropyShear Wave anisotropy

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Maximizing production in tight reservoirsMaximizing production in tight reservoirs

To significantly increase To significantly increase production from low production from low permeability and widely permeability and widely dispersed resources, dispersed resources, correct correct well bore positioning is well bore positioning is mandatory!mandatory!This requires extensive use of This requires extensive use of While Drilling Formation While Drilling Formation Evaluation technologies such Evaluation technologies such as as Advanced GeosteeringAdvanced Geosteeringtechniques based on deep techniques based on deep reading Seismic and E. M. reading Seismic and E. M. technologies.technologies.


Deep Resistivity measurementsDeep Resistivity measurements

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Cross hole Electro Magnetic TomographyCross hole Electro Magnetic Tomography

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The IRD suite of technologies includes:The IRD suite of technologies includes:natural fracture identification technologiesnatural fracture identification technologiesto delineate highto delineate high--productivity sections productivity sections within a multiwithin a multi--township tight gas township tight gas accumulation;accumulation;well logging technologieswell logging technologies that reliably that reliably distinguish between gas and water bearing distinguish between gas and water bearing sands, and can help identifying and sands, and can help identifying and quantifying volumes of secondary porosity;quantifying volumes of secondary porosity;multimulti--zone completion technologieszone completion technologies that that can efficiently stimulate multiple zones can efficiently stimulate multiple zones without damaging the formation;without damaging the formation;well testing technologieswell testing technologies to establish to establish drainage volumes, welldrainage volumes, well--toto--well well communication and anisotropic flow communication and anisotropic flow patterns. patterns. Gas TIPS Gas TIPS –– Winter 2004Winter 2004

Tight Gas Sands Development: Tight Gas Sands Development: how to improve Recovery Efficiencyhow to improve Recovery Efficiency

((IIntensive ntensive RResource esource DDevelopment DOE/NETL)evelopment DOE/NETL)

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Time to prepare for the future: Time to prepare for the future: advanced technologies in Tight Gas Sandsadvanced technologies in Tight Gas Sands

Exotic drilling & Well Clustering (offshore technology Exotic drilling & Well Clustering (offshore technology brought to on shore)brought to on shore)Advanced Advanced geosteeringgeosteeringState of the art Well Logging technologies (OH & CH, State of the art Well Logging technologies (OH & CH, WL & WD)WL & WD)Integrated GeosciencesIntegrated GeosciencesNew well completion technologiesNew well completion technologiesNew stimulation techniquesNew stimulation techniquesOn site waste managementOn site waste managementRemote operation control & integrated data Remote operation control & integrated data handling/interpretationhandling/interpretationWell performance surveillance and data handling of Well performance surveillance and data handling of very long term Production Logs &/or Permanent very long term Production Logs &/or Permanent Sensor measurementsSensor measurements


Time to prepare for the future:Time to prepare for the future:what do we need?what do we need?

Implementation of adequate organizational Implementation of adequate organizational strategies in both Operators and Service strategies in both Operators and Service providersprovidersMaking available adequate Making available adequate technicaltechnical (rigs, (rigs, geological and logging units, etc.) and geological and logging units, etc.) and humanhuman(expert geoscientist and engineers) (expert geoscientist and engineers) resourcesresourcesDevelop new geological/geophysical approachesDevelop new geological/geophysical approachesMaking use of advanced Making use of advanced petrophysicalpetrophysical Real Time Real Time (LWD) acquisition/interpretation methods(LWD) acquisition/interpretation methodsImplementation of long term organizational plans Implementation of long term organizational plans and strong integration among the different and strong integration among the different disciplinesdisciplines

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Lessons learned from previous lecturesLessons learned from previous lectures

Steps toward Steps toward ultimate drilling ultimate drilling

performanceperformanceMansur Al Hammad Mansur Al Hammad

Saudi AramcoSaudi Aramco

ConclusionsConclusions::uultimate performance is ltimate performance is a profit of well spent a profit of well spent investments in the investments in the following stepsfollowing steps

TIME


Reserve Analysis for Tight GasReserve Analysis for Tight GasS. A. Cox, Marathon Oil Co.S. A. Cox, Marathon Oil Co.

Regardless the Reserve Analysis Regardless the Reserve Analysis Method used, we need to face several Method used, we need to face several challenges:challenges:

models in use are often models in use are often oversimplified;oversimplified;very long time is required to minimize very long time is required to minimize the uncertainties on the results;the uncertainties on the results;operators need to cope with vast operators need to cope with vast amount of data for a very extended amount of data for a very extended range of time;range of time;strong integration of disciplines is strong integration of disciplines is required.required.

Lessons learned from previous lecturesLessons learned from previous lectures

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Gas ShalesGas ShalesGas shalesGas shales are fine grained rocks are fine grained rocks where the predominant where the predominant gas gas storagestorage mechanism ismechanism is sorptionsorption and and gas is stored in volumes that are gas is stored in volumes that are potentially economic. potentially economic. Since the Since the sorption capacitysorption capacity is mainly is mainly related to related to surface areasurface area and the and the micromicro--porous organic fractionporous organic fraction has the has the highest surface areahighest surface area, gas shales are , gas shales are of necessity organic rich.of necessity organic rich.Rocks included in this definition of Rocks included in this definition of gas shales are gas shales are organic rich organic rich shalesshales, , true shalestrue shales, , mud rocksmud rocks, , siltstonessiltstones, , and and very fine grained sandstonesvery fine grained sandstones..In many basins, gas shales are In many basins, gas shales are gradational with tight sands.gradational with tight sands.Courtesy of HalliburtonCourtesy of Halliburton


Formation Evaluation of Gas ShalesFormation Evaluation of Gas Shales

Primary porosity and permeability Primary porosity and permeability very lowvery lowSuccessful projects depend upon Successful projects depend upon interconnectedness of natural interconnectedness of natural fracture networks, mineralogy and fracture networks, mineralogy and thermal maturity of the shale.thermal maturity of the shale.Shale reservoir analysis is very Shale reservoir analysis is very similar to that is used in CBM similar to that is used in CBM plays, combining petrophysics and plays, combining petrophysics and lab measurements.lab measurements.Wire Line logs can be a very useful Wire Line logs can be a very useful tool in scouting for shale plays and tool in scouting for shale plays and quantifying the reservoir potentialquantifying the reservoir potential

M. Mullen et al. 2004M. Mullen et al. 2004

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Typical well logging response of Typical well logging response of Organic Rich ShalesOrganic Rich Shales

high GRhigh GRhigh Resistivityhigh Resistivitylow densitylow densityhigh Neutronhigh Neutronhigh transit timehigh transit timehigh PEFhigh PEF……

Organic Rich Shale


Total Organic Carbon Total Organic Carbon evaluation using well dataevaluation using well data


Relationships between TOC and Relationships between TOC and Gas content in Organic Rich Shales Gas content in Organic Rich Shales

Gas Shale Gas Shale Characterization Characterization tools are tools are available but available but they need to be they need to be further further developed to developed to maximize gas maximize gas production from production from the source type.the source type.


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Natural Gas from CoalNatural Gas from CoalCoal is the most abundant Coal is the most abundant fossil fuel in the world.fossil fuel in the world.The direct use of coal The direct use of coal dramatically contribute to dramatically contribute to pollution but coal also play as pollution but coal also play as host to plentiful natural gas host to plentiful natural gas resources. resources. Natural gas reserves from coalNatural gas reserves from coalare reported as between are reported as between 100100and and 300 Tm300 Tm33 worldwide.worldwide.Natural gas produced from coal Natural gas produced from coal seams is a more acceptable seams is a more acceptable energy source already being energy source already being exploited in several locations in exploited in several locations in the world.the world.

Schlumberger White Paper on Unconventional Gas (2004)

bp statistical review of world energy June 2004

Important but not documented activity in Central & Eastern Europe


CoalCoalCoal is a compound of solid organic minerals rich in Coal is a compound of solid organic minerals rich in carboncarbon, with very different compositions and properties, , with very different compositions and properties, owing their origin to slow decomposition and chemical owing their origin to slow decomposition and chemical conversion (conversion (coalificationcoalification) of immense masses of organic ) of immense masses of organic material (material (maceralsmacerals, originated mainly from plants), , originated mainly from plants), generally found in stratified deposits in association with generally found in stratified deposits in association with shales and ashes.shales and ashes.

incr

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Some relevant chemical and physical characteristics of coals claSome relevant chemical and physical characteristics of coals classified by rankssified by rank

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Why Natural Gas from Coal ?Why Natural Gas from Coal ?

During coalification, During coalification, large large quantities of methane rich gas quantities of methane rich gas are generated and stored within are generated and stored within the coal on internal surfacesthe coal on internal surfaces..Because coal has such a large Because coal has such a large internal surface area, it can store internal surface area, it can store surprisingly large volumes of surprisingly large volumes of natural gas, six or seven times natural gas, six or seven times as much gas as a conventional as much gas as a conventional natural gas reservoir of equal natural gas reservoir of equal rock volume can hold.rock volume can hold.Methane generation is a function Methane generation is a function of maceral type and thermal of maceral type and thermal maturation process.maturation process.

Producing Natural Gas from Coal – Schlumberger Oilfield Review - Autumn 2003Producing Natural Gas from Coal – Schlumberger Oilfield Review - Autumn 2003


How Natural Gas is produced from Coal ?How Natural Gas is produced from Coal ?Water permeates coal beds and its Water permeates coal beds and its pressure traps methane within coal.pressure traps methane within coal.To produce methane from coals beds, To produce methane from coals beds, water must be drawn off first, water must be drawn off first, lowering the pressure so methane lowering the pressure so methane can flow out of the coal to the well can flow out of the coal to the well bore.bore.Coal beds are often fractured, Coal beds are often fractured, therefore fractures & cleats may therefore fractures & cleats may strongly contribute to gas production.strongly contribute to gas production.Cleat and natural fracture network Cleat and natural fracture network characterization is therefore characterization is therefore important to better define reserves important to better define reserves and in optimizing drilling and and in optimizing drilling and production strategies.production strategies.

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Pre drilling assessmentPre drilling assessment of nature and geometry of the coal of nature and geometry of the coal reservoir (geology and geophysics)reservoir (geology and geophysics)While drilling informationWhile drilling information about main coal reservoir characteristics about main coal reservoir characteristics (coal ranking, reservoir geometry and structure, (coal ranking, reservoir geometry and structure, petrophysicalpetrophysical, , geochemical and geomechanical properties of the reservoir, etc.)geochemical and geomechanical properties of the reservoir, etc.)In situ estimation of permeabilityIn situ estimation of permeability from cleats and natural fractures from cleats and natural fractures and their relationships with in situ stressand their relationships with in situ stressPost drilling integrated Reservoir CharacterizationPost drilling integrated Reservoir Characterization and and ModelingModelingCementing and completionCementing and completion strategies defined in accordance with strategies defined in accordance with the results of Reservoir Characterization/Modeling and the results of Reservoir Characterization/Modeling and Geomechanical studiesGeomechanical studiesIntegrated Production MonitoringIntegrated Production Monitoring and and Reservoir ManagementReservoir Managementstrategies strategies ((i.ei.e stimulation, fracturing, etc.)stimulation, fracturing, etc.) aimed at the aimed at the maximization of gas production and minimization of operational maximization of gas production and minimization of operational costs and environmental impact costs and environmental impact (i.e. water management, etc.)(i.e. water management, etc.)

Natural Gas from Coal: key factorsNatural Gas from Coal: key factors


Formation Evaluation GoalsFormation Evaluation GoalsCoal seams geometry assessmentCoal seams geometry assessmentProximate analysis Proximate analysis (lithology, volume of ashes, fixed carbon, (lithology, volume of ashes, fixed carbon, volatiles, clays, etc.)volatiles, clays, etc.)Coal rank determinationCoal rank determinationAdsorbed gas contentAdsorbed gas contentCleats/natural fracture distribution, aperture & porosityCleats/natural fracture distribution, aperture & porosityIn situ stresses and Geomechanical propertiesIn situ stresses and Geomechanical propertiesProduction monitoring & stimulation strategiesProduction monitoring & stimulation strategies

Formation Evaluation toolsFormation Evaluation toolsFull bore core analysis (Geology & Full bore core analysis (Geology & PetrophysicsPetrophysics))Surface logging & Geochemical dataSurface logging & Geochemical dataOH & CH loggingOH & CH loggingFormation & Well testing, Production Logs & MonitoringFormation & Well testing, Production Logs & Monitoring

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Formation Evaluation aspectsFormation Evaluation aspectsProximate Analysis & Coal rankingProximate Analysis & Coal ranking

ResistivityResistivityDensity/Neutron Density/Neutron Natural & Induced GR spectrometryNatural & Induced GR spectrometryFull bore core dataFull bore core dataSurface logging DataSurface logging DataQuantitative well log interpretationQuantitative well log interpretationGeochemistry of coal & waterGeochemistry of coal & water

Impact onImpact onUnderstanding coal reservoirsUnderstanding coal reservoirsAdsorbed Gas & Reserve evaluationAdsorbed Gas & Reserve evaluationReservoir Modeling & GeomechanicsReservoir Modeling & GeomechanicsEnvironmental issuesEnvironmental issues Producing Natural Gas from Coal Producing Natural Gas from Coal

Schlumberger Oilfield Review Schlumberger Oilfield Review Autumn 2003Autumn 2003


Cleat & fracture characterization, Cleat & fracture characterization, in situ stress and Geomechanicsin situ stress and Geomechanics

OH & CH conventional logsOH & CH conventional logsImage Logging (electrical/acoustic)Image Logging (electrical/acoustic)Digital Acoustic LoggingDigital Acoustic LoggingSurface Logging DataSurface Logging DataFull bore Core dataFull bore Core dataFormation & Well testingFormation & Well testing

Impact on optimization ofImpact on optimization ofDrilling, Drilling, Stimulation Stimulation Production StrategiesProduction StrategiesEnvironmental issuesEnvironmental issues

Formation Evaluation aspectsFormation Evaluation aspects

Producing Natural Gas from Coal Schlumberger Oilfield Review

Autumn 2003

Producing Natural Gas from Coal Producing Natural Gas from Coal Schlumberger Oilfield Review Schlumberger Oilfield Review

Autumn 2003Autumn 2003

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Formation Evaluation AspectsFormation Evaluation AspectsNew developments in Gamma New developments in Gamma Ray Spectrometry improve Ray Spectrometry improve lithology and mineralogy lithology and mineralogy characterization to enhance characterization to enhance Formation Evaluation of Coal Formation Evaluation of Coal Beds for Natural Gas production Beds for Natural Gas production in terms of location, ranking and in terms of location, ranking and geometry.geometry.It is important to remind that a It is important to remind that a rough evaluation of gas rate rough evaluation of gas rate from the estimated volumes of from the estimated volumes of coal is:coal is:

5050--70 ft70 ft33 per ton of coalper ton of coaleconomical thickness of coal economical thickness of coal seems is 20 ft (6 m) or moreseems is 20 ft (6 m) or more


What next in FE techniques used in E&P to What next in FE techniques used in E&P to produce Natural Gas from Coal ?produce Natural Gas from Coal ?

Need to improve geological, geochemical and hydrological Need to improve geological, geochemical and hydrological characterization of natural gas generation and production characterization of natural gas generation and production from coal by means of:from coal by means of:

introduction of novel integrated well data acquisition technologintroduction of novel integrated well data acquisition technologiesiesimprovement of existing well data interpretation methodsimprovement of existing well data interpretation methodsimprovement of existing reservoir engineering and reservoir modeimprovement of existing reservoir engineering and reservoir modeling ling techniquestechniques

Need to improve integration among disciplines to maximize Need to improve integration among disciplines to maximize production and minimize operational costs and environmental production and minimize operational costs and environmental impactimpactNeed to improve education and integration among the Need to improve education and integration among the different actors operators (often small), service contractors different actors operators (often small), service contractors and academia:and academia:

Geoscientists, Reservoir engineers, Drillers, Completion & ProduGeoscientists, Reservoir engineers, Drillers, Completion & Production ction engineers, HSE specialists, Economists, Portfolio & Asset Manageengineers, HSE specialists, Economists, Portfolio & Asset Managers, rs, etc.etc.

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About the actorsAbout the actors

We have seen that each Unconventional Resource type We have seen that each Unconventional Resource type and even each reservoir need the adoption of adequate and even each reservoir need the adoption of adequate and often and often complex integrated strategiescomplex integrated strategies involving many involving many different disciplines, experts and competences.different disciplines, experts and competences.We have seen also the We have seen also the fundamental role of Formation fundamental role of Formation EvaluationEvaluation for the correct handling of the E&P process for the correct handling of the E&P process in Unconventional Hydrocarbon Reservoirs.in Unconventional Hydrocarbon Reservoirs.A potential problemA potential problem of this aspect is related to nature of this aspect is related to nature and size of the operators in the arena of Unconventional and size of the operators in the arena of Unconventional Hydrocarbon Reservoirs (Hydrocarbon Reservoirs (often small independent often small independent companies, National Labs and Academiacompanies, National Labs and Academia) where the ) where the lack lack of financial resources, expertise, team working attitude of financial resources, expertise, team working attitude and adequate Hardware/Software environmentsand adequate Hardware/Software environments, may , may dramatically dramatically influence the efficiency of the processinfluence the efficiency of the process..


Unconventional Hydrocarbon ResourcesUnconventional Hydrocarbon Resourcesrelevant environmental issuesrelevant environmental issues

Tight reservoirsTight reservoirs(land & offshore)(land & offshore)

Gas ShalesGas Shales(land)(land)

Natural gas from Natural gas from coalcoal (land)(land)

Very large number of wells requiredVery large number of wells requiredIntensive stimulation treatments requiredIntensive stimulation treatments required

Water/gas ratio from large to moderateWater/gas ratio from large to moderateIntensive stimulation treatments requiredIntensive stimulation treatments requiredVery large number of wells requiredVery large number of wells required

Very large production of water in early stages Very large production of water in early stages of productionof productionVery large number of wells requiredVery large number of wells required

Formation Evaluation & Integrated Formation Evaluation & Integrated GeoscienceGeoscience Studies canStudies canstrongly contribute to the mitigation of this undesiredstrongly contribute to the mitigation of this undesired

environmental effects.environmental effects.

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Conclusion 1/2Conclusion 1/2

Much is yet to be learned for a successful Much is yet to be learned for a successful exploitation of Unconventional Hydrocarbon exploitation of Unconventional Hydrocarbon resources:resources:

about occurrence, controls and recoverability about occurrence, controls and recoverability (geosciences, engineering, etc.);(geosciences, engineering, etc.);about environmental implications of their about environmental implications of their development and exploitation;development and exploitation;about the global economical and industrial impact of about the global economical and industrial impact of the exploitation.the exploitation.

Formation Evaluation plays a fundamental role of in Formation Evaluation plays a fundamental role of in the integration of the different aspects of the E&P the integration of the different aspects of the E&P Unconventional Hydrocarbon Resources process, but Unconventional Hydrocarbon Resources process, but ......


Conclusion 2/2Conclusion 2/2…… the Formation Evaluation challenge can only be the Formation Evaluation challenge can only be won if:won if:

existing and novel well data acquisition & existing and novel well data acquisition & interpretation technologies are correctly applied;interpretation technologies are correctly applied;planning, acquisition, interpretation of well data planning, acquisition, interpretation of well data process is shared among the different specialist process is shared among the different specialist involved;involved;both Operators and Service Providers are ready to both Operators and Service Providers are ready to cope large volume of data and for long term cope large volume of data and for long term investments in technical & human resources;investments in technical & human resources;highly trained and prone to team working professionals highly trained and prone to team working professionals are involved;are involved;adequate Knowledge Management systems are adequate Knowledge Management systems are implemented.implemented.

Documents

050607Formation Evaluation-tight gas.pdf