页岩气富集带地质控制因素及地震预测方法
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摘要
首先对页岩气富集带的地质控制因素及各家的评价指标进行了探讨,认为页岩气的评价指标可以分为两大类:一类是评价页岩气量的多少,即资源因素,它决定了该区页岩气资源潜力及储量的多少,是页岩气资源评价、有利区块优选的关键指标。主要包括页岩厚度、有机质(TOC)丰度、干酪根类型、成熟度(Ro)、天然气含量及状态(游离、吸附)等。另一类决定了页岩气能否经济地开采出来,以及产量的高低,即所谓的"核心区"或"甜点"区。包括埋藏深度、页岩本身的矿物成分、脆度、孔隙度(裂缝)、渗透率以及原始地应力大小、方向及差异等。这两类指标共同控制了页岩气的富集和最终产量。因此,在页岩气勘探开发过程中,应首先利用地质和地球化学方法对第一类指标进行评价,从中优选出有利区块。在有利区块内,可以利用地震相关技术对第二类指标预测和评价,从中优选出适合钻井和开采的页岩气富集带或"甜点"区。根据对页岩气富集带(甜点)地质控制因素的讨论,可以将页岩气划分为"裂隙"型页岩气藏及"脆性"型页岩气,两种类型均需位于弱应力各向异性区,以便于压裂过程中得到理想的复杂网状裂缝系统。笔者认为,对于"裂隙"型页岩气藏,几何地震属性分析技术(包括相干体、蚂蚁体、曲率体等)可以很好地刻画断层、隐伏断层及裂缝发育带,对这些成果的解释可以以玫瑰图的方式展示,从而可以揭示该区域的裂缝的主要发育方向及次要方向,进而推断该区的局部主应力方向,为水平井位部署提供依据。而对于"脆性"型页岩气藏,叠前反演技术、叠后反演技术可以揭示低泊松比(υ),纵横波速比等来进行有利目标(甜点)识别。曾经在常规油气勘探中发挥重要作用的地震技术,在页岩气等非常规油气资源勘探开发中,仍然是一种不可或缺的关键技术。
This paper first discusses about the geological controlling factors of shale gas plays and various evaluation indicators.It is thought that the evaluation indicators of shale gas can be classified into two types.One type should evaluate the volume of gas,i.e.,the resource factors,which decide the resource potential and reserves of this area.This is a key indicator for shale gas resource evaluation and favorable blocks selection,which mainly includes shale thickness,total organic carbon(TOC),types of kerogen,thermal maturity(Ro),natural gas content and condition(free gas or absorbed gas),etc.The other determines whether the shale gas can be recovered economically as well as the output,i.e.,determines a so-called "core zone" or "sweet spot" zone,which includes buried depth,the mineral content of shale itself,brittleness,porosity(fracture),permeability as well as magnitude,orientation and difference of original in-situ stress.The two kinds of indicators jointly control the accumulation and final production of shale gas.Therefore,during the process of shale gas exploration and production,the first indicator should firstly be evaluated by utilizing geological and geochemical methods so as to select optimum favorable blocks,while the second indicator can be predicted and evaluated by using seismic related techniques to select optimum shale gas enrichment area or "sweet spot" zone suitable for drilling and production.According to the discussion about geological controlling factors for shale gas enrichment zone("sweet spot"),the shale gas can be classified into fractured shale gas play and brittle shale gas play.Both of them need to be located in areas of small stress anisotropy so as to obtain complicated fracture network as desired.The author holds that for fractured shale gas play,the geometrical seismic attributes(including coherency,ant-tracking volume and curvature,etc.) can well characterize fault,subtle fault and fractured zone.The interpretation of these outcomes can be displayed through rose diagram.In this way,the dominant orientation and minor orientation of fractures in this area can be disclosed and then deduce the direction of local principal stress,providing foundation for well deployment.As for brittle shale gas play,pre-stack inversion and post-stack inversion technology can disclose low Poisson's ratio,vp/vs ratio and Mu-Rho multi-component analysis to identify favorable object("sweet spot").The seismic technology,once playing a great role in conventional hydrocarbon exploration,is still a necessary technology for unconventional oil and gas exploration and development.
This paper first discusses about the geological controlling factors of shale gas plays and various evaluation indicators.It is thought that the evaluation indicators of shale gas can be classified into two types.One type should evaluate the volume of gas,i.e.,the resource factors,which decide the resource potential and reserves of this area.This is a key indicator for shale gas resource evaluation and favorable blocks selection,which mainly includes shale thickness,total organic carbon(TOC),types of kerogen,thermal maturity(Ro),natural gas content and condition(free gas or absorbed gas),etc.The other determines whether the shale gas can be recovered economically as well as the output,i.e.,determines a so-called "core zone" or "sweet spot" zone,which includes buried depth,the mineral content of shale itself,brittleness,porosity(fracture),permeability as well as magnitude,orientation and difference of original in-situ stress.The two kinds of indicators jointly control the accumulation and final production of shale gas.Therefore,during the process of shale gas exploration and production,the first indicator should firstly be evaluated by utilizing geological and geochemical methods so as to select optimum favorable blocks,while the second indicator can be predicted and evaluated by using seismic related techniques to select optimum shale gas enrichment area or "sweet spot" zone suitable for drilling and production.According to the discussion about geological controlling factors for shale gas enrichment zone("sweet spot"),the shale gas can be classified into fractured shale gas play and brittle shale gas play.Both of them need to be located in areas of small stress anisotropy so as to obtain complicated fracture network as desired.The author holds that for fractured shale gas play,the geometrical seismic attributes(including coherency,ant-tracking volume and curvature,etc.) can well characterize fault,subtle fault and fractured zone.The interpretation of these outcomes can be displayed through rose diagram.In this way,the dominant orientation and minor orientation of fractures in this area can be disclosed and then deduce the direction of local principal stress,providing foundation for well deployment.As for brittle shale gas play,pre-stack inversion and post-stack inversion technology can disclose low Poisson's ratio,vp/vs ratio and Mu-Rho multi-component analysis to identify favorable object("sweet spot").The seismic technology,once playing a great role in conventional hydrocarbon exploration,is still a necessary technology for unconventional oil and gas exploration and development.
引文
①http://www.petersco.com/pdf/Shale%20Gas%20-%20Panel%203%20-%20Devon%20Energy%20Corporation.pdf.
①Paddock D.3Dseismic profiles of U.S.shale plays-An AAPG E-Symposium.http://www.pttc.org/aapg/Paddock-US-Shale-Plays-Presentation.pdf.
[1]张金川,金之钧,袁明生.页岩气成藏机理和分布[J].天然气工业,2004,24(7):15-18.
[2]邹才能,陶士振,袁选俊,等.“连续型”油气藏及其在全球的重要性:成藏、分布与评价[J].石油勘探与开发,2009,36(6):669-681.
[3]Jacobi D,Gladkikh M,LeCompte B,et al.Integrated petro-physical evaluation of shale gas reservoirs[C]∥CIPC/SPE Gas Technology Symposium2008Joint Conference.SPE 114925-MS.2008:1-23.
[4]Curtis J B.A Comparison of estimates of ultimately recovera-ble natural gas in the United States[M]∥Colorado School of Mines,Potential Gas Agency.Gas Resource Studies8.2001:7-14.
[5]Curtis J B.Fractured shale-gas systems[J].AAPG Bulletin,2002,86(11):1921-1938.
[6]Montgomery S L,Jarvie D M,Bowker K A,et al.Mississip-pian Barnett Shale,Fort Worth Basin,north-central Texas:Gas-shale play with multi-trillion cubic foot potential[J].AAPG Bulletin,2005,89(2):155-175.
[7]Bowker K A.Barnett Shale gas production,Fort Worth Ba-sin:Issues and discussion[J].AAPG Bulletin,2007,91(4):523-533.
[8]Gareth R L,Chalmers R,Bustin M.Lower Cretaceous gas shales in northeastern British Columbia,Part II:Evaluation of regional potential gas resources[J].Bulletin of Canadian Petroleum Geology,2008,56(1):22-61.
[9]张金川,薛会,张德明,等.页岩气及其成藏机理[J].现代地质,2003,17(4):466.
[10]陈更生.页岩气藏形成机理与富集规律初探[J].天然气工业,2009,29(5):17-21.
[11]聂海宽,唐玄,边瑞康.页岩气成藏控制因素及中国南方页岩气发育有利区预测[J].石油学报,2009,30(4):484-491.
[12]刘德华,肖佳林,关富佳.页岩气开发技术现状及研究方向[J].石油天然气学报,2011,33(1):119-123.
[13]Parshall J.Barnett Shale showcases tight-gas development[J].Journal of Petroleum Technology,2008,60(9):49-55.
[14]孙赞东,贾承造,李相方,等.非常规油气勘探与开发[M].北京:石油工业出版社,2011:911-952.
[15]Hunter C D,Young D M.Relationship of natural gas occur-rence and production in eastern Kentucky(Big Sandy gas field)to joints and fractures in Devonian bituminous shale[J].AAPG Bulletin,1953,37(2):282-299.
[16]Kucuk F,Sawyer W K.Transient flow in naturally fractured reservoirs and its application to Devonian gas shales[C]∥SPE9397-MS,Presented at SPE Annual Technical Conference and Exhibition of the Society of Petroleum Engineers of AIME,Dallas,Texas,September21-24,1980.doi:10.211819397-MS.
[17]Shumaker R C.A detailed geologic study of three fractured Devo-nian shale gas fields in the Appalachian basin[C]∥SPE10791-MS,Presented at SPE Unconventional Gas Recovery Symposium,16-18May1982,Pittsburgh,Pennsylvania.1982:1-4.
[18]Frohne K H,Mercer J C.Fractured shale gas reservoir per-formance study:An offset well interference field test[J].Journal of Petroleum Technology,1984,36(2):291-300.
[19]MacDonald R J,Frantz J H,Merriam G W,et al.Applica-tion of innovative technologies to fractured Devonian shale reservoir exploration and development activities[C]∥SPE 84816-MS,Presented at SPE Eastern Regional Meeting,6-10 September2003,Pittsburgh,Pennsylvania.2003:1-7.
[20]Paktinat J,Pinkhouse J A,Johnson N,et al.Case study:Optimizing hydraulic fracturing performance in Northeastern United States fractured shale formations[C]∥SPE104306-MS,Presented at SPE Eastern Regional Meeting,11-13Oc-tober2006,Canton,Ohio,USA.2006:1-5.
[21]Gale J F W,Reed R M,Holder J.Natural fractures in the Barnett Shale and their importance for hydraulic fracture treatments[J].AAPG Bulletin,2007,91(4):603-622.
[22]Boyer III,Anstey J A,Nigel A,et al.Seismic velocity ana-lyses to locate shale gas wells[C]∥SPE8972-MS,Presented at SPE Unconventional Gas Recovery Symposium,18-21May 1980,Pittsburgh,Pennsylvania.1980:1-10.
[23]Hilterman F J.Seismic Amplitude Interpretation[M].Tul-sa:Society of Exploration Geophysics,2001:70-85.
[24]Goodway B,Varsek J,Abaco C.Practical applications of P-wave AVO for unconventional gas resource plays:Part1[J].CSEG Recorder,2006,31(3):90-95.
[25]Goodway B,Varsek J,Abaco C.Practical applications of P-wave AVO for unconventional gas resource plays:Part2[J].CSEG Recorder,2006,31(4):53-65.
[26]Goodway B,Perez M,Varsek J,et al.Methods of seismic petrophysics and isotropic-anisotropic AVO for unconvention-al gas exploration[J].The Leading Edge,2010,29(12):1500-1508.
[27]Gray D,Anderson P,Logel J,et al.Estimation of stress and geomechanical properties using3D seismic data[J].First Break,2012,30(3):59-68.
[28]Hunt L,Reynolds R,Brown T,et al.Quantitative estimate of fracture density variations in the Nordegg with azimuthal AVO and curvature:A case study[J].The Leading Edge,2010,29(9):1122-1137.
[29]Zhu Y P,Liu E R,Martinez A,et al.Understanding geo-physical responses of shale gas plays[J].The Leading Edge,2011,30(3):332-338.
①Paddock D.3Dseismic profiles of U.S.shale plays-An AAPG E-Symposium.http://www.pttc.org/aapg/Paddock-US-Shale-Plays-Presentation.pdf.
[1]张金川,金之钧,袁明生.页岩气成藏机理和分布[J].天然气工业,2004,24(7):15-18.
[2]邹才能,陶士振,袁选俊,等.“连续型”油气藏及其在全球的重要性:成藏、分布与评价[J].石油勘探与开发,2009,36(6):669-681.
[3]Jacobi D,Gladkikh M,LeCompte B,et al.Integrated petro-physical evaluation of shale gas reservoirs[C]∥CIPC/SPE Gas Technology Symposium2008Joint Conference.SPE 114925-MS.2008:1-23.
[4]Curtis J B.A Comparison of estimates of ultimately recovera-ble natural gas in the United States[M]∥Colorado School of Mines,Potential Gas Agency.Gas Resource Studies8.2001:7-14.
[5]Curtis J B.Fractured shale-gas systems[J].AAPG Bulletin,2002,86(11):1921-1938.
[6]Montgomery S L,Jarvie D M,Bowker K A,et al.Mississip-pian Barnett Shale,Fort Worth Basin,north-central Texas:Gas-shale play with multi-trillion cubic foot potential[J].AAPG Bulletin,2005,89(2):155-175.
[7]Bowker K A.Barnett Shale gas production,Fort Worth Ba-sin:Issues and discussion[J].AAPG Bulletin,2007,91(4):523-533.
[8]Gareth R L,Chalmers R,Bustin M.Lower Cretaceous gas shales in northeastern British Columbia,Part II:Evaluation of regional potential gas resources[J].Bulletin of Canadian Petroleum Geology,2008,56(1):22-61.
[9]张金川,薛会,张德明,等.页岩气及其成藏机理[J].现代地质,2003,17(4):466.
[10]陈更生.页岩气藏形成机理与富集规律初探[J].天然气工业,2009,29(5):17-21.
[11]聂海宽,唐玄,边瑞康.页岩气成藏控制因素及中国南方页岩气发育有利区预测[J].石油学报,2009,30(4):484-491.
[12]刘德华,肖佳林,关富佳.页岩气开发技术现状及研究方向[J].石油天然气学报,2011,33(1):119-123.
[13]Parshall J.Barnett Shale showcases tight-gas development[J].Journal of Petroleum Technology,2008,60(9):49-55.
[14]孙赞东,贾承造,李相方,等.非常规油气勘探与开发[M].北京:石油工业出版社,2011:911-952.
[15]Hunter C D,Young D M.Relationship of natural gas occur-rence and production in eastern Kentucky(Big Sandy gas field)to joints and fractures in Devonian bituminous shale[J].AAPG Bulletin,1953,37(2):282-299.
[16]Kucuk F,Sawyer W K.Transient flow in naturally fractured reservoirs and its application to Devonian gas shales[C]∥SPE9397-MS,Presented at SPE Annual Technical Conference and Exhibition of the Society of Petroleum Engineers of AIME,Dallas,Texas,September21-24,1980.doi:10.211819397-MS.
[17]Shumaker R C.A detailed geologic study of three fractured Devo-nian shale gas fields in the Appalachian basin[C]∥SPE10791-MS,Presented at SPE Unconventional Gas Recovery Symposium,16-18May1982,Pittsburgh,Pennsylvania.1982:1-4.
[18]Frohne K H,Mercer J C.Fractured shale gas reservoir per-formance study:An offset well interference field test[J].Journal of Petroleum Technology,1984,36(2):291-300.
[19]MacDonald R J,Frantz J H,Merriam G W,et al.Applica-tion of innovative technologies to fractured Devonian shale reservoir exploration and development activities[C]∥SPE 84816-MS,Presented at SPE Eastern Regional Meeting,6-10 September2003,Pittsburgh,Pennsylvania.2003:1-7.
[20]Paktinat J,Pinkhouse J A,Johnson N,et al.Case study:Optimizing hydraulic fracturing performance in Northeastern United States fractured shale formations[C]∥SPE104306-MS,Presented at SPE Eastern Regional Meeting,11-13Oc-tober2006,Canton,Ohio,USA.2006:1-5.
[21]Gale J F W,Reed R M,Holder J.Natural fractures in the Barnett Shale and their importance for hydraulic fracture treatments[J].AAPG Bulletin,2007,91(4):603-622.
[22]Boyer III,Anstey J A,Nigel A,et al.Seismic velocity ana-lyses to locate shale gas wells[C]∥SPE8972-MS,Presented at SPE Unconventional Gas Recovery Symposium,18-21May 1980,Pittsburgh,Pennsylvania.1980:1-10.
[23]Hilterman F J.Seismic Amplitude Interpretation[M].Tul-sa:Society of Exploration Geophysics,2001:70-85.
[24]Goodway B,Varsek J,Abaco C.Practical applications of P-wave AVO for unconventional gas resource plays:Part1[J].CSEG Recorder,2006,31(3):90-95.
[25]Goodway B,Varsek J,Abaco C.Practical applications of P-wave AVO for unconventional gas resource plays:Part2[J].CSEG Recorder,2006,31(4):53-65.
[26]Goodway B,Perez M,Varsek J,et al.Methods of seismic petrophysics and isotropic-anisotropic AVO for unconvention-al gas exploration[J].The Leading Edge,2010,29(12):1500-1508.
[27]Gray D,Anderson P,Logel J,et al.Estimation of stress and geomechanical properties using3D seismic data[J].First Break,2012,30(3):59-68.
[28]Hunt L,Reynolds R,Brown T,et al.Quantitative estimate of fracture density variations in the Nordegg with azimuthal AVO and curvature:A case study[J].The Leading Edge,2010,29(9):1122-1137.
[29]Zhu Y P,Liu E R,Martinez A,et al.Understanding geo-physical responses of shale gas plays[J].The Leading Edge,2011,30(3):332-338.
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