页岩气储层地层压力预测方法及其在四川盆地的应用
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摘要
在构造稳定区,页岩气储层超压的成因以生烃增压为主,常规基于欠压实成因的地层压力预测方法并不适合直接应用于页岩气储层的地层压力预测。为此,以Clay-Plus-Silt(CPS)模型为基础,考虑干酪根生烃的影响,基于岩石物理建模的思路,提出了一种新的正常压实速度趋势线构建方法,并结合Eaton方程形成新的页岩气储层地层压力预测模型。该模型能够更好地反映岩性变化对正常压实速度的影响,并且对实测压力数据的要求更低。基于该模型正演得到的正常压实速度,结合高精度叠后波阻抗反演,建立了页岩气储层地震地层压力预测技术流程。四川盆地某页岩气区块实际应用表明,该方法能有效提高页岩气储层钻前地层压力的预测精度。
Overpressure in tectonically stable regions of shale gas reservoirs is primarily caused by hydrocarbon generation.Conventional undercompaction-based methods are not applicable in these regions.Based on the Clay-Plus-Silt(CPS)model,along with the hydrocarbon effect,a normal compaction trend(NCT)was constructed using the rock physics modeling approach.The NCT was further combined with Eaton's equation to form a new pressure prediction model for shale reservoirs.This model can better reflect the influence of lithological change on normal compaction velocity with fewer measured pressure data.Combining the normal compaction velocity obtained by forward modeling,using the proposed model,with high-precision poststack impedance inversion,a seismic overpressure prediction workflow for shale gas reservoirs was constructed.Application results of this model from the Sichuan basin of China indicate its superiority in predicting predrill pore pressure.
Overpressure in tectonically stable regions of shale gas reservoirs is primarily caused by hydrocarbon generation.Conventional undercompaction-based methods are not applicable in these regions.Based on the Clay-Plus-Silt(CPS)model,along with the hydrocarbon effect,a normal compaction trend(NCT)was constructed using the rock physics modeling approach.The NCT was further combined with Eaton's equation to form a new pressure prediction model for shale reservoirs.This model can better reflect the influence of lithological change on normal compaction velocity with fewer measured pressure data.Combining the normal compaction velocity obtained by forward modeling,using the proposed model,with high-precision poststack impedance inversion,a seismic overpressure prediction workflow for shale gas reservoirs was constructed.Application results of this model from the Sichuan basin of China indicate its superiority in predicting predrill pore pressure.
引文
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[16]BACKUS G E.Long-wave elastic anisotropy produced by horizontal layering[J].Journal of Geophysical Research,1962,67(11):4427-4440
[17]SAYERS C M.The effect of kerogen on the elastic anisotropy of organic-rich shales[J].Geophysics,2013,78(2):D65-D74
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[19]VERNIK L,NUR A.Ultrasonic velocity and anisotropy of hydrocarbon source rocks[J].Geophysics,1992,57(5):727-735
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[22]RASOLOFOSAON P,TONELLOT T.Method for quantitative evaluation of fluid pressures and detection of overpressures in an underground medium:US20090093963A1[P].2008-10-02
[23]郭旭升.涪陵页岩气田礁石垻区块富集机理与勘探技术[M].北京:科学出版社,2014:267-271GUO X S.Accumulation mechanism and exploration technology for the Jiaoshiba block of Fuling shale gas field[M].Beijing:Science Press,2014:267-271
[2]孙武亮,孙开峰.地震地层压力预测综述[J].勘探地球物理进展,2007,30(6):428-432SUN W L,SUN K F.Summarization of geopressure prediction using seismic data[J].Progress in Exploration Geophysics,2007,30(6):428-432
[3]PENNEBAKER E S J R.Seismic data indicate depth,magnitude of abnormal pressure[J].World Oil,1968,166:73-78
[4]EATON B A.Graphical method predicts geopressure worldwide[J].World Oil,1972,182:51-56
[5]FILLIPPONE W R.Estimation of formation parameters and the prediction of overpressure from seismic data[J].Expanded Abstracts of 52nd Annual Internat SEG Mtg,1982:502-503
[6]DUTTA N C.Geopressure prediction using seismic data:current status and the road ahead[J]:Geophysics,2002,67(6):2012-2041
[7]TERZAGHI K.Theoretical soil mechanics[M].New York:John Wiley and Sons,1943:528-530
[8]吴波,王荐,潘树林,等.基于高低频速度闭合技术的地层压力预测[J].石油物探,2017,56(4):575-580WU B,WANG J,PAN S L,et al.Formation pressure prediction based on a closed velocity body by merging the high frequency velocity with the low frequency velocity[J].Geophysical Prospecting for Petroleum,2017,56(4):575-580
[9]李金磊.涪陵焦石坝页岩气层压力预测技术研究[J].石油物探,2017,56(4):567-574LI J L.Pressure prediction of Jiaoshiba shale gas reservoir in the Fuling Shale Gasfield[J].Geophysical Prospecting for Petroleum,2017,56(4):567-574
[10]SUWANNASRI K,PROMRAK W,UTITSAN S,et al.Reducing the variation of Eaton's exponent for overpressure prediction in a basin affected by multiple overpressure mechanisms[J].Expanded Abstracts of 84th Annual Internat SEG Mtg,2014:SB57-SB68
[11]HUFFMAN A R,BOWERS G L.The future of pressure prediction using geophysical methods[J].AAPG Memoir,2002,76:217-233
[12]PERVUKHINA M,DEWHURST D,GUREVICH B,et al.Stress-dependent elastic properties of shales:measurement and modeling[J].The Leading Edge,2008,27(6):772-779
[13]PERVUKHINA M,GOLODONIUC P,GUREVICH B,et al.An estimation of sonic velocities in shale using clay and silt fractions from the elemental capture spectroscopy log[J].Extended Abstract of 74th EAGE Conference&Exhibition,2012:4-7
[14]PERVUKHINA M,CLAUDIO D P,DEWHURST D N,et al.An estimation of pore pressure in shales from sonic velocities[J].Expanded Abstracts of 83rd Annual Internat SEG Mtg,2013:2653-2657
[15]HAN T,PERVUKHINA M,CLENNELL M B.Overpressure prediction in shales[J].Extended Abstract of76th EAGE Conference&Exhibition,2014:16-19
[16]BACKUS G E.Long-wave elastic anisotropy produced by horizontal layering[J].Journal of Geophysical Research,1962,67(11):4427-4440
[17]SAYERS C M.The effect of kerogen on the elastic anisotropy of organic-rich shales[J].Geophysics,2013,78(2):D65-D74
[18]GUO Z Q,CHAPMAN M,LI X Y.A shale rock physics model and its application in the prediction of brittleness index,mineralogy,and porosity of the Barnett Shale[J].Expanded Abstracts of 82nd Annual Internat SEG Mtg,2012:1-5
[19]VERNIK L,NUR A.Ultrasonic velocity and anisotropy of hydrocarbon source rocks[J].Geophysics,1992,57(5):727-735
[20]VERNIK L,LANDIS C.Elastic anisotropy of source rocks,implications for hydrocarbon generation and primary migration[J].AAPG Bulletin,1996,80(4):531-544
[21]石万忠,何生,陈红汉.多地震属性联合反演在地层压力预测中的应用[J].石油物探,2006,45(6):580-585SHI W Z,HE S,CHEN H H.Application of joint inverse modeling of multi-seismic-attributes in predicting formation pressure[J].Geophysical Prospecting for Petroleum,2006,45(6):580-585
[22]RASOLOFOSAON P,TONELLOT T.Method for quantitative evaluation of fluid pressures and detection of overpressures in an underground medium:US20090093963A1[P].2008-10-02
[23]郭旭升.涪陵页岩气田礁石垻区块富集机理与勘探技术[M].北京:科学出版社,2014:267-271GUO X S.Accumulation mechanism and exploration technology for the Jiaoshiba block of Fuling shale gas field[M].Beijing:Science Press,2014:267-271