Prediction for formation pressure coefficients based on an equivalent petrophysical model of shale
CHEN Chao1,2, YIN Xingyao1, CHEN Zuqing2, LIU Xiaojing2, XIE Jiatong2
1. School of Geosciences, China University of Petroleum (East China), Qingdao, Shandong 266580, China; 2. SINOPEC Exploration Branch Co., Chengdu, Sichuan 610041, China
Abstract：In recent years, shale gas exploration and development have shown a positive correlation between shale gas production and pressure coefficients, but the accurate seismic prediction is difficult. Shale gas reservoirs contain rich organic matter and pores, and the mineral composition and microstructure are more complex than those of conventional reservoirs. Therefore, this paper built a petrophysical model suitable for marine shale and proposed a coefficient prediction technology for shale formation pressure. Firstly, in combination with the microstructure characteristics of shale re-servoirs and the difference in supporting minerals, the background medium was simulated by SCA and DEM models separately, and an equivalent petrophysical model was constructed given the characteristics of pores and fluids. Secondly, the bulk modulus of the background medium and the equi-valent rock bulk modulus of saturated fluids were calculated, and it was found that the difference between the two moduli positively correlated with the actual drilling pressure coefficient. On this basis, a seismic prediction model was built. Finally, a direct inversion method for the bulk modulus of Gray approximation-based elastic impedance was derived and developed, which realizes the quantitative prediction of the bulk modulus and pressure coefficients of shale formation. The predicted results are in good agreement with actual drilling and poste-rior wells.
郭旭升.南方海相页岩气"二元富集"规律——四川盆地及周缘龙马溪组页岩气勘探实践认识[J].地质学报,2014,88(7):1209-1218.GUO Xusheng.Rules of Two-factor enrichiment for marine shale gas in southern China-understanding from the Longmaxi formation shale gas in Sichuan basin and its surrounding area[J].Acta Geologica Sinica,2014,88(7):1209-1218.
[2]
郭旭升,胡东风,黄仁春,等.四川盆地深层-超深层天然气勘探进展与展望[J].天然气工业,2020,40(5):1-14.GUO Xusheng,HU Dongfeng,HUANG Renchun,et al.Deep and ultra-deep natural gas exploration in the Sichuan Basin:progress and prospect[J].Natural Gas Industry,2020,40(5):1-14.
[3]
何治亮,聂海宽,胡东风,等.深层页岩气有效开发中的地质问题——以四川盆地及其周缘五峰组-龙马溪组为例[J].石油学报,2020,41(4):379-391.HE Zhiliang,NIE Haikuan,HU Dongfeng,et al.Geological problems in the effective development of deep shale gas:a case study of Upper Ordovician Wufeng-Lower Silurian Longmaxi formations in Sichuan basin and its periphery[J].Acta Petrolei Sinica,2020,41(4):379-391.
[4]
黄仁春,魏祥峰,王强.四川盆地东南缘丁山地区页岩气成藏富集的关键控制因素[J].海相油气地质,2017,22(2):25-30.HUANG Renchun,WEI Xiangfeng,WANG Qiang.Key factors of shale gas accumulation in Dingshan area of southeastern Sichuan basin[J].Marine Origin Petroleum Geology,2017,22(2):25-30.
[5]
EATON B A.The equation for geopressure prediction from well logs[C].Fall Meeting of the Society of Petroleum Engineers of AIME,Dallas,Texas,1975,SPE-5544-MS.
[6]
EBERHART-PHILLIPS D,HAN D H,ZOBACK M D.Empirical relationships among seismic velocity,effective pressure,porosity,and clay content in sandstone[J].Geophysics,1989,54(1):82-89.
[7]
FILLIPPONE W R.Estimation of formation parameters and the prediction of overpressures from seismic data[C].SEG Technical Program Expanded Abstracts,1982,1:502-503.
[8]
云美厚.地震地层压力预测[J].石油地球物理勘探,1996,31(4):575-586.YUN Meihou.Formation pressure prediction using seismic data[J].Oil Geophysical Prospecting,1996,31(4):575-586.
[9]
TERZAGHI K.Theoretical Soil Mechanics[M].New York:J.Wiley and Sons,Inc,1943.
[10]
HAN D H,NUR A,MORGAN D.Effects of porosity and clay content on wave velocities in sandstones[J].Geophysics,1986,51(11):2093-2107.
[11]
樊洪海.异常地层压力分析方法与应用[M].北京:科学出版社,2016.FAN Honghai.Analysis methods and applications of abnormal formation pressures[M].Science Press,Beijing,2016.
[12]
SINGH R,RAI C,SONDERGELD C.Pressure depen-dence of elastic wave velocities in sandstones[C].SEG Technical Program Expanded Abstracts,2006,25:1883-1887.
[13]
KHAZANEHDARI J,DUTTA N.High-resolution pore pressure prediction using seismic inversion and velocity analysis[C].SEG Technical Program Expanded Abstracts,2006,25:1540-1544.
[14]
马霄一,李呈呈,白俊,等.基于超声测试的页岩岩石物理特征分析[J].石油地球物理勘探,2021,56(4):801-808.MA Xiaoyi,LI Chengcheng,BAI Jun,et al.Analysis of physical characteristics of shale rock based on ultrasonic testing[J].Oil Geophysical Prospecting,2021,56(4):801-808.
[15]
刘财,邓馨卉,郭智奇,等.基于岩石物理的页岩储层各向异性表征[J].石油地球物理勘探,2018,53(2):339-346.LIU Cai,DENG Xinhui,GUO Zhiqi,et al.Shale reservoir anisotropic characterization based on rock physics[J].Oil Geophysical Prospecting,2018,53(2):339-346.
[16]
刘致水,刘俊州,董宁,等.富有机质岩石横波速度预测方法[J].石油地球物理勘探,2021,56(1):127-136,154.LIU Zhishui,LIU Junzhou,DONG Ning,et al.Investigation to shear-wave velocity prediction method for organic-rich rock[J].Oil Geophysical Prospecting,2021,56(1):127-136,154.
[17]
LEI T,YIN X Y,ZONG Z Y.Pore pressure prediction in orthotropic medium based on rock physics modeling of shale gas[J].Journal of Natural Gas Science and Engineering,2020,74:103091.
[18]
巫芙蓉,周诗雨,邓小江,等.一种改进的页岩气地震约束多因素孔隙压力预测方法[J].天然气工业,2021,41(1):198-204.WU Furong,ZHOU Shiyu,DENG Xiaojiang,et al.An improved seismic-constrained multi-factor pore pressure prediction method for shale gas reservoirs[J].Natural Gas Industry,2021,41(1):198-204.
[19]
郭旭升,胡东风,李宇平,等.涪陵页岩气田富集高产主控地质因素[J].石油勘探与开发,2017,44(4):481-491.GUO Xusheng,HU Dongfeng,LI Yuping,et al.Geological factors controlling shale gas enrichment and high production in Fuling shale gas field[J].Petro-leum Exploration and Development,2017,44(4):481-491.
[20]
郭旭升,李宇平,腾格尔,等.四川盆地五峰组-龙马溪组深水陆棚相页岩生储机理探讨[J].石油勘探与开发,2020,47(1):193-201.GUO Xusheng,LI Yuping,BORJIGEN Tenger,et al.Hydrocarbon generation and storage mechanisms of deep-water shelf shales of Ordovician Wufeng Formation-Silurian Longmaxi Formation in Sichuan Basin,China[J].Petroleum Exploration and Development,2020,47(1):193-201.
[21]
BERRYMAN J G.Long-wavelength propagation in composite elastic media I.spherical inclusions[J].The Journal of the Acoustical Society of America,1980,68(6):1809-1819.
[22]
张光荣,聂海宽,唐玄,等.基于有机孔和生物成因硅优选页岩气富集高产层段的方法及应用——以四川盆地及其周缘五峰组-龙马溪组页岩为例[J].天然气地球科学,2021,32(6):888-898.ZHANG Guangrong,NIE Haikuan,TANG Xuan,et al.Optimization method and application of shale gas enrichment layer based on biogenic silica and organic matter pore:case study of Wufeng-Longmaxi formations shale in the Sichuan basin and its periphery[J].Natural Gas Geoscience,2021,32(6):888-898.
[23]
GRAY D,GOODWAY B,CHEN T W.Bridging the gap:using AVO to detect changes in fundamental elastic constants[C].SEG Technical Program Expanded Abstracts,1999,18:852-855.
[24]
CONNOLLY P.Elastic impedance[J].The Leading Edge,1999,18(4):438-452.
[25]
WHITCOMBE D N.Elastic impedance normalization[J].Geophysics,2002,67(1):60-62.
