In response to the insufficient understanding of multi-scale fluid flow behavior under fluid-solid coupling in shale reservoirs,stress sensitivity experiments and Biot coefficient measurements were employed to study the inherent characteristics of shale matrix and fractures and their sensitivity to stress respectively.The interactions between micro-scale seepage and macro-scale effective stress were analyzed.Based on the effective stress principle,mathematical models were established for shale reservoir matrix-fracture porosity and permeability under effective stress,and the impacts of various fluid-solid coupling parameters on multi-scale flow in shale reservoirs were analyzed.The results show that the average stress sensitivity coefficients of the matrix and fractures are 0.220 and 0.081 respectively,indicating the matrix is more stress-sensitive than fractures.The average Biot coefficients of the matrix and fractures are 0.310 and 0.710 respectively,indicating the matrix's Biot coefficient is smaller than that of the fractures,thus pore pressure in fracture-developed reservoirs has a non-negligible impact on reservoir productivity.The smaller the normal stiffness,elastic modulus,Poisson's ratio,and initial porosity,the larger the Biot coefficient,and the stronger the fluid-solid coupling interaction between the matrix and fracture network,resulting in more obvious permeability reduction.Gas desorption-induced expansion causes deformation of shale matrix grains,enhancing fluid-solid coupling in the matrix.In proppant-filled fractures,larger proppant size and more layers of sand increase the normal stiffness of fractures,thereby improving fracture flow conductivity and weakening fluid-solid coupling effects.The proposed seepage model more comprehensively considers the influence of fluid-solid coupling mechanical parameters and can more accurately analyze the impact of fluid-solid coupling on multi-scale seepage behavior in shale,greatly simplifying calculations and improving computation speed.The findings provide a theoretical basis for the effective development of shale reservoirs.
[1] ZHANG Q,WANG D W,SU L Y,et al.A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics[J].Petroleum Science,2024,21(1):327-342.
[2] 张志强,师永民,李鹤.致密油气藏储层应力敏感各向异性及其微观机制——以鄂尔多斯盆地安塞油田长6油层为例[J].石油与天然气地质,2016,37(1):117-124.
ZHANG Zhiqiang,SHI Yongmin,LI He.Stress sensitivity anisotropy and its microscopic mechanism of tight oil and gas reservoirs:a case from Chang 6 Reservoir in Ansai Oilfield of Ordos Basin[J].Oil & Gas Geology,2016,37(1):117-124.
[3] 慎国强,刘浩杰,王振涛,等.致密储层复杂缝网流固耦合渗流规律及产能模拟[J].大庆石油地质与开发,2023,42(4):157-165.
SHEN Guoqiang,LIU Haojie,WANG Zhentao,et al.Fluid-solid coupling seepage law and productivity simulation of complex fracture networks in tight reservoirs[J].Petroleum Geology & Oilfield Development in Daqing,2023,42(4):157-165.
[4] LIU W R,LIU P.Novel shale permeability model considering the internal dependencies of effective stress, gas sorption, and flow-regime effects[J].Energy and Fuels,2023,37(8):5777-5791.
[5] SINHA S,BRAUN E M,DETERMAN M D,et al.Steady-state permeability measurements on intact shale samples at reservoir conditions-effect of stress,temperature,pressure,and type of gas[C].SPE164263,2013:1-11.
[6] HAN Z,PIDHO J J,YAN C,et al.Study on multiscale fluid-solid coupling theoretical model and productivity analysis of horizontal well in shale gas reservoirs[J].Energy and Fuels,2023,37(7):5059-5077.
[7] 赵谦平,王博涛,姜磊,等.页岩气多场耦合渗透率计算模型[J].特种油气藏,2017,24(2):125-130.
ZHAO Qianping,WANG Botao,JIANG Lei,et al.Computational model for multi-field coupling permeability of shale gas[J].Special Oil & Gas Reservoirs,2017,24(2):125-130.
[8] 吴建发,朱维耀,张德良,等.页岩气藏两相流固耦合无网格数值模拟[J].特种油气藏,2023,30(4):96-103.
WU Jianfa,ZHU Weiyao,ZHANG Deliang,et al.Non-grid numerical simulation of two-phase fluid-solid coupling for shale gas reservoir[J].Special Oil & Gas Reservoirs,2023,30(4):96-103.
[9] YANG Y,APLIN A C.Permeability and petrophysical properties of 30 natural mudstones[J].Journal of Geophysical Research,2007,112(B03206):1-14.
[10] CHALMERS G R L,ROSS D J K,BUSTIN R M.Geological controls on matrix permeability of Devonian gas shales in the Horn River and Liard Basins,Northeastern British Columbia,Canada[J].International Journal of Coal Geology,2012,103(23):120-131.
[11] 马东旭.页岩气藏多重介质流-固耦合渗流规律研究[D].北京:北京科技大学,2019.
MA Dongxu.Study on fluid-solid coupling in multiple medium and its influence on seepage law for shale gas reservoirs[D].Beijing:University of Science and Technology Beijing,2019.
[12] WALSH J B,GROSENBAUGH M A.A new model for analyzing the effect of fractures on compressibility[J].Journal of Geophysical Research,1979,84(B7):3532-3536.
[13] 乔丽苹,王者超,李术才.基于Tight gas致密砂岩储层渗透率的有效应力特性研究[J].岩石力学与工程学报,2011,30(7):1422-1427.
QIAO Liping,WANG Zhechao,LI Shucai.Effective stress law for permeability of Tight gas reservoir sandstone[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(7):1422-1427.
[14] 朱维耀,马东旭,亓倩,等.复杂缝网页岩压裂水平井多区耦合产能分析[J].天然气工业,2017,37(7):60-68.
ZHU Weiyao,MA Dongxu,QI Qian,et al.Multi-zone coupling productivity of horizontal well fracturing with complex fracture networks in shale gas reservoirs[J].Natural Gas Industry,2017,37(7):60-68.
[15] 朱维耀,陈震,宋智勇,等.中国页岩气开发理论与技术研究进展[J].工程科学学报,2021,43(10):1397-1412.
ZHU Weiyao,CHEN Zhen,SONG Zhiyong,et al.Research progress in theories and technologies of shale gas development in China[J].Chinese Journal of Engineering,2021,43(10):1397-1412.
[16] 张宏学.页岩储层渗流-应力耦合模型及应用[D].北京:中国矿业大学,2015.
ZHANG Hongxue.Seepage and stress coupling model for shale reservoir and its application[D].Beijing:China University of Mining and Technology,2015.
[17] 陈更生, 石学文, 刘勇, 等. 四川盆地南部地区五峰组-龙马溪组深层页岩气富集控制因素新认识[J]. 天然气工业, 2024, 44(1): 58-71.
CHEN Gengsheng, SHI Xuewen, LIU Yong, et al. New understandings of the factors controlling of deep shale gas enrichment in the Wufeng Formation-Longmaxi Formation of the southern Sichuan Basin[J]. Natural Gas Industry, 2024, 44(1): 58-71.
[18] 吴永辉, 姜振学, 吴建发, 等. 渝西地区高含水页岩气藏特征、形成机理及地质意义[J]. 天然气工业, 2024, 44(8): 58-71.
WU Yonghui, JIANG Zhenxue, WU Jianfa, et al. Characteristics, formation mechanism and geological implications of high water-cut shale gas reservoirs in western Chongqing Area[J]. Natural Gas Industry, 2024, 44(8): 58-71.
