针对页岩气藏受两相复杂流动与流固耦合作用影响导致产能预测难度大的问题,将渗流场分为主改造区、次改造区和未改造区,结合多流态统一输运模型及等效连续非均匀介质物理模型,建立多尺度气-水两相流动流固耦合数学模型,并利用无网格广义有限差分法对数学模型进行编程求解。研究结果表明:无网格广义有限差分法能适应不同计算域情况,避免传统差分网格与非结构网格耦合所导致的运算不稳定;压降前缘在未改造区的传播仅为20 m左右,固体位移主要发生在次改造区与未改造区的交界区域;忽略应力场的影响,气井投产初期产气量被显著高估,到生产后期这种影响逐渐下降;低初始含水饱和度的页岩气藏更有益于开发,储层优选时应重点考虑含水饱和度。研究成果对流固耦合数值模拟及非常规油气藏产能预测具有指导意义。
Aiming at the difficulty of productivity prediction in shale gas reservoirs due to the influence of two-phase complex flow and fluid-solid coupling, the seepage field is divided into the primary modified zone, the secondary modified zone and the unmodified zone, and a multi-scale gas-water two-phase flow-fluid-solid coupling mathematical model is established by combining the multi-fluid unified transport model and the equivalent continuous non-uniform medium physical model, and the mathematical model is programmed and solved by gridless generalized finite difference. The results of the study show that the gridless generalized finite difference method can adapt to different computational domains and avoid the arithmetic instability caused by the coupling of traditional difference grids with unstructured grids; the propagation of the pressure drop leading edge in the unmodified zone is only about 20 m, and the solid displacement mainly occurs in the junction area between the secondary modified and unmodified zones; neglecting the influence of the stress field, the gas production is significantly overestimated at the early stage of gas well production, and this influence gradually decreases at the later stage of production; the shale gas reservoirs with low initial water saturation are more beneficial for development, focusing on water saturation during reservoir selection. The study results have important guidance for future numerical simulations of fluid-solid coupling and unconventional oil and gas reservoir capacity prediction.
[1] 邹才能,赵群,丛连铸,等.中国页岩气开发进展、潜力及前景[J].天然气工业,2021,41(1):1-14.
ZOU Caineng,ZHAO Qun,CONG Lianzhu,et al.Development progress,potential and prospect of shale gas in China[J].Natural Gas Industry,2021,41(1):1-14.
[2] LIN Botao,GUO Jiancheng,LIU Xing,et al.Prediction of flowback ratio and production in Sichuan shale gas reservoirs and their relationships with stimulated reservoir volume[J].Journal of Petroleum Science and Engineering,2020,184:106529.
[3] CUI Guanglei,LIU Jishan,WEI Mingyao,et al.Evolution of permeability during the process of shale gas extraction[J].Journal of Natural Gas Science and Engineering,2018,49:94-109.
[4] ZHAO Yulong,LU Guang,ZHANG Liehui,et al.Numerical simulation of shale gas reservoirs considering discrete fracture network using a coupled multiple transport mechanisms and geomechanics model[J].Journal of Petroleum Science and Engineering,2020,195:107588.
[5] ZAMZAMIAN K,HASHEMIB M Y.A novel meshless method for incompressible flow calculations[J].Engineering Analysis with Boundary Elements,2015,56:106-118.
[6] XU Yunfeng,SHENG Guanglong,ZHAO Hui,et al.A new approach for gas-water flow simulation in multi-fractured horizontal wells of shale gas reservoirs[J].Journal of Petroleum Science and Engineering,2021,199:108292.
[7] BODDULA S,ELDHO T I.A moving least squares based meshless local petrov-galerkin method for the simulation of contaminant transport in porous media[J].Engineering Analysis with Boundary Elements,2017,78:8-19.
[8] DENG Jia,ZHU Weiyao,QI Qian,et al.Study on the steady and transient pressure characteristics of shale gas reservoirs[J].Journal of Natural Gas Science & Engineering,2015,24:210-216.
[9] JAVADPOUR F,FISHER D,UNSWORTH M.Nanoscale gas flow in shale gas sediments[J].Journal of Canadian Petroleum Technology,2007,46(10):55-61.
[10] 亓倩.页岩气储层多级压裂水平井多场耦合非线性渗流理论研宄[D].北京:北京科技大学,2020.
QI Qian.Research on theory of multi-field coupling nonlinear seepage of multi-stage fractured horizontal well in shale gas reservoir[D].Beijing:University of Science and Technology Beijing,2020.
[11] LIU Jiaxuan,SHANG Xinchun,ZHU Weiyao.Investigation on nonlinear multi-scale effects of unsteady flow in hydraulic fractured horizontal shale gas wells[J].Applied Mathematics and Mechanics,2018,39(2):181-192.
[12] BENITO J,UREÑA F,GAVETE L.Influence of several factors in the generalized finite difference method[J].Applied Mathematical Modelling,2001,25(12):1039-1053.
[13] WEI Shiming,JIN Yan,XIA Yang,et al.The flowback and production analysis in sub-saturated fractured shale reservoirs[J].Journal of Petroleum Science and Engineering,2020,186:106694.
[14] GUO Xuyang,SONG Hongqing,WU Kan,et al.Pressure characteristics and performance of multi-stage fractured horizontal well in shale gas reservoirs with coupled flow and geomechanics[J].Journal of Petroleum Science and Engineering,2018,163:1-15.
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