考虑岩石变形的页岩气藏双重介质数值模拟  

Dual media numerical simulation of shale gas reservoirs considering rock deformation

作　　者：姜瑞忠[1] 原建伟 崔永正 潘红[2] 李广 张海涛 JIANG Ruizhong;YUAN Jianwei;CUI Yongzheng;PAN Hong;LI Guang;ZHANG Haitao(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao City,Shandong Province,266580,China;Oil Production Technology Institute of Dagang Oilfield Company,PetroChina,Tianjin City,300280,China)

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580 [2]中国石油大港油田分公司采油工艺研究院,天津300280

出　　处：《油气地质与采收率》2019年第4期70-76,共7页Petroleum Geology and Recovery Efficiency

基　　金：国家自然科学基金项目“页岩气藏多级压裂水平井流动特征及产能评价方法研究”(51374227);国家科技重大专项“厚层非均质性气藏产能评价及预测技术研究”(2016ZX05027004-004)和“低渗特低渗油藏耦合力学特性的多重介质模拟方法”(2017ZX05013-002)

摘　　要：为了准确预测页岩气产能,指导实际生产,通过考虑岩石变形所造成的渗透率变化以及页岩气黏性流、表面扩散、Knudsen扩散等渗流机理,将地质力学效应与流体流动进行耦合,建立综合考虑应力敏感和页岩气多种渗流机理的数学模型,采用离散裂缝模型对地层微裂缝和水力裂缝进行描述,利用有限元方法进行求解。结果表明,在表面扩散与Knudsen扩散的作用下,页岩基质渗透率增加,使页岩气累积产气量增加,而应力敏感效应使得基质渗透率降低,从而导致累积产气量降低。表面扩散系数和Langmuir体积越大或井底压力越低,页岩气累积产气量越高。对于Langmuir体积越高的页岩气藏,通过降低井底压力进行开采,更有开发潜力。新建模型的模拟结果与实际历史生产数据拟合效果较好,验证了所建模型的准确性。In order to accurately predict the shale gas productivity and guide the actual production,in the consideration of the permeability change caused by rock deformation and the viscous flow,surface diffusion and Knudsen diffusion of shale gas,and by coupling the geomechanical effect with the fluid flow,a mathematical model that comprehensively considers the stress sensitivity and the various percolation mechanisms of shale gas was proposed. The discrete fracture model was used to describe the microfractures and hydraulic fractures in the formation,and it was solve by finite element method. The results show that surface diffusion and Knudsen diffusion increase shale permeability and further increase the shale gas production. The stress-sensitive effect reduces the matrix permeability,resulting in a decrease in cumulative gas production. The larger surface diffusion coefficient and the Langmuir volume or the lower bottom hole pressure would increase the cumulative gas production of shale gas. For the shale gas reservoirs with a larger Langmuir volume,it is beneficial to reduce the pressure at the bottom of the well to reach a higher production potential. The simulation results of the model fit well with the actual historical production data,which verifies the correctness of the model.

关 键 词：页岩气 岩石变形 应力敏感 表面扩散 Knudsen扩散 

分 类 号：TE328[石油与天然气工程—油气田开发工程]