摘要
页岩气藏渗透率极低,储层存在很强的应力敏感性,所以需对其进行水力压裂。通过分析吸附解吸、Knudsen 扩散、非稳态窜流和渗流等多种气体运移机制来建立页岩气藏复合模型,采用 Mathieu 函数、Pedrosa 变量代换、正则摄动理论、拉普拉斯变换和 Stehfest 数值反演等方法来求解数学模型,并绘制出无因次拟压力曲线,同时对渗透率模量、SRV 半径、外区裂缝渗透率、扩散系数和解吸压缩系数等相关参数进行敏感性分析。结果显示:气体流动阶段可划分为 9 段,渗透率模量的增加导致气井定产量生产时所需压差增大,而 SRV 半径和解吸压缩系数的增大使得压差减小;较大的外区裂缝渗透率与较小的流度比相对应,扩散系数越大,页岩基质表观渗透率越大,窜流发生的越早。提出的试井模型可提高页岩气藏压力动态分析的准确性,对压裂开发页岩气藏具有一定的理论指导意义。
The permeability of shale gas reservoirs is extremely low,and the formation is stress-sensitive strongly. The hydraulic fracturing is one of the effective exploitation methods. A composite shale gas reservoir model was established by introducing some gas migration mechanisms,such as shale gas adsorption and desorption,Knudsen diffusion,unsteady cross flow and seepage. Mathieu function,Pedrosa variable substitution,regular perturba- tion theory,Laplace transform and Stehfest numerical inversion methods were used to solve the mathematical model,and then the typical curves of dimensionless pseudo-pressure were plotted. The sensitivity analyses were conducted on the relevant parameters,such as permeability modulus,SRV radius,outer region fracture permeability,diffusion coefficient and desorption compressibility. The results show that the gas flow can be divided into nine stages. A larger permeability modulus resulted in a larger pressure difference required for gas well constant production. The larger the SRV radius and the desorption compressibility are,the smaller the pressure difference is. The larger fracture permeability in outer zone corresponds to a smaller mobility ratio. The larger the diffusion coefficient is,the larger the apparent permeability of the shale matrix is,and the earlier the cross flow occurs. The proposed well test model can improve the accuracy of pressure dynamic analysis of shale gas reservoirs and has certain theoretical guiding significance for fracturing development of shale gas reservoirs.
作者
姜瑞忠
张福蕾
崔永正
潘红
张旭
张春光
沈泽阳
JIANG Ruizhong;ZHANG Fulei;CUI Yongzheng;PAN Hong;ZHANG Xu;ZHANG Chunguang;SHEN Zeyang(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,Shandong,China;Research Institute of Oil Production Technology,PetroChina Dagang Oilfield Company,Tianjin 300280,China)
出处
《岩性油气藏》
CSCD
北大核心
2019年第4期149-156,共8页
Lithologic Reservoirs
基金
国家自然科学基金项目“致密储层体积压裂缝网扩展模拟研究”(编号:51574265)
国家重大科技专项“厚层非均质气藏产能评价及预测技术”(编号:2016ZX05027004-004)
“低渗、特低渗油藏水驱扩大波及体积方法与关键技术”(编号:2017ZX05013-002)联合资助
关键词
页岩气
复合模型
压力
应力敏感
椭圆SRV
压裂井
shale gas
composite model
pressure
stress sensitivity
elliptical SRV
fractured well
