页岩气藏压裂水平井产量递减曲线分析法  

Advanced production decline analytical method for a multi-fractured horizontal well in shale gas reservoirs

作　　者：魏明强[1] 段永刚[1] 方全堂[1] 李安豪 卢婷[1] 

机构地区：[1]西南石油大学石油与天然气工程学院,四川成都610500

出　　处：《天然气地球科学》2016年第5期898-904,共7页Natural Gas Geoscience

基　　金：国家重点基础研究发展计划项目"页岩气气藏工程方法基础研究"(编号:2013CB228005)资助

摘　　要：页岩气藏属于典型的超低孔、超低渗气藏,一般采用多级压裂水平井才具有经济开采价值。与常规气藏相比,页岩储层中气体流动存在吸附解吸、扩散和渗流等多重运移机制,并且页岩基质表面的气体吸附解吸、扩散与压力间存在很强的非线性关系,采用解析/半解析法开展其产量递减分析存在很大的局限性。为此,基于压裂水平井非结构PEBI网格,引入尘气模型建立并推导了综合考虑页岩气藏吸附解吸、扩散和达西流运移机制下的无限导流压裂水平井产量递减数学模型,结合Blasingame产量递减方法原理计算获得了页岩气藏无限导流压裂水平井Blasingame产量递减典型曲线,讨论了相关参数对典型曲线的影响。结果表明:页岩气藏无限导流压裂水平井产量递减曲线划分为地层线性流、裂缝早期径向流、复合线性流和边界拟稳定流4个流动阶段;吸附解吸作用越强,q/Δp_p、(q/Δp_p)_i和(q/Δp_p)_(id)值越大,且PL对典型曲线的影响是非线性的,而VL对其影响是线性的;扩散系数具有提高超低渗页岩储层的气体流动能力,起到增加气井产量的作用;渗透率、裂缝数量和裂缝半长越大,产量递减典型曲线对应值就越大;裂缝间距主要影响产量递减曲线复合线性流段,裂缝间距越大,典型曲线进入复合线性流的时间越晚;井控半径主要影响典型曲线拟稳定流段,井控半径越大,系统进入拟稳定流段的时间越晚。Multi-stage fractured horizontal well（MFHW）technology is widely applied in typical ultra-low porosity and permeability shale gas reservoirs.Compared to conventional reservoirs,there are several transport mechanisms such as adsorption/desorption,diffusion and Darcy flow in the shale gas reservoirs.And there is a significant limitation of using analytical/semi-analytical method to analyze transient pressure behaviors since a strong nonlinear relationship between adsorption/desorption,diffusion and pressure.Thus,Based on multi-fractured horizontal well（MFHW）＇s perpendicular bisection（PEBI）grids,the production decline numerical mathematical model of infinite conductive MFHW which considers adsorption/desorption,diffusion and Darcy flow in shale gas reservoir is established and derived by introducing the Dusty Gas Model.According to the basic principle of Blasingame production decline,the Blasingame production decline typical curves are calculated through computer programming.The results show that the flow behaviours of infinite conductive MFHW＇s Blasingame production decline typical curves are divided into four stages（i.e.,early formation linear flow around fracture,early radial flow,compound linear flow,and pseudo-radial elliptic flow）.The effect of adsorption/desorption is stronger,q/Δpp,（q/Δpp）i and（q/Δpp）i dvalue become larger,meanwhile the typical curves are influenced by PLnonlinearly,and by VLlinearly.The flow capability in shale gas reservoirs with ultra-permeability and the well rate can be improved by diffusion parameter.As the formation permeability（k）,fracture number（nf）,and fracture half-length（xf）increase,the values of q/Δpp,（q/Δpp）i,and （q/Δpp）（id） of the production decline type curves become larger.The fracture spacing dfinfluences the compound linear flow stage of production decline typical curves,and the compound linear flow appears later with dfincreasing.And the pseudo-radial flow is mainly affected by distance from the well to the circular

关 键 词：页岩气 吸附解吸 压裂水平井 PEBI网格 产量递减 

分 类 号：TE37[石油与天然气工程—油气田开发工程]