页岩储层多段压裂后裂缝自然闭合压力递减规律

发布时间：2018-08-17 11:08

【摘要】：页岩储层具有低孔隙度、超低渗透率的物性特征,目前通过水平井分段多级压裂对储层进行增产改造是高效开发页岩等非常规储层的关键技术。但由于流体在水平井多条裂缝同时闭合时的流动特征与单条裂缝时明显不同,导致现阶段针对压裂直井成熟的压力递减分析方法不能直接应用于页岩储层分段多级压裂后的压力递减分析。考虑裂缝自然闭合时引起的应力敏感效应和页岩储层中天然微裂隙发育的地质特征,采用双重孔隙介质渗流模型,分析压裂液在页岩储层中的滤失,并结合以弹塑性力学理论为基础的拟三维裂缝模型,建立裂缝体积守恒方程,得到针对页岩储层分段多级压裂后关井期内裂缝自然闭合条件下的压力递减模型。分析结果表明,储层中基质孔隙度、裂缝渗透率和应力敏感系数是影响关井时压力递减的主要因素。
[Abstract]:Shale reservoir has the characteristics of low porosity and ultra-low permeability. At present, it is the key technology to develop shale and other unconventional reservoirs efficiently by multi-stage fracturing in horizontal wells. However, the flow characteristics of fluid in horizontal wells with multiple fractures closing at the same time are obviously different from those of single fractures. As a result, the pressure decline analysis method, which is mature for fracturing vertical wells at present, can not be directly applied to the pressure decline analysis of shale reservoir after multistage fracturing. Considering the stress-sensitive effect caused by the natural closure of fractures and the geological characteristics of the development of natural micro-fractures in shale reservoir, the filtration loss of fracturing fluid in shale reservoir is analyzed by using a dual porous medium percolation model. Combined with the pseudo-three-dimensional fracture model based on elasto-plastic mechanics theory, the fracture volume conservation equation is established, and the pressure decline model is obtained under the condition of natural closure of fractures in shut-in stage after multistage fracturing in shale reservoirs. The results show that the matrix porosity, fracture permeability and stress sensitivity coefficient are the main factors that affect the pressure decline during shut-in.
【作者单位】：西南石油大学油气藏地质及开发工程国家重点实验室;
【基金】：国家自然科学基金重大项目“页岩地层动态随机裂缝控制机理与无水压裂理论”(51490653) 国家“973”计划“中国南方海相页岩气高效开发的基础研究”(2013CB228004)
【分类号】：TE377

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