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页岩气藏矿场压裂实践表明,储层有效改造体积(effective stimulated reservoir volume,简称ESRV)是影响页岩气藏体积压裂水平井生产效果的关键因素,ESRV的准确计算对页岩气藏压裂方案评价与体积压裂水平井产量预测具有重要作用.基于页岩储层改造体积(stimulated reservoir volume,简称SRV)多尺度介质气体运移机制,建立了SRV区域正交离散裂缝耦合双重介质基质团块来表征单元体渗流模型(representation elementary volume,简称REV),并结合北美页岩储层实例研究了次生裂缝间距、宽度等缝网参数对页岩气藏气体运移规律的影响.在此基础上根据SRV区域次生裂缝分布特征,采用分形质量维数定量表征裂缝间距分布规律,结合页岩气藏次生裂缝间距对基质团块内流体动用程度的影响规律,得到了页岩气藏体积压裂ESRV计算方法.结果表明SRV区域次生裂缝间距对基质团块内吸附及自由气影响较大,次生裂缝间距小于0.20m时可以实现SRV区域基质团块内流体向各方向裂缝的“最短距离”渗流.选取北美典型页岩储层生产井体积压裂数据进行ESRV计算,页岩气藏目标井ESRV占体积压裂SRV的37.78%.因此ESRV受改造区域次裂缝分布规律及SRV有效裂缝间距界限的影响,是储层固有性质及人工压裂因素综合作用的结果.
Fracturing practices in shale gas reservoirs have shown that effective stimulated reservoir volume (ESRV) is the key factor affecting the productivity of fractured horizontal wells in shale gas reservoirs. The accurate calculation of ESRV affects the shale gas The evaluation of reservoir fracturing program plays an important role in the prediction of volumetric fracturing horizontal well production.Based on the multi-scale medium gas migration mechanism of stimulated reservoir volume (SRV), the orthogonal discrete fractures coupling dual Medium matrix clumps to characterize the representation elementary volume (REV). Combined with the case of North American shale reservoirs, the effects of secondary crack spacing, width and other seam parameters on gas migration in shale gas reservoirs were studied Based on the distribution characteristics of secondary cracks in SRV area, the fractal dimension was used to quantitatively characterize the distribution of fracture spacing and the influence of the secondary crack spacing of shale gas reservoir on the degree of fluid utilization in the matrix was obtained. ESRV calculation method for volumetric fracturing of gas reservoirs.The results show that the secondary crack spacing in SRV region has a significant effect on the adsorption and free gas , And the shortest distance seepage flow can be achieved when the secondary fracture spacing is less than 0.20m.According to the ESRV calculation of the volumetric fracturing data of North American typical shale production wells, The target reservoir ESRV accounts for 37.78% of the volumetric fracturing SRV, so the ESRV is affected by the distribution of secondary fractures in the area and the effective SRV effective fracture spacing limit, which is the result of the integrated nature of the reservoir properties and fracturing factors.