由于天然裂缝系统分布十分复杂,造成裂缝性储层水力压裂施工砂堵、多裂缝延伸等复杂情况时有发生,施工失败几率增多.从裂缝性储层压裂数值分析的难点入手,引入分形几何理论系统分析断裂和裂缝分布的分形维数,建立大、小尺寸裂缝分形维数之间的回归关系式,并编制可视化软件研究天然裂缝的二维迹线分布和分形参数对天然裂缝孔隙度及渗透率等参数的影响,并在二维PKN和KGD模型的基础上分析了分形参数对压裂缝几何特征的影响规律.研究结果表明:大尺寸断裂与小尺寸裂缝在分布上具有相似性,天然裂缝分布的孔隙度和渗透率随着裂缝发育程度的变化呈正增长趋势,PKN、KGD模型计算的缝长、缝宽都随分形维数的增大呈递减趋势.%The complexity distribution of natural fracture system leads to complex situations in hydraulic fracturing in reservoirs with rrnnatural fractures, such as proppant plugging and the extension of multi -fractures, and leads to high probability of failure rrnoperation. Starting from the difficult points of numerical simulation for fracturing in reservoirs with natural fractures, rrnfractal geometry theory is introduced to systematically analyze the fractal geometry of cracks and fracture distribution; the rrnregression relations among fracture fractal dimension; software is programmed to study the influence of 2D line distribution rrnand fractal parameters on the parameters of natural fractures, such as porosity, permeability, etc; the influence regularity rrnof fractal parameters on the geometry regularity of fractured fractures based on 2D models of PKN and KGD. The study results rrnshow that the distribution of large fractures and small fractures are similar; porosity and permeability of natural fracture rrndistribution take on increasing; and the fracture length and width calculated with PKN and KGD decrease with the increase in rrnfractal dimension.
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