吉木萨尔凹陷页岩油密切割压裂多簇裂缝竞争扩展模拟

针对吉木萨尔凹陷芦草沟组页岩油储层地质特征，建立了重点改造井的密切割体积压裂裂缝扩展三维离散元数值模型，模型依据成像测井资料设置了随机分布的天然层理和高角度裂缝，依据纵向分层数据设置了小层及层间界面。模型模拟了不同分簇数和簇间距下的复杂裂缝扩展过程，分析了密切割体积压裂改造过程中多簇裂缝竞争扩展规律和改造后裂缝系统的立体产状。通过数值模拟分析可知：①页岩油储层密切割压裂过程中，多条水力裂缝竞争扩展程度随分簇数的增加及簇间距的减小而增强；②裂缝的竞争扩展是一个地应力、裂缝形态、裂缝宽度动态平衡的过程；③在相同泵排量和压裂时长条件下多簇裂缝系统的波及范围与储层改造面积（SRA）负相关；④高角度天然裂缝更易阻滞和捕获横切缝（垂直于水平井眼的人工主裂缝）；⑤多簇裂缝系统的包络面呈"礼帽"形状，采用交错布置邻井压裂段位置有利于缩减井间未动用储层中油气的渗流距离。

Simulation of competitive propagation of multi-fractures on shale oil reservoir multi-clustered fracturing in Jimsar sag

Based on the geological characteristics of shale oil reservoirs in Lucaogou Formation,Jimsar sag,this paper establishes a three-dimensional discrete element numerical model for the fracture propagation of dense cutting volume fracturing fractures,with a focus on well reconstruction.The model builds the randomly distributed natural beddings and high angle fractures according to the imaging logging data,as well as the sublayer and inter-layer interfaces according to the vertical layering data.It simulates the complex fracture propagation process under different cluster numbers and cluster spacing,analyzes the law of multi-fractures competitive propagation during the reconstruction by dense cutting volume fracturing,and the three-dimensional occurrence of the reconstructed fracture system.The numerical simulation analysis shows that:(1)During the dense cutting fracturing of shale oil reservoir,the degree of competitive propagation of multi hydraulic fractures increases with the increase of cluster number and the decrease of cluster spacing.(2)The competitive propagation of fractures is a dynamic balance process of in-situ stress,fracture morphology and fracture width.(3)The impact range of multi-fracture system is negatively correlated with the stimulated reservoir area(SRA)under the same pump displacement and fracturing duration.(4)High-angle natural fractures are easier to block and capture transverse fractures(main artificial fractures perpendicular to horizontal wellbore).(5)The enveloping area of the multi-fracture system is in the shape of a top hat,and the staggered arrangement of the fracturing sections of adjacent wells is helpful for reducing the seepage distance of oil and gas in the undeveloped reservoirs.