Abstract Oriented perforation steering fracturing technology with the purpose of enlarging fracture extension scale and increasing reservoir reconstruction volume is a common method for stimulating and reforming low permeability oil and gas reservoirs. Accurate prediction of the fracture deflection trajectory is the key to successful implementation of this technology. Based on the relevant theories of elastic fracture mechanics and the microelement method, a prediction model for the fracture deflection trajectory of steering fracturing is established by comprehensively considering the influences of horizontal in situ stress difference, perforation parameters, injection parameters and formation mechanics parameters. The model completes the cyclic iteration calculation between the minor increment and the propagation direction angle of the crack tip using the calculation program compiled by Visual Basic and realizes the simulation of the dynamic propagation of steering fractures. Taking the tight sandstone reservoir of the Shihezi Formation in Linxing block as an example, the differences between the hydraulic fracture trajectory calculated by this model and the extended finite element model and the micro-seismic monitoring values in the fracturing field were compared, and the influence of various factors on the deflection distance of the hydraulic fracture trajectory were studied. The results show that, compared with the XFEM model, the hydraulic fracture trajectory simulated by this model has better matching with the micro-seismic monitoring results. The deflection distance decreases negatively logarithmically with increasing horizontal in situ stress difference and increases linearly with increasing fracturing fluid displacement and viscosity. The larger the perforated angle, the longer the deflection distance, and the length of perforation has little effect on the deflection distance. The model and conclusions are significant to further understand oriented perforation steering fracturing.

中文翻译：

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基于微元法的低渗透油藏定向射孔导向压裂动态裂缝扩展模型

摘要 以扩大裂缝延伸规模、增加储层改造量为目的的定向射孔导向压裂技术是低渗透油气藏增产改造的常用方法。准确预测裂缝偏转轨迹是该技术成功实施的关键。基于弹性断裂力学相关理论和微元法，综合考虑水平地应力差、射孔参数、注入参数和地层力学参数的影响，建立了导向压裂裂缝偏转轨迹预测模型。该模型利用Visual Basic编写的计算程序完成了裂纹尖端微小增量与扩展方向角之间的循环迭代计算，实现了转向裂缝动态扩展的模拟。以临兴区块石河子组致密砂岩储层为例，对比了该模型与扩展有限元模型计算出的水力压裂轨迹与压裂现场微地震监测值的差异，并对其影响进行了对比分析。研究了影响水力压裂轨迹偏转距离的各种因素。结果表明，与XFEM模型相比，该模型模拟的水力压裂轨迹与微地震监测结果具有更好的匹配性。偏转距离随着水平地应力差的增加呈负对数减少，随着压裂液位移和粘度的增加呈线性增加。穿孔角度越大，偏转距离越长，穿孔长度对偏转距离影响不大。该模型和结论对于进一步理解定向射孔导向压裂具有重要意义。