低渗透储层射孔参数对起裂压力的影响

裂缝起裂是关系水力压裂成败的关键，而射孔参数是影响裂缝起裂的关键因素之一。根据岩石力学、渗流力学、弹塑性力学，建立了低渗透储层射孔地应力力学模型，在考虑流固耦合效应及动态效应的基础上，运用有限元法，建立耦合有限元模型，并采用Newton法求解，以获得低渗透储层?历钻井?固井?射孔?压裂不同阶段后的地应力分布状态。结合岩石的破裂准则，分析射孔参数对起裂压力的影响:地层破裂压力随着方位角的增加而增大，射孔与最大水平地应力的夹角最好不超过30°；随孔眼直径增加，破裂压力降低，选择16 mm孔眼较为合适；随射孔密度增加，起裂压力整体呈下降趋势；在射孔根部起裂时，随着孔深增加，起裂压力先减小后增加，孔深为0.5 m时，起裂压力最低，在射孔尖端起裂时，随着孔深增加，起裂压力降低。此研究结果可作为低渗透储层射孔参数优化的依据。

Effect analysis of perforating parameters upon initiation pressure in low permeability reservoir

Hydraulic fracturing is carried on the perforated well, and the fracture breakdown influenced by the perforating parameters is critical to the result of hydraulic fracturing. Based on the rock mechanics, percolation mechanics and plastoelasticity, the perforation mechanical model for low permeability reservoir is established. Using the finite element method, the finite element model is established considering fluid-solid coupling effect and transient effect, then the Newton method is used to solve, the geostress distribution can be obtained after different stages from drilling to cementing, perforation and fracturing. Combined with the rock fracture criterion, the effect of perforation parameters upon initiation pressure can be analyzed. The results may be used as basis to optimize the perforating parameters for the low permeability reservoir.