中文摘要：

水力压裂技术已经在低渗地层的石油天然气开采中得到广泛的应用,螺旋射孔是该技术中的常用措施,在此条件下地层的破裂压力是影响施工成功率和效果的重要因素之一.采用三维有限元方法对螺旋射孔条件下地层的破裂压力进行了研究,建立了套管完井（考虑水泥环及套管的存在）情况下井筒及地层的三维计算模型,首先计算和分析了定向射孔时不同的射孔密度和射孔方向角对地层的破裂压力的影响,与前人的实验结论进行了比较,在此基础上,进行了螺旋射孔条件下不同射孔方位角、相位角以及射孔密度对地层破裂压力的影响的研究,通过数值模拟的结果,给出了螺旋射孔对地层破裂压力的影响规律,可作为进一步研究螺旋射孔条件下的裂缝扩展规律的基础,同时对压裂设计和实际压裂施工中螺旋射孔参数的选取给出了具体的建议.

英文摘要：

Hydraulic fracturing is widely used in natural gas and oil exploitation of low permeability reservoir.Helical perforation is a technology commonly used in hydraulic fracture treatments.A full-scale 3D vertical oil well model under cased completion（including cement sheath and casing） was established.The influence of helical perforations on formation fracture initiation pressure was studied by three-dimensional finite element method.The formation fracture initiation pressure of oriented perforation obtained from the simulation was compared with the experiment results of former research.The formation fracture initiation pressure with different helical perforation orientation angles,phase angles and perforation densities were calculated.The results were compared with the oriented perforation and the influences of helical perforation on fracture initiation pressure were obtained.Suggestions were given for parameter optimization on helical perforation and hydraulic fracturing design.