定向射孔压裂起裂与射孔优化设计方法研究

目前定向射孔压裂时起裂压力的预测仅立足于裸眼的情况，忽视套管对起裂压力的影响，在工程应用中将产生较大的误差。考虑套管作用，推导建立定向井井周应力模型。假设地层岩石为张性破坏，并综合以上模型，得到定向射孔井水力压裂起裂压力和起裂角的预测模型。根据该模型编程开发一套定向射孔压裂起裂与射孔优化的软件，可预测定向射孔井的压裂起裂压力和起裂角，并优化选择射孔角度和射孔长度。应用软件对渤海油田三口井进行模拟计算和射孔优化，结果发现，模型的起裂压力预测结果与现场实测结果误差最大仅为4.33%，预测的起裂角也与实际结果相一致，从而验证了本模型的正确性。模型和软件对于现场压裂施工和射孔优化有重要的指导作用。

Research on initiation of oriented perforation fracturing and perforation optimization design method

In the oriented perforation fracturing, current predicting initiation pressure just considers the naked borehole and neglects the effect of casing, which will lead to the greater errors in the engineering applications. Considering the effect of casing, wellbore stress models of directional well are obtained. According to tensile failure criteria, fracturing initiation pressure and angle models of oriented perforation well are presented. A software is developed, which includes the initiation prediction and perforation optimization of oriented perforation well. The software can predict the initiation pressure and initiation angle of oriented perforation fracturing considering the effect of casing, and optimize the perforation angle and length. Comparing to the actual initiation pressures, the maximum error of the prediction initiation pressures in the software is 4.33% and the predicting initiation angles are consistent with actual initiation angles, so as to prove the accuracy of fracturing initiation pressure and angle models. The models and software can offer instructions to the field fracturing and perforation optimization.