多薄层压裂流量分配判定准则

Theoretic criterion of injection profiles in multiple thin layer fracturing

袁灿明 郭建春 陈 健 肖勇军

川庆钻探工程公司井下作业公司，四川 成都 610051 西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610500

Downhole Services Company, Chuanqing Drilling Engineering Company, CNPC, Chengdu 610051, China State Key Laboratory of Oil and Gas Reservoir Geology and Exploration, Southwest Petroleum University, Chengdu 610500, China)

通过分析传统“限流法”流量分配模型和多薄层地层的实际影响参数，认为建立多薄层压裂流量分配判定准则非常必要。以油层中部深度为准，推导出射孔孔眼末端剩余压力的计算公式，建立了流量进入地层的判定准则。利用该判定准则，判定各层段的液体进入状况，达到判定准则所确定的裂缝开启初始临界条件的层段就会起裂，并且有液体进入该层段，未达到起裂初始临界条件则该层段暂时不起裂。如该层段在整个过程都未达到判定准则所要求的起裂初始临界条件，则会导致在整个压裂过程中都无法到达起裂临界条件，从而导致在压裂施工中产生所谓的“盲区”，即压裂液无法到达的层段。

Based on the analysis of injection profiles of limited entry fracturing and the affecting factors of multiple thin layer zones, it is considered that it is necessary to build the theoretic criterion of injection profiles. It is established by deducing the calculation formula for the residual pressure in perforation tip based on mid-point of pay-zone. The criterion can be used to determine the flowing fluid in the pay-zones. The fluid will flow into the pay-zone at the initial critical condition of crack-open, otherwise the fracture will keep closed. The pay-zone will not achieve the critical condition of crack-open during the whole fracturing processes as the result of the whole actual processes could not achieve the initial critical condition of crack-open just as the criterion required. Then blind zone will appear during fracturing, which means the fracturing fluid will not flow into the pay-zone as expected.