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长期以来,油气井压裂施工结束后压裂液返排时机的选择一直以压裂液的破胶时间作为主要依据,但相当数量井的返排效果并不理想。研究表明,压裂液返排时机不仅仅与压裂液破胶时间有关,更与储层物性,尤其是储层力学参数及应力等息息相关。首先从储层物性特征着手,返排的时机既要保证措施地层具有足够的返排能量,又要控制支撑剂回流;其次对压裂液快速破胶进行研究,主要包括室内研究、地层温度场的模拟及不同温度下压裂液破胶的变化情况研究。不同岩性的储层,压裂液返排时机选择依据不同:针对埋深较深、压实较好的刚性地层,应以压裂液的快速破胶作为依据;对于较疏松的地层,应兼顾地层闭合时间及压裂液破胶时间,首先取得准确的地层闭合时间,再以其作为调整压裂液破胶时间的主要依据,最后根据压裂液破胶时间确定开井返排时间。
For a long time, the timing of fracturing fluid return after fracturing construction of oil and gas wells has been based on fracturing fluid gel breaking time as the main basis, but a considerable number of wells return effect is not satisfactory. The research shows that the timing of fracturing fluid flow back is not only related to the breaking time of fracturing fluid, but also to reservoir physical properties, especially reservoir mechanical parameters and stress. First of all, starting from the physical properties of the reservoir, the timing of the return should not only ensure that the formation has sufficient energy return, but also control the backflow of proppant. Secondly, the rapid breaking of fracturing fluid is studied, including indoor research, formation temperature field Simulation and fracturing fluid under different temperature gel breaker changes. For different lithology reservoirs and fracturing fluids, the timing of fracturing fluid return should be based on different reasons. For the deeper strata with better compaction, quick fracturing fluid should be used as the basis; for more loose strata, Taking account of formation closing time and breaking time of fracturing fluid, the accurate formation closing time is obtained firstly, and then it is used as the main basis for adjusting the breaking time of fracturing fluid. Finally, the timing of opening the well is determined according to the breaking time of fracturing fluid.