致密气储层压后返排动态控制研究

Study on dynamic control of flowback after fracturing in tight gas reservoirs

在控制支撑剂回流的基础上实现压裂液快速返排对于提高致密气储层压裂效果来说十分重要。但目前的压后返排研究缺乏气液两相流情况下的返排特征分析,忽略了裂缝闭合后支撑剂排列方式及受力状态的改变,制定压后返排制度未考虑各排液参数的动态变化。为此,本文给出了不同相态下的井口嘴流控制方程,推导了裂缝闭合后支撑剂压实粘结状态下的支撑剂回流模型,并在此基础上以LM-5井为例进行了实例计算并绘制了相应的最大油嘴直径动态调节曲线,从而实现对致密气储层压后返排的动态控制。

It is important to accelerate the flowback of fracturing fluid and avoid the backflow of proppant for the fracturing effect of tight gas reservoirs. But some defects of flowback research are existed such as lack of flowback characters analysis under gas-liquid two phase flow, neglect of the proppants' arrangement and stress state after fracture closure, improper flowback procedure without consideration of flowback parameter's dynamic change. Therefor nozzle flow equations for different phase states are given and a proppant backflow model with consideration of proppant compression and cementation is established. Then taking well LM-5 as an example dynamic curves of maximum nozzle diameter are draw according to the change of flowback parameters with the presented method to implement the dynamic control of flowback after fracturing in tight gas reservoirs.