关键词: 强制返排, 支撑剂回流, 运动模型, 起动模型, 临界流速

Abstract:

To lowpermeability reservoirs，forced flowback technology is usually adopted after fracturing operation.Whether proppant flows back or not is the key evaluation criteria to forced flowback.The motion and start model is presented in the paper，which is based on the analysis of physical process of proppant backflow and the force on the last injected proppant.The calculation result shows that the last injected proppant stop immediately near fracture mouth and whether the proppant flow back or not is depended on flow velocity of fracturing fluid.Beginning with small choke and changing a bigger choke latter during forced flowback is not only discharge fracturing fluid in time but also can avoid proppant backflow.The results provide theoretical support to quantitative analysis of proppant flowback and optimize the flowback technology.

Key words: forced flowback, proppant back flow, motion model, start model, critical flow velocity