单裂缝中携砂液流动规律研究

摘要

The flow of the proppant-laden fluid in fractures is a two phase flow.The migration of the proppant laden fluid and the transportation and the arrangement of the proppant in the fracture are the key to keep the flow conductivity in the fracture.Based on the FLUENT software for the fluid mechanics,the two-fluid model is adopted,and the solid phase and the liquid phase are regarded as the pseudo-fluid and the newtonian fluid,respectively.The effects of the proppant volume fraction,the Ar number,the Re number,and the inlet boundary on the flow are investigated.It is shown that four different zones are developed with different volumetric fractions,including the sand bank zone,the sand tumble zone,the sand suspension zone,and the sand free zone.The thickness of the settled proppants increases with the increase of the proppant concentration and the Ar number,while it decreases with the increase of the Re number.Under the condition of the mesh type boundary,the accumulation of the proppants occurs at the inlet due to the sudden increase of the flow area.%裂缝中携砂液流动是一种固液两相流,携砂液的运移与支撑剂的铺置是水力压裂裂缝保持导流能力的关键.本文基于FLUENT流体计算软件,采用双流体模型,将颗粒看作拟流体,携砂液按照牛顿流体处理,分析了支撑剂体积分数αs、阿基米德数Ar、颗粒雷诺数Re以及裂缝入口边界对流动规律的影响.研究结果表明:携砂液在裂缝中的流动过程中,发展成为支撑剂体积分数不同的四个区域,包括砂堤区、颗粒悬浮区、颗粒滚流区和无砂区;支撑剂的沉降程度随着支撑剂体积分数和阿基米德数的增加而增加,而随着雷诺数增加而降低;入口为网眼型时,进入裂缝后过流面积的增加导致流速突降,使得支撑剂更容易在入口处产生堆积,在同一入口流速下,较均匀入口的工况铺砂高度大.