防砂充填颗粒对地层的作用机理研究

充填砂砾随携砂液进入地层时的运动状态对充填防砂的效果有着重要的影响,也是研究充填防砂作用机理的关键所在。利用液固两相流理论分析了充填砂粒流经炮眼时的受力情况和运动状态,得到了砂砾最大加速距离以及喷射速度与携砂液流量的关系;从能量守恒的角度分析了颗粒群与地层的作用,得到了充填砂砾破坏地层胶结物所需的最小喷射速度;分析了后续施工所产生高压对已形成砂墙的压实作用,得到了砂墙的当量直径表达式。计算结果表明,通常情况下,充填砂砾的加速距离小于炮眼深度,即砂砾以最大喷速进入地层,而且随着施工的进行,该喷射速度可以达到破坏地层胶结物所需的最小速度。

Mechanism of effect of packing grains on formations in sand control operation

The movement state of packing sands along with the sand carrier when entering into the formation exerts great effect on the performance of sand control,which is also the crux of the research on sand control mechanism.The stress and the movement of packing sands while passing the bore are analyzed based on the solid-liquid two-phase flow theory.What’s more,the relations between the maximum acceleration distance,the jet velocity,and the flow of sand carrier are obtained.The effect of particles on base layers are analyzed from the aspect of the energy conservation,so the minimum jet velocity of packing sands while destroying base cement is also obtained.The compaction effect of high pressure caused by sequent operation on sand walls is analyzed and the expression of equivalent diameter of sand wall is obtained.It is indicated that the acceleration distance of packing sands is less than the bore depth,that is,sands entering into the formation with the maximum jet velocity can reach the minimum velocity to destroy the formation cement in the operation.