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.