关键词: 抽油机井, 水驱, 杆管偏磨, 临界条件, 力学机理

Abstract: The calculating formula for critical axial load of worn rod string and tubing was set up.The critical axial load only depends on the diameter and axial distributed load of the rod string.The simulating method of axial distributed load of the rod string was given by means of the wave equation of the rod string.The formula for calculating the liquid shock load in the low sinking depth wells was set up,and the formula for the axial load in the down stroke of the plunger was established.The influences of running conditions of the oil wells on the wear of rod string and tubing were systematically analyzed.The bellow conclusions can be obtained:(1) The water content ratio and the low sinking depth have important affect on the wear of rod string and tubing.When the wells run at the low sinking depth,the critical axial load is greatly reduced.(2) When the pump cylinder could not be filled with enough liquid,the liquid shock will occur,and the liquid shock load will make the down stroke axial load of the plunger increase.(3) When the suction parameters of the wells increase,the critical axial load will decrease,and the down stroke axial load of the plunger will increase.When wells run at one or some of the above states,and the practical down stroke axial load of the plunger is greater than the critical axial load,the wear of rod string and tubing will take place.

Key words: rod pumping system, water-flooding oilfield, rod string and tubing, wear, critical condition, mechanics