Rod and tubing eccentric wear regularities and eccentric wear prevention and control techniques in CBM well

Based on the actual data of eccentric wear wells, rod and tubing eccentric wear characteristics and regularity of CBM wells were studied by using the methods of CBM development theory and statistics, and the prevention and control measures of rod and tubing eccentric wear of CBM wells are actively discussed. Studies suggest that rod and tubing eccentric wear problem is widespread in the process of production of CBM wells, and the eccentric wear location is about 200 m higher than the pump basically, rod and tubing eccentric wear happens not longer than one year from the production, and the eccentric wear degree eases with time. This phenomenon is more prone to occur in inclined wells, deep wells with depth of more than 500m and wells with punching number of more than 3 times/min. In addition, acid composition in produced fluid and coal powder help to accelerate rod and tubing eccentric wear speed. Optimization of production equipments, reasonable control of production parameters and taking comprehensive prevention and control measures according to the CBM wells characteristics are considered to be the main prevention and control means of rod and tubing eccentric wear in CBM wells.