Mechanism Of Leaning Attrition In Pumping Units Well And Prevention Technology

Sucker rod pump is so far the traditional and dominant artificial lift method in oil production engineering of oil industry. In China, About 80 percent of producing wells took sucker rod pump production technology. With the development of drilling technology, there are more and more horizontal wells, lateral horizontal wells, the gradient directional wells cluster wells in major oil fields and the side attrition of oil pipe in these wells becomes increasingly severe due to the special well structure. Workover operations caused by side attrition of pipe-rod account for approximate 1/4 of total well servicing operations and present an increasing trend year by year. Now the settlement of side attrition only relys on the sucker rod centralized implement owing to lack of accurate knowledge about side attrition mechanism and the improvement is inefficient. Therefore side attrition could be effectively prevented and solved ongl by the study of side attrition of rod pipe.In this paper, on the basis of analysis of force impact on oil pipe and sucker rod , the mechanism of side attrition is put forward by analyzing the effect of pump diameter, water content, submergence depth, suction parameters on the side attrition of sucker rod using laboratory testing, combining with the distribution rule of rod side attrition for Ciyutuo oilfield and the Horqin oilfield. Produced fluid with high water content deteriorated the lubrication condition between sucker rod and pipe and exacerbated side attrition in high water cut oilfield. Under the condition of high water cut and low submergence depth, the phenomenon of liquid strike will happen to working sucker rod, and increase the vibration load. Meanwhile, predegassing of oil will lead to wax deposition on sucker rod and pipe, and to increase the axial stress concentration and decrease the axial distributed force with the condition of low submergence depth. In addition, larger suction parameters will also bring about occurence of rod side attrition. Above-mentioned are the factors which could arose side attrition. The primary measure to prevent side attrition is to take advantage of centralized implement to restrict sucker rod and to optimize the sucker rod assemblage and location distribution of centralized implement by establishing mathematical models about sucker rod and pipe. Another prevention method is to use wear resistant materials to improve the wear resistance properties of sucker rod and to optimize the working condition of oil well, change the force status of sucker rod.