Abstract
Hailar Oilfield is a new block of Daqing Oilfield developed from the end of last century. In the beginning of the development, beam pumping unit was the only lifting method of the Oilfield. Due to the low pump efficiency and higher rod failure rate as well as the 2000m lift, beam pumping system was not as economic as other in blocks of Daqing Oilfield. As the result, PCP was put into production from 2005. Though all the four wells had a good performance with high pumping efficiency in the beginning, after several months' operation, rod strings suffered from severe oscillation and resulted in fatigue failures in a short period. Theoretical and experimental study indicated that, high working temperature (85 centigrade) and special oil characteristics caused much higher swelling degree of elastomer than in other blocks, which led to the increment of interference fit and friction force between rotor and stator.
In the initial application, although pump parameter and elastomer formula were adjusted before treatment to reduce the swelling effect, these adjustments didn’t take into effect as predicted. In that case, a personalized PCP design was brought forward which gave an integrated methodology for PCP application in Hailar Oilfield. In this design, all the lifting parts from surface to downhole equipments were considered as a whole system. FEM analysis was applied to make a detailed description of the pump for different operating temperature. Based on deeper adjustment of elastomer and pump's structure parameters, the optimum design of rod and other equipments were take into consideration as well. In the end of 2006, 4 new personalized design pumps were put into production. In the following year, despite of small oscillation in the first few days due to the influence of treatment water, all PCP systems performed stably with high efficiency.
