Rod-tubing wear and suck rod failure are two serious problems in many oil fields, which take 45% of the whole workover. Because of the problem, in some area, the average mean-time-between-failure is only 200 days. The workover costs lots of money, not including the loss of oil production. A rodless artificial lift system, electric submersible progressive cavity pump (ESPCP), was developed and had been successfully deployed. This paper focuses on the ESPCP technology and field application.
The system included a progressive cavity pump driven by a downhole permanent magnet synchronous motor, which allowed adjusting the rotation speed between 50-500 rpm. a motor protector and a flexible shaft connecting the pump and the motor protector. More than 20 ESPCP systems has been deployed. The power of these motors was 9-15 kilowatts. The average pump setting depth was 1100 meters and the average production rate was 7-70 cubic meters per day. The application results showed that the average pump efficiency was 75.2% and the system could save more than 20% of the electricity power. In some area, the average time between workovers from 192 days of the traditional sucker rod pump to more than 400 days.
The longest running life was more than 500 days. By using this technology, the production and workover cost could be greatly saved and increased production days can be increased accordingly. Moreover, the system was located at the bottom of oil well, so less site occupation, more safety and less noise pollution to the environment were achieved.
The ESPCP system is of great of significance for some special wells such as directional well, highly-deviated well, it also can avoid the pollution in wetland and floodplain field.