Today the number of highly-deviated and horizontal wells, viscous and heavy oil wells, sandy and waxy oil wells are increasing. Electric submersible progressing cavity pump (ESPCP) is a good measure for the new situations.
Conventional asynchronous induction motors are currently used most commonly to drive ESPCPs. For energy-efficient and shortening the conventional ESPCP system, a new system – ESPCP directly driven by low-speed permanent magnet synchronous motor (PMSM) – is developed. Compared with the conventional ESPCP system, there is no planetary gear reducer in the new system. To obtain low speed, PMSM with a 36-slot stator and a rotor built with 12 tiles of magnet adopts variable frequency drive. The rated speed of PMSM is 150rpm and the rated output torque is 611Nm.
A pipeline system simulating oil production is built and the load test is carried out, which is under different pressure and flow. The motor runs smoothly during testing and both the torque ripple and speed ripple are small. Test results show that the average efficiency of PMSM is about 70% and the power factor is near to 1. The temperature rise of PMSM is low because of lower specific heat release. The PMSM also has wider ranges of rotation frequency regulation. Now the new system is still being tested in factory and the filed test will be carried out in the near future.
The new system can pass the kick-off section of horizontal wells or deviated wells more easily, and will be a new energy-saving and cost-reducing means of oil production.