Electric submersible screw pump (ESPCP) for use in Kulin horizontal wells

Electric submerged screw pumps used in Kulin horizontal wells were installed in 95 / 8in production bays with straight-well sections with well slopes below 2 ° / 100ft. Screw in the stator rubber working temperature range of 135 ~ 150oF, lower than the temperature limit of rubber. Flow and pump efficiency are controlled by ground-based variable speed drives (VSDs). The output of these two horizontal wells is 2.5-3.5 times higher than the average output of vertical wells in the same area.

1. Electric submersible screw pump design

Electric submersible screw pump using electric submersible pump as a downhole drive system. Screw pump is the rotor in the center of the stator rotation, as the rotor rotates to pump fluid. Rotor made of stainless steel, chrome-plated surface corrosion. Manufacturers can provide different temperature limits according to bottomhole temperature stator rubber. Existing products can withstand temperatures up to 95 ° C (203 ° C), 105 ° C (221 ° C), 135 ° C (275 ° C) and 150 ° C (302 ° C). As the bottom hole temperature is about 65.6 ℃, so choose the temperature of 95 ℃ (203?) Products. In addition, consider whether the rubber is compatible with the aromatic hydrocarbons in the fluid. At the same time, the power required to start the operation of the screw pump, casing size, bottom hole temperature determines the size of the electric submersible pump motor. The main function of the gear reducer is to provide the required speed and torque of the screw pump. The seal prevents underflow fluid from entering the gear unit and motor. The flexible shaft converts the rotation of the seal shaft into the torque required for the screw pump.

2 electric submersible screw pump installation

The design and installation limits for ESP pumps are straight sections with a well slope of up to 15 ° / 100ft. The electric submersible screw pump from the well KL082 was installed at a well depth of 1440 ft with a true vertical depth of 1267 ft and an inclination of 64 ° with a well slope of 1.6 ° / 100 ft. The KL083 well was installed at a depth of 1014 ft with a true vertical depth of 891 ft and an inclination of 58 ° with a well slope of 1.5 ° / 100 ft using a 31/2 in. Tubing. At the same time, install a 31 / 2in control valve and a mixing valve at 90ft above the pump and install a cable protector to prevent friction between the cable and the bushing. Installed two electric submersible pump motor actual speed of 2333rpm, gear reducer transmission ratio 9: 1, pump speed 259rpm, screw pump flow 881bbl / d.

3. Field application

KL082 well electric submersible screw pump work 800 days, the average pump efficiency of 66%, did not find any signs of failure, but found some problems during the initial run, the reason may be blocked the inlet, reverse reverse washing through the motor successfully removed, transferred to normal production . KL083 well electric submersible screw pump work for 450 days, the average pump efficiency of 56%, there is no pump failure caused the problem of downtime.

4 Conclusion

(1) The electric submersible screw pump is a combination of an electric submersible pump and a screw pump, and has many features that are suitable for horizontal wells: a. High production efficiency even for viscous fluids with high solid content; b. The system eliminates the friction loss; c. There is no packing box to avoid the surface oil spill; d. The torque is high; e. The backwash can be reversed by the motor.

(2) The average pump efficiency of Kulin horizontal well electric submersible screw pump is 56% ~ 66%. In stark contrast, the pumping efficiency of rod pump with Duri horizontal well is less than 30%.

(3) The working life of electric submersible screw pump is long, which is fully reflected in the production of well KL082 and well KL083. As of June 2004, the well of the well KL082 has been stable for more than 800 days and the well of the well KL083 has survived for more than 450 days.