Patent ID: 6929064

Claim:
A downhole pump comprising: a first body comprising a stator, a second body comprising a rotor, the rotor being provided within the stator and carrying at least one piston, a chamber within the rotor, an inlet to the chamber provided at an upstream end of the chamber, and an outlet from the chamber provided at a downstream end of the chamber, the at least one piston being provided longitudinally between the inlet and the outlet, the at least one piston comprising a means for varying a volume of the chamber, and the at least one piston being mounted in a respective aperture passing through a side wall of the rotor, the respective aperture being substantially transverse to a longitudinal axis of the pump, wherein, in use, relative rotation of the rotor and the stator causes reciprocal movement of the at least one piston within the respective aperture thereby varying the volume of the chamber, whereby well production fluid is caused to be pumped downstream through the chamber.