Patent ID: 8210253

Claim:
A modular pump system for use downhole in a well, having at least a first pump comprising a tube and a cylinder block, the cylinder block defining at least one cylinder with a respective piston inside the cylinder, the movement of the piston in the cylinder causing fluid to be drawn into the first pump through a pump inlet before being pushed out through a pump outlet, the cylinder block being housed in the tube, the tube having a cammed surface formed by an internal wall of the tube, the piston having a cam follower such that rotation of the cylinder block to the tube causes the piston to move relative to the cylinder; the first pump having two ends, the tube and the cylinder block being connectable at each of the ends in series relation respectively to the corresponding tube and cylinder block of a further said pump such that the tube is rotationally locked to the corresponding tube of the further said pump to form a modular pump assembly.