Downhole pumping system

Abstract

A downhole motor and pump assembly for use in a tube has a support that suspends the assembly downhole, a housing capable of forming a seal against an inside surface of the tube to divide the tube into a lower region below the seal and an upper region above the seal, an electric motor, and a power supply for the electric motor. A hydraulic pump driven by the electric motor has a high pressure output. A piston is operated by a directional valve such that the high pressure output from the hydraulic pump is directed by the directional valve alternately above and below the piston so as to reciprocate the piston. A fluid pump driven by the piston pumps well fluid from the lower region to the upper region.

1 . A downhole motor and pump assembly for use in a tube, the assembly comprising
 support means for suspending the assembly downhole,   a housing capable of forming a seal against an inside surface of the tube to divide the tube into a lower region below the seal and an upper region above the seal,   an electric motor,   power means for supplying the electric motor,   a hydraulic pump driven by the electric motor and having a high pressure output,   a piston operated by a directional valve such that the high pressure output from the hydraulic pump is directed by the directional valve alternately above and below the piston so as to reciprocate the piston, and   a fluid pump driven by the piston for pumping well fluid from the lower region to the upper region.   
     
     
         2 . The assembly according to  claim 1  wherein the high pressure outlet acts on a smaller area on one side of the piston than the other so that the piston operates with more force during one direction of its reciprocal motion than the other direction. 
     
     
         3 . The assembly according to  claim 1  wherein the directional valve is housed in the piston. 
     
     
         4 . The assembly according to  claim 1  wherein the piston is connected to the hydraulic pump by a slidable tube which moves with the piston. 
     
     
         5 . The assembly according to  claim 1  wherein the directional valve includes a spool that switches between two positions during a cycle of the piston. 
     
     
         6 . The assembly according to  claim 5  wherein the spool is switched by the relative movement of the piston and a collet located around the piston. 
     
     
         7 . The assembly according to  claim 1  wherein energy storing and releasing means such as springs are associated with the piston to assist the piston's movement and the switching of the spool. 
     
     
         8 . The assembly according to  claim 1  wherein the fluid pump operates at a compression ratio of 80:1 or higher.