Electrical submersible pump

Abstract

A method and apparatus for lifting fluids from a well is provided. In one embodiment, a pump assembly comprises a rotary motor adapted to actuate a reciprocating pump. The motor shaft of the rotary motor is threadedly coupled to a drive member of the reciprocating pump. In operation, rotation of the rotary motor causes reciprocation of the reciprocating pump.

1 . A pump assembly, comprising:
 a rotary motor adapted to actuate a reciprocating pump.   
   
   
       2 . The pump assembly of  claim 1 , wherein the rotary motor is coupled to the reciprocating pump using a ball screw type connection. 
   
   
       3 . The pump assembly of  claim 2 , wherein rotation of the rotary motor causes a reciprocating action of the reciprocating pump. 
   
   
       4 . The pump assembly of  claim 1 , wherein the rotary motor comprises a permanent magnet motor. 
   
   
       5 . The pump assembly of  claim 1 , wherein rotation of the rotary motor causes a reciprocating action of the reciprocating pump. 
   
   
       6 . The pump assembly of  claim 1 , wherein the reciprocating pump comprises a positive displacement pump. 
   
   
       7 . The pump assembly of  claim 1 , wherein the pump assembly comprises an electrical submersible pump. 
   
   
       8 . The pump assembly of  claim 1 , further comprising a motor seal coupled to the reciprocating pump, the motor seal adapted for fluid expansion. 
   
   
       9 . The pump assembly of  claim 1 , wherein the reciprocating pump comprises a first valve and a second valve adapted to regulate flow into and out of a fluid chamber. 
   
   
       10 . The pump assembly of  claim 9 , wherein reciprocation in a first direction causes the first valve to open, thereby supplying fluid into the fluid chamber. 
   
   
       11 . The pump assembly of  claim 10 , wherein reciprocation in a second direction causes the second valve to open, thereby expelling fluid out of the fluid chamber. 
   
   
       12 . The pump assembly of  claim 1 , wherein the reciprocating pump comprises an expandable member adapted for reciprocating movement. 
   
   
       13 . The pump assembly of  claim 12 , wherein the expandable member comprises a diaphragm or bellow. 
   
   
       14 . The pump assembly of  claim 1 , wherein the reciprocating pump is adapted to discharge directly into a tubing. 
   
   
       15 . A method of lifting fluids from a wellbore, comprising:
 providing a pump assembly having a reciprocating pump actuated by a rotary motor;   positioning the pump assembly in the wellbore;   operating the rotary motor to actuate the reciprocating pump; and   lifting fluids from the wellbore.   
   
   
       16 . The method of  claim 15 , wherein a drive member of the reciprocating pump is threadedly coupled to a motor shaft of the rotary motor. 
   
   
       17 . The method of  claim 16 , wherein rotation of the motor shaft causes the drive member to move along the motor shaft. 
   
   
       18 . The method of  claim 17 , wherein movement of the drive member causes a fluid chamber to expand or compress. 
   
   
       19 . The method of  claim 15 , wherein actuating the reciprocating pump comprises reciprocating the pump in a first direction and a second direction. 
   
   
       20 . The method of  claim 19 , wherein reciprocating in the first direction supplies fluid into a fluid chamber and reciprocating in a second direction expels fluid from the fluid chamber. 
   
   
       21 . The method of  claim 15 , further comprising reciprocating an expandable member. 
   
   
       22 . A pump assembly, comprising:
 a pump adapted to pump a fluid between at least two fluid cavities; and   a rotary motor adapted to actuate the pump, wherein a flow of the fluid between the at least two fluid cavities is reversed by changing a rotational direction of the rotary motor.   
   
   
       23 . The pump assembly of  claim 22 , wherein each of the fluid cavities is expandable. 
   
   
       24 . The pump assembly of  claim 22 , wherein each of the fluid cavities comprise an expandable member. 
   
   
       25 . The pump assembly of  claim 22 , wherein the each of the fluid cavities is at least partially disposed in a chamber. 
   
   
       26 . The pump assembly of  claim 25 , wherein expansion or retraction of the fluid cavity controls the flow of a pumped fluid in the chamber. 
   
   
       27 . The pump assembly of  claim 22 , wherein the rotary motor comprises a permanent magnet motor. 
   
   
       28 . A method of lifting fluids from a wellbore, comprising:
 providing a pump assembly having a rotary motor and a fluid chamber;   rotating the rotary motor in a first direction to introduce fluid into the fluid chamber;   rotating the rotary motor in a second direction to discharge fluid from the fluid chamber; and   lifting the discharge fluid from the wellbore.   
   
   
       29 . The method of  claim 28 , wherein the pump assembly comprises a second fluid chamber, wherein the second fluid chamber is discharging fluid while fluid chamber is accumulating fluid. 
   
   
       30 . The method of  claim 28 , further comprising discharging fluid from a second chamber while the fluid is being introduced into the fluid chamber. 
   
   
       31 . The method of  claim 28 , further comprising expanding an expandable member in the fluid chamber while fluid is being discharged from the fluid chamber. 
   
   
       32 . The method of  claim 28 , further comprising retracting an expandable member in the fluid chamber while fluid is being introduced into the fluid chamber.