Tubing inserted balance pump

Abstract

Pump assemblies for use with a subsurface fluid reservoir include an upper barrel connected to a fluid filled conduit extending to the surface, a lower barrel connected to the upper barrel and in fluid communication with the reservoir, and a plunger assembly movably located within the upper and lower barrels. As the fluid pressure within production tubing, external to the pump assembly, increases, movement of the plunger draws fluid into the pump. As the fluid pressure within the production tubing decreases, the plunger pushes fluid into the production tubing.

What is claimed is: 
     
         1 . A pump assembly positioned within and in fluid communication with production tubing extending between a subsurface fluid reservoir and a well surface, the pump assembly comprising:
 an upper barrel connected to a fluid conduit that extends between the upper barrel and the well surface;   a lower barrel connected to the upper barrel and in fluid communication with the subsurface fluid reservoir; and   a plunger assembly comprising:
 an upper plunger movably disposed within the upper barrel; and 
 a lower plunger connected by a shaft to the upper plunger and movably disposed within the lower barrel, 
   wherein the plunger assembly draws fluid from the subsurface fluid reservoir into the pump assembly and pushes fluid out of the pump assembly into the production tubing in response to fluid pressure changes within the production tubing.   
     
     
         2 . The pump assembly of  claim 1 , wherein the fluid conduit is filled with balancing fluid, wherein the fluid within the production tubing moves the plunger in a first direction as fluid pressure within the production tubing increases, and wherein the balancing fluid in the fluid conduit moves the plunger in a second direction as fluid pressure within the production tubing is released. 
     
     
         3 . The pump assembly of  claim 1 , further comprising sealing elements located on the upper plunger, wherein the sealing elements allow the upper plunger to move laterally within the upper barrel while maintaining sealing action. 
     
     
         4 . The pump assembly of  claim 1 , wherein the upper plunger has an outside diameter that is sized to permit axial movement within the upper barrel when the upper barrel is compressed or bent by an external force. 
     
     
         5 . The pump assembly of  claim 1 , wherein the plunger assembly moves at least 18 feet or more within the pump assembly. 
     
     
         6 . The pump assembly of  claim 1 , wherein the upper plunger is greater than 20 inches in length. 
     
     
         7 . A pump assembly for pumping fluid from a subsurface fluid reservoir comprising:
 an upper barrel connected to a lower barrel and a fluid conduit, wherein the lower barrel is in fluid communication with the subsurface fluid reservoir, and wherein the fluid conduit extends from the upper barrel to a surface of a well; and   a plunger assembly movably disposed within the upper barrel and the lower barrel,   wherein fluid pressure within a production tubing external to the fluid conduit moves the plunger assembly in a first direction to draw fluid into the lower barrel, wherein fluid pressure within the fluid conduit moves the plunger assembly in a second direction to push fluid into the production tubing, and wherein the pump assembly prevents fluid flow from the production tubing into the fluid reservoir.   
     
     
         8 . The pump assembly of  claim 7 , wherein the plunger assembly further comprises:
 a lower plunger movable within the lower barrel; and   an upper plunger movable within the upper barrel, wherein the upper plunger has an outside diameter that is smaller than an inside diameter of the upper barrel for permitting axial movement of the upper plunger within the upper barrel when the upper barrel is compressed or bent by an external force, and wherein sealing elements on the upper plunger prevent fluid flow through an annulus between the upper barrel and the upper plunger.   
     
     
         9 . The pump assembly of  claim 8 , wherein the pump assembly is configured for insertion into the production tubing, wherein the pump assembly further comprises a mating area configured for attachment to the production tubing, and wherein the mating area prevents fluid communication between the production tubing and the fluid reservoir through an annular space between the production tubing and the pump assembly. 
     
     
         10 . The pump assembly of  claim 8 , wherein the sealing elements comprise piston ring seals, lip-seals, cup seals, or combinations thereof, and wherein the sealing elements permit lateral movement of the upper plunger within the upper barrel. 
     
     
         11 . The pump assembly of  claim 8 , wherein the sealing elements permit axial movement of the upper plunger within the upper barrel when the upper barrel is compressed or bent by an external force. 
     
     
         12 . The pump assembly of  claim 8 , wherein the upper plunger is greater than 20 inches in length. 
     
     
         13 . The pump assembly of  claim 8 , wherein the upper and lower plungers are configured to move more than 18 feet within the upper and lower barrels respectively. 
     
     
         14 . A pump assembly, comprising
 an upper barrel connected to a lower barrel, wherein the upper barrel is fluidly connected to the lower barrel, and wherein the upper barrel is fluidly connectable to a fluid conduit;   the lower barrel fluidly connectable to a fluid reservoir;   a plunger assembly comprising an upper plunger movable within the upper barrel and a lower plunger movable within the lower barrel, wherein the upper plunger and the lower plunger are connected,   wherein the plunger assembly is movable in a first direction to draw fluid from the fluid reservoir into the lower barrel responsive to a pressure increase external to the pump assembly, and   wherein the plunger assembly is movable in a second direction to push fluid out of the pump assembly responsive to a pressure decrease external to the pump assembly.   
     
     
         15 . The pump assembly of  claim 14 , wherein the pump assembly is configured for insertion into a production tubing, wherein the pump assembly further comprises a mating area configured for attachment to the production tubing, and wherein the mating area prevents fluid communication between the production tubing and the fluid reservoir through an annular space between the production tubing and the pump assembly. 
     
     
         16 . The pump assembly of  claim 14 , wherein the pump assembly further comprises:
 a check valve, wherein the check valve prevents fluid from flowing from the lower barrel to the fluid reservoir.   
     
     
         17 . The pump assembly of  claim 14 , wherein the upper plunger has an outside diameter that is smaller than an inside diameter of the upper barrel for permitting axial movement of the upper plunger within the upper barrel when the upper barrel is compressed or bent by an external force, and wherein the upper plunger comprises sealing elements which seal an annular area between the upper plunger and the upper barrel. 
     
     
         18 . The pump assembly of  claim 17 , wherein the sealing elements comprise piston ring seals, lip-seals, cup seals, or combinations thereof, and wherein the sealing elements permit axial movement of the upper plunger within the upper barrel when the upper barrel is compressed or bent by an external force 
     
     
         19 . The pump assembly of  claim 14 , wherein the upper plunger is greater than or equal to 20 inches in length. 
     
     
         20 . The pump assembly of  claim 14 , wherein the upper and lower plungers are configured to move at least 18 feet or more within the upper and lower barrels respectively.