Device for pumping fluid from a wellbore

Abstract

A pump device for pumping fluid from a wellbore, comprising: a piston member ( 38 ) movably arranged in a pump chamber ( 36 ) between a first position and a second position, in a manner allowing the piston member to perform a series of pump strokes, whereby at each pump stroke a volume of said fluid is pumped out of the pump chamber ( 36 ) by the piston member; a fluid conduit ( 20 ) arranged to move the piston member ( 38 ) from the first position to the second position by a selected fluid pressure increase in the fluid conduit; an inlet channel ( 60 ) connecting the pump chamber to a storage chamber ( 52 ) for receiving said volume of fluid from the pump chamber ( 36 ); first valve means ( 62 ) arranged in the inlet channel for allowing fluid flow from the pump chamber ( 36 ) to the storage chamber ( 52 ) and for preventing fluid flow from the storage chamber to the pump chamber; pressurising means ( 57 ) for applying hydraulic pressure to the volume of fluid in the storage chamber ( 52 ); an outlet channel ( 64 ) for discharging the volume of fluid from the storage chamber ( 52 ) into the fluid conduit ( 20 ); second valve means ( 68 ) for allowing fluid flow from the storage chamber ( 52 ) to the pump chamber ( 36 ) and for preventing fluid flow from the pump chamber to the fluid conduit ( 20 ); a fluid inlet ( 46 ) for inflow of said volume of fluid from the wellbore into the pump chamber ( 36 ); and third valve means ( 50 ) to prevent outflow of fluid from the pump chamber ( 36 ) to the fluid inlet ( 46 ).

1 . A pump device for pumping fluid from a wellbore, comprising:
 a piston member movably arranged in a pump chamber between a first position and a second position, in a manner allowing the piston member to perform a series of pump strokes, whereby at each pump stroke a volume of said fluid is pumped out of the pump chamber by the piston member;   a fluid conduit arranged to move the piston member from the first position to the second position by a selected fluid pressure increase in the fluid conduit;   an inlet channel connecting the pump chamber to a storage chamber for receiving said volume of fluid from the pump chamber;   first valve means arranged in the inlet channel for allowing fluid flow from the pump chamber to the storage chamber and for preventing fluid flow from the storage chamber to the pump chamber;   pressurising means for applying hydraulic pressure to the volume of fluid in the storage chamber;   an outlet channel for discharging the volume of fluid from the storage chamber into the fluid conduit;   second valve means for allowing fluid flow from the storage chamber to the pump chamber and for preventing fluid flow from the pump chamber to the fluid conduit;   a fluid inlet for inflow of said volume of fluid from the wellbore into the pump chamber; and   third valve means to prevent outflow of fluid from the pump chamber to the fluid inlet.   
     
     
         2 . The device of  claim 1 , wherein the pressurising means include a reciprocating member arranged in the storage chamber and force means for exerting a force to the reciprocating member to press the reciprocating member against the volume of fluid in the storage chamber. 
     
     
         3 . The device of  claim 2 , wherein said force means comprise a volume of compressed gas. 
     
     
         4 . The device of  claim 3 , wherein said volume of compressed gas comprises Nitrogen gas. 
     
     
         5 . The device of  claim 1 , wherein the second valve means comprise an opening in a wall of the piston member. 
     
     
         6 . The device of  claim 5 , wherein the opening provides fluid communication between the outlet channel and the interior of the conduit in between successive pump strokes of the piston member for opening the outlet channel when the opening is aligned with the outlet channel, and for closing the outlet channel when the opening is not aligned with the outlet channel. 
     
     
         7 . The device of  claim 6 , wherein the opening provides fluid communication between the outlet channel and the interior of the fluid conduit when the piston member is in the first position. 
     
     
         8 . The device of  claim 1 , wherein the wellbore is provided with a production tubing for transporting produced hydrocarbon fluid to surface, wherein the pump device is positioned in a lower portion of the production tubing, and wherein the fluid conduit extends through the production tubing to surface. 
     
     
         9 . The device of  claim 1 , wherein the wellbore contains a body of water that has entered the wellbore from the surrounding earth formation, and wherein the device is arranged to pump water from the body of water via the fluid conduit to surface. 
     
     
         10 . The device of  claim 1 , wherein the pump device or a part thereof is retrievably connected to the conduit so as to allow the pump device or said part thereof to be retrieved through the fluid conduit to surface by means of a wire line. 
     
     
         11 . The device of  claim 1 , wherein the piston member is arranged to perform a series of return strokes alternatingly with the series of pump strokes, and wherein the device further comprises a spring for inducing each return stroke, the spring being adapted to be compressed during each pump stroke by said selected fluid pressure increase in the fluid conduit. 
     
     
         12 . A method of pumping fluid from a wellbore formed in an earth formation, the method comprising:
 providing a piston member movably arranged in a pump chamber between a first position and a second position, in a manner allowing the piston member to perform a series of pump strokes, whereby at each pump stroke a volume of said fluid is pumped out of the pump chamber by the piston member;   applying a selected fluid pressure increase in a fluid conduit to move the piston member from the first position to the second position to induce a pump stroke;   receiving said volume of fluid from the pump chamber in a storage chamber via an inlet channel;   arranging first valve means in the inlet channel for allowing fluid flow from the pump chamber to the storage chamber and for preventing fluid flow from the storage chamber to the pump chamber;   applying hydraulic pressure to the volume of fluid in the storage chamber using pressurising means;   discharging the volume of fluid from the storage chamber into the fluid conduit via an outlet channel; and   arranging second valve means in the outlet channel for allowing fluid flow from the storage chamber to the pump chamber and for preventing fluid flow from the pump chamber to the fluid conduit; and   arranging third valve means for allowing inflow of said volume of fluid from the wellbore via a fluid inlet into the pump chamber, and to prevent outflow of fluid from the pump chamber to the fluid inlet.   
     
     
         13 . The method of  claim 12 , wherein the piston member performs a series of return strokes alternating with the series of pump strokes, wherein each return stroke is induced by a spring force applied to the piston member using a spring, and wherein the spring is compressed during each pump stroke by application of said selected fluid pressure increase in the fluid conduit