Single circuit double-acting pump

Abstract

Removing water from a subterranean formation entails pumping hydraulic oil from a surface-located hydraulic oil pump through a hydraulic oil line to a downhole water pump piston to drive it in a first direction to pump water through a downhole water line to a water chamber of a hydraulic accumulator at the surface. A piston separates the water chamber and an oil chamber and moves to compress the hydraulic oil in the oil chamber of the hydraulic accumulator. The hydraulic oil pump may then pump hydraulic oil into the oil chamber causing the piston to move toward the water chamber, thereby moving water in the downhole water line and resetting the piston in the downhole water pump. A water valve in the downhole water line at the surface may open and release water when the piston in the downhole water pump reaches a predetermined or reset position.

1 . A method of removing fluid from a subterranean formation to an earthen surface, the method comprising:
 providing a hydraulic oil pump at the earthen surface;   providing a downhole water pump;   providing a hydraulic accumulator at the earthen surface;   supplying only one downhole hydraulic oil line from the hydraulic oil pump to the downhole water pump;   supplying only one downhole water line from the downhole water pump to the hydraulic accumulator; and   supplying a hydraulic accumulator hydraulic oil line from the hydraulic oil pump to the hydraulic accumulator.   
     
     
         2 . The method according to  claim 1 , wherein providing a hydraulic accumulator further comprises providing a hydraulic accumulator that defines an internal chamber, a first inlet/outlet at a first end of the hydraulic accumulator, a second inlet/outlet at a second end of the hydraulic accumulator and a hydraulic accumulator piston within the internal chamber that divides the internal chamber into a hydraulic accumulator water chamber and a hydraulic accumulator hydraulic oil chamber. 
     
     
         3 . The method according to  claim 2 , further comprising:
 pumping hydraulic fluid from the hydraulic oil pump via the only one downhole hydraulic oil line to a rod side of a piston within the downhole water pump thereby moving the piston in a first direction.   
     
     
         4 . The method according to  claim 3 , further comprising:
 pumping hydraulic oil from the hydraulic oil pump through the hydraulic accumulator hydraulic oil line to the hydraulic accumulator and increasing an internal pressure of the hydraulic accumulator hydraulic oil chamber;   moving the hydraulic accumulator piston away from the hydraulic accumulator hydraulic oil chamber;   increasing pressure within the only one downhole water line; and   increasing force against a non-rod-side of the water pump piston within the downhole water pump thereby moving the piston in a second direction.   
     
     
         5 . The method according to  claim 4 , further comprising:
 providing a water valve in the downhole water line at the earthen surface; and   opening the water valve when the water pump piston reaches a prescribed position with the downhole water pump to evacuate water from the downhole water line.   
     
     
         6 . A method of removing water from a subterranean formation to an earthen surface, the method comprising:
 pumping hydraulic oil from a hydraulic oil pump at the earthen surface to a downhole water pump through only one downhole hydraulic oil line from the hydraulic oil pump to the downhole water pump; and   pumping water from the downhole water pump to the earthen surface through only one downhole water line from the downhole water pump to the earthen surface.   
     
     
         7 . The method according to  claim 6 , further comprising:
 providing a hydraulic accumulator at the earthen surface and a hydraulic accumulator hydraulic oil line from the hydraulic oil pump to the hydraulic accumulator; and   wherein providing only one downhole water line from the downhole water pump to the earthen surface further comprises providing one downhole water line from the downhole water pump to the hydraulic accumulator.   
     
     
         8 . The method according to  claim 7 , further comprising:
 pumping hydraulic fluid from the hydraulic oil pump via the only one downhole hydraulic oil line to a rod side of a downhole water pump piston thereby moving the downhole water pump piston in a first direction and pumping water into a hydraulic accumulator water chamber;   pumping hydraulic oil from the hydraulic oil pump through the hydraulic accumulator hydraulic oil line to a hydraulic oil chamber of the hydraulic accumulator thereby increasing an internal pressure of the hydraulic accumulator hydraulic oil chamber;   moving a hydraulic accumulator piston away from the hydraulic accumulator hydraulic oil chamber due to the internal pressure of the hydraulic accumulator hydraulic oil chamber;   increasing pressure within the only one downhole water line; and   increasing force against a non-rod-side of the water pump piston thereby moving the water pump piston in a second direction.   
     
     
         9 . The method according to  claim 8 , further comprising:
 providing a water valve in the downhole water line at the earthen surface;   moving the water pump piston in a non-pumping direction; and   opening the water valve when the water pump piston reaches a prescribed position within the downhole water pump thereby evacuating water from the downhole water line.   
     
     
         10 . A method of removing water from a subterranean formation to an earthen surface, the method comprising:
 providing a hydraulic oil pump at the earthen surface;   providing a downhole water pump;   providing a surface water pump at the earthen surface;   supplying only one downhole hydraulic oil line from the hydraulic oil pump to the downhole water pump; and   supplying only one downhole water line from the downhole water pump to the surface water pump.   
     
     
         11 . The method according to  claim 10 , further comprising:
 pumping hydraulic fluid from the hydraulic oil pump via the only one downhole hydraulic oil line to a rod-side of a downhole water pump piston within the downhole water pump;   moving the downhole water pump piston in a water-pumping direction; and   moving water through the downhole water line to the earthen surface.   
     
     
         12 . The method according to  claim 11 , further comprising:
 moving water through a water repository water valve in a water respository filling tube; and   depositing water into a water repository at the earthen surface.   
     
     
         13 . The method according to  claim 12 , further comprising:
 closing the water repository water valve; and   pumping water with the surface water pump at the earthen surface to the downhole water pump via the water removal line.   
     
     
         14 . The method according to  claim 13 , wherein pumping water with the surface water pump at the earthen surface to the downhole water pump via the water removal line further comprises:
 pumping water to a non-rod-side of the downhole water pump piston within the downhole water pump.   
     
     
         15 . The method according to  claim 14 , further comprising:
 moving the water pump piston in a direction opposite to the water-pumping direction.   
     
     
         16 . The method according to  claim 15 , further comprising:
 opening a hydraulic drain line valve in a hydraulic drain line at the earthen surface; and   moving hydraulic oil through the hydraulic drain line valve and into the hydraulic fluid tank as the water pump piston is moving in a direction opposite to the water-pumping direction.