Downhole hydraulically operated fluid pump

In a hydraulically actuated pump which includes a main body adapted to be connected to a production fluid discharge conduit extending to the surface of a borehole and having a cylindrical power fluid chamber, a power piston disposed in slidable reciprocating sealed relationship in said power fluid chamber dividing it into upper and lower power fluid chambers, a cylindrical production fluid chamber disposed beneath said power fluid chamber, a production piston disposed in slidable reciprocating sealed relationship in said production fluid chamber dividing it into upper and lower production fluid chambers, an elongate hollow tubular piston rod disposed in slidable reciprocating sealed relationship in said main body and having an upper portion extending from said production piston through said power fluid chamber with a central bore in fluid communication with the production fluid discharge conduit, a lower portion extending through said production fluid chamber to be reciprocatingly submerged in a production fluid in said borehole with a central bore in fluid communication with the production fluid in the borehole, said power piston connected with said piston rod upper portion in spaced relation to said production piston whereby reciprocation of said power piston causes concurrent reciprocation of said piston rod and said production piston, the improvement which comprises:

• a production fluid inlet passageway extending through said production piston in fluid communication with said piston rod lower portion central bore and said upper and lower production fluid chambers;
• production fluid inlet valve means in said production fluid inlet passageway for conducting production fluid from said piston rod lower portion central bore into said upper and lower production fluid chambers only upon downward movement of said production piston;
• a production fluid discharge passageway extending through said production piston in fluid communication with said piston rod upper portion central bore and said lower production fluid chamber;
• and
• production fluid discharge valve means in said production fluid discharge passageway for conducting production fluid from said lower production fluid chamber to said piston rod upper portion central bore and the discharge conduit only upon downward movement of said production piston.

A pumping system for controlling the operation of a plurality of hydraulically actuated pumps each disposed downhole in a respective well at various locations to produce fluid from the respective well formations comprising:

• a plurality of hydraulically operated pump assemblies each having an elongate tubular main body with a cylindrical power fluid chamber and a cylindrical production fluid chamber disposed beneath said power chamber and coaxial therewith, said main body adapted to be connected at an upper end to a production fluid discharge conduit extending to the surface of the respective well, a power piston disposed in slidable reciprocating sealed relationship in said power fluid chamber dividing it into upper and lower power fluid chambers, a first and second power fluid line each connected at one end to said upper power fluid chamber and said lower power fluid chamber, respectively, of each of said plurality of pump assemblies to alternately supply and exhaust power fluid under pressure to said upper and lower power fluid chambers for reciprocating said power piston;
• each said pump assembly having an elongate hollow production piston disposed in slidable reciprocating sealed relationship in said production fluid chamber dividing it into upper and lower production fluid chambers, an elongate hollow tubular piston rod disposed in slidable reciprocating sealed relationship in said main body and having an upper portion extending from said production piston through said power fluid chamber with a central bore in fluid communication with the production fluid discharge conduit, a lower portion extending through said production fluid chamber to be reciprocatingly submerged in a production fluid in the respective well with a central bore in fluid communication with the production fluid in the respective well, said power piston connected with said piston rod upper portion in spaced relation to said production piston whereby reciprocation of said power piston causes concurrent reciprocation of said piston rod and said production piston;
• each said pump assembly having an elongate hollow production fluid inlet passageway extending through said production piston in fluid communication with said piston rod lower portion central bore and said upper and lower production fluid chambers, production fluid inlet valve means in said production fluid inlet passageway for conducting production fluid from said piston rod lower portion central bore into said upper and lower production fluid chambers only upon downward movement of said production piston;
• each said pump assembly having a production fluid discharge passageway extending through said production piston in fluid communication with said piston rod upper portion central bore and said lower production fluid chamber, and production fluid discharge valve means in said production fluid discharge passageway for conducting production fluid from said lower production fluid chamber to said piston rod upper portion central bore and the discharge conduit only upon downward movement of said production piston;
• said first and second power fluid line of each of said plurality of pump assemblies connected at another end to a common source of power fluid disposed at the surface of the respective wells;
• a common hydraulic power control system disposed at the surface of the respective wells connected to said first and second power fluid lines for independently controlling the operation of said power piston of each said pump assembly, said control system comprising:
• a positive displacement pump connected with said first power fluid lines driven by a prime mover to conduct power fluid from said common source of power fluid to said upper power fluid chamber of each of said plurality of pump assemblies;
• an adjustable relief valve connected with said positive displacement pump controlled by a remotely activated solenoid pilot valve to vent said relief valve and unload said positive displacement pump, at a predetermined low pressure, to said common source of power fluid;
• a solenoid pilot controlled directional flow control valve connected with said first and said second power fluid lines between said positive displacement pump and said upper and lower power fluid chambers;
• a fluid flow sensitive switch connected with said second power fluid lines between said solenoid pilot controlled directional flow control valve and said common source of power fluid, and electrically connected with said pilot solenoid controlled directional flow control valve through an electronic flip-flop signal processor;
• a restricted return line between said directional control valve and said source of power fluid;
• and
• a flow blocking valve connected in said first and second power fluid lines of each of said plurality of pump assemblies, each said flow blocking valve having a solenoid connected with a timing device adjusted to the well fluid recovery cycle of the respective well in which said pump assembly is disposed, each said timing device adjusted to provide time windows for the operating sequence of the respective pump assembly in each respective well, and the time delay required for the recovery of said respective well in which said respective pump assembly is disposed.