Hydraulically operated downhole oil well pump

In combination with a well bore having a string of casing therein that extends downwardly from the ground surface to a position adjacent a geological formation to communicate with the latter, said formation containing production fluid and some gas, a first tubing string of substantially less external diameter than the interior diameter of said casing string that extends downwardly in the latter from the ground surface, said tubing string in communication with a source of pressurized working oil, a hydraulically operated pump disposed in said bore hole adjacent said formation and actuated by said pressurized working oil, said hydraulically operated pump including:

• a. an elongate tubular housing having an upper end portion in which a first opening is defined through which said pressurized working oil discharges downwardly and (a) an externally threaded lower (open) end portion having a second opening therein through which said production fluid from said formation may enter the interior of said housing;
• b. upper and lower elongate helical screws in said housing that are vertically spaced;
• c. upper and lower stationary resilient tubular stators inside said housing that define double threads and that substantially envelop said upper and lower helical screws and are in pressure contact therewith;
• d. first means for establishing communication between said first opening in upper end portion and said first tubing, with said pressurized working oil after entering said housing rotating said first helical screw in a first direction to allow said pressurized working oil to flow downwardly in said first stator to discharge through a third opening in said housing below said first stator to subsequently flow to the ground surface in a path within said casing;
• e. second means for connecting said first helical screw to said second helical screw to rotate the latter in said first direction relative to said lower stator to draw said production fluid from said bore hole into said housing to subsequently flow to the ground surface in a path within said casing;
• f. a threaded probe secured to said threads on said housing, said probe including a tubular member;
• and
• g. a packer disposed in said casing above said formation, said packer having a first passage engaged by said tubular member of said probe with pressurized working oil when discharged downwardly through said first tubing string exiting through said third opening into an annulus space between said first tubing string and casing above said packer after having driven said upper helical screw, and production fluid and gas in said bore hole below said packer being drawn upwardly through said tubular member of said probe structure by the rotation of said lower helical screw to discharge into the same annulus space as said pressurized working oil.