Method and apparatus for high-efficiency gas separation upstream of a submersible pump

Claim 1

A submersible pump system for producing hydrocarbons from a gassy well in which liquid components of a production fluid are produced through a production tubing and gaseous components of the production fluid are produced through an annulus formed in a wellbore between a casing and the production tubing, said submersible pump system comprising: (A) a motor; (B) a power supply connected to the motor; (C) A first-stage gas separator comprising; (1) a first-stage housing supporting the motor; (2) a first-stage inlet through the housing in communication with the production fluid within the wellbore; (3) a primary means for separating gas from the production fluid within the first-stage housing and in communication with production fluid entering the first-stage inlet; (4) a first-stage gas outlet through the first-stage housing positioned to receive the gaseous components separated in the primary means for separating gas and discharging the separated gaseous components to the annulus; and (5) a first-stage liquid outlet through the first-stage housing which receives the liquid components forwarded from the primary means for separating gas from the production fluid; (D) a second-stage separator; (1) a second-stage housing supporting the first-stage housing from its lower end; (2) a second-stage inlet through the lower end of the second-stage housing in communication with the first-stage liquid outlet; (3) A secondary means for separating the gas from the production fluid within the second-stage housing and in communication with the second-stage inlet; (4) a second-stage gas outlet through the second-stage housing positioned to receive gaseous components separated by the secondary means for separating gas and discharging the separated gaseous components to the annulus; and (5) a second-stage liquid outlet; (E) a coupling connecting the first- and second-stage gas separators establishing a conduit receiving separated liquid components discharged through the axial first-stage liquid outlet of the first-stage gas separator; (F) an adaptor connected to the coupling and to the second-stage gas separator having a bushing which rotatably receives the shaft and providing a plurality of axial flow passages establishing communication between the coupling and the second-stage gas separator; (G) a pump connected to the production tubing on one end and supporting the second-stage housing on its other end, said pump comprising: (1) a pump housing; (2) a pump inlet positioned to receive the separated liquid components of the production fluid which passes through the second-stage liquid outlet; (3) means for pumping the separated liquid component of the production fluid in communication with the pump inlet; and (4) a pump outlet in communication with the production tubing in position to receive the liquid component discharged from the means for pumping; and (H) a shaft engaged to be driven by the motor and extending through the first-stage gas separator and the second-stage gas separator to drive the pump.