Patent ID: 7610956

Claim:
A wellhead assembly to seal and suspend an in-casing hydraulic drive unit for a downhole pump, the hydraulic drive unit being of a type having a hydraulic cylinder, a driven element within the hydraulic cylinder, and one or more hydraulic fluid supply lines providing hydraulic fluid to drive the driven element, the wellhead assembly comprising: a) one or more pressure-containing wellhead body members forming a vertical bore extending therethrough and forming a production bore at an uppermost portion of the vertical bore; b) a hydraulic pump hanger retained and sealed within the vertical bore of the one or more wellhead body members, the hydraulic pump hanger comprising: i) a lower end configured to suspend and seal the hydraulic cylinder of the hydraulic drive unit; ii) a bore extending vertically therethrough and communicating with the production bore; iii) at least one hydraulic line to communicate with the one or more hydraulic fluid supply lines of the hydraulic drive unit; iv) a hydraulic inlet port communicating with each hydraulic line; and v) a check valve sealed in each hydraulic inlet port; c) a stem port formed in the one or more wellhead body members and aligned to communicate with each hydraulic inlet port; d) a valve actuating stem sealed in each stem port to actuate each check valve between a normally closed position and an open position to open and close each check valve; and e) at least one hydraulic injection port formed through the wall of the one or more wellhead body members to supply hydraulic fluid to one or more of the hydraulic inlet ports.