Patent attributes
A wellhead hydraulic drive unit to operate various styles of downhole pumps, including a hydraulic cylinder having a piston positioned therein for reciprocation within the cylinder; hydraulic fluid supply conduits contained within the hydraulic cylinder and fluidly communicative with the piston such that hydraulic fluid flowing through the hydraulic fluid supply conduits produces reciprocation of the piston within the hydraulic cylinder, a ram within the cylinder and operably connected to the piston, the ram having a bore; and production tubing inserted through the bore of the ram for enabling well fluid to be discharged from the well, wherein the hydraulic fluid supply conduits are radially offset from a longitudinal axis of the cylinder and the ram is oppositely radially offset from the longitudinal axis of the cylinder. Offsetting the hydraulic fluid supply conduits and the ram allows for a larger inside diameter in both the production tubing and ram, increases the sizes of downhole pumps which can be installed/removed without removal of the drive unit, and serves as an anti-rotational feature with regards to the piston and ram.
