Slant mounted hydraulic pumping system

A hydraulic pumping method for use with a subterranean well, the method comprising:

• mounting a hydraulic actuator above a wellhead, whereby a lower stroke extent of a piston of the actuator is located above the wellhead, the hydraulic actuator and the wellhead being axially aligned with each other and inclined relative to vertical, wherein the hydraulic actuator is unsupported by any additional substructure or guy wires after the mounting;
• and
• reciprocating a rod string with the hydraulic actuator, the reciprocating comprising displacing the rod string in response to pressure applied to the hydraulic actuator by a hydraulic pressure source connected to the hydraulic actuator, the hydraulic pressure source including an accumulator, and automatically regulating pressure in the accumulator in response to measurements of the pressure applied to the hydraulic actuator, wherein the accumulator receives nitrogen gas from a nitrogen concentrator assembly while a hydraulic fluid flows between the hydraulic pressure source and the hydraulic actuator.