Valve assembly for downhole hydraulically actuated pump

A method of operating a hydraulically actuated engine for a downhole pump of the type having a hydraulically actuated engine connected to actuate a downhole pump apparatus;

• wherein said engine has an axial passageway within which an engine piston is reciprocatingly received, with said engine piston having opposed faces, and a control valve reciprocatingly received within the engine axial passageway and connected to supply power fluid to one face of the engine piston to thereby stroke the engine piston which in turn strokes the downhole pump;
• and with said control valve having and upper end opposed to a lower end thereof;
• and stop means at opposed ends of said axial passageway for abuttingly engaging the opposed ends of said control valve;
• comprising the steps of:
• providing a downhole force in close proximity of said upper end of said control valve;
• said downhole force being exerted on the upper end of said control valve when the upper end of the control valve is abuttingly engaged with the stop therefor, said downhole force being greater respective to the uphole force thereon and thereby moves said control valve downhole following each uphole stroke,
• forming an upwardly opening interior within the upper marginal end of the control valve;
• forming a circumferentially extending face at the upper terminal end of the control rod for abuttingly engaging the stop means and thereby forming an interface therebetween that separates the interior of the control rod from the exterior thereof;
• effecting the downhole force on the upper end of said control rod by forming a flow passageway adjacent the upper terminal end of the control valve and extending the passageway from the interior of the control valve to the exterior thereof to equalize the power fluid pressure across the upper end thereof and thereby provide additional area by which the control valve is forced to move downhole into an alternate position.

In a downhole pump assembly of the type having a hydraulically actuated engine connected to stroke a production pump uphole and downhole, said engine having a power fluid inlet and a spent power fluid outlet;

• said production pump having a formation fluid inlet and a produced fluid outlet;
• said engine having an improved valve assembly connected to supply power fluid to the engine and to exhaust spent power fluid therefrom;
• said valve assembly comprising a control valve reciprocatingly received within said valve assembly and having opposed ends which abuttingly engages an upper and a lower stop means, respectively, at the end of each uphole and downhole stroke, respectively, as the control valve shifts from one to an alternate position of operation in response to reciprocation of the engine piston;
• said control valve having an interior and an exterior;
• means on said upper end of said control valve by which a downhole force is effected on said control valve, including a flow passageway adjacent the upper end of the control valve and extending from the interior to the exterior of the control valve and thereby communicating the interior of the control valve with the exterior thereof whereby power fluid flow occurs between the interior of the control valve and the exterior thereof to thereby equalize the pressure across the upper marginal end of the control valve and thereby contact the entire upper end of the control valve with power fluid to force the control valve to move downhole into an alternate position due to the differential in pressure effected on opposed ends of the control valve.