Hydraulic oil well pumping unit

Abstract

An oil well pumping unit comprising an oil pump unit and a hydraulic cylinder coupled in driving relation to the pump unit and adapted to be mounted along with the pump unit within a bore hole. The cylinder has top and bottom fluid ports and a cylinder rod operatively driving the pump unit. Hydraulic drive/control means is coupled to one of the fluid ports to provide a hydraulic power stroke of said cylinder rod in one direction. The other of the fluid ports of said cylinder is coupled to the well fluid column above said cylinder or to a closed energy storage system to provide energy for producing a return stroke of the cylinder rod. The oil pump unit includes: an elongated cylindrical pump barrel with a first stationary valve mounted at a bottom end of the pump barrel for controlling the entry of bore hole fluid and a second stationary valve mounted at a top end for controlling the exit of oil from the pump barrel into the well casing above said pumping unit. A packing means is mounted in an intermediate position on the pump barrel for retaining the pump barrel in a position within the well casing and forming a seal between the inner wall of the well casing and the pump barrel to define high and low pressure regions of the well respectively above and below the packing means. A cylinder mounting means is provided for mounting said hydraulic cylinder in a substantially sealed manner on top of the pump barrel with the cylinder rod coaxial with the pump barrel and sized to be received within the pump barrel on a downstroke of the cylinder rod to displace bore hole fluid within the pump barrel through the second valve.