Hydraulically actuated pump assembly

In a fluid operated pump assembly for operation downhole in a wellbore and including means to convey power fluid from the surface of the ground downhole to the pump assembly, spent power fluid uphole to the surface of the ground, and fluid produced by the well uphole to the surface of the ground;

• said pump assembly having a valve and engine section, and a pump section, all connected together to form said pump assembly, with the valve section controlling the flow of power fluid into and from the engine to thereby enable the engine to extract power from the power fluid, and with there being connecting means by which the engine section drives the pump section to enable the pump to perform the stated function of lifting fluid uphole;
• the improvement comprising:
• said engine section includes a cylinder having a piston reciprocatingly received therein, said piston dividing said cylinder into an upper and a lower cylindrical engine chamber;
• a control valve assembly which includes a control rod and a valve element;
• means forming an axial bore within said piston, said control rod being axially aligned and reciprocatingly received within said axial bore such that an annulus is formed therebetween;
• said valve element being reciprocatingly received within said annulus;
• power fluid flow passageway means extending from the power fluid source to said valve assembly and from said valve assembly to said lower cylinder chamber;
• spent power fluid flow passageway means extending from said valve assembly to said upper engine chamber;
• means connected to said control rod and to the extremities of said cylinder of said engine for abuttingly engaging said control rod to cause said control rod to reciprocate between two alternate positions in response to reciprocal movement of said piston respective to said cylinder, to thereby cause said valve element to shift between an upper and a lower alternate position;
• said pump section includes a production barrel and a production piston reciprocatingly received therein, said production piston dividing said barrel into upper and lower production chambers;
• said upper production chamber being directly connected to said lower engine chamber;
• said lower production chamber having inlet and outlet means;
• means directly connecting said upper engine chamber to said production fluid outlet;
• so that said lower engine chamber is alternately connected to said power fluid source and said production fluid outlet;
• to thereby cause the engine piston to reciprocate the production piston.

A fluid operated pump assembly for operation downhole in a well bore, said pump assembly has a valve and engine section, and a pump section, all operatively connected together to form said pump assembly, with the valve section controlling the flow of power fluid into and from the engine to thereby enable the engine to extract power from the power fluid, and with there being connecting means by which the engine section drives the pump section to enable the pump to lift fluid uphole, the improvement comprising:

• said engine section includes a cylinder having a piston reciprocatingly received therein, said piston dividing said cylinder into an upper and a lower cylindrical engine chamber;
• a control valve assembly which includes a control rod and a valve element;
• means forming an axial bore within said piston, said control rod being axially aligned and reciprocatingly received within said axial bore such that an annulus is formed therebetween;
• said valve element being reciprocatingly received within said annulus;
• a produced fluid outlet, a power fluid inlet, a power fluid flow passageway means extending from said power fluid inlet to said valve assembly, another passageway means extending from said valve assembly to said lower engine chamber;
• a spent power fluid flow passageway means extending from said valve assembly to said produced fluid outlet;
• abutment means connected to said control rod;
• means connected to the extremities of said engine cylinder for abuttingly engaging said control rod abutment means to cause said control rod to reciprocate between alternate positions in response to reciprocal movement of said piston respective to said cylinder, means associated with said control rod and valve element by which power fluid causes said valve element to shift between an upper and a lower alternate position in response to said control rod being moved between said alternate positions;
• said valve means connects said power fluid inlet to said another passageway when said valve element is in one of the recited positions and said valve means connects said another passageway to said spent power fluid flow passageway when said valve element is in the other one of the recited positions;
• said production pump includes a production barrel and a production piston reciprocatingly received therein, said production piston dividing said barrel into upper and lower production chambers;
• said upper production chamber being directly connected to said lower engine chamber;
• said lower production chamber having inlet and outlet means;
• said upper engine chamber being directly connected to said production fluid outlet;
• so that said lower engine chamber is alternately connected to said power fluid source and said production fluid outlet;
• to thereby cause the engine piston to reciprocate the production piston.