Wells – With below and above ground modification – Eduction pump or plunger in well
Reexamination Certificate
1999-08-10
2001-01-16
Tsay, Frank (Department: 3672)
Wells
With below and above ground modification
Eduction pump or plunger in well
C166S105500
Reexamination Certificate
active
06173768
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to equipment for the production of hydrocarbons and, more particularly, to a method and apparatus for downhole oil/water separation during oil well pumping operations.
BACKGROUND OF THE INVENTION
The production of underground hydrocarbons often requires substantial investment in drilling and pumping equipment. When production is underway, up-front costs can be recouped provided operating costs remain low enough for the sale of oil and/or gas to be profitable. One factor which significantly effects the operating costs of many wells is the amount of water present within the associated hydrocarbon producing formation. Many profitable wells become uneconomic because of excessive water production. Costs involved with pumping, separating, collecting, treating and/or disposing of water often have a devastating impact on the profit margins, particularly for older wells with declining hydrocarbon production.
Over the years, many attempts have been made to limit the amount of water produced by a well. Down-hole video has been utilized to determine which perforations within the well produce the most oil, and which perforations produce the most water. Chemicals and/or cement may then be utilized in an effort to shut off water producing perforations. One such down-hole video revealed that oil droplets were distinctly separate from the water that was being produced. More importantly, it was recognized that oil and water are typically separated by gravity segregation in the wellbore until they are mixed together by the downhole pump.
In order to capitalize on this phenomena, the Dual Action Pumping System (“DAPS”) was developed wherein a dual ported, dual plunger rod pump produced oil and water from the annulus on the upstroke while injecting water on the down stroke. In many suitable wells DAPS have substantially increased production while simultaneously reducing power requirements.
SUMMARY OF THE INVENTION
In accordance with teachings of the present invention an improved method and apparatus for down-hole oil/water separation during pumping operations is provided to substantially improve hydrocarbon production as compared to prior down-hole oil/water separating pumps.
One embodiment of the present invention includes a conventional sucker rod pump disposed within a tubing string which may be disposed within the casing of a wellbore. The sucker rod pump may be releasably attached to a sucker rod at one end. The sucker rod pump may have a single ball and seat type traveling valve with the bottom check valve or standing valve removed.
In another embodiment, the casing may also contain a plurality of injection perforations which may be spaced down-hole from a plurality of production perforations. A packer may be located in a down-hole position between the production perforations and the injection perforation. The packer may circumferentially surround the tubing string to form a fluid seal within the annulus between the casing string and the tubing string.
In yet another embodiment, a side intake valve may be disposed within the tubing string at a position down-hole from the sucker rod pump. The side intake valve may also be disposed at an elevation above the packer and above the production perforations.
In still another embodiment, a check valve may be located within the tubing string at a position down-hole from the sucker rod pump. The check valve is preferably disposed at an elevation below the side intake valve. In one embodiment, the check valve may be of the gravity operated type. In another embodiment, the check valve may be of the spring-loaded type.
In yet another embodiment, the sucker rod may be attached to a standard pumping jack located at the surface of the wellbore. The tubing string may be attached to production piping at the surface of the wellbore. In one embodiment, the production piping may be configured to form a bypass loop. The bypass loop may further contain a check valve to regulate the direction of flow of the produced fluid. An automatic control valve may also be located within the bypass loop to allow the produced fluid to bypass the check valve. A back pressure regulator may be installed within the production piping on the side of the bypass loop opposite the wellbore. In one embodiment, an accumulator may also be connected to the production piping between the bypass loop and the back pressure regulator.
Technical advantages of the present invention include providing a sucker rod pump for down-hole oil/water segregation during pumping operations. In particular, the apparatus of the present invention may separate oil and water in the tubing string and/or the annulus between the tubing string and the casing. This allows the apparatus to produce oil with a limited amount of water to the surface of the well while injecting water back into the formation, during pumping operations.
Another technical advantage of the present invention includes the simplicity and compactness of its design. This permits the apparatus to operate utilizing standard downhole well equipment with minor modifications. Accordingly, downhole equipment incorporating teachings of the present invention can be built and maintained at a reduced cost and operators require very minimal training. Furthermore, this apparatus is not limited in application and can be incorporated into any standard-sized casing or tubing string.
Yet another technical advantage of the present invention includes the injection pressure supplied by the accumulator located at the well surface. There is no pressure limit for this pump because high pressure wells can be counteracted by raising the pressure in the accumulator thereby increasing the injection pressure.
Further technical advantages of the present invention include providing a pump which eliminates the problem of gas-lock which occurs in dual-plunger pumping systems. Furthermore, the present invention provides a pumping system which minimizes or eliminates the injection of oil into the formation when the upper pump has “pumped off.”
REFERENCES:
patent: 4026661 (1977-05-01), Roeder
patent: 4427345 (1984-01-01), Blann et al.
patent: 5988275 (1999-11-01), Brady et al.
patent: 6082452 (2000-07-01), Shaw et al.
patent: 6116341 (2000-09-01), Stuebinger et al.
Halliburton Energy Service,s Inc.
Herman Paul I.
Smith Marlin R.
Tsay Frank
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