Pumps – One fluid pumped by contact or entrainment with another – Jet
Reexamination Certificate
1999-08-23
2001-10-02
Walberg, Teresa (Department: 3742)
Pumps
One fluid pumped by contact or entrainment with another
Jet
C137S375000
Reexamination Certificate
active
06296453
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field oil and gas production equipment and, more particularly, to a flow line choke that increases production from a low pressure well.
BACKGROUND OF THE INVENTION
Chokes, i.e., fluid flow regulating devices, are used in flow lines leading from wells such as oil and/or gas wells in the earth. Some of these well flow line chokes are positive chokes (fixed flow) and others are adjustable (variable flow rate). A variable flow rate choke has a movable means for varying the amount of restriction on well fluids flowing through the choke. Normally, the movable means in the choke body is designed to mate with an insert which is fixed in the body of the choke to cause the restricting effect on the fluids. This insert acts like a valve seat, and the solid valve stem may be moved axially for greater or lesser choking of the fluid flow. Such a well flow line choke is well described in Wolcott et al., U.S. Pat. No. 4,712,579.
A number of effective and successful flow line chokes are commercially available, notably from Cameron Willis, Best, OCT, Grayloc, Thornhill-Craver, Master-Flo, and BST Lift Systems. These chokes do an excellent job of regulating the flow of oil and gas from the wellhead, controlling the rate of production and the rate of introduction of hydrocarbons into the sales stream. However, as the well becomes depleted, wellhead pressure drops, and eventually no flow regulation is required since the well operates full open and may even require a compressor to introduce the hydrocarbons into the sales stream. None of the chokes known heretofore can enhance the flow of oil and gas through the fluid flow line as the well becomes depleted and wellhead pressure decreases to a low pressure.
Thus, there remains a need for a well flow line choke which can enhance oil and gas recovery from a well at low wellhead pressure.
SUMMARY OF THE INVENTION
The present invention addresses these and other drawbacks in the art by providing a venturi in the choke to draw a vacuum in the choke body. This vacuum creates a pressure differential between the producing strata below and the choke body, thereby increasing flow of fluid from the well.
In one aspect, the present invention provides a gas recirculation line from the outlet of the choke, through a compressor, back to the choke. The compressor provides gas flow through a venturi to create the vacuum. Gas flow through the venturi may also be provided from another source of pressurized gas.
In another aspect of this invention, there is provided a modified fluid flow choke with a flow line through the choke stem. The flow line through the stem is injected with pressurized and recirculated gas from the outlet of the choke. The region within the body between an insert, serving as a valve seat, and a conical region of the stem, serving as a valve disk, acts as a venturi to create an ideal vacuum at the venturi, preferably about 30″, and thereby in the choke body.
The present invention provides a number of advantages over the flow restricting chokes of the art. For example, the production booster of this invention alleviates flaring from the well, thereby reducing pollution. Gas, which otherwise would be flared, is instead compressed and recirculated into the choke of this invention. There, the compressed gas is injected onto a choke beam, creating a venturi effect and drawing fluid from the well to increase productivity and increase the useful life of the well. In another aspect of this invention, if higher tubing well pressure is available and accessible, this higher tubing pressure can be jumped off to inject through the choke of this invention, thereby keeping a marginal well flowing, and increasing it's production until the well is depleted. A further advantage of this invention is the reduction in time required to return a well to normal flowing rate after a shut in. Finally, by recirculating and using gas that would otherwise be flared, the total recovery from a well is increased.
The present invention is easily adapted to any of the currently commercially available well flow line chokes. This provides the advantage of inexpensive retrofit of operating installations as wellhead pressure drops to commercially unviable levels. Further, the compressor does not require an expensive overhaul and modification to maintain the well in operation.
These and other aspects, features, and advantages of the present invention will be apparent to those skilled in the art from a review of the following description.
REFERENCES:
patent: 3552490 (1971-01-01), Dollison
patent: 3683965 (1972-08-01), McClure et al.
patent: 3834414 (1974-09-01), McMurry
patent: 4025235 (1977-05-01), Newbrough
patent: 4106562 (1978-08-01), Barnes et al.
patent: 4390061 (1983-06-01), Short
patent: 4555872 (1985-12-01), Yie
patent: 4557329 (1985-12-01), Savard et al.
patent: 4618314 (1986-10-01), Halley
patent: 4712579 (1987-12-01), Wolcott et al.
patent: 4716970 (1988-01-01), Henning
patent: 4825895 (1989-05-01), Maltman
patent: 4988389 (1991-01-01), Adamache et al.
patent: 5105889 (1992-04-01), Misikov et al.
patent: 5246074 (1993-09-01), Ayres
patent: 5427151 (1995-06-01), Pauley
patent: 5485867 (1996-01-01), Stoll
patent: 5752570 (1998-05-01), Shaposhnikov et al.
Printout of Internet Web Site for Thornhill Craver Adjustable Chokes: www.camerondiv.com.
Printout of Internet Web Site for Cameron Willis Choke Products: www.camerondiv.com.
Bracewell & Patterson L.L.P.
Fastovsky Leonid
Walberg Teresa
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