Wells – Processes – Disassembling well part
Reexamination Certificate
2001-10-11
2004-02-17
Bagnell, David (Department: 3672)
Wells
Processes
Disassembling well part
C166S378000, C166S372000, C166S105000, C166S322000
Reexamination Certificate
active
06691787
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to artificial lift for hydrocarbon wells. More particularly, the invention relates to gas operated pumps for use in a wellbore. More particularly still, the invention relates to a gas operated pump having a removable valve insertable in a housing with fluid pathways in the housing that operate in conjunction with the valve.
2. Description of the Related Art
Oil and gas wells include a wellbore formed in the earth to access hydrocarbon-bearing formations. Typically, a borehole is initially formed and thereafter the borehole is lined with steel pipe, or casing in order to prevent cave in and facilitate the isolation of portions of the wellbore. To complete the well, at least one area of the wellbore casing is perforated to form a fluid path for the hydrocarbons to enter the wellbore. In some instances, natural formation pressure is adequate to bring production fluid to the surface for collection. More commonly however, some form of artificial lift is necessary to retrieve the fluid.
Artificial lift methods are numerous and include various pumping arrangements. One common pump is a gas operated pump, as shown in FIG.
1
.
FIG. 1
is a section view of a wellbore with a gas operated pump disposed therein. The pump
30
is located adjacent perforations in the wellbore
10
. The pump operates with pressured gas injected from a high pressure gas vessel
24
into a gas supply line
80
to a valve assembly
40
disposed in a body of the pump
30
. The valve assembly
40
consists of an injection control valve
70
for controlling the input of gas into a accumulation chamber
34
and a vent control valve
90
for controlling the venting of gas from the chamber
34
. Operational power is brought to the valve assembly
40
by input lines
75
,
77
. The pump
30
has a first one-way valve
36
at the lower end
38
of the chamber
34
. An aperture
37
at the lower end
38
of the chamber permits formation fluid to flow through open valve
36
to enter the chamber
34
. After the chamber
34
is filled with formation fluid, the vent control valve
90
closes and the injection control valve
70
opens. Gas from the gas supply line
80
is allowed to flow through the open injection control valve
70
into the chamber
34
. As gas enters the chamber
34
, gas pressure forces the formation fluid downward, thereby closing the first one-way valve
36
. As the gas pressure increases, formation fluid therebelow is urged into outlet
42
and opens a second one-way valve
47
. Fluid enters the valve
47
and travels along passageway
32
and into the tubing string
20
. After formation fluid is displaced from the chamber
34
, the injection control valve
70
is closed, thereby restricting the flow of gas from the high pressure gas vessel
24
.
Hydrostatic fluid pressure in the passageway
32
acts against second one-way valve
47
, thereby closing the valve
47
and preventing fluid from entering the chamber
34
. The vent control valve
90
is opened to allow gas in the chamber
34
to exit a vent line
100
into an annulus
22
formed between the casing
12
and the tubing string
20
. As the gas vents, the gas pressure decreases thereby reducing the force on the valve
36
. At a point when the formation fluid pressure is greater than the gas pressure in the chamber
34
the valve
36
opens thereby allowing formation fluid to once again fill the chamber
34
. In this manner, a pump cycle is completed. As the gas operated pump
30
continues to cycle, formation fluid gathers in the tubing string
20
and eventually reaches the surface of the well for collection.
U.S. Pat. No. 5,806,598 to Mohammad Amani, incorporated herein by reference in its entirety, discloses a method and apparatus for pumping fluids from a producing hydrocarbon formation utilizing a gas operated pump having a valve actuated by a hydraulically actuation mechanism. In one embodiment, a valve assembly is disposed at an end of coiled tubing and may be removed from the pump for replacement.
The conventional pumps illustrated in FIG.
1
and described in the '598 patent suffer from problems associated with size limitations in downhole pumps. These valve assemblies for a gas operated pump have an internal bypass passageway for injecting gas into the chamber. The internal bypass passageway must be a large enough diameter to facilitate a correct amount of gas flow into the chamber. These internal structures necessarily make the valve large and bulky. A bulky valve assembly is difficult to insert in a downhole pump because of space limitations in a wellbore and in a pump housing.
There is a need, therefore, for a gas operated pump having a valve assembly that is less bulky. There is a further need for a gas operated pump with a removable valve that does not include a bypass passageway.
SUMMARY OF THE INVENTION
The present invention generally provides a gas operated pump having a removable and insertable valve. In one aspect, the invention includes a pump housing having a fluid path for pressurized gas and a second fluid path for exhaust gas. The fluid paths are completed when the valve is inserted into a longitudinal bore formed in the housing.
REFERENCES:
patent: 2336683 (1943-12-01), Hatfield
patent: 2923357 (1960-02-01), Daffin
patent: 3334690 (1967-08-01), Garrett
patent: 3833060 (1974-09-01), Craggs et al.
patent: 3873238 (1975-03-01), Elfarr
patent: 3883060 (1975-05-01), Scarpa
patent: 3889748 (1975-06-01), Tausch
patent: 4239082 (1980-12-01), Terral
patent: 4534414 (1985-08-01), Pringle
patent: 4667736 (1987-05-01), Rumbaugh et al.
patent: 4791990 (1988-12-01), Amani
patent: 4901798 (1990-02-01), Amani
patent: 5058670 (1991-10-01), Crawford et al.
patent: 5325917 (1994-07-01), Szarka
patent: 5806598 (1998-09-01), Amani
patent: 6068015 (2000-05-01), Pringle
patent: 6206645 (2001-03-01), Pringle
patent: 6227302 (2001-05-01), Pringle et al.
International Search Report from the European Patent Office for International Appl. No. PCT/GB01/04535, dated Apr. 15, 2002.
“Subsurface Safety Accessory Equipment,” Halliburton, pp. 4-12-4-13, (undated).
“Basic Camco Side Pocket Mandrel Designs,” Camco Products and Services, pp. 63-66 (undated).
Bagnell David
Moser, Patterson & Sheridan L.L.P.
Smith Matthew J
Weatherford / Lamb, Inc.
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