Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR REMOVING FLUIDS
FROM UNDERGROUND WELLS
10
BACKGROUND OF TILE INVENTION
1. Field of the Invention
The invention relates to a method and apparatus for removing fluids from
hydrocarbon
producing wells to improve production and, more particularly, to a gas
operated pump for
pumping fluids from a producing formation to the surface, and still more
particularly to an
improved valve for a gas operated pump.
2. Background
In the past, various methods and systems for removing fluids from hydrocarbon
producing wells to improve production have been suggested. Prior art
techniques and devices
are discussed in U.S. Patent 4,791,990, which issued on December 20, 1988 to
Mahmood
Amani; U.S. Patent 4,901,798, which issued on February 20, 1990 to Mahmood
Amani; and the
1993 SPE 25422 Paper entitled HYhRAULIC GAS PUe~P AND GAS WEGL DE-W.ITERING
SYSTEM: TWO
NEW ARTIFICUL-LIFT SYSTEMS FOR OIL AND GAS WELLS by Mahmood Amani, all of
which are
incorporated herein by reference.
Generally, prior art gas operated pumps operate by injecting pressurized gas
into a
subsurface chamber to force formation liquids to the surface through a U-
shaped tube and
venting the gas from the chamber to allow the chamber to refill with liquids.
Typically, these
pumps include tlae following additional elements: a first check valve that
allows one-way
entry of formation liquids into the chamber; flow tubing extending from the
chamber to the
surface through the well bore; a second check valve to prevent the downward
flow of liquid
from the (low tubing into the chamber; t;as supply tubing for delivering
pressurized gas to the
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chamber; an injection control valve for controlling the input of gas into the
clamber; and a
vent valve fox controlling the venting of gas from the chamber.
U.S. Patents 660,545, 3,617,152 and 4,427,345 describe techniques utilizing
the
forces of pressurized gas and springs to open and close the injection control
valve and vent
valve. When the gas supply line is pressurized, the force of the gas causes
the injection
control valve to open and the vent valve to close. As pressure is relieved,
the spring force
closes the injection control valve and opens the vent valve. Thus, by
alternately pressurizing
and de-pressurizing the gas supply line, the valves are actuated.
U.S. Patent 4,405,291 describes actuating the injection control valve and vent
valve
by the upward and downward movement of a piston located within the pump
clamber. The
piston moves downwardly by the force of the pressurized gas and upwardly by
the force of
formation liquids filling the pump chamber. In U.S. Patent 4,791,990 to
Mahmood Amani
(incorporated herein by reference), the injection control valve is actuated by
the force of the
pressurized gas and the vent valve is opened and closed by a subsurface
actuator, which
responds to hydraulic pressure transmitted through one or more hydraulic
control lines
extending from the surface.
These devices and methods lave deficiencies for various reasons. First, in
many
instances, one or both valves are actuated by the pump's pressurized gas, by
formation fluids
or by springs, none of which can be precisely controlled from the surface. In
particular, many
prior art devices use the pump's pressurized gas to actuate either or both
valves. First, the
deeper the well, the greater the quantity of gas which is necessary to
overcome the differential
pressure in the gas supply line to open the valve. For wells deeper than a few
hundred feet,
substantial quantities of pressurized gas are needed. Secondly, to close a
valve that is opened
by the force of pressurized gas, it is necessary to vent or bleed the gas line
to release the
pressure on the valve. This causes a time lag between the closing of that
valve and the
opening of the other valve, resulting in slow valve cycling and pump rates. In
addition,
operating costs are high with the prior art devices and methods because of the
significant
energy needed to operate the pressurized gas source and the high volume of
pressurized gas
that is necessary. Further, the reliance on resilient means, such as springs,
to open or close
the valves opposite differential pressure of the system is ineffective at
depths over a few
hundred feet because of the magnitude of the differential pressure. ,
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Attempts have been made to overcome these problems by actuating the inlet
control
valve and vent valve by the reciprocating movement of the flow tubing, such as
in U.S. Patent
2,416,359. That device includes flow tubing extending in the wellbore from the
surface to the
pump chamber that is reciprocated by a hydraulic piston located at the
surface. Because the
flow tube is usually long and heavy, this method causes structural fatigue and
is inefficient
and unreliable.
Thus, there exists a need for an efficient and effective gas operated valve
for pumping
fluids to the surface from an underground well. Accordingly, prior to the
development of the
present invention, there has been no method of pumping formation fluids to the
surface with a
gas operated pump having inlet control and vent valves capable of being opened
and closed
by an independently actuated mechanism that: can be controlled from the
surface; provides
improved valve cycle rates; does not rely on or use the pump's pressurized gas
for valve
actuation; does not rely on resilient urging means to overcome system
differential pressure;
does not require movement of the tubing in the well bore; and operates cost
effectively.
Therefore, the art has sought a method and apparatus for pumping fluids from a
producing
hydrocarbon formation utilizing a gas operated pump having valves actuated by
an
independent hydraulic actuation mechanism to provide increased effectiveness
and enhanced
efficiency.
The present invention overcomes the deficiencies of the prior art.
SUMMARY OF THE INVENTION
The apparatus of the present invention includes a supply valve having an open
supply
position to supply gas to a downhole accumulation chamber and a closed supply
position, a
vent valve having an open vent position to vent gas from the chamber and a
closed vent
position, and an actuator communicating with a pressurized fluid source at the
surface for
actuating the valves. The actuator moves the supply valve to the open supply
position and the
vent valve to the closed vent position, and alternately moves the vent valve
to the open vent
position and the supply valve to the closed supply position. The actuator may
include one or
two hydraulically actuated reciprocating members, each reciprocating member
having a
slidably movable piston disposed within a cylinder. A pair of biasing members
for biasing
each valve in either the open or closed position, respectively, may be
included.
When the apparatus includes a single reciprocating member, each end of the
reciprocating member is associated with one of the valves. In operation,
hydraulic fluid is
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alternately injected from the surface into the cylinder above and below the
piston, forcing the
reciprocating member to reciprocate. When the reciprocating member is moved in
one
direction, the supply valve is opened and the vent valve is permitted to
close, allowing
pressurized gas to be inserted from the surface to displace fluids in the
accumulation
chamber. When the reciprocating member is moved in the opposite direction, the
vent valve
is opened and the supply valve is closed, allowing gas from the accumulation
chamber to be
vented through the apparatus.
If the apparatus of the present invention includes a pair of reciprocating
members, the
terminal end of the first reciprocating member is associated with the supply
valve, while the
terminal end of the second reciprocating member is associated with the vent
valve. In
operation, the injection of hydraulic fluid into the cylinder on one side of
each reciprocator
piston causes the reciprocating members to move in opposite directions. This
forces the
supply valve to open and permits the vent valve to close, allowing the
insertion of pressurized
gas into the chamber. The release of hydraulic pressure in the actuator allows
the
reciprocating members to move hack to their original positions, opening the
vent valve and
permitting the supply valve to close. This allows the venting of the chamber.
A conduit may
be connected to the actuator opposite the hydraulically pressurized side of
the piston of each
reciprocating member, providing a constant hydrostatic pressure thereto. This
force will
encourage movement of the reciprocating members in the second direction as
described
above. This hydrostatic pressure also allows enhanced control of the operation
of the
assembly by constantly providing a force opposite the hydraulic force.
The present invention thus provides an improved apparatus and method for use
with a
gas pump and well tubing for removing fluid from underground wells that does
not rely on
the use of the pump's pressurized gas for valve actuation. Further, valve
actuation with the
present invention can be controlled from the surface, improving efficiency and
effectiveness.
Other objects, features and advantages of the present invention will be
apparent froixl the
drawings, the specifications and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a detailed description of preferred embodiments of the invention,
reference will now
be made to the accompanying drawings, wherein:
FIG. 1 is a cross-sectional schematic view of a first embodiment of an
improved
hydraulic valve assembly for a gas operated fluid pump;
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FIG. 2 is an elevational schematic view showing the valve assembly of FIG. 1
as a
component of a gas operated pump with the accumulation chamber filled with
formation
liquids;
FIG. 3 is an elevational schematic view showing high pressure gas flowing into
the gas
accumulation chamber, forcing the accumulated formation liquids up the
flowbore of a tubing
string to the surface;
FIG. 4 is elevational schematic view showing the accumulation chamber filled
with high
pressure gas;
FIG. 5 is an elevational schematic view showing the high pressure gas venting
from the
accumulation chamber and the accumulation chamber f ping with formation
liquids;
FiG. 6 is a cross-sectional schematic view of a second embodiment of an
improved
valve assembly for a gas operated pump;
FIG. 7 is an elevational schematic view showing the valve assembly of FIG. 6
in use
with a gas operated pump; and
Fig. 8 is an elevational schematic view showing a gas operated pump having an
improved valve assembly with a pair of hydraulic input lines concentrically
disposed within a
gas supply line.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the description which follows, like parts are marked throughout the
specification and
drawings with the same reference numerals, respectively. The drawings are not
necessarily to
scale and certain features in certain views of the drawings may be shown
exaggerated in scale or
in schematic form in the interest of clarity and conciseness.
Refernng initially to FIG. 2, a hydrocarbon producing well 10 is illustrated
having a
conventional casing 12 with perforations 14, providing fluid communication
between the
producing formation 16 and the flowbore 18 of casing 12. A tubing string 20
extends from the
surface down through the flowbore 18 of casing 12. The hydrocarbons produced
by the
formation flow to the surface through a flowbore 46 in the tubing string 20.
In the preferred embodiments of FIGS. 2-5, a pressure vessel 24 is used to
store and
supply high pressure gas. The source for the high pressure gas can be a high
pressure gas
producing well, or a gas sales line. A compressor 26 compresses the gas from
well 10, or from
other gas sources, into the high pressure gas vessel 24 to maintain the
required pressurized gas
volume.
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FIG. 2 further illustrates a gas operated pump 30 disposed at the lower end of
the tubing
string 20. The pump 30 includes an accumulation chamber 34 for the
accumulation of
formation fluids, a bypass passageway 32, and a valve assembly 40 of the
present invention.
The accumulation chamber 34 includes a one-way valve such as a check valve 36
at its lower
terminal end 38. The one-way valve 36 allows formation fluids to flow into the
accumulation
chamber 34 through an aperture 37 and prevents the accumulated fluids from
flowing back out
of accumulation chamber 34 through the aperture 37 in the lower terminal end
38 of the
chamber 34.
The bypass passageway 32 extends from an outlet 42 proximate to the lower
terminal
end 38 of the chamber 34, and extends around the chamber 34 and the valve
assembly 40 to an
inlet aperture 44 for communicating with the lower end of the flowbore 46 of
the tubing string
20. A one-way valve 47 is disposed in the bypass passageway 32 at the lower
end thereof to
allow flow upwardly through the bypass passageway 32, but closing the
passageway 32 to
downward flow back into the accumulation chamber 34. Another check valve (not
shown) may
be added at the inlet 44 to prevent sand or other debris from settling in the
bypass passageway
32 when the pump 30 is shut down.
Referring now to the preferred embodiment of FIG. l, the valve assembly 40
includes a
valve housing 50 and a side bore, or flowway, 52. The side bore or flowway 52,
shown as an
integral part of the housing 50, communicates with the accumulation chamber 34
of the pump
30 (FIG. 2) via an aperture 64. The housing 50 includes an inlet chamber 54
for receiving high
pressure gas, a first or upper communication chamber 56 in fluid communication
with the inlet
chamber 54, an enclosure or cylinder 58, an outlet chamber 60 for venting high
pressure gas,
and a second or lower communication chamber 62 in fluid communication with the
outlet
chamber 60. The upper and lower communication chambers 56, 62 are each also in
fluid
communication with the side bore 52. The side bore 52 has an inlet 68 into
upper
communication chamber 56 and an outlet 66 into lower communication chamber 62.
Pressurized gas is supplied to the inlet chamber 54 of the valve assembly 40
through an
inlet port 78 from a gas supply line 80 extending from the pressure gas vessel
24 (FIG. 2). A
gas inlet, or injection control, valve 70 is disposed between the inlet
chamber 54 and the upper
communication chamber 56 to control the inflow of pressurized gas into the
flowway 52 for
forcing formation fluids from the accumulation chamber 34 into the tubing
string 20. The
injection control valve 70 is movable between open and closed positions and
may be any among
IpED°SH~E~
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a variety of conventional gas valves. In the preferred embodiment of FIG. 1,
the valve 70
includes a valve closure member 74 that is sealably enagageable with a valve
seat 72, and a
surface 73 for engagement with an actuation mechanism 109, as will be
described further
below. A resilient urging means, such as a spring 76, may be included for
biasing the closure
S member 74 to the closed position in sealing engagement with the valve seat
72.
The valve assembly 40 also includes a gas vent valve 90 disposed between the
outlet
chamber 60 and the lower communication chamber 62. The vent valve 90 is
movable between
open and closed positions and may take the same general form as the injection
control valve 70.
The vent valve 90 shown in FIG. 1 includes a valve closure member 94 that is
sealably
enagageable with a valve seat 92, and has a surface 93 for engagement with the
actuation
mechanism 109. A resilient urging means, such as a spring 96, may be included
for biasing the
closure member 94 to the closed position in sealing engagement with the valve
seat 92. The
vent valve 90 permits the exhaust or venting of gas from the accumulation
chamber 34 and the
valve assembly 40 through a vent port 98 in the outlet chamber 60. As show in
FIGS. 1 and 2,
the vent port 98, communicates with a vent line 100 which extends into an
annulus 22 between
the tubing string 20 and the casing 12. Alternately, the exhausted gas can be
directed into a
collection vessel (not shown) from the outlet chamber 60.
The valve assembly 40 also includes an actuator 109 associated with a
hydraulic input
mechanism for actuating the inlet control valve 70 and the vent valve 90. When
connected to a
hydraulic source 25 (FIG. 2) located above ground via a hydraulic input
mechanism, the
actuator 109 and thus the actuation of the valves 70, 90 may be controlled
from the surface.
Generally, one phase of operation of the actuator 109 causes the input control
valve 70 to open
and the vent valve 90 to close, while another phase causes the opposite valve
movements. The
valve assembly 40 can thus be operated with little or no time lag between the
opening of one
valve and the closing of the other valve to effect efficient pumping of fluid
from the
accumulation chamber 34. .
Still with respect to the preferred embodiment of FIG. l, a single
reciprocating member
110 is disposed within the enclosure, or cylinder, 58. The reciprocating
member 110 includes a
stem 112.with ends 124, 122 extending through apertures 114x, 116a in the end
walls 114, 1 I6
of the cylinder 58, respectively. Seals 115 and 117 may be mounted, or
encased, within
apertures 114a, 116x, respectively, to provide a fluid seal about the stem 112
as it reciprocates
therein, as will be described below. The stem 112 extends between the
injection control valve
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70 and the vent valve 90 whereby the terminal ends 124, 122 of the stem 112
are adapted to
engage the engagement surfaces 73, 93 of valves 70, 90, respectively, to open
one or the other
of the valves 70, 90 upon reciprocation within the enclosure or cylinder 58.
The reciprocating member 110 has a piston 113 that slideably, sealably engages
the
inner wall 59 of the cylinder 58, effectively dividing the cylinder 58 into
first and second sides
or cells 58A, 58B. The reciprocating member 110 is driven by hydraulic
pressure from a
hydraulic input mechanism. In the preferred embodiment of FIGS. 1-5, the
hydraulic input
mechanism includes input conduits 118, 120 connected with a hydraulic source
25. The first
hydraulic input conduit 118 communicates with the first side 58A of the
cylinder 58 through a
port 58C. The second hydraulic input conduit 120 extends from the hydraulic
source 25 to a
port 58D in the second side 58B of the cylinder 58.
In operation, upon pressurization through the first hydraulic input conduit
118, the first
side 58A is pressurized, forcing the piston 113 and, thus, the reciprocating
member 110 to move
downwardly within the cylinder 58. The lower terminal end 122 of the stem 112
then engages
the engagement surface 93 of the vent valve 90, thereby compressing the second
resilient urging
means 96 and unseating the closure member 94 from the valve seat 92 to open
the vent valve
90. This then allows gas to vent finm the lower communication chamber 62
through the outlet
chamber 60 and out of the valve assembly 40 via the vent port 98. Gas is thus
released into the
annulus 22 through the vent line 100, or otherwise directed into a collection
vessel as desired.
Alternately, upon pressurization of the second hydraulic input conduit 120,
supply side
58B of the enclosure 58 is pressurized, causing the reciprocating member 110
to move
upwardly so that the upper terminal end 124 of the stem 112 engages the
engagement surface 73
of the closure member 74. Upon compressing the first resilient urging member
76, the closure
member 74 unseats from the valve seat 72 and allows gas to flow from gas
supply line 80
through the inlet chamber 54 and into upper communication chamber 56. As one
valve 70, 90 is
opened, the other valve 70, 90 is closed by the force of the resilient urging
means 76, 96,
respectively, without having to overcome any differential pressure in the
system.
Referring now to FIGS. 2-5, in operation, formation fluids flow through one-
way valve
36 and fill accumulation chamber 34. FIG. 2 illustrates the accumulation
chamber 34 filled with
formation liquids. The accumulated liquids are pumped fi-om the accumulation
chamber 34 by
the valve assembly 40 by applying hydraulic pressure through conduit 120 (FIG.
3). As
discussed with respect to and shown in FIG. 1, the reciprocating member 110 is
thus moved
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upwardly such that the upper terminal end 124 engages the engagement surface
73 of the
injection control valve 70 to open the valve 70. Gas from the supply line 80
and the inlet
chamber 54 then passes into upper communication chamber 56, through port 68
and, as shown
in FIG. 3, down side bore 52 and into the accumulation chamber 34. The high
pressure gas
forces the accumulated formation liquids through outlet 42, into bypass
passageway 32 and up
flowbore 46 of the tubing 20. The accumulated formation liquids cannot pass
out of the
aperture 37 of the chamber 34 due to the one-way valve 36 closing the lower
end 38 of chamber
34 to the formation.
Referring now to FIGS. 4 and 5, upon filling the accumulation chamber 34 with
gas, or
otherwise attaining a desired fluid level in the accumulation chamber 34, the
hydraulic pressure
in the conduit 120 can be reduced and the pressure in the conduit 118
increased, causing the
reciprocating member 110 (FIG. 1) to move downwardly to open the vent valve 90
and allow
injection control valve 70 to close as previously described. Upon opening the
vent valve 90, gas
in the accumulation chamber 34 is allowed to vent upwardly through the
communication
chamber 62 (FIG. 1), the outlet chamber 60 and into the vent line 100 (FIG.
5). As the gas is
vented from the accumulation chamber 34, formation liquids are allowed to flow
through the
one-way valve 36 to again fill the accumulation chamber 34 with formation
fluids. Any
formation gas that enters the accumulation chamber 34 is pumped out with the
pressurized gas.
The above procedure is repeated as required to pump formation fluids to the
surface.
Another preferred embodiment of the valve assembly 40 of the present invention
for use
with a gas operated pump, such as pump 30, is shown in FIGS. 6 and 7. Valve
assembly 40
operates as a component of the pump 30 similar to the embodiment of the
invention shown in
FIGS. 2-5 with respect to the accumulation chamber 34, the bypass passageway
32, the
pressurized gas source 24 and the hydraulic pressure source 25, except as
noted below.
Referring now to FIG. 6, the valve assembly 40 includes a valve housing 50
with a flowway, or
side communication passageway, 52. The housing 50 also includes an inlet
chamber 54 for
receiving high pressure gas, an upper communication chamber 56 communicating
with the
flowway 52, an upper enclosure or cylinder 200, a lower enclosure or cylinder
202, an outlet
chamber 60 for venting gas, and a lower communication chamber 62 also
communicating with
the flowway 52. The flowway 52 communicates with the upper terminal end of the
accumulation chamber 34 at an aperture 64 and includes an outlet 66 into lower
communication
chamber 62 and an inlet 68 into the upper communication chamber 56.
I~INfLADED SHEET
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A first, or injection control, valve 70 is disposed between the inlet chamber
54 and the
upper communication chamber 56. Injection control valve 70 includes a valve
seat 72, a valve
closure member 74, and a resilient urging means, such as a spring 76, for
biasing the closure
member 74 into the closed position in sealing engagement with the valve seat
72. The inlet
S chamber 54 includes an inlet port 78 connected to a gas supply line 80,
which extends to the
surface and is connected to high pressure gas vessel 24 (FIG. 7). High
pressure gas vessel 24
supplies high pressure gas through the supply line 80 to the inlet chamber 54,
similarly as
described with respect to the embodiment of the FIG. 1.
A second, or vent, valve 90 is disposed between the vent chamber 60 and the
lower
communication chamber 62. The vent valve 90 similarly includes a seat 92, a
closure member
94 and a resilient urging means or spring 96. As will be described further
below, the spring 96
biases the closure member 94 into the open position. The outlet chamber 60
includes a vent
port 98 which communicates with a vent line 100, which may extend into the
annulus 22 for
venting the gas (FIG. 7).
A first reciprocating member 210 is disposed within the upper cylinder 200.
The
reciprocating member 210 includes an elongate portion, or actuator stem, 212,
which extends
through an aperture 214 in an end wall 201 of the upper cylinder 200. The
actuator stem 212 is
associated with, or connected to, the closure member 74 of the injection
control valve 70. Thus,
upon upward movement of the reciprocating member 210, the actuator stem 212
moves the
valve closure member 74 to its open position.
A second reciprocating member 220 is disposed within the lower cylinder 202.
The
reciprocating member 220 includes an actuator stem 222, which extends through
an aperture
224 in an end wall 203 of the cylinder 202. The actuator stem 222 is
associated with, or
connected to, the closure member 94 of the vent value 90. Upon downward
movement of the
reciprocating member 220, the actuator stem 222 moves the closure member 94
into its closed
position.
Each reciprocating member 210, 220 has a piston portion 211, 221 that
slideably,
sealably engages the wall of each respective cylinder, dividing it into two
cells. The piston
portion 211 divides the first cylinder 200 into a first, or supply cell 200A
and a second, or vent,
cell 200B. Likewise, the piston 221 divides the cyliniier 202 into a first, or
supply, cell 202A
and a second or vent cell 202B. A hydraulic supply conduit 120 extends from
the surface and
~IUI~NDED ~ Si~9~'~'
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connects to the first or supply cells 200A, 202A of the cylinders 200, 202 at
ports 200C and
202C, respectively.
In operation, upon providing hydraulic pressure through supply conduit 120,
the supply
cells 200A, 202A are pressurized, causing the second reciprocating member 220
to move
downwardly within the cylinder 202 and the first reciprocating member 210 to
move upwardly
in the cylinder 200. As the second reciprocating member 220 moves downwardly,
the actuator
stem 222 moves the valve closure member 94 downwardly, compressing the spring
96 and
seating the closure member 94 upon the valve seat 92 to close the vent valve
90. This prevents
gas from flowing through the valve assembly 40 from the accumulation chamber
34. As the
first reciprocating member 210 moves upwardly, the actuator stem 212 moves the
closure
member 74 upwardly, compressing the spring 76 and unseating the closure member
74 from the
valve seat 72. Thus, high pressure gas is permitted to flow from the gas
supply line 80 through
the inlet chamber 54 and into the upper communication chamber 56. The high
pressure gas
passes through the inlet 68, down flowway 52 and into the upper end of the
accumulation
chamber 34, forcing accumulated formation liquids into the bypass passageway
32 (FIG. 7) and
up the flow bore 46 of the tubing 20 (FIG. 7).
Upon filling the accumulation chamber 34 with gas, or otherwise attaining a
desired
fluid level in the accumulation chamber 34, the hydraulic pressure in supply
line 120 can be
reduced to allow the resilient urging means 76, 96 to expand. This will force
the first
reciprocating member 2I0 downwardly, seating the valve closure member 74 upon
the valve
seat 72, and the second reciprocating member 220 upwardly, unseating the valve
closure
member 94 from the valve seat 92. To provide greater opening and closing force
during this
movement, a hydrostatic conduit 230 connecting the vent cells 200B, 202B of
each cylinder
with the tubing sting flowbore 46 may be included. In the preferred embodiment
of FIGS. 6
and 7, hydrostatic conduit 230 connects the cells 200B, 202B of the cylinders
200 and 202,
respectively, with the flowbore 46 (FIG. 7) of the tubing string 20 at a port
240 in the tubing
string 20 above the valve assembly 40. The conduit 230 thus provides fluid
communication
between the tubing string 20 and the vent cells 200B, 202B, such that the
hydrostatic weight of
fluid in the flowbore 46 above the valve assembly 40 exerts fluid pressure
against the pistons
r 30 211, 221 (FIG. 6) opposite the hydraulic pressure in the first cells
200A, 202A. This force on
one side of each piston 211, 221 allows enhanced operational control of the
valve assembly 20
because the opposing hydraulic force can be controlled from the surface.
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As the injection control valve 70 closes, the input of pressurized gas from
the supply
line 80 is reduced. Upon opening the vent valve 90, gas in the accumulation
chamber 34 is
allowed to vent upwardly through the communication chamber 62, the outlet
chamber 60 and
into the vent line 100. As gas is vented from the accumulation chamber 34,
formation liquids
are allowed to flow through the one-way valve 36 (FIG. 7) to again fill the
accumulation
chamber 34 with formation liquids. Thus, the valve assembly 40 can be actuated
by controlling
hydraulic pressure in a single line. The above procedure is repeated as
required to pump
formation liquids to the surface.
FIG. 8 illustrates the pump 30 and valve assembly 40 having hydraulic input
lines 118,
120 concentrically disposed within the gas supply line 80. With this
configuration, an improved.
technique for installation and removal of the valve assembly 40 may be
performed. Utilizing
this technique, the hydraulic input lines 118 and 120 are concentrically
disposed within the
supply line 80 at the surface. The supply line 80 may be conventional coiled
tubing (not shown)
and the hydraulic input lines 118, 120 may be pre-manufactured or pre-
installed therein. Also at
the surface, the valve assembly 40 is connected to the supply line 80 and the
hydraulic input
lines 118 and 120.
The valve assembly 40 and the supply line 80 are then lowered into the tubing
string 20,
such that the supply line 80 is concentrically disposed within the tubing
string 20. This double
concentric configuration of the hydraulic input lines 118, 120, supply line 80
and tubing string
20 assists in protecting the lines 80, 118, 120 from damage or malfunctioning
that may occur
when the lines 80, 118, 120 extend within the annulus 22. Further, when coiled
tubing is used
for the supply line 80 as described above, the valve assembly 40 can be easily
installed and
removed with conventional coiled tubing techniques.
Thereafter, the valve assembly 40 is connected with the accumulation chamber
34, such
as by securing the valve assembly within a conventional seating nipple 300
disposed proximate
to the accumulation chamber 34. The seating nipple 300 may be any among a
variety of
commercially available seating nipples compatible for use with the present
invention. This
installation technique provides a simplified, time efficient method utilizing
existing equipment
for installing the valve assembly 40 in the well 10 and for retrieving the
valve assembly 40 from
the well 10 for maintenance and repairs.
It is to be understood that the invention is not limited to the exact details
of construction,
operation, exact materials or embodiments shown and described, as obvious
modifications and
AMENDf D ~ SET
12
CA 02254722 1998-08-21
WO 97J38226 PCTJUS97I04787
equivalents will be apparent to one skilled in the art without departing from
the scope and spirit
of the invention as defined by the appended claims. Accordingly, the invention
is therefore to
be limited only by the scope of the appended claims.
13
SUBSTITUTE SHEET (RULE 26)
