Note: Descriptions are shown in the official language in which they were submitted.
CA 02600740 2007-09-07
1 "DISCHARGE PRESSURE ACTUATED PUMP"
2
3 FIELD OF THE INVENTION
4 Embodiments of the invention are related to pumps and more
particularly to single conduit pumps for use in locations remote from the
pump's
6 discharge including being located in wellbores, the pumps being actuated
7 remotely such as by cycling pressure at the discharge of the pump.
8
9 BACKGROUND OF THE INVENTION
Pumps are well known to move fluids from at least a first location to
11 a second location. A large number of pump configurations are known, each
with
12 particular advantages and disadvantages and which may have been designed
13 for particular uses in a variety of fluid-moving industries.
14 It is well known to provide pumping apparatus situated in
subterranean wellbores for pumping fluid therefrom to the surface.
16 Conventionally, a prime mover, such as an electric motor, has been
located at
17 the pump or mechanically connected thereto so as to permit actuation of
pumps,
18 such as a rod pump or progressive cavity pump, to lift liquids such as
produced
19 fluids and accumulated fluids therefrom. In the case of wellbores,
particularly
those situated in remote locations, it is desirable to situate the pump within
the
21 wellbore and to actuate the pump remotely. Typically, many of the pumps
known
22 in the art require two conduits, one to provide a motive force to
operate the
23 pump, such as in the case of hydraulic-actuated pumps, and the second to
24 permit production of the fluids to surface.
CA 02600740 2007-09-07
1 In the case
of said wellbores, it is known to provide remotely
2 actuated
pumps, such as those which are actuated by sonic or acoustic pressure
3 waves (US
Patent 4,295,799 to Bentley, US Patent 1,730,336 to Bellocq, US
4 Patents
2,444,912, 2,553,541, 2,553,042, 2,553,043, and 2,953,095, to Bodine
Jr.)
6 Further it is
known to provide remotely actuated pumps which are
7 actuated by
alternately applying and releasing pressure at discharge of the
8 pump. One
such pump is taught in US Patent 4,390,326 to Callicoate which
9 teaches an
annular external piston and an internal piston movable in concentric
annular and internal chambers. The internal chamber has an inlet end and an
11 outlet end
fit with one-way valves. The internal piston divides an internal barrel
12 into a lower
chamber and an upper chamber. The lower chamber has an inlet
13 valve and an
outlet valve through which pumped fluid is transferred to the upper
14 chamber. The
upper chamber has an outlet valve through which fluids are
transferred into conduit thereabove. As the pump is stroked, fluid from below
the
16 pump is
sucked into the lower chamber on the upstroke. On the downstroke, the
17 fluid in the
lower chamber is transferred to the upper chamber through the valve
18 positioned
therebetween. On the next upstroke, while fluid is being drawn into
19 the lower
chamber, the fluid in the upper chamber is transferred from the space
above, through the upper chamber's outlet valve, while the external piston
21 causes the
fluid in the space above to be pumped to surface. Pressure is applied
22 cyclically to
the conduit causing the pistons to be moved downhole. An energy
23 storing
means, such as a spring, returns the pistons uphole as the pressure is
24 relieved at the conduit discharge.
2
CA 02600740 2007-09-07
1 Remotely actuated pumps are particularly advantageous for use in
2 oil wells to produce hydrocarbons to surface and for deliquification of
gas wells,
3 wherein the pump can be situated at or near the perforations, and can be
4 actuated to pump accumulated liquids such as water and condensate, to
surface
which, if left to accumulate in the conduit through which the gas is produced
6 causes backpressure on the formation which impedes gas flow and which may
7 eventually kill gas production.
8 In the case of deliquification of gas wells, conventionally beam
9 pumps or hydraulic pumps, including piston downhole pumps and jet pumps
have been used, as have electric submersible pumps and progressive cavity
11 pumps however the cost of these pumps is relatively high. Regardless the
use,
12 providing power for actuation of such pumps in remote locations, size of
the
13 pumps and interference due to produced gas during use in deliquification
have
14 typically been problematic.
Further, other technologies such as foam lift, gas lift and plunger lift
16 have been used to deliquify gas wells. In some of the known
technologies, the
17 gas well must be shut-in for at least a period of time to permit
sufficient energy to
18 be built up to lift the accumulated fluids which results in, at best, a
cyclic
19 production of gas from the wellbore.
Clearly, there is interest in a large variety of fluid-moving industries
21 or technologies, including pumping apparatus, which have relatively low
power
22 requirements, are capable of being remotely actuated and which have a
23 relatively high pumping efficiency. Of particular interest are pump
apparatus for
24 use in producing fluids from wellbores, including but not limited to
deliquifying of
gas wells to improve and maintain production therefrom.
3
CA 02600740 2013-04-08
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention there is provided a
fluid apparatus including a pump barrel having a first barrel section in fluid
communication with a fluid source and a second barrel section in fluid
communication with a discharge conduit. The first barrel section has a
diameter
greater than the second barrel section, the first and second barrel sections
being
fluidly connected therebetween. The apparatus includes a first piston housed
in
the first barrel section for axial movement therein and a second piston housed
in
the second barrel section for axial movement therein. The apparatus also
includes connecting provisions between the first and second pistons for
concurrent axial movement within the pump barrel between an inlet position and
a discharge position, the first and second pistons being spaced apart for
forming
a chamber of variable volume therebetween. The apparatus also includes biasing
provisions for biasing the first and second pistons to the discharge position,
an
inlet check valve to permit fluid to move from the fluid source to the
variable
volume chamber, and an outlet check valve to permit fluid to move from the
variable volume chamber to the discharge conduit. The apparatus also includes
a
bypass passageway having an inlet end in fluid communication with the fluid
source and an outlet end in fluid communication with the discharge conduit.
The
bypass passageway forms a second chamber fluidly connected to the variable
volume chamber, wherein the inlet check valve is positioned at the inlet end
of
the bypass passageway and the outlet check valve is positioned at the outlet
end
of the bypass passageway. When an actuating pressure sufficient to overcome
the biasing provisions is applied to the second piston through the discharge
conduit, the outlet valve closes and the first and second pistons move to the
inlet
position and increase the variable volume chamber by a differential volume,
opening the inlet valve and permitting the flow of the differential volume of
fluid
from the fluid source through the inlet valve into the variable volume
chamber.
When the actuating pressure is released, the biasing provisions return the
first
and second pistons to the discharge position for displacing the differential
volume
of fluid from the variable volume chamber, closing the inlet valve and opening
the
4
CA 02600740 2013-04-08
outlet valve for discharging the differential volume of fluid through the
outlet valve
to the discharge conduit.
In accordance with another aspect of the invention there is provided
a method for producing accumulated liquids from a gas well involving
positioning
a fluid apparatus in the wellbore and forming an annulus therebetween. The
apparatus includes a pump barrel having a first barrel section in fluid
communication with a fluid source and a second barrel section in fluid
communication with a discharge conduit. The first barrel section has a
diameter
greater than the second barrel section, the first and second barrel sections
being
fluidly connected therebetween. The apparatus also includes a first piston
housed in the first barrel section for axial movement therein, a second piston
housed in the second barrel section for axial movement therein, and a
connector
between the first and second pistons for concurrent axial movement within the
pump barrel between an inlet position and a discharge position. The first and
second pistons are spaced apart for forming a chamber of variable volume
therebetween. The first and second pistons are biased to the discharge
position.
The apparatus also includes an inlet check valve to permit fluid to move from
the
fluid source to the variable volume chamber and an outlet check valve to
permit
fluid to move from the variable volume chamber to the discharge conduit. The
apparatus also includes a bypass passageway having an inlet end in fluid
communication with the fluid source and an outlet end in fluid communication
with the discharge conduit. The bypass passageway forms a second chamber
fluidly connected to the variable volume chamber, wherein the inlet check
valve
is positioned proximate the inlet end of the bypass passageway and the outlet
check valve is positioned proximate the outlet end of the bypass passageway.
When an actuating pressure, sufficient to overcome a biasing force, is applied
to
the second piston through the discharge conduit, the outlet valve closes and
the
first and second pistons move to the inlet position and increase the variable
volume chamber by a differential volume, opening the inlet valve and
permitting
the flow of the differential volume of fluid from the fluid source through the
inlet
valve and the bypass passageway into the variable volume chamber. When the
CA 02600740 2013-04-08
actuating pressure is released, the first and second pistons are
biased to the discharge position for displacing the differential volume of
fluid from
the variable volume chamber, closing the inlet valve and opening the outlet
valve
for discharging the differential volume of fluid through the bypass passageway
to
the discharge conduit. The method also involves producing gas to surface
through the annulus, with liquid accumulating in the wellbore adjacent the
distal
end of the conduit. The method also involves cyclically applying an actuating
pressure at the discharge conduit such that when the force of the actuating
pressure is greater than the force exerted by the biasing provisions and a
force of
pressure at the fluid source, the discharge valve operates to the closed
position,
the first and second pistons move to the inlet position, and the inlet valve
operates to the open position for charging the accumulated fluids from the
wellbore into the variable volume chamber. The method also involves releasing
the actuating pressure so that the first and second pistons are biased to
return to
the discharge position, the inlet valve moving to the closed position, the
discharge valve moving to the open position and pumping the differential
volume
from the variable volume chamber through the discharge valve to the discharge
conduit.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit, a first piston housed in the
first
barrel section for axial movement therein and a second piston housed in the
second barrel section for axial movement therein in response to application of
an
actuating pressure to the discharge conduit. The first and second pistons
define
a variable volume chamber between the first and second pistons. The apparatus
also includes a biasing element coupled to at least one of the first and
second
pistons, an inlet check valve operable to permit fluid to flow from the fluid
source
into the variable volume chamber, and an outlet check valve operable to permit
fluid to flow from the variable volume chamber into the discharge conduit. The
apparatus also includes a bypass passageway having an inlet end in fluid
5A
CA 02600740 2013-04-08
communication with the fluid source and an outlet end in fluid communication
with the discharge conduit, the bypass passageway being in fluid communication
with the variable volume chamber, and wherein the inlet check valve is
disposed
at the inlet end of the bypass passageway and operable to permit fluid to flow
through the bypass passageway into the variable volume chamber, and the outlet
check valve is positioned at the outlet end of the bypass passageway and
operable to permit fluid to be discharged from the variable volume chamber
through the bypass passageway. The apparatus also includes provisions for
connecting the first and second pistons to cause movement of the first piston
in
response to movement of the second piston caused by the actuating pressure.
The respective movements of the first and second pistons are operable to
increase the volume of the variable volume chamber thereby drawing fluid into
the variable volume chamber through the inlet check valve while causing energy
to be stored in the biasing element. The stored energy in the biasing element
is
subsequently operable to cause respective return movement of the first and
second pistons when the actuating pressure is decreased. The respective return
movements of the first and second pistons are operable to reduce the volume of
the variable volume chamber thereby causing fluid to be discharged from the
variable volume chamber through the outlet check valve.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit. The apparatus also includes a
first
piston housed in the first barrel section for axial movement therein, a second
piston housed in the second barrel section for axial movement therein in
response to application of an actuating pressure to the discharge conduit, the
first and second pistons defining a variable volume chamber between the first
and second pistons. The apparatus also includes a biasing element coupled to
at
least one of the first and second pistons, an inlet check valve operable to
permit
fluid to flow from the fluid source into the variable volume chamber, and an
outlet
check valve operable to permit fluid to flow from the variable volume chamber
5B
CA 02600740 2013-04-08
into the discharge conduit. The apparatus also includes a bypass passageway
having an inlet end in fluid communication with the fluid source and an outlet
end
in fluid communication with the discharge conduit. The bypass passageway is in
fluid communication with the variable volume chamber, wherein the inlet check
valve is disposed at the inlet end of the bypass passageway and is operable to
permit fluid to flow through the bypass passageway into the variable volume
chamber, and the outlet check valve is positioned at the outlet end of the
bypass
passageway and is operable to permit fluid to be discharged from the variable
volume chamber through the bypass passageway. The apparatus also includes a
connector between the first and second pistons. The connector is operably
configured to cause movement of the first piston in response to movement of
the
second piston caused by the actuating pressure. The respective movements of
the first and second pistons are operable to increase the volume of the
variable
volume chamber thereby drawing fluid into the variable volume chamber through
the inlet check valve while causing energy to be stored in the biasing
element.
The stored energy in the biasing element is subsequently operable to cause
respective return movement of the first and second pistons when the actuating
pressure is decreased. The respective return movements of the first and second
pistons are operable to reduce the volume of the variable volume chamber
thereby causing fluid to be discharged from the variable volume chamber
through
the outlet check valve.
In accordance with another aspect of the invention there is provided
a method for producing accumulated liquids from a gas well. The method
involves positioning a fluid apparatus in a wellbore and forming an annulus
therebetween. The fluid apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit. The apparatus also includes a
first
piston housed in the first barrel section for axial movement therein and a
second
piston housed in the second barrel section for axial movement therein. The
first
and second pistons define a variable volume chamber between the first and
second pistons. The apparatus also includes a biasing element coupled to at
5C
CA 02600740 2013-04-08
least one of the first and second pistons, an inlet check valve operable to
permit
fluid to flow from the fluid source to the variable volume chamber and an
outlet
check valve operable to permit fluid to flow from the variable volume chamber
to
the discharge conduit. The apparatus also includes a bypass passageway having
an inlet end in fluid communication with the fluid source and an outlet end in
fluid
communication with the discharge conduit. The bypass passageway is in fluid
communication with the variable volume chamber, wherein the inlet check valve
is disposed at the inlet end of the bypass passageway and is operable to
permit
fluid to flow through the bypass passageway into the variable volume chamber
and the outlet check valve is disposed at the outlet end of the bypass
passageway and is operable to permit fluid to be discharged from the variable
volume chamber through the bypass passageway. The apparatus also includes a
connector between the first and second pistons. The connector is operably
configured to cause movement of the first piston in response to movement of
the
second piston. The method also involves producing gas to surface through the
annulus to cause liquid to accumulate in the wellbore adjacent the distal end
of
the conduit and cyclically applying an actuating pressure at the discharge
conduit
to cause the first and second pistons to move to increase the volume of the
variable volume chamber thereby drawing accumulated liquid into the variable
volume chamber through the inlet check valve while causing energy to be stored
in the biasing element. The method also involves releasing the actuating
pressure to permit the stored energy in the biasing element to cause
respective
return movement of the first and second pistons. The respective return
movements of the first and second pistons are operable to reduce the volume of
the variable volume chamber thereby causing fluid to be discharged from the
variable volume chamber through the outlet check valve to the discharge
conduit.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit, a first piston housed in the
first
barrel section for axial movement therein and a second piston housed in the
5D
CA 02600740 2013-04-08
second barrel section for axial movement therein in response to application of
an
actuating pressure to the discharge conduit. The first and second pistons
define
a variable volume chamber between the first and second pistons. The apparatus
also includes a biasing element coupled to at least one of the first and
second
pistons and a bypass passageway having an inlet end in fluid communication
with the fluid source and an outlet end in fluid communication with the
discharge
conduit. The bypass passageway is in fluid communication with the variable
volume chamber through at least one port. The bypass passageway further
includes first one-way valve provisions for permitting one-way fluid flow into
the
bypass passageway, the first one-way valve provisions being operable to
facilitate fluid flow from the inlet end, through the at least one port, into
the
variable volume chamber. The bypass passageway also includes second one-
way valve provisions for permitting one-way fluid flow out of the bypass
passageway. The second one-way valve provisions are operable to facilitate
fluid
flow from the variable volume chamber, through the at least one port, and out
the
outlet end into the discharge conduit. The apparatus also includes a connector
between the first and second pistons. The connector is operably configured to
cause movement of the first piston in a first axial direction in response to
movement of the second piston in the first axial direction caused by the
actuating
pressure. The respective movements of the first and second pistons in the
first
axial direction is operable to increase the volume of the variable volume
chamber
thereby drawing fluid into the variable volume chamber through the first one-
way
valve provisions while causing energy to be stored in the biasing element. The
stored energy in the biasing element is subsequently operable to cause
respective movement of the first and second pistons in a second axial
direction,
opposite to the first axial direction. When the actuating pressure is
decreased,
the respective movement of the first and second pistons in the second axial
direction is operable to reduce the volume of the variable volume chamber
thereby causing fluid to be discharged from the variable volume chamber,
through the second one-way valve provisions, and into the discharge conduit.
5E
CA 02600740 2013-04-08
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit. The first barrel section has a
diameter greater than the second barrel section. The first and second barrel
sections are fluidly connected therebetween. The apparatus includes a first
piston housed in the first barrel section for axial movement therein, a second
piston housed in the second barrel section for axial movement therein and
provisions connecting between the first and second pistons for concurrent
axial
movement within the pump barrel between an inlet position and a discharge
position. The first and second pistons are spaced apart for forming a chamber
of
variable volume therebetween. The apparatus includes biasing provisions for
biasing the first and second pistons to the discharge position, wherein the
biasing
provisions are positioned within the second barrel. The apparatus also
includes
an inlet check valve to permit fluid to move from the fluid source to the
variable
volume chamber and an outlet check valve to permit fluid to move from the
variable volume chamber to the discharge conduit. When an actuating pressure
sufficient to overcome the biasing provisions is applied to the second piston
through the discharge conduit, the outlet valve closes and the first and
second
pistons move to the inlet position and increase the variable volume chamber by
a
differential volume, opening the inlet valve and permitting the flow of the
differential volume of fluid from the fluid source through the inlet valve
into the
variable volume chamber. When the actuating pressure is released, the biasing
provisions returns the first and second pistons to the discharge position for
displacing the differential volume of fluid from the variable volume chamber,
closing the inlet valve and opening the outlet valve for discharging the
differential
volume of fluid through the outlet valve to the discharge conduit.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit. The apparatus also includes a
first
5F
CA 02600740 2013-04-08
piston housed in the first barrel section for axial movement therein and a
second
piston housed in the second barrel section for axial movement therein in
response to application of an actuating pressure to the discharge conduit. The
first and second pistons define a variable volume chamber between the first
and
second pistons. The apparatus also includes a biasing element coupled to the
second piston and at least partially located in the second barrel section, an
inlet
check valve operable to permit fluid to flow from the fluid source into the
variable
volume chamber, and an outlet check valve operable to permit fluid to flow
from
the variable volume chamber into the discharge conduit. The apparatus also
includes provisions for connecting the first and second pistons to cause
movement of the first piston in response to movement of the second piston
caused by the actuating pressure. The respective movements of the first and
second pistons are operable to increase the volume of the variable volume
chamber thereby drawing fluid into the variable volume chamber through the
inlet
check valve while causing energy to be stored in the biasing element. The
stored
energy in the biasing element is subsequently operable to cause respective
return movement of the first and second pistons when the actuating pressure is
decreased. The respective return movements of the first and second pistons are
operable to reduce the volume of the variable volume chamber thereby causing
fluid to be discharged from the variable volume chamber through the outlet
check
= =
valve.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit. The first barrel section has a
diameter greater than the second barrel section. The first and second barrel
sections are fluidly connected therebetween. The apparatus also includes a
first
piston housed in the first barrel section for axial movement therein, a second
piston housed in the second barrel section for axial movement therein, and a
connector between the first and second pistons for concurrent axial movement
5G
CA 02600740 2013-04-08
within the pump barrel between an inlet position and a discharge position. The
first and second pistons are spaced apart for forming a chamber of variable
volume therebetween. The first and second pistons are biased to the discharge
position by biasing provisions. The apparatus also includes an inlet check
valve
to permit fluid to move from the fluid source to the variable volume chamber
and
an outlet check valve to permit fluid to move from the variable volume chamber
to
the discharge conduit. When an actuating pressure is applied to the second
piston through the discharge conduit sufficient to overcome a biasing force
applied by the biasing provisions to the first and second pistons, the outlet
valve
closes and the first and second pistons move to the inlet position and
increase
the variable volume chamber by a differential volume, opening the inlet valve
and
permitting the flow of the differential volume of fluid from the fluid source
through
the inlet valve into the variable volume chamber. When the actuating pressure
is
released, the first and second pistons are biased to the discharge position
for
displacing the differential volume of fluid from the variable volume chamber,
closing the inlet valve and opening the outlet valve for discharging the
differential
volume of fluid through the outlet valve to the discharge conduit. The biasing
provisions include a liquid spring comprising a sealed spring chamber, a
compressible fluid stored in the sealed spring chamber, and a displacing
element
operatively connected to the first and second pistons for reducing the volume
of
the sealed spring chamber when the connected first and second pistons are
moved to the inlet position and for biasing the first and second pistons to
the
discharge position.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel forming at least a
portion of a sealed spring chamber for containing a compressible fluid and
having
a first barrel section in fluid communication with a fluid source and a second
barrel section in fluid communication with a discharge conduit. The apparatus
also includes a first piston housed in the first barrel section for axial
movement
therein and a second piston housed in the second barrel section for axial
movement therein in response to application of an actuating pressure to the
511
CA 02600740 2013-04-08
discharge conduit. The first and second pistons define a variable volume
chamber between the first and second pistons. The apparatus also includes a
liquid spring biasing element including the sealed spring chamber and a
displacing element received in the sealed spring chamber for reducing the
volume of the sealed spring chamber. The displacing element is coupled to at
least one of the first and second pistons. The sealed spring chamber includes
a
portion of the first barrel section of the pump barrel. The apparatus also
includes
an inlet check valve operable to permit fluid to flow from the fluid source
into the
variable volume chamber, an outlet check valve operable to permit fluid to
flow
from the variable volume chamber into the discharge conduit, and a connector
between the first and second pistons. The connector is operably configured to
cause movement of the first piston in response to movement of the second
piston
caused by the actuating pressure. The respective movements of the first and
second pistons are operable to increase the volume of the variable volume
chamber thereby drawing fluid into the chamber through the inlet check valve
while causing energy to be stored in the liquid spring biasing element. The
stored
energy in the liquid spring biasing element is subsequently operable to cause
respective return movement of the first and second pistons when the actuating
pressure is decreased. The respective return movements of the first and second
pistons are operable to reduce the volume of the variable volume chamber
thereby causing fluid to be discharged from the chamber through the outlet
check
valve.
In accordance with another aspect of the invention there is provided
a method for producing accumulated liquids from a gas well. The method
involves positioning a fluid apparatus in a wellbore and forming an annulus
therebetween. The fluid apparatus includes a pump barrel forming at least a
portion of a sealed spring chamber for containing a compressible fluid and
having
a first barrel section in fluid communication with a fluid source and a second
barrel section in fluid communication with a discharge conduit, a first piston
housed in the first barrel section for axial movement therein and a second
piston
housed in the second barrel section for axial movement therein. The first and
51
CA 02600740 2013-04-08
second pistons define a variable volume chamber between the first and second
pistons. The apparatus also includes a liquid spring biasing element
comprising
the sealed spring chamber and a displacing element received in the sealed
spring chamber for reducing the volume of the sealed spring chamber. The
displacing element is operably coupled to at least one of the first and second
pistons. The sealed spring chamber includes a portion of the first barrel
section
of the pump barrel. The apparatus also includes an inlet check valve operable
to
permit fluid to flow from the fluid source to the variable volume chamber, an
outlet check valve operable to permit fluid to flow from the variable volume
chamber to the discharge conduit and a connector between the first and second
pistons, the connector being operably configured to cause movement of the
first
piston in response to movement of the second piston. The method also involves
producing gas to surface through the annulus, while liquid is accumulating in
the
wellbore adjacent a distal end of the conduit. The method also involves
cyclically
applying an actuating pressure at the discharge conduit to cause the first and
second pistons to move to increase the volume of the variable volume chamber
thereby drawing accumulated liquid into the chamber through the inlet check
valve while causing energy to be stored in the liquid spring biasing element.
The
method also involves releasing the actuating pressure to permit the stored
energy in the liquid spring biasing element to cause respective return
movement
of the first and second pistons. The respective return movements of the first
and
second pistons are operable to reduce the volume of the variable volume
chamber thereby causing fluid to be discharged from the chamber through the
outlet check valve to the discharge conduit.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel forming at least a
portion of a sealed spring chamber configured to contain a compressible fluid
and having a first barrel section proximate the sealed spring chamber and in
fluid
communication with a fluid source and a second barrel section in fluid
communication with a discharge conduit. The apparatus also includes a first
piston housed in the first barrel section for axial movement therein, a second
5J
CA 02600740 2013-04-08
piston housed in the second barrel section for axial movement therein in
response to application of an actuating pressure to the discharge conduit. The
first and second pistons define a variable volume chamber between the first
and
second pistons. The apparatus also includes a liquid spring biasing element
comprising the sealed spring chamber and a displacing element received in the
sealed spring chamber for reducing the volume of the sealed spring chamber.
The displacing element is coupled to at least one of the first and second
pistons.
The apparatus includes an inlet check valve operable to permit fluid to flow
from
the fluid source into the variable volume chamber, an outlet check valve
operable
to permit fluid to flow from the variable volume chamber into the discharge
conduit and a connector between the first and second pistons. The connector is
operably configured to cause movement of the first piston in response to
movement of the second piston caused by the actuating pressure. The
respective movements of the first and second pistons are operable to increase
the volume of the variable volume chamber thereby drawing fluid into the
chamber through the inlet check valve while causing energy to be stored in the
liquid spring biasing element. The stored energy in the liquid spring biasing
element is subsequently operable to cause respective return movement of the
first and second pistons when the actuating pressure is decreased. The
respective return movements of the first and second pistons are operable to
reduce the volume of the variable volume chamber thereby causing fluid to be
discharged from the chamber through the outlet check valve.
In accordance with another aspect of the invention there is provided
a fluid apparatus. The apparatus includes a pump barrel having a first barrel
section in fluid communication with a fluid source and a second barrel section
in
fluid communication with a discharge conduit, a first piston housed in the
first
barrel section for axial movement therein and a second piston housed in the
second barrel section for axial movement therein in response to application of
an
actuating pressure to the discharge conduit. The first and second pistons
define
a variable volume chamber between the first and second pistons. The apparatus
also includes a biasing element coupled to at least one of the first and
second
5K
CA 02600740 2013-04-08
pistons. The biasing element includes a liquid spring including a sealed
chamber
operable to hold a compressible fluid and a displacing element operable to be
received in the sealed chamber to reduce the volume thereof. The displacing
element includes a spring rod received in the sealed chamber and adapted to
avoid buckling when an unsupported free end of the spring rod is maximally
extended into the sealed chamber during operation. The apparatus also includes
an inlet check valve operable to permit fluid to flow from the fluid source
into the
variable volume chamber, an outlet check valve operable to permit fluid to
flow
from the variable volume chamber into the discharge conduit and a connector
between the first and second pistons. The connector is operably configured to
cause movement of the first piston in response to movement of the second
piston
caused by the actuating pressure. The respective movements of the first and
second pistons are operable to increase the volume of the variable volume
chamber thereby drawing fluid into the chamber through the inlet check valve
while causing energy to be stored in the biasing element. The stored energy in
the biasing element is subsequently operable to cause return movement of the
first and second pistons when the actuating pressure is decreased. The return
movements of the first and second pistons are operable to reduce the volume of
the variable volume chamber thereby causing fluid to be discharged from the
chamber through the outlet check valve.
In accordance with another aspect of the invention there is provided
a fluid apparatus including a pump barrel having a first barrel section in
fluid
communication with a fluid source and a second barrel section in fluid
communication with a discharge conduit. The first barrel section has a
diameter
greater than the second barrel section and the first and second barrel
sections
are fluidly connected therebetween. The apparatus also includes a first piston
housed in the first barrel section for axial movement therein, a second piston
housed in the second barrel section for axial movement therein and provisions
connecting between the first and second pistons for concurrent axial movement
within the pump barrel between an inlet position and a discharge position, the
first and second pistons being spaced apart for forming a chamber of variable
5L
CA 02600740 2013-04-08
volume therebetween. The apparatus also includes biasing provisions for
biasing
the first and second pistons to the discharge position, wherein the biasing
provisions comprises a liquid spring, an inlet check valve to permit fluid to
move
from the fluid source to the variable volume chamber, and an outlet check
valve
to permit fluid to move from the variable volume chamber to the discharge
conduit. When an actuating pressure sufficient to overcome the biasing
provisions is applied to the second piston through the discharge conduit, the
outlet valve closes and the first and second pistons move to the inlet
position and
increase the variable volume chamber by a differential volume, opening the
inlet
valve and permitting the flow of the differential volume of fluid from the
fluid
source through the inlet valve into the variable volume chamber. When the
actuating pressure is released, the biasing provisions returns the first and
second
pistons to the discharge position for displacing the differential volume of
fluid
from the variable volume chamber, closing the inlet valve and opening the
outlet
valve for discharging the differential volume of fluid through the outlet
valve to the
discharge conduit.
In accordance with another aspect of the invention there is provided
a method for producing accumulated liquids from a gas well. The method
involves positioning a fluid apparatus in the wellbore and forming an annulus
therebetween. The apparatus includes a pump barrel having a first barrel
section
in fluid communication with a fluid source and a second barrel section in
fluid
communication with a discharge conduit. The first barrel section has a
diameter
greater than the second barrel section, the first and second barrel sections
being
fluidly connected therebetween. The apparatus includes a first piston housed
in
the first barrel section for axial movement therein, a second piston housed in
the
second barrel section for axial movement therein and a connector between the
first and second pistons for concurrent axial movement within the pump barrel
between an inlet position and a discharge position. The first and second
pistons
are spaced apart for forming a chamber of variable volume therebetween and
the first and second pistons are biased to the discharge position. The
apparatus
also includes an inlet check valve to permit fluid to move from the fluid
source to
5M
CA 02600740 2013-04-08
the variable volume chamber and an outlet check valve to permit fluid to move
from the variable volume chamber to the discharge conduit. When an actuating
pressure, sufficient to overcome a biasing force, is applied to the second
piston
through the discharge conduit, the outlet valve closes and the first and
second
pistons move to the inlet position and increase the variable volume chamber by
a
differential volume, opening the inlet valve and permitting the flow of the
differential volume of fluid from the fluid source through the inlet valve
into the
variable volume chamber. When the actuating pressure is released, the first
and
second pistons are biased to the discharge position for displacing the
differential
volume of fluid from the variable volume chamber, closing the inlet valve and
opening the outlet valve for discharging the differential volume of fluid
through
the outlet valve to the discharge conduit. The method also involves producing
gas to surface through the annulus, liquid accumulating in the wellbore
adjacent
the distal end of the conduit. The method also involves applying an actuating
pressure at the discharge conduit such that when the force of the actuating
pressure is greater than the force exerted by the biasing provisions and a
force of
pressure at the fluid source. The discharge valve operates to the closed
position,
and the first and second pistons move to the inlet position and the inlet
valve
operates to the open position for charging the accumulated fluids from the
wellbore into the variable volume chamber. The method also involves releasing
the actuating pressure so that the first and second pistons are biased to
return to
the discharge position with the inlet valve moving to the closed position, the
discharge valve moving to the open position and pumping the differential
volume
from the variable volume chamber through the discharge valve to the discharge
conduit. The method also involves activating the fluid apparatus at
predetermined
intervals in response to data representing historical liquid accumulation for
a
particular reservoir type.
Generally, in exemplary embodiments, a fluid apparatus for moving
fluid from a fluid source to a discharge incrementally pumps a differential
volume
of fluid due to a chamber having a variable volume formed between two
5N
CA 02600740 2013-04-08
connected pistons which are moveable axially within a pump barrel of stepped
diameter.
In some embodiments, a fluid apparatus comprises: a pump barrel
having a first barrel section in fluid communication with a fluid source and a
second barrel section in fluid communication with a discharge conduit, the
first
barrel section having a diameter greater than the second barrel section, the
first
and second barrel sections being fluidly connected therebetween; a first
piston
housed in the first barrel section for axial movement therein; a second piston
housed in the second barrel section for axial movement therein; means
connecting between the first and second pistons for concurrent axial movement
within the pump barrel between an inlet position and a discharge position, the
first and second pistons being spaced apart for forming a chamber of variable
volume therebetween; biasing means for biasing the first and second pistons to
the discharge position; an inlet check valve to permit fluid to move from the
fluid
source to the variable volume chamber; and an outlet check valve to permit
fluid
to move from the variable volume chamber to the discharge conduit, wherein
when an actuating pressure sufficient to overcome the biasing means is applied
to the second piston through the discharge conduit, the outlet valve closes
and
the first and second pistons move to the inlet position and increase the
variable
volume chamber by a differential volume, opening the inlet valve and
permitting
the flow of the differential volume of fluid from the fluid source through the
inlet
valve into the variable volume chamber; and when the actuating pressure is
released, the biasing means returns the first and second pistons to the
discharge
position for displacing the differential volume of fluid from the variable
volume
chamber, closing the inlet valve and opening the outlet valve for discharging
the
differential volume of fluid through the outlet valve to the discharge
conduit.
In some embodiments, the biasing means can be housed within the
variable volume chamber or in the pump barrel below the first piston and is
connected between the pump barrel and one of either the first or second
piston.
CA 02600740 2013-04-08
The inlet and discharge valves are positioned at an inlet end and a
discharge end, respectively, of the pump pistons or alternately at an inlet
and
discharge end of a bypass passageway fluidly connected to the variable volume
chamber.
Embodiments of the invention are used to move fluid from a source
location to a discharge location and may be particularly advantageous for
remote
actuation in wellbores for deliquifying wellbores having an accumulation of
liquid
therein which reduces or potentially stops wellbore production.
Therefore in some embodiments, a method for producing
accumulated liquids from a gas well comprises: positioning a fluid apparatus
in
the wellbore and forming an annulus therebetween, the apparatus having a pump
barrel having a first barrel section in fluid communication with a fluid
source and
a second barrel section in fluid communication with a discharge conduit, the
first
barrel section having a diameter greater than the second barrel section, the
first
and second barrel sections being fluidly connected therebetween; a first
piston
housed in the first barrel section for axial movement
5P
CA 02600740 2007-09-07
1 therein; a second piston housed in the second barrel section for axial
movement
2 therein; means connecting between the first and second pistons for
concurrent
3 axial movement within the pump barrel between an inlet position and a
discharge
4 position, the first and second pistons being spaced apart for forming a
chamber
of variable volume therebetween; biasing means for biasing the first and
second
6 pistons to the discharge position; an inlet check valve to permit fluid
to move
7 from the fluid source to the variable volume chamber; and an outlet check
valve
8 to permit fluid to move from the variable volume chamber to the discharge
9 conduit, wherein when an actuating pressure sufficient to overcome the
biasing
means is applied to the second piston through the discharge conduit, the
outlet
11 valve closes and the first and second pistons move to the inlet position
and
12 increase the variable volume chamber by a differential volume, opening
the inlet
13 valve and permitting the flow of the differential volume of fluid from
the fluid
14 source through the inlet valve into the variable volume chamber; and
when the
actuating pressure is released, the biasing means returns the first and second
16 pistons to the discharge position for displacing the differential volume
of fluid
17 from the variable volume chamber, closing the inlet valve and opening
the outlet
18 valve for discharging the differential volume of fluid through the
outlet valve to
19 the discharge conduit; producing gas to surface through the annulus,
liquid
accumulating in the wellbore adjacent the distal end of the conduit;
cyclically
21 applying an actuating pressure at the discharge conduit such that when
the force
22 of the actuating pressure is greater than the force exerted by the
biasing means
23 and a force of pressure at the fluid source, the discharge valve
operates to the
24 closed position, the first and second pistons move to the inlet position
and the
inlet valve operates to the open position for charging the accumulated fluids
from
6
CA 02600740 2007-09-07
1 the wellbore
into the variable volume chamber; and releasing the actuating
2 pressure so
that the first and second pistons are urged to return to the discharge
3 position, the
inlet valve moving to the closed position, the discharge valve
4 moving to the open position and pumping the differential volume from the
variable volume chamber through the discharge valve to the discharge conduit.
6
7 BRIEF DESCRIPTION OF THE DRAWINGS
8 Figures 1A-1C
are partial longitudinal sectional views of a pump
9 according to
an embodiment of the invention, first and second pistons positioned
in a pump barrel connected to a single conduit and biasing means for storing
11 energy to return the pistons located below the first piston, more
particularly,
12 Fig. 1A
illustrates an idle position wherein an outlet valve and an
13 inlet valve are in a closed position;
14 Fig. 1B
illustrates the first position wherein the first and second
pistons are moved causing the inlet valve to open and a variable volume
16 chamber
between the first and second pistons to be charged with fluid;
17 and
18 Fig. 1C
illustrates a second position wherein the first and second
19 pistons are
moved causing the outlet valve to be be opened, the fluid
being displaced from the variable volume chamber, pumping a differential
21 volume
created by the variable volume chamber into the conduit above
22 the pump barrel;
23 Figure 1D is
a cross sectional view along section A-A, according to
24 Fig. 1A;
7
CA 02600740 2007-09-07
1 Figures 2A-2C
are partial longitudinal sectional views of a pump
2 according to one embodiment of the invention, the biasing means being
3 positioned
between the first and second piston in the variable volume chamber,
4 more particularly,
Fig. 2A illustrates an idle position wherein an outlet valve and an
6 inlet valve are in a closed position;
7 Fig. 2B
illustrates the first position wherein the first and second
8 pistons are
moved causing the inlet valve to open and a variable volume
9 chamber
between the first and second pistons to be charged with fluid;
and
11 Fig. 20
illustrates a second position wherein the first and second
12 pistons are
moved causing the outlet valve to be be opened, the fluid
13 being
displaced from the variable volume chamber, pumping a differential
14 volume
created by the variable volume chamber into the conduit above
the pump barrel;
16 Figure 2D is
a cross sectional view along section B-B, according to
17 Fig. 2A;
18 Figures 3A-3C
are partial longitudinal sectional views of a pump
19 according to one embodiment of the invention, the biasing means being
positioned in the variable volume chamber, the inlet valve and outlet valve
being
21 housed in a
third chamber fluidly connected to the variable volume chamber,
22 more particularly,
23 Fig. 3A
illustrates an idle position wherein an outlet valve and an
24 inlet valve are in a closed position;
8
CA 02600740 2007-09-07
1 Fig. 3B
illustrates the first position wherein the first and second
2 pistons are
moved causing the inlet valve to open and a variable volume
3 chamber
between the first and second pistons to be charged with fluid;
4 and
Fig. 3C illustrates a second position wherein the first and second
6 pistons are
moved causing the outlet valve to be opened, the fluid being
7 displaced
from the variable volume chamber, pumping a differential
8 volume
created by the variable volume chamber into the conduit above
9 the pump barrel;
Figure 3D is a cross sectional view along section C-C, according to
11 Fig. 3A;
12 Figure 4A is
a partial longitudinal sectional view of a pump
13 according to Fig. 1A, the biasing means being a Belleville spring;
14 Figure 4B is
a partial longitudinal sectional view of a pump
according to Fig. 1A, the biasing means being a coil spring;
16 Figure 5 is a
partial longitudinal sectional view of a pump according
17 to Figs. 2A-
2C positioned in a wellbore, the pump having a single conduit
18 extending to
surface for producing accumulated liquids from the wellbore, gas
19 being produced to surface in an annulus between the conduit and the
wellbore;
Figures 6A-6C are partial longitudinal sectional views of a pump
21 according to
one embodiment of the invention, the biasing means being a
22 compressible liquid spring, more particularly
23 Fig. 6A
illustrates an idle position wherein an outlet valve and an
24 inlet valve are in a closed position;
9
CA 02600740 2007-09-07
1 Fig. 6B
illustrates the first position wherein the first and second
2 pistons are
moved causing the inlet valve to open and a variable volume
3 chamber
between the first and second pistons to be charged with fluid, a
4 rod extending
downwardly from the first piston and into a sealed spring
chamber moving into the liquid spring for compressing liquid therein; and
6 Fig. 6C
illustrates a second position wherein the first and second
7 pistons are
moved causing the outlet valve to be opened, the fluid being
8 displaced
from the variable volume chamber, pumping a differential
9 volume
created by the variable volume chamber into the conduit above
the pump barrel, the rod extending downwardly from the first piston being
11 moved out of
the sealed spring chamber to release compression of the
12 liquid in the liquid spring;
13 Figure 6D is
a cross sectional view along section D-D, according to
14 Fig. 6A;
Figure 7 is a graphical representation of the percentage
16
compressibility of silicone versus pressure in an embodiment of the invention;
17 and
18 Figure 8 is a
graphical representation of buckling forces versus
19 unsupported
length of a displacing element or rod in an embodiment of the
invention.
CA 02600740 2007-09-07
1 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
2 Embodiments
of the invention are disclosed herein in the context of
3 a fluid
device, or pump, particularly useful in the production of fluids through a
4 single discharge conduit extending from surface to a subterranean zone of
interest. Description in this context is in no way intended to limit the scope
of the
6 invention to
fluid devices for use in a subterranean wellbore, the device being
7 equally
applicable for remotely actuating and pumping fluids from any fluid
8 source to a
discharge in a variety of contexts, including from a sump, lake or
9 pipeline.
Having reference to Figs. 1A-1D, 2A-2D, 3A-3D, 4A, 4B, 5 and 6A-
11 6D and in a
wellbore context, a subterranean zone of interest or fluid source F
12 (Fig. 5) is
located remote from the surface where the fluid, such as a liquid, is to
13 be produced.
A discharge conduit 1 having a liquid discharge end 2 at surface 3
14 extends
downhole to an inlet end 4 in fluid communication with the fluid source
F. A fluid apparatus or pump 10, according to an embodiment of the invention,
is
16 fluidly
connected at the inlet end 4 for pumping liquid from the fluid source F to
17 surface 3 as
a result of an actuating pressure P being applied to the discharge
18 conduit 1, typically at surface 3.
19 Having
reference to Figs. 1A-1D and 2A-2D, the pump 10
comprises a pump barrel 11 having a first barrel section 12 and a second
barrel
21 section 13
the first and second sections 12,13 being fluidly connected
22 therebetween.
The first barrel section 12 is in fluid communication with the fluid
23 source F and
the second barrel section 13 is in fluid communication with the
24 discharge
conduit 1. A diameter of the first barrel section 12 is greater than the
diameter of the second barrel section 13. A pump piston comprises a first
piston
11
CA 02600740 2007-09-07
1 14 housed within the first barrel section 12 for axial movement therein,
and a
2 second piston 15 housed within the second barrel section 13 for axial
movement
3 therein. The first and second pistons 14,15 are connected therebetween and
4 spaced apart by a connector such as a rod 16, forming a variable volume
chamber 17 therebetween which changes volume as the pistons 14,15 are
6 actuated to concurrently move axially within the barrel sections 12,13.
As the
7 pistons 14,15 move towards the first barrel section 12, the variable
volume
8 chamber 17 increases in volume and as the pistons 14,15 move towards the
9 second barrel section 13, the variable volume chamber 17 decreases in
volume.
More particularly, a differential volume is created when the
11 connected pistons 14,15 are actuated to move toward the first larger
diameter
12 barrel section 12 which permits a larger volume of fluid to enter the
variable
13 volume chamber 17 than the chamber 17 will contain when the connected
14 pistons 14,15 are subsequently actuated to move toward the second
smaller
diameter barrel section 13. Reciprocating movement or stroking of the pump
16 pistons 14,15 in the pump barrel 11 creates the differential volume
which is
17 forcibly discharged from the variable volume chamber 17 to the discharge
18 conduit 1 on each pump stroke.
19 More specifically, an inlet one way or check valve 18 is positioned
at an inlet end 20 of the pump barrel 11 to permit the flow of fluid from the
fluid
21 source F into the variable volume chamber 17. A discharge one way or
check
22 valve 19 is positioned at a discharge end 21 of the pump barrel 11 to
permit the
23 flow of fluid from the variable volume chamber 17 to the discharge
conduit 1.
24 Having reference again to Figs. 1A-1D and 2A-2D and in one
embodiment, the inlet check valve 18 is located in the first piston 14, and
the
12
CA 02600740 2007-09-07
1 discharge check valve 19 is located in the second piston 15. In one
embodiment,
2 the inlet check valve 18 and the discharge check valve 19 are ball
valves.
3 In use, to actuate the pump 10, pressure is cyclically exerted at a
4 discharge end 22 of the discharge conduit 1. The connected first and
second
pistons 14,15 are actuated to move from an idle position (Figs. 1A, 2A, 3A and
6 6A) to a first inlet position (Figs. 1B, 2B, 3B and 6B) wherein the first
and second
7 pistons 14,15 are moved toward the inlet end 20 of the pump barrel 11,
typically
8 a downhole movement in the context of a wellbore pump. To complete the
9 pumping cycle, the first and second pistons 14,15 move to a second
discharge
position (Figs. 1C, 2C, 3C and 6C), returning to the discharge end 21 of the
11 pump barrel 11.
12 In the idle and discharge positions, fluid pressure at the inlet
check
13 valve 18 causes the inlet check valve 18 to close. As the first and
second
14 pistons 14,15 are moved to the first inlet position, the volume in the
variable
volume chamber 17 becomes larger. The inlet check valve 18 is caused to open
16 and fluid L from the fluid source F adjacent the inlet end 20 of the
pump barrel 11
17 is caused to be sucked into the variable volume chamber 17 through the
inlet
18 check valve 18.
19 Optionally, the inlet and discharge valves 18, 19 can form the
pistons 14,15 which sealably engage the barrel 11 or the inlet and discharge
21 valves 18,19 can be supported in a piston housing. As shown, each piston
18,
22 19 comprises a cylindrical housing 23 having ports 24 formed therein for
23 conducting fluids from the inlet and discharge check valves 18, 19
through the
24 pistons 14,15.
13
CA 02600740 2007-09-07
1 Biasing means 25 acting between the pump pistons 14,15 and
2 pump barrel 11 to store energy as the first and second pistons 14,15 are
moved
3 downhole to the inlet position. Preferably, the biasing means 25 is a
spring,
4 pressurized bellows, elastomeric element or the like. As shown, examples
of the
spring 25 include a spring washer, such as a Belleville spring (Figs 1A-4A.),
or,
6 as schematically represented in Fig. 4B, a coil spring or as shown in
Figs 6A-6D
7 a compressible liquid spring.
8 Thus, when the force of the actuating pressure P applied to the
9 discharge conduit 1 and acting at the second piston 15 exceeds the
combined
force of the pressure at a fluid source F and the spring 25 biasing, the
pistons
11 14,15 are caused to move to the inlet position, typically downhole in
the context
12 of a wellbore. Release of the actuating pressure P permits the spring 25
to
13 release stored energy and causes the pistons 14,15 to move to the
discharge
14 position, typically uphole in the context of a wellbore.
As the pistons 14,15 are caused to move to the discharge position,
16 the volume of the variable volume chamber 17 becomes smaller resulting
in a
17 differential volume, being the difference in volume of the variable
volume
18 chamber between the inlet and discharge positions. The inlet check valve
18 is
19 caused to close and as the volume of the variable volume chamber 17
becomes
smaller, the discharge check valve 19 is opened and the differential volume is
21 discharged into the discharge conduit 1. Cyclically repeating the
application and
22 the release of pressure P at the discharge end 22 of the discharge
conduit 1,
23 results in fluids being pumped from the fluid source F, through the pump
10 and
24 into the discharge conduit 1 for eventual transport to a discharge 2,
such as at
surface 3.
14
CA 02600740 2007-09-07
1 In an
embodiment of the invention a hydraulic circuit (not shown)
2 may be used
to apply actuating pressure P at the discharge end 22. Alternately,
3 actuating
pressure P may be applied using a positive displacement pump, such
4 as a plunger pump (not shown).
In one embodiment of the invention shown in Figs. 1A-1C, the
6 biasing means
25 is housed in the pump barrel 11 between the first piston 14
7 and a stop 26
formed adjacent the inlet end 20 of the pump barrel 11. An inlet
8 port 27 is
formed in the stop 26 to permit fluid L from the fluid source F to enter
9 the pump 10.
As the pistons 14,15 are moved to the inlet position, the biasing
means 25 is compressed by the pistons 14,15 against the stop 26, thereby
11 storing
energy in the biasing means 25. When the actuating pressure P is
12 released at
the discharge end 22 of the discharge conduit 1, the biasing means
13 25 acts
between the stop 26 and the pistons 14, 15 to move the pistons 14,15 to
14 the discharge position. Preferably, the biasing means is a spring 25.
In one embodiment as shown in Figs. 2A-2C, the biasing means 25
16 is positioned
in the variable volume chamber 17 between the second piston 15
17 and a stop 28
formed adjacent a lower end 29 of the second barrel section 13.
18 One or more
ports 30 are formed in the stop 28 to permit passage of the rod 16
19 and for the
flow of fluids L therethrough between the first and second pump
sections 12,13. Further, the rod 16 is hollow to aid in moving fluids from the
inlet
21 valve 18 to the discharge valve 19.
22 In one
embodiment shown in Figs. 3A-3D, the pump barrel 11
23 further
comprises a bypass passageway 40 for forming a second chamber 41
24 which is
fluidly connected to the variable volume chamber 17. The inlet valve 18
is positioned at an inlet end 42 of the second chamber 41 in fluid
communication
CA 02600740 2007-09-07
with the fluid source F. The discharge valve 19 is positioned at a discharge
end
2 43 of the second chamber 41 in fluid communication with the discharge
conduit 1.
3 A port 44 is formed between the variable volume chamber 17 and the second
4 chamber 41 and between the first and second pistons 14,15. As actuating
pressure P is applied at the discharge end 22 of the discharge conduit 1 and
the
6 discharge valve is in the closed position, the pistons 14, 15 are caused
to move
7 to the inlet position and the inlet valve 18 is opened for admitting
fluid L to the
8 second chamber 41 and through port 44 to the variable volume chamber 17.
As
9 the actuating pressure P is released at the discharge end 22 of the
discharge
conduit 1, the inlet valve 18 is caused to close, the pistons 14,15 are biased
to
11 the discharge position by the biasing means 25 and the discharge valve 19
12 opens for discharging the differential volume of fluid from the second
chamber
13 41 into the discharge conduit 1. Ports 24 are not required in the
pistons 14,15 in
14 this embodiment as fluid flow is directed through port 44.
The biasing means 25, like the previous embodiments, may be
16 housed in the same manner in the variable volume chamber 17 or in the
pump
17 barrel 11 below the first piston 14.
18 As shown in Figs. 6A-6D and in an embodiment of the invention
19 wherein the biasing means 25 is a compressible liquid spring, the liquid
spring
comprises a sealed, pressurized spring chamber 50 which is operatively
21 connected to the first and second pistons 14,15 for compressing and
releasing a
22 compressible fluid FC stored therein. One such suitable fluid FC is
silicone
23 however any compressible fluid may be used which is suitable to meet the
24 desired design specifications.
16
CA 02600740 2007-09-07
1 In one
embodiment shown in Figs. 6A-6D, the sealed pressurized
2 spring
chamber 50 is formed within or in an extended portion of the pump barrel
3 11 and spaced
below the first piston 14. An upper wall 51 of the spring chamber
4 50 comprises
a port 52 through which a displacing element 53, such as a spring
rod, protrudes, operatively connected to and extending downwardly from the
first
6 piston 14.
The port 52 further comprises a chamber seal 54 which seals about
7 the spring rod 53 which reciprocates therethrough. The inlet 27 for fluid
8 communication
with the fluid source F is formed in the first barrel section 12
9 between the first piston 14 and the upper wall 51 of the spring chamber
50.
Similarly, in embodiments of the invention, the spring 25 shown in
11 Figs. 2A-3D
could be substituted with a compressible fluid FC, the second barrel
12 portion 13
being sealed at the stop 28 for forming the pressure chamber 50, the
13 compressible
fluid FC being compressed upon movement of the first and second
14 pistons 14, 15 to the inlet position.
As the first and second pistons 14,15 are caused to move to the
16 inlet
position, as previously described by cyclical application of pressure at
17 surface, the
spring rod 53 is moved into the fluid FC in the spring chamber 50
18 and acts to
displace and compress the fluid FC sealed within the chamber 50,
19 storing
energy therein. As pressure is released at surface, the first and second
pistons 14,15 are biased to the discharge position as a result of release of
the
21 energy stored in the fluid FC and acting upon the spring rod 53.
22 Actuation of
the pump 10 is accomplished remotely through the
23 application
and release of pressure at the discharge 21 and therefore a prime
24 mover is not
required to be situated at or near the pump in the wellbore. Further,
where a plurality of wells are situated in close proximity, the plurality of
wells
17
CA 02600740 2007-09-07
1 could be connected hydraulically to a single source of cyclic pressure
for
2 operating the plurality of wells.
3 Where the fluid source F is positioned substantially vertical and
up
4 to about a 60 degree inclination relative to the discharge 21, ball and
seat valves
are suitable for use as the inlet and discharge check valves 18,19. However,
6 where the fluid source F is positioned substantially horizontal to the
discharge
7 21, such as in a horizontal pipeline, spring loaded check valves may be
more
8 suitable for use as the inlet and discharge valves 18,19.
9 One particular use as shown in Fig. 5, wherein embodiments of the
invention are particularly well suited, is the deliquification of gas wells. A
distal
11 end of a single conduit, such as a tubing string 114, is fit with a pump
110
12 according to an embodiment of the invention. The pump 110 is lowered
into a
13 wellbore 111 of a gas well and forms an annulus 112 between the conduit
114
14 and the wellbore 111. The discharge end 122 of the conduit 114 is
positioned at
surface 3. The pump 110 is positioned adjacent a zone of interest 115 where
16 liquid L co-produced from the gas-producing formation accumulate and,
which if
17 left in the wellbore 111, would eventually hinder or stop gas
production. Gas G is
18 typically produced through the annulus 112 from the zone of interest 115
to
19 surface 3. The inlet end 4 of conduit 114 is typically positioned below
perforations in the zone of interest. The inlet end 4 of conduit 114 typically
21 extends below the inlet end 20 of the pump 110 sufficient to urge the
liquid L to
22 enter the pump 110 while the gas G is directed to the annulus 112.
23 Actuation pressure P is cyclically applied and released at the
24 discharge end 122 of the conduit 114 such as through a hydraulic circuit
or a
positive displacement pump. The actuation pressure P acts at piston 15 of the
18
CA 02600740 2007-09-07
1 pump 110. The pump 110 is actuated, as discussed herein, to produce
2 accumulated liquids L to surface 3 through the conduit 114 thereby
reducing any
3 hydrostatic head caused by the accumulation of the liquids L in the
wellbore 111
4 and permitting production of the gas G through the annulus 112.
Actuation of the pump 110 can be continuous or intermittent. If
6 operated continuously, the pump 110 removes even small accumulations of
7 liquid L. Alternatively, the pump 110 can be operated intermittently on a
fixed
8 (similar to continuous) or a dynamically controlled periodic basis.
Typically, a
9 controller would activate the pump 110 either at regular predetermined
intervals
based on historical liquid accumulation for a particular reservoir type, or
11 dynamically in response to a remote sensor which is able to sense a
12 predetermined volume of fluid accumulation. In either case, actuation of
the
13 pump 110 would typically require very low power, such as can be provided
by,
14 for example, a natural gas powered engine in remote locations not
accessible to
a utility grid or using an electric motor where electricity is available.
Further, an
16 accumulator on a hydraulic circuit or a flywheel on a plunger pump drive
may be
17 used to conserve energy.
18
19 Examples
Mechanical Biasing Means
21 A variety of configurations of embodiments of the pump 110
22 disclosed herein have been modeled for use in wellbore casings of
different
23 diameter. Various configurations using Belleville springs are shown in
Table A.
24 Embodiments of the invention using Belleveille springs as the
biasing means may be more suitable for shallower pump applications to avoid
19
CA 02600740 2007-09-07
1 excessive spring height required to achieve a desired stroke for deeper
well
2 pumps within the confines of the narrow pump diameter required for
wellbore
3 applications.
4
Table A
Units 1 2 3 4 5
Outlet barrel bore API inches 1.5 2.25 1.5 2.25 1.5
Inlet barrel bore API inches 2.25 2.75 2.75 3.25 3.25
Outlet barrel bore, metric mm 38.1 57.15 38.1 57.15 38.1
Inlet barrel bore, metric mm 57.15 69.85 69.85 82.55 82.55
Outlet barrel x-section area mm2 1140 2564 1140 2564 1140
Inlet barrel x-section area mm' 2564 3830 3830 5349 5349
Ratio of inlet to outlet areas 2.250 1.494 3.361 2.086 4.694
Depth of pump m 500 500 500 500 500
Static head on pump w. water column Bar 50 50 50 50 50
Static force on outlet piston N 5695 12814 5695 12814
5695
Pressure applied at surface Bar 80 90 130 150 100
(target -3x static at pump)
Additional force on outlet piston N 9112 23066 14808 38443
11391
Total force on outlet piston N 14808 35880 20503 51258 17086
Ratio static to pressurized P at pump 2.60 2.80 3.60 4.00 3.00
Belleville spring # D5025425 , D633135 D63313 D80364 D80363
Height mm 3.9 4.9 4.8 6.2 5.7
Thickness mm 2.5 3.5 3 4 3
Cone height (H-t) mm 1.4 1.4 1.8 2.2 2.7
# disks per stack 2 3 2 3 2
Height of one disk stack mm 6.4 11.9 7.8 14.2 8.7
75% force, one stack N 9063 15025 12356 21400 11919
75% force, stacked disks N 18126 45075 25072 64200 23838
(max deflection)
75% deflection, one disk stack mm 1.05 1.05 1.35 1.65
2.025
Static (initial) deflection mm 0.330 0.299 0.307 0.329 0.484
One disk stack
Ratio, initial to 75% deflection 0.314 0.284 0.227 0.200 0.239
Total deflection with applied pressure mm 0.858 0.836 1.104
1.317 1.451
Ratio, operating to 75% deflection 0.82 0.80 0.82 0.80 0.72
(target 80%) .
Effective stroke one disk stack mm 0.528 0.537 0.797 0.988
0.968
Target stroke length mm 500 500 750 500 750
Volume of fluid pumped per stroke mmi , 712196 633063 2017889
1392739 3157403
Volume of fluid pumped per stroke bbls/d 0.712 0.633 2.018
1.393 3.157
Cycles per minute 6.0 6.0 6.0 6.0 6.0
Volume of fluid pumped per day mi/d 6.2 5.5 17.4 12.0 27.3
Volume of fluid pumped per day bbls/d 38.8 34.5 109.8 75.8
171.9
# disk pairs to achieve target stroke 947 931 941 506 775
length .
Total # disks 1894 2793 1882 1518 1550
Total disk height mm 6062 11074 7337 7186 6743
6
CA 02600740 2007-09-07
1 As discussed above, the volume of the variable volume chamber
2 17 is greater when the pistons 14,15 are in the inlet position than when
the
3 pistons 14, 15 are in the discharge position. Various arrangements can
result in
4 this characteristic including the embodiments of Figs. 1A-3D wherein the
first
piston 14 and first barrel section 12 have a larger diameter than the second
6 piston 15 and second barrel section 13. A connecting rod 16 fixes the
spacing of
7 the first and second pistons 14,15. An advantage includes maximizing the
barrel
8 diameter for inserting into a wellbore or other annular constraint at the
fluid
9 source F.
Another example of an arrangement causing a differential swept
11 volume includes replacing the fixed connecting rod 16 with an axial
movement
12 multiplier between the first and second pistons 14,15 such that the
axial
13 movement of the first piston 14 is augmented relative to the second
piston 15. A
14 simple mechanical lever with an offset fulcrum would suffice.
Further, the inlet and discharge valves 18,19 can be integrated with
16 the pistons 14,15, as shown in Figs. 1A- 2C or as shown in Figs. 3A-3C,
one or
17 both can be located in a second chamber 41 positioned along a sidewall
of the
18 pump barrel 11 and fluidly connected thereto through a port 44 between
the first
19 and second pistons 14,15 to the variable volume chamber 17 therebetween.
21
CA 02600740 2007-09-07
1 Compressible Liquid Biasing Means
2 As shown in Figs. 6A-6D and in an embodiment of the invention, a
3 liquid spring can be used as the biasing means 25.
4 A compressible fluid FC, such as silicone or any other suitable
compressible fluid, may be used. In an embodiment of the invention, silicone
6 was selected as it is a low viscosity fluid and is chemically inert, non-
flammable
7 and is thermally stable. An interpolation of available data was performed
to
8 determine compressibility of silicone under operating pressure of from
about 70
9 barg (1015 psi) to about 415 barg (6020 psi), assuming approximately
linear
compressibility properties. The data is shown in Fig. 7.
11 Assuming an operating temperature of about 40 C and the data
12 shown in Fig. 7, the expected compressibility of silicone was determined
to be
13 about 0.0106% per bar of pressure to achieve a desired stroke of about
50 cm.
14 Based upon wellbore conditions, such as in a demanding 1000m
total vertical depth (TVD) well, generated pressures and expected
displacements
16 were calculated for both the static (input) and pressurized (discharge)
positions
17 as shown in Table B.
22
CA 02600740 2007-09-07
1 Table B
Static condition
(inlet position)
cc of fluid /
Rod compresses 5.717352 cm
of movement
Compressibility 0.010645 % / bar
Static pressure in coil 98.1 bar
Load on liquid spring 11174 N
Pressure in spring chamber 19.54429 N/mmA2 (Mpa)
Pressure in spring chamber 195.4429 bar
Volume of spring chamber 13.5 litres
Volume of spring chamber 13500 cc
Compressed liquid dV) 280.8661 cc
Rod movement 49.1252 cm
Pressurized position
(discharge position)
Additional pressure 100 bar
Additional load 11391 N
Added pressure in chamber 19.92282 N/mmA2 (Mpa)
Added pressure in chamber 199.2282 bar
Total pressure in chamber 394.6711 bar
Volume of spring chamber 13.5 litres
Volume of spring chamber 13500 cc
Compressed liquid (dV) 567.172 cc
Additional Movement 50.07666 cm
Totals
Coiled tubing pressure 100 bar at surface
CT pressure at depth 198.1 bar at depth
Total force on rod 22565 N
Total pressure in spring 394.6711 bar
Total Movement 99.20186 cm
Length of liquid spring cylinder 5.262734 m
2
3 As determined from Table B, a spring rod 53 length of
4 approximately 1m is required to achieve a 50cm stroke. To minimize
buckling
force, the diameter of spring rod 53 used to compress the fluid F in the
6 pressurized sealed spring chamber 50 was selected to have an OD of 27mm
(1-
7 1/16") for a spring chamber 50 having a volume of 13.51. Further, it was
8 determined that the spring rod 53 would therefore have a maximum
unsupported
23
CA 02600740 2007-09-07
1 length of 1.2m at 70% allowable force as demonstrated on Fig. 8 which was
2 created using the following calculations:
3 Johnson's Equation for Short Column Buckling (Local Buckling):
4 F lb = Sy*As*(1-(L/R/G)^2/(2*(S Rc)A2))
and
6 Euler's Equation for Long Column Buckling (Major Axis Buckling):
7 Feb = (3.14)^2*E*1/(L)A2
8 Where: As = steel cross sectional area
9 Sy = yield stress of steel
I = moment of inertia
11 RG = radius of gyration
12 SR = slenderness ratio for a given length
13 SRc = critical slenderness ratio
14 L = unsupported length
16 At maximum compression, approximately 1m of the spring rod 53
17 is freely extending into the fluid FC in the spring chamber 50, the
freely
18 extending portion of the spring rod 53 being supported thereabouts by
the fluid
19 FC which exerts an equal pressure around the spring rod 53 decreasing
any
tendency for buckling.
21 In one embodiment, a fill port was formed in a bottom wall of the
22 spring chamber 50 to permit filling with compressible fluid FC after
assembly of
23 the pump. Further, a bleed screw was included to permit removal of all
air
24 present in the chamber 50.
In one embodiment, a standard API pump barrel 11 having an OD
26 of 69.9 mm (2.75") and an ID of 57.15 mm (2.25") was used for the spring
27 chamber 50 cylinder. The cylinder was made of AISI C1040 Carbon Steel
and
28 behaved essentially as a pressure vessel containing a pressurized fluid.
Fatigue
24
CA 02600740 2007-09-07
1 calculations using thick-walled cylinder assumptions and Von Mises stress
2 analysis were performed to determine the factor of safety the cylinder
provided
3 under maximum loading at 1000m TVD. The resulting fatigue factor of
safety for
4 a fluctuating pressure from 200 barg (2900psi) to 400 barg (5800psi) was
1.86.
The chamber seal 54, utilized to seal about the spring rod 53
6 extending through the port 52 in the spring chamber 50, was required to
provide
7 a reliable seal at approximately 400 barg (5800 psi) psi. Using silicone
as the
8 compressible fluid F of choice in this embodiment, the chemical
properties of the
9 chamber seal 54 were constrained only in that the material for the seal
54 could
not be a like material, in this case silicone. In an embodiment of the
invention, a
11 nitrile t-seal having nylon backups and a wiper to protect the seal 54
from
12 produced fluids within the wellbore was selected.
13
