U.S. patent application number 15/415582 was filed with the patent office on 2018-07-26 for hydraulic actuator with pressure-based piston position feedback.
The applicant listed for this patent is General Electric Company. Invention is credited to Bodhayan Dev, Christopher Martin Middleton, Brian Paul Reeves, Deepak Trivedi.
Application Number | 20180209413 15/415582 |
Document ID | / |
Family ID | 62906034 |
Filed Date | 2018-07-26 |
United States Patent
Application |
20180209413 |
Kind Code |
A1 |
Dev; Bodhayan ; et
al. |
July 26, 2018 |
HYDRAULIC ACTUATOR WITH PRESSURE-BASED PISTON POSITION FEEDBACK
Abstract
A hydraulic actuator includes a piston housing having a head end
and a base end opposite the head end and a drive piston movable
between a first piston position proximate to the head end and a
second piston position proximate to the base end. The hydraulic
actuator further includes a control valve positionable between a
first control valve position, in which the control valve directs
fluid into the base end, and a second control valve position, in
which the control valve directs fluid into the head end. A
pressure-based position feedback system configured to facilitate
transition of the control valve between the first control valve
position and the second control valve position in response to
predetermined head end and base end pressures.
Inventors: |
Dev; Bodhayan; (Niskayuna,
NY) ; Middleton; Christopher Martin; (Norman, OK)
; Reeves; Brian Paul; (Edmond, OK) ; Trivedi;
Deepak; (Halfmoon, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
62906034 |
Appl. No.: |
15/415582 |
Filed: |
January 25, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 47/08 20130101;
F04B 9/1035 20130101; F04B 49/22 20130101; F04B 53/10 20130101;
E21B 43/126 20130101; F04B 11/0008 20130101; F04B 53/144 20130101;
F04B 49/002 20130101; F04B 53/16 20130101 |
International
Class: |
F04B 47/08 20060101
F04B047/08; F04B 49/00 20060101 F04B049/00; F04B 49/22 20060101
F04B049/22; F04B 53/10 20060101 F04B053/10; F04B 53/16 20060101
F04B053/16; F04B 53/14 20060101 F04B053/14; E21B 43/12 20060101
E21B043/12 |
Claims
1. A hydraulic actuator comprising: a piston housing having a head
end and a base end opposite said head end; a drive piston disposed
within said piston housing and movable between a first piston
position proximate to said head end and a second piston position
proximate to said base end; a control valve positionable between a
first control valve position and a second control valve position,
wherein: in the first control valve position, said control valve is
configured to direct fluid into said base end; and in the second
control valve position, said control valve is configured to direct
fluid into said head end; and a pressure-based position feedback
system comprising: a first pressure actuated valve coupled in fluid
communication with said head end, said first pressure actuated
valve configured to facilitate transition of said control valve
from the first control valve position to the second control valve
position in response to a predetermined head end pressure; and a
second pressure actuated valve coupled in fluid communication with
said base end, said second pressure actuated valve configured to
facilitate transition of said control valve from the second control
valve position to the first control valve position in response to a
predetermined base end pressure.
2. The actuator in accordance with claim 1, wherein at least one of
said first pressure actuated valve and said second pressure
actuated valve is a pilot-operated pressure sequence valve.
3. The actuator in accordance with claim 1 further comprising at
least one deceleration feature proximate to at least one of said
first piston position and said second piston position.
4. The actuator in accordance with claim 3, wherein said at least
one deceleration feature comprises at least one of a groove defined
by said piston housing, a spring, a hydraulic cushion, and a
bumper.
5. The actuator in accordance with claim 1, wherein said control
valve comprises at least one of a two-position, detented, four-way
directional control valve and a three-position, detented, four-way
directional control valve.
6. The actuator in accordance with claim 1 further comprising a
unitary valve manifold comprising each of said control valve, said
first pressure actuated valve, and said second pressure actuated
valve.
7. A downhole pump system comprising: a piston rod pump assembly;
and a hydraulic actuator coupled to said piston rod pump assembly,
said hydraulic actuator comprising: a piston housing having a head
end and a base end opposite said head end; a drive piston disposed
within said piston housing and movable between a first piston
position proximate to said head end and a second piston position
proximate to said base end; a control valve positionable between a
first control valve position and a second control valve position,
wherein: in the first control valve position, said control valve is
configured to direct fluid into said base end; and in the second
control valve position, said control valve is configured to direct
fluid into said head end; and a pressure-based position feedback
system comprising: a first pressure actuated valve coupled in fluid
communication with said head end, said first pressure actuated
valve configured to facilitate transition of said control valve
from the first control valve position to the second control valve
position in response to a predetermined head end pressure; and a
second pressure actuated valve coupled in fluid communication with
said base end, said second pressure actuated valve configured to
facilitate transition of said control valve from the second control
valve position to the first control valve position in response to a
predetermined base end pressure.
8. The downhole pump system in accordance with claim 7 further
comprising: an actuator pump configured to provide fluid to said
piston housing through said control valve; and an actuator motor
coupled to said actuator pump and configured to drive said actuator
pump.
9. The downhole pump system in accordance with claim 8 further
comprising at least one of an accumulator and a compensator bag,
coupled in fluid communication with said actuator pump.
10. The downhole pump system in accordance with claim 8, wherein
said actuator pump is a positive displacement pump.
11. The downhole pump system in accordance with claim 7, wherein at
least one of said first pressure actuated valve and said second
pressure actuated valve is a pilot-operated pressure sequence
valve.
12. The downhole pump system in accordance with claim 7 further
comprising at least one deceleration feature proximate to at least
one of the first piston position and the second piston
position.
13. The downhole pump system in accordance with claim 12, wherein
said at least one deceleration feature comprises at least one of a
groove defined by said piston housing, a spring, a hydraulic
cushion, and a bumper.
14. The downhole pump system in accordance with claim 7, wherein
said control valve comprises at least one of a two-position,
detented, four-way directional control valve and a three-position,
detented, four-way directional control valve.
15. The downhole pump system in accordance with claim 7 further
comprising a unitary valve manifold comprising each of said control
valve, said first pressure actuated valve, and said second pressure
actuated valve.
16. The downhole pump system in accordance with claim 7, further
comprising a piston rod extending from said drive piston, said
piston rod coupling said drive piston to said piston rod pump
assembly.
17. A method of controlling a hydraulic actuator, the hydraulic
actuator including a piston housing having a head end and a base
end opposite the head end, a drive piston disposed within the
piston housing and movable between a first piston position
proximate to the head end and a second piston position proximate to
the base end, and a control valve positionable between a first
control valve position and a second control valve position, said
method comprising: determining, using a first pressure actuated
valve coupled in fluid communication with the head end, a head end
pressure exceeds a predetermined head end pressure threshold;
transitioning, in response to determining the head end pressure
exceeds the predetermined head end pressure threshold, the control
valve into the second control valve position; determining, using a
second pressure actuated valve coupled in fluid communication with
the base end, a base end pressure exceeds a predetermined base end
pressure threshold; and transitioning, in response to determining
the base end pressure exceeds the predetermined base end pressure
threshold, the control valve into the first control valve
position.
18. The method in accordance with claim 17 further comprising
latching the control valve in at least one of the first control
valve position and the second control valve position after
translating the control valve into the first control valve position
and second control valve position, respectively.
19. The method in accordance with claim 17, wherein at least one of
the first pressure actuated valve and the second pressure actuated
valve is a pilot-operated pressure sequence valve.
20. The method in accordance with claim 17, wherein the first
predetermined fluid pressure corresponds to a fluid pressure within
the head end when the drive piston is substantially in the first
piston position, and the second predetermined fluid pressure
corresponds to a fluid within the base end when the drive piston is
substantially in the second piston position.
Description
BACKGROUND
[0001] The field of the disclosure relates generally to oil and gas
downhole pump assemblies and, more specifically, to hydraulic
actuators for use in oil and gas pumping operations.
[0002] At least some known rod pumps are used in oil and gas wells,
for example, to pump fluids from subterranean depths towards the
surface. In operation, a pump assembly is placed within a well
casing, well fluid enters the casing through perforations, and
mechanical lift forces the fluids from subterranean depths towards
the surface. For example, at least some known rod pumps utilize a
downhole pump with complicated geometry, which by reciprocating
action of a rod string, lifts the well fluid towards the
surface.
[0003] In some known oil and gas well pump systems, one or more
actuators may be used to facilitate the reciprocating action
required for pumping fluid. In certain known systems, such
actuators rely on one or more electronic components for providing
power and/or control. However, due to the harsh conditions inherent
in downhole pumping operations, electronic components can be
subject to reduced reliability, significantly reducing the
operational life of the actuator and increasing costs and downtime
for repairs and replacements. Moreover, operators must rely on
batteries with limited lifespans, expensive downhole generators,
and/or long power supply lines to provide adequate power to the
electronic components. Accordingly, a reliable actuator without the
limitations associated with electronic power and control systems is
desirable.
BRIEF DESCRIPTION
[0004] In one aspect, a hydraulic actuator for a downhole pump is
provided. The hydraulic actuator includes a piston housing having a
head end and a base end opposite the head end and a drive piston
disposed within the piston housing. The drive piston is movable
between a first piston position proximate to the head end and a
second piston position proximate to the base end. The hydraulic
actuator further includes a control valve positionable between a
first control valve position and a second control valve position.
In the first control valve position, the control valve is
configured to direct fluid into the base end. In the second control
valve position, the control valve is configured to direct fluid
into said head end. The hydraulic actuator further includes a
pressure-based position feedback system including a first pressure
actuated valve coupled in fluid communication with the head end and
a second pressure actuated valve coupled in fluid communication
with the base end. The first pressure actuated valve is configured
to facilitate transition of the control valve from the first
control valve position to the second control valve position in
response to a predetermined head end pressure. The second pressure
actuated valve is configured to facilitate transition of the
control valve from the second control valve position to the first
control valve position in response to a predetermined base end
pressure.
[0005] In a further aspect, a downhole pump system is provided. The
downhole pump system includes a piston rod pump assembly and a
hydraulic actuator coupled to the piston rod pump assembly. The
hydraulic actuator includes a piston housing having a head end and
a base end opposite the head end and a drive piston disposed within
the piston housing. The drive piston is movable between a first
piston position proximate to the head end and a second piston
position proximate to the base end. The hydraulic actuator further
includes a control valve positionable between a first control valve
position and a second control valve position. In the first control
valve position, the control valve is configured to direct fluid
into the base end. In the second control valve position, the
control valve is configured to direct fluid into said head end. The
hydraulic actuator further includes a pressure-based position
feedback system including a first pressure actuated valve coupled
in fluid communication with the head end and a second pressure
actuated valve coupled in fluid communication with the base end.
The first pressure actuated valve is configured to facilitate
transition of the control valve from the first control valve
position to the second control valve position in response to a
predetermined head end pressure. The second pressure actuated valve
is configured to facilitate transition of the control valve from
the second control valve position to the first control valve
position in response to a predetermined base end pressure.
[0006] In another aspect, a method of controlling a hydraulic
actuator is provided. The hydraulic actuator includes a piston
housing having a head end and a base end opposite the head end. Thy
hydraulic actuator further includes a drive piston disposed within
the piston housing and movable between a first piston position
proximate to the head end and a second piston position proximate to
the base end. The hydraulic actuator also includes a control valve
positionable between a first control valve position and a second
control valve position. The method includes determining, using a
first pressure actuated valve coupled in fluid communication with
the head end, a head end pressure exceeds a predetermined head end
pressure threshold. The method further includes transitioning, in
response to determining the head end pressure exceeds the
predetermined head end pressure threshold, the control valve into
the second control valve position. The method also includes
determining, using a second pressure actuated valve coupled in
fluid communication with the base end, a base end pressure exceeds
a predetermined base end pressure threshold. The method further
includes transitioning, in response to determining the base end
pressure exceeds the predetermined base end pressure threshold, the
control valve into the first control valve position.
DRAWINGS
[0007] These and other features, aspects, and advantages of the
present disclosure will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0008] FIG. 1 is a perspective schematic illustration of an
exemplary downhole pump system;
[0009] FIG. 2 is a schematic view of an exemplary hydraulic
actuator that may be used in the downhole pump system of FIG.
1;
[0010] FIG. 3 is a schematic illustration of the hydraulic actuator
shown in FIG. 2; and
[0011] FIG. 4 is a flow chart illustrating a method for controlling
a hydraulic actuator, such as the hydraulic actuator of FIGS. 2 and
3.
[0012] Unless otherwise indicated, the drawings provided herein are
meant to illustrate features of embodiments of the disclosure.
These features are believed to be applicable in a wide variety of
systems comprising one or more embodiments of the disclosure. As
such, the drawings are not meant to include all conventional
features known by those of ordinary skill in the art to be required
for the practice of the embodiments disclosed herein.
DETAILED DESCRIPTION
[0013] In the following specification and the claims, reference
will be made to a number of terms, which shall be defined to have
the following meanings.
[0014] The singular forms "a", "an", and "the" include plural
references unless the context clearly dictates otherwise.
[0015] "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, and that the
description includes instances where the event occurs and instances
where it does not.
[0016] Approximating language, as used herein throughout the
specification and claims, may be applied to modify any quantitative
representation that could permissibly vary without resulting in a
change in the basic function to which it is related. Accordingly, a
value modified by a term or terms, such as "about",
"approximately", and "substantially", are not to be limited to the
precise value specified. In at least some instances, the
approximating language may correspond to the precision of an
instrument for measuring the value. Here and throughout the
specification and claims, range limitations may be combined and/or
interchanged, such ranges are identified and include all the
sub-ranges contained therein unless context or language indicates
otherwise.
[0017] The actuator assemblies and associated methods described
herein facilitate extending pump operation in harsh oil and gas
well environments. Specifically, actuator assemblies described
herein include a control valve configured to induce reciprocating
motion of piston assemblies. To do so, the control valve
alternately directs pressurized hydraulic fluid into a head end and
base end of the piston assembly, inducing corresponding movement of
a drive piston disposed within the piston assembly. The control
valve is switched between two configurations, each configuration
corresponding to a different fluid flow path, in response to
feedback provided by a pressure-based position feedback system. The
pressure-based position feedback system is configured to induce
transition of the control valve in response to pressure at the base
end and head end of the piston assembly exceeding a predetermined
pressure threshold. In the exemplary embodiment, a first
predetermined pressure threshold corresponds to a pressure at the
head end of the piston assembly when the drive piston is
substantially in the first piston position and a second
predetermined pressure threshold corresponds to a pressure at the
base end of the piston assembly when the drive piston is
substantially in the second piston position.
[0018] FIG. 1 is a perspective schematic illustration of an
exemplary downhole pump system 100. In the exemplary embodiment,
pump system 100 includes a well head 102, production tubing 104
coupled to well head 102, and a pump assembly 110 coupled to
production tubing 104 and positioned within a well bore 106. Well
bore 106 is drilled through a surface 108 to facilitate the
production of subterranean fluids such as, but not limited to,
water and/or petroleum fluids. As used herein, "petroleum fluids"
may refer to mineral hydrocarbon substances such as crude oil, gas,
and combinations thereof.
[0019] Pump assembly 110 includes a piston rod pump assembly 112
and a hydraulic actuator 114 configured to actuate piston rod pump
assembly 112. Hydraulic actuator 114 generally includes a hydraulic
power section 116, a control section 118, and a piston section 120.
During operation, a drive piston 122 disposed within piston section
120 is driven by hydraulic power section 116 subject to control by
control section 118. More specifically, power section 116 provides
pressurized hydraulic fluid to drive piston 122 while control
assembly 118 dynamically redirects the pressurized hydraulic fluid
provided by power section 116 to facilitate reciprocation of drive
piston 122.
[0020] FIG. 2 is a schematic view of an exemplary hydraulic
actuator 114 that may be used in downhole pump system 100 (shown in
FIG. 1). FIG. 3 is a schematic illustration of hydraulic actuator
114. In the exemplary embodiment, hydraulic actuator 114 includes
power section 116, control section 118, and piston section 120.
Power section 116 includes an actuator motor 224 and an actuator
pump 226. Actuator pump 226 is coupled in fluid communication with
control section 118 and, more specifically, a valve manifold 228
including a control valve 230 disposed within control section 118.
Control section 118 further includes a first pressure actuated
valve 232 and a second pressure actuated valve 234 coupled in fluid
communication with control valve 230 through a first hydraulic
control line 258 and a second hydraulic control line 260,
respectively. In the exemplary embodiment, first pressure actuated
valve 232 and second pressure actuated valve 234 are pilot-operated
sequence valves. For example, pressure actuated valves 232 and 234
are direct-acting sequence valves having an integral check valve to
provide reverse flow from a sequence port (not shown) to an inlet
port (not shown). Pressure actuated valves 232 and 234 supply a
secondary circuit (e.g., hydraulic control lines 258 and 260) with
fluid flow once the pressure at the inlet port has exceeded a
predetermined pressure threshold. In alternative embodiments, first
pressure actuated valve 232 and a second pressure actuated valve
234 are any suitable valves configured to actuate in response to
detecting a predetermined pressure.
[0021] In certain embodiments, valve manifold 228 is a unitary
valve manifold that includes first pressure actuated valve 232 and
second pressure actuated valve 234. In such embodiments, valve
manifold 228 may be manufactured using various techniques,
including, without limitation, additive manufacturing. Hydraulic
actuator 114 further includes piston section 120 including a piston
housing 236 and drive piston 122 disposed within piston housing
236. In addition, hydraulic actuator 114 includes a compensator bag
or compensator 244 that functions as a fluid volume storage device
for hydraulic actuator 114 as well as actuator pump 226.
Compensator 244 facilitates damping of pump pulsations transmitted
through the fluid as well as energy storage, shock absorption, and
other reservoir functions (e.g., fluid leakage make-up and fluid
volume compensation due to temperature changes, etc.). In
alternative embodiments, hydraulic actuator 114 further includes an
accumulator 242 to facilitate accounting for variations in fluid
volume during operation of hydraulic actuator 114, and in
particular during a transition of control valve 230.
[0022] During operation, with reference to FIG. 3, drive piston 122
reciprocates between a first piston position 250 proximate to a
head end 246 of piston housing 236 and second piston position 252
proximate to a base end 248 of piston housing 236. To facilitate
reciprocation of drive piston 122, control valve 230 is configured
to alternately direct fluid from actuator pump 226, which is driven
by actuator motor 224, to head end 246 and base end 248 in response
to the position of drive piston 122. More specifically, control
valve 230 is configured to operate in a first control valve
position in which pressurized fluid provided by actuator pump 226
is directed into head end 246 and a second control valve position
in which the pressurized fluid is directed into base end 248. As
the pressurized fluid is provided into head end 246, drive piston
122 is moved to second piston position 252 proximate to base end
248. Similarly, as pressurized fluid is provided into base end 248,
drive piston 122 is moved to first piston position 250 proximate to
head end 246. Accordingly, as control valve 230 alternates between
the first control valve position and the second control valve
position, drive piston 122 reciprocates within piston housing
236.
[0023] Control valve 230 switches between the first control valve
position and the second control valve position in response to
positional feedback provided by first pressure actuated valve 232
and second pressure actuated valve 234. First pressure actuated
valve 232 is coupled in fluid communication with head end 246 of
piston housing 236 and second pressure actuated valve 234 is
coupled in fluid communication with base end 248. In the exemplary
embodiment, first pressure actuated valve 232 is coupled in fluid
communication with a head end hydraulic line 238 for providing
hydraulic fluid from actuator pump 226 to head end 246 of piston
housing 236, and second pressure actuated valve 234 is coupled in
fluid communication with a base end hydraulic line 240 for
providing hydraulic fluid from actuator pump 226 to base end 248 of
piston housing 236. In alternative embodiments, first pressure
actuated valve 232 and second pressure actuated valve 234 are
otherwise coupled in fluid communication to each of head end 246
and base end 248 to detect hydraulic fluid pressure corresponding
to each of head end 246 and base end 248, respectively. For
example, in certain embodiments, first pressure actuated valve 232
and second pressure actuated valve 234 are coupled in fluid
communication with head end 246 and base end 248, respectively,
through pressure taps installed in head end 246 and base end 248 of
piston housing 236.
[0024] Each of first pressure actuated valve 232 and second
pressure actuated valve 234 are configured to actuate in response
to experiencing a predetermined fluid pressure. In the exemplary
embodiment, first pressure actuated valve 232 is configured to
actuate in response to a head end pressure exceeding a
predetermined head end pressure threshold, and second pressure
actuated valve 234 is configured to actuate in response to a base
end pressure exceeding a predetermined based end pressure
threshold. More specifically, first pressure actuated valve 232 is
coupled in fluid communication with head end 246 by head end
hydraulic line 238 and actuates in response to a pressure within
head end hydraulic line 238 corresponding to a head end pressure
exceeding the predetermined head end pressure threshold. For
example, as drive piston 122 is moved to first piston position 250
(i.e., drive piston 122 dead ends against head end 246), a pressure
in the hydraulic fluid is increased, or spikes, to a pressure
exceeding the predetermined head end pressure threshold. Similarly,
second pressure actuated valve 234 is coupled in fluid
communication with base end 248 by base end hydraulic line 240 and
actuates in response to a pressure within base end hydraulic line
240 corresponding to a base end pressure exceeding the
predetermined base end pressure threshold.
[0025] During operation, when control valve 230 is in the first
control valve position, control valve 230 directs fluid provided by
actuator pump 226 into base end 248 and drive piston 122 moves
towards head end 246. As drive piston 122 moves towards head end
246, pressure within head end hydraulic line 238 increases until
the predetermined head end pressure threshold is exceeded. When the
predetermined head end pressure threshold is exceeded, first
pressure actuated valve 232 actuates, causing pressurized fluid to
flow to control valve 230 via hydraulic control line 258 to
translate control valve 230 into the second control valve position.
In the exemplary embodiment, the predetermined head end pressure
threshold is selected such that first pressure control valve 232
actuates when drive piston 122 is located substantially in first
piston position 250, thereby providing positional feedback
corresponding to the position of drive piston 122 within piston
housing 236. In the second control valve position, control valve
230 directs fluid provided by actuator pump 226 into head end 246
and drive piston 122 moves towards base end 248. As drive piston
122 moves towards base end 248, pressure within base end hydraulic
line 240 increases until the predetermined base end pressure
threshold is exceeded. When the predetermined base end pressure
threshold is exceeded, second pressure actuated valve 234 actuates,
causing pressurized fluid to flow to control valve 230 via
hydraulic control line 260 to translate control valve 230 into the
first control valve position. In the exemplary embodiment, the
predetermined base end pressure threshold is selected such that
second pressure actuated valve 234 actuates when drive piston 122
is located substantially in second piston position 252. The
foregoing process of control valve 230 redirecting fluid
alternately into head end 246 and base end 248 may be repeated to
facilitate reciprocating motion of drive piston 122.
[0026] In the exemplary embodiment, control valve 230 is a
two-position, detented, four-way directional valve. Alternatively,
control valve 230 may be a three-position, detented, four-way valve
or any other valve configuration that enables pump system 100 to
function as described herein. In the exemplary embodiment, control
valve 230 includes an internal mechanical detent that facilitates
holding the valve in position until a minimum pilot fluid pressure
is applied to a pilot port (not shown) of control valve 230. For
example, in the exemplary embodiment, control valve 230 is switched
between the first control valve position and the second control
valve position by applying the minimum pilot fluid pressure to one
of the pilot ports, where control valve 230 remains in that
position, with no pilot fluid pressure applied, until a new pilot
fluid pressure signal is temporarily applied to the opposite pilot
port. As such, control valve 230 is configured to remain in either
the first control valve position or the second control valve
position until either first pressure actuated valve 232 or second
pressure actuated valve 234 is actuated, respectively. Accordingly,
control valve 230 continues to direct fluid into head end 246 and
base end 248 until drive piston 122 is substantially in second
piston position 234 and first piston position 232,
respectively.
[0027] In certain embodiments, hydraulic actuator 114 includes
features configured to reduce forces of components as drive piston
122 reciprocates within piston housing 236. Drive piston 122 is
configured to dead end in head end 246 and base end 248 of piston
housing 236, and as such, hydraulic actuator 114 includes
deceleration features configured to facilitate decelerating drive
piston 122 to facilitate increasing its longevity. For example,
piston housing 236 defines a plurality of longitudinal grooves 266
proximate to head end 246 and base end 248 such that as drive
piston 122 approaches head end 246 and base end 248, a pressure
differential across drive piston 122 is reduced due to leakage of
the fluid through grooves 266, causing deceleration of drive piston
122. In alternative embodiments, piston housing 236 includes other
deceleration features including, without limitation, springs and
bumpers disposed in head end 246 and base end 248 to facilitate
deceleration of drive piston 122 and/or hydraulic cushioning
features including a tapered piston bore and similar tapered
features on drive piston 122.
[0028] FIG. 4 is a flow chart illustrating a method 400 for
controlling a hydraulic actuator, such as hydraulic actuator 114
(shown in FIGS. 2 and 3). Referring to FIG. 2, FIG. 3, and FIG. 4,
hydraulic actuator 114 generally includes piston housing 236 having
head end 246 and base end 248 opposite head end 246, drive piston
122 disposed within piston housing 236 and movable between first
piston position 250 proximate to head end 246 and second piston
position 252 proximate to base end 248. Hydraulic actuator 114
further includes control valve 230 positionable between a first
control valve position and a second control valve position. Control
valve 230 is positionable between the first control valve position
and the second control valve position based, at least in part, on
positional feedback provided by first pressure actuated valve 232
and second pressure actuated valve 234. More specifically, first
pressure actuated valve 232 is configured to actuate in response to
a fluid pressure within head end 246 exceeding a predetermined head
end pressure threshold and, upon actuation, to cause control valve
230 to translate into the second control valve position. Similarly,
second pressure actuated valve 234 is configured to actuate in
response to a fluid pressure within base end 248 exceeding a
predetermined base end pressure threshold and, upon actuation, to
cause control valve 230 to translate into the first control valve
position. In the exemplary embodiment, each of first pressure
actuated valve 232 and second pressure actuated valve 234 are
pilot-operated pressure sequence valves.
[0029] Method 400 includes determining 402, using first pressure
actuated valve 232, that a head end pressure within head end 246
exceeds a predetermined head end pressure threshold. For example,
in the exemplary embodiment, first pressure actuated valve 232 is
coupled in fluid communication with head end 246 by a head end
hydraulic line 238 and is configured to respond to pressure within
head end 246 through head end hydraulic line 238. As drive piston
122 moves within piston housing 246, pressure within head end
hydraulic line 238 varies. More specifically, as drive piston 122
moves towards head end 246, pressure within head end 246, and by
extension head end hydraulic line 238, increases until first
pressure actuated valve 232 actuates in response to the pressure
within head end 246 exceeding the predetermined head end pressure
threshold. In the exemplary embodiment, the predetermined head end
pressure threshold corresponds to a head end pressure when drive
piston 122 is substantially in first piston position 250.
[0030] Method 400 further includes transitioning 404, in response
to determining the head end pressure exceeds the predetermined head
end pressure threshold, control valve 230 into the first control
valve position. In the first control valve position, control valve
230 is configured to direct fluid into head end 246 of piston
housing 236. In actuator assembly 114, for example, first pressure
actuated valve 232 is coupled in fluid communication with control
valve 230 via hydraulic control line 258 such that when first
pressure actuated valve 232 is actuated when the head end pressure
exceeds the predetermined head end pressure threshold, first
pressure actuated valve 232 facilitates transition of control valve
230 into the second control valve position.
[0031] Method 400 also includes determining 406, using second
pressure actuated valve 234, that a base end pressure within base
end 248 exceeds a predetermined base end pressure threshold. For
example, in the exemplary embodiment, second pressure actuated
valve 234 is coupled in fluid communication with base end 248 by a
base end hydraulic line 240 and is configured to respond to
pressure within base end 248 through base end hydraulic line 240.
As drive piston 122 moves within piston housing 246, pressure
within base end hydraulic line 240 varies. More specifically, as
drive piston 122 moves towards base end 248, pressure within base
end 248, and by extension base end hydraulic line 240, increases
until second pressure actuated valve 232 actuates in response to
the pressure within base end 248 exceeding the predetermined base
end pressure threshold. In the exemplary embodiment, the
predetermined base end pressure threshold corresponds to a base end
pressure when drive piston 122 is substantially in second piston
position 252.
[0032] Method 400 further includes transitioning 408, in response
to determining the base end pressure exceeds the predetermined base
end pressure threshold, control valve 230 into the second control
valve position. In the second control valve position, control valve
230 is configured to direct fluid into base end 248 of piston
housing 236. In actuator assembly 114, for example, second pressure
actuated valve 234 is coupled in fluid communication with control
valve 230 via hydraulic control line 260 such that when second
pressure actuated valve 234 is actuated when the second fluid
pressure exceeds the predetermined base end pressure threshold,
second pressure actuated valve 234 facilitates transition of
control valve 230 into the second control valve position. In the
exemplary embodiment, control valve 230 is configured to latch into
the first control valve position upon transitioning. As indicated
in FIG. 4, after the step of transitioning 408 control valve 230
into the second control valve position, steps 402-408 may repeat,
thereby resulting in a reciprocating action of drive piston
122.
[0033] In the exemplary embodiment, control valve 230 is configured
to latch into the first and second control valve positions upon
transitioning. For example, in the exemplary embodiment, control
valve 230 is a detent valve configured to stay in either the first
or second control valve position until drive piston 122 completes
its stroke and the pressure thresholds at each end are exceeded,
which triggers control valve 230 to unlatch to move to a different
position.
[0034] The actuator assemblies described herein facilitate
extending pump operation in harsh oil and gas well environments.
Specifically, the actuator assemblies described herein facilitate
reciprocation of a drive piston based on a pressure-based position
feedback system. The pressure-based position feedback system is
configured to translate a control valve to alternately direct fluid
into a head end and a base end of a piston housing. As the drive
piston reaches either the head end or the base end, the position
feedback system switches the control valve to direct fluid into the
piston housing to facilitate movement of the drive piston in the
opposite direction.
[0035] An exemplary technical effect of the methods, systems, and
assembly described herein includes at least one of: (a) improving
reliability of actuator assemblies as compared to electronically
controlled actuator assemblies; (b) improving the operational life
of actuator assemblies; (c) improving the service life of downhole
pump systems including actuator assemblies; and (d) reducing
downhole pump operating costs.
[0036] Exemplary embodiments of methods, systems, and apparatus for
actuator assemblies are not limited to the specific embodiments
described herein, but rather, components of systems and/or steps of
the methods may be utilized independently and separately from other
components and/or steps described herein. For example, the methods,
systems, and apparatus may also be used in combination with other
pumping systems outside of the oil and gas industry. Rather, the
exemplary embodiment can be implemented and utilized in connection
with many other applications, equipment, and systems that may
benefit from improved reciprocating actuator assemblies.
[0037] Although specific features of various embodiments of the
disclosure may be shown in some drawings and not in others, this is
for convenience only. In accordance with the principles of the
disclosure, any feature of a drawing may be referenced and/or
claimed in combination with any feature of any other drawing.
[0038] This written description uses examples to disclose the
embodiments, including the best mode, and also to enable any person
skilled in the art to practice the embodiments, including making
and using any devices or systems and performing any incorporated
methods. The patentable scope of the disclosure is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal language of the claims.
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