U.S. patent application number 14/175543 was filed with the patent office on 2014-08-14 for system and method to improve operation of hydraulic pump for subsea service.
This patent application is currently assigned to OCEANEERING INTERNATIONAL, INC.. The applicant listed for this patent is Donald H. Hay, II, Christopher Mancini. Invention is credited to Donald H. Hay, II, Christopher Mancini.
Application Number | 20140224498 14/175543 |
Document ID | / |
Family ID | 51296664 |
Filed Date | 2014-08-14 |
United States Patent
Application |
20140224498 |
Kind Code |
A1 |
Hay, II; Donald H. ; et
al. |
August 14, 2014 |
System and Method to Improve Operation of Hydraulic Pump for Subsea
Service
Abstract
The operating performance and reliability of a pump, e.g. a
hydraulic pump, can be significantly improved by incorporating an
actively controlled positive displacement control valve in fluid
communication with a fixed displacement pump, supply fluid line,
and return fluid line. In use, the pump may be used to move fluid
from the suction side to the discharge side of the pump, including
fully opening the suction circuit to the pump cylinder and fully
closing the pump discharge circuit during a pump suction stroke,
fully closing the suction circuit and fully opening the pump
discharge circuit to a downstream circuit during a pump discharge
stroke, and allowing fluid to be pumped without the fluid passing
through a valve spring loaded check valve.
Inventors: |
Hay, II; Donald H.;
(Hockley, TX) ; Mancini; Christopher; (Magnolia,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hay, II; Donald H.
Mancini; Christopher |
Hockley
Magnolia |
TX
TX |
US
US |
|
|
Assignee: |
OCEANEERING INTERNATIONAL,
INC.
Houston
TX
|
Family ID: |
51296664 |
Appl. No.: |
14/175543 |
Filed: |
February 7, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61762743 |
Feb 8, 2013 |
|
|
|
Current U.S.
Class: |
166/335 |
Current CPC
Class: |
E21B 43/127 20130101;
E21B 43/16 20130101 |
Class at
Publication: |
166/335 |
International
Class: |
E21B 43/12 20060101
E21B043/12; E21B 43/16 20060101 E21B043/16 |
Claims
1. A system for pumping fluids subsea, comprising: a. a fixed
displacement pump, the fixed displacement pump comprising: i. a
drive cylinder, comprising a drive piston configured to be
cyclically reciprocated by a separate hydraulic power unit and
directional control valve; and ii. a pumping cylinder, comprising a
pumping piston configured to be cyclically reciprocated by the
separate hydraulic power unit and directional control valve, the
drive cylinder operatively linked to the pumping cylinder; b. an
inlet valve in fluid communication with the fixed displacement
pump; c. a supply fluid line in fluid communication with the inlet
valve; d. an outlet valve in fluid communication with the fixed
displacement pump; e. a return fluid line in fluid communication
with the outlet valve; f. an actively controlled positive
displacement control valve in fluid communication with the fixed
displacement pump, the supply fluid line, and the return fluid
line; g. a suction line port in fluid communication with the
positive displacement control valve; and h. a discharge line port
in fluid communication with the positive displacement control
valve.
2. The system of claim 1, wherein the fixed displacement pump may
be driven hydraulically, electrically, and/or mechanically.
3. The system of claim 1, wherein the inlet valve and the positive
displacement control valve may be controlled actively and/or
passively and may further be operated hydraulically, electrically,
and/or mechanically.
4. The system of claim 1, further comprising an active controller
operatively connected to the pump, the inlet valve, and the
positive displacement control valve.
5. The system of claim 4, wherein the active controller further
comprises instrumentation adapted for providing feedback to the
active controller.
6. The system of claim 5, wherein the instrumentation further
comprises a position sensor, a pressure sensor, a temperature
sensor, a flow meter, or a sensor configured to aid in fluid
qualitative analysis.
7. The system of claim 4, wherein the positive displacement control
valve comprises contamination resistant, hardened metal seal
elements.
8. The system of claim 1, wherein the drive cylinder is larger than
the pumping cylinder.
9. A method of improving operation of a subsea pump for a subsea
service, comprising: a. disposing a pump subsea, the comprising: i.
a fixed displacement pump, the fixed displacement pump comprising:
1. a drive cylinder, comprising a drive piston configured to be
cyclically reciprocated by a separate hydraulic power unit and
directional control valve; and 2. a pumping cylinder, comprising a
pumping piston configured to be cyclically reciprocated by the
separate hydraulic power unit and directional control valve, the
drive cylinder operatively linked to the pumping cylinder; ii. an
inlet valve in fluid communication with the fixed displacement
pump; iii. a supply fluid line in fluid communication with the
inlet valve; iv. an outlet valve in fluid communication with the
fixed displacement pump; v. a return fluid line in fluid
communication with the outlet valve; vi. an actively controlled
positive displacement control valve in fluid communication with the
fixed displacement pump, the supply fluid line, and the return
fluid line; vii. a suction line port in fluid communication with
the positive displacement control valve; and viii. a discharge line
port in fluid communication with the positive displacement control
valve; and b. using the pump to move fluid from the suction side to
the discharge side of the pump, moving comprising: i. during a pump
suction stroke, fully opening the suction circuit to the pump
cylinder and fully closing the pump discharge circuit; ii. during a
pump discharge stroke, fully closing the suction circuit and fully
opening the pump discharge circuit to a downstream circuit; and
iii. allowing fluid to be pumped without the fluid passing through
a valve spring loaded check valve.
10. The method of claim 9, further comprising reducing suction
pressure without needing to overcome a spring force in a suction
check valve.
11. The method of claim 9, further comprising not limiting the pump
design by compression ratio.
12. The method of claim 9, wherein the subsea service comprises
preventing auto-siphoning of the fluid through a chemical metering
pump in applications where discharge pressure is lower than suction
pressure.
13. The method of claim 9, further comprising synchronizing the
operation of the positive displacement control valve with the pump
operation.
14. The method of claim 9, wherein the positive displacement
control valve is configured to perform where conditions at the
inlet valve or outlet valve are above or below ambient pressures in
any combination.
15. The method of claim 9, further comprising operating the
positive displacement control valve hydraulically, electrically, or
mechanically through a linkage to the pump drive mechanism.
16. The method of claim 9, wherein the subsea service comprises
using the positive displacement control valve where a pressure of a
subsea production is lower than the minimum possible controllable
delivery pressure of a topsides metering pump.
17. The method of claim 9, wherein the subsea service comprises at
least one of chemical injection into a fluid flowline, chemical
metering, hydraulic fluid supply and power, pressure management,
integrity testing, or blockage remediation.
18. The method of claim 9, wherein: a. during the pump suction
stroke, allowing fluid to flow through the pump suction port into
the pump cylinder and drawing the fluid from a local reservoir or
supply conduit by the movement of the pump piston; and b. during
the pump discharge stroke, pushing the fluid within the pump
cylinder out of the pump by the pump piston and allowing the fluid
to exit through the pump discharge port.
19. The method of claim 9, wherein exiting fluid it is routed to a
pipeline or tank.
Description
CLAIM TO PRIORITY
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119(e) from U.S. Provisional Patent Application No.
61/762,743 entitled "Method to Improve Operation of Hydraulic Pump
for Subsea Service", filed Feb. 8, 2013, which is incorporated
herein in its entirety by this reference.
FIELD OF THE INVENTION
[0002] The operating performance and reliability of a pump, e.g. a
hydraulic pump, can be significantly improved by incorporating
"Positive Displacement Control Valve" technology as shown in the
following figures and description.
BACKGROUND OF THE INVENTION
[0003] A single cycle of a reciprocating piston pump typically has
two components: a suction stroke and a discharge stroke. During the
pump suction stroke, fluid flows through a pump suction port into
the pump cylinder. The movement of the pump piston usually draws
the fluid from a local reservoir or supply conduit. With the pump
discharge stroke, the fluid within the pump cylinder is pushed out
of the pump by the pump piston; exiting through a pump discharge
port where it is routed to a different location like, for example,
a pipeline or tank.
[0004] In the simplest terms, a pump moves fluid from the suction
side to the discharge side of the pump, and, in doing so, adds
energy to the displaced fluid. As a secondary effect of moving the
fluid through the pump, the pump generally reduces pressure on the
suction side while increasing pressure on the discharge side of the
pump.
[0005] A pump must be driven by a mechanism that supplies the
energy to move the pump piston. A simple hydraulic driven
intensifier pump is really two back-to-back hydraulic cylinders.
One hydraulic cylinder contains a piston which is cyclically
reciprocated by a separate hydraulic power unit and directional
control valve. This "drive cylinder" is mechanically linked to,
thereby also reciprocating, a second piston in a "pumping
cylinder."
[0006] Fluid must flow through the pump in only one direction; from
the suction port to the discharge port. In conventional pumps,
check valves are used in the suction and discharge lines to/from
the pump to ensure that the flow is uni-directional. These check
valves are, in general, spring loaded, poppet-and-seat type valves
that only allow flow through the valve in one direction. A pressure
differential in the "flow" direction moves the poppet off the seat,
compressing the spring, and opening a flow path through the check
valve. When this pressure differential sufficiently decreases, the
spring forces the poppet against the seat, closing off the reverse
flow path through the check valve. By automatically responding to
internal pressure differentials, check valves provide automatic
passive operation requiring no additional external controls. Check
valves provide a simple and effective solution for controlling flow
direction in conventional pumping applications. However, as will be
explained below there are several disadvantages with using check
valves in the unconventional applications as we have in deepwater
subsea oilfield service.
[0007] Check valves are sensitive to solid contaminants in the
fluid being pumped. The geometry of the poppet and seat arrangement
in a check valve tends to trap contaminants between the poppet and
seat preventing the check valve from shutting off flow in the
reverse "no-flow" direction. This is a major limitation of check
valves in any service involving contaminated liquids.
[0008] One growing unconventional subsea application requires the
use of pumps to reduce the pressure in a subsea piping system that
has been blocked due to a hydrocarbon "ice" (methane hydrate or
methane clathrate) plug that can form under certain conditions.
Reducing the pressure around the plug causes the ice to melt,
allowing the piping circuit to be restored to normal operation. The
lower the pressure that can be achieved by the pump, the faster the
ice plug will melt.
[0009] Another application includes the use of subsea pumps for
delivering various treating chemicals into the subsea well or
production piping system. In most of these cases, the volume of
chemical delivered must be controlled and measured. So the subsea
pump becomes not only a fluid pumping device, but also a fluid
volumetric metering device; hence the name "metering pump".
Metering pumps are commonly used for conventional non-subsea
applications. Indeed, the conventional pump depicted in the
original disclosure is commonly used for chemical metering
applications for conventional non-subsea applications.
[0010] There are several limitations to using conventional pump
check valves in certain applications. The oilfield piping circuit
containing the ice plug can contain significant solid contaminants
that can become lodged in the pump check valves resulting in
pumping system failure. Plugs can sometimes be composed of hydrate
mixed with other materials common in crude oil that can plug lines,
like asphaltenes, waxes or polymer formations. The pressure in the
piping circuit can only be reduced to the opening pressure of the
pump suction check valve; increasing the time that it takes to melt
the ice plug. The basic design of a reciprocating pump in gas
service is limited by the "pressure ratio" which is an engineering
relationship between pump stroke volume and operating pressure of
the pump check valves. There is also a significant limitation to
using conventional check valves in unconventional subsea pumping
applications.
[0011] After some period of continued production from a subsea
oilfield, the pressure in the hydrocarbon reservoir, and downstream
piping system, decreases to a level below which the treating
chemical will actually free-flow or "auto-siphon" from the storage
reservoir through the pump check valves and into the subsea piping
system bypassing the capability and purpose of the metering pump to
control the volume of chemical used. Indeed the chemical metering
pump discharge pressure in a subsea production system may vary from
15,000 psi to -4000 psi relative to the pump suction pressure over
the production life of a deepwater oilfield.
[0012] One possible way of mitigating this auto-siphoning effect is
to introduce an in-line relief valve or back-pressure valve
downstream of the pump. However this type of device is subject to
high mechanical stresses, sensitive to contamination, and must be
adjusted for changing conditions over the field life.
FIGURES
[0013] The figures supplied herein disclose various embodiments of
the claimed invention.
[0014] FIG. 1 is a block diagram of an exemplary embodiment of a
pump; and
[0015] FIG. 2 is a block diagram of an exemplary embodiment of a
system incorporating a pump.
DESCRIPTION OF VARIOUS EMBODIMENTS
[0016] Referring generally to FIG. 1 and FIG. 2, the operating
performance and reliability of a subsea pump can be improved by
incorporating the technology as shown in the following figures and
description. In its embodiments, the disclosed system 1 (FIG. 2)
may be technology used for, e.g., subsea chemical injection pumping
systems and presents an improvement in subsea pumps used for
hydrate remediation work.
[0017] As will be apparent to those of ordinary skill in subsea
pump arts, in the various embodiments system 1 may be used to help
prevent auto-siphoning of fluids through pump when operating in
sub-ambient discharge conditions; provide positive displacement
operation allowing metered flow of fluids independent of suction or
discharge conditions; eliminate lower reliability spring-loaded
check valves; provide full flow bores through pump suction and
discharge to improve contamination resistance; allow lower suction
pressure, which is an advantage to pipeline scavenging operations
such as a subsea hydrate remediation operation; and provide a pump
design that is not limited by compression ratio.
[0018] Referring to FIG. 1, in an embodiment, system 1 (FIG. 2)
comprises subsea pump 2 useful for subsea service. Subsea pump 2
comprises fixed displacement pump 10, inlet valve 21 in fluid
communication with fixed displacement pump 10; supply fluid line 25
in fluid communication with inlet valve 21; return fluid line 26 in
fluid communication with inlet valve 21; outlet valve 23 in fluid
communication with fixed displacement pump 10; suction line 32 in
fluid communication with outlet valve 23; and discharge line 36 in
fluid communication with outlet valve 23.
[0019] In preferred embodiments fixed displacement pump 10
comprises drive cylinder 11, further comprising drive piston 12
which is cyclically reciprocated by a separate hydraulic power unit
and directional control valve (not shown in the figures) and
pumping cylinder 13, further comprising pumping piston 14 which is
cyclically reciprocated by the separate hydraulic power unit and
directional control valve.
[0020] However, fixed displacement pump 10 may be driven
hydraulically, electrically, and/or mechanically. Additionally,
valves 20,30 may be controlled actively and/or passively and may
further be operated hydraulically, electrically, and/or
mechanically.
[0021] Drive cylinder 11 may be operatively linked to pumping
cylinder 13. In some embodiments, drive cylinder 11 is larger than
pumping cylinder 13.
[0022] Referring additionally to FIG. 2, system 1 may further
comprise active controller 40 operatively connected to the fixed
displacement pump 10 and valves 20,30. Active controller 40 may
further comprise instrumentation 41 suitable for feedback, such as
a position sensor, a pressure sensor, a temperature sensor, a flow
meter, a sensor configured to aid in fluid qualitative analysis, or
the like, or a combination thereof.
[0023] In certain embodiments, positive displacement control valve
30 may be configured using very robust, contamination resistant,
hardened metal seal elements similar to those used in subsea
oilfield gate valves and blowout preventer (BOP) control systems.
This type of seal element is capable of shearing even large solid
contaminants that may enter positive displacement control valve 30
when, for example, pumping liquids from a hydrocarbon pipeline.
[0024] In the operation of exemplary embodiments, operation of
subsea pump 2 may be improved for a subsea service by using the
disclosed system which can be used without requiring spring loaded
check valves. In general, the method includes the use an actively
controlled positive displacement control valve 30 in the pumping
circuit instead of conventional check valves, as described above.
In its embodiments, this method allows fluid to be pumped without
passing through a check valve, eliminating many limitations of a
pump that uses this type of valve. Subsea pump 2, which is more
contamination resistant and inherently more reliable, is capable of
reducing the suction pressure without the limitation of overcoming
the spring force in the suction check valve. Additionally, the pump
design is no longer as limited by compression ratio as prior art
pumps.
[0025] Platform mounted chemical metering pumps are commonly used
to inject chemicals into subsea wells and flowlines via long
umbilical tubes extending to the subsea injection point. However,
the deepwater subsea applications, largely in the Gulf of Mexico,
have only recently matured to the point where the subsea production
pressures are lower than the minimum possible controllable delivery
pressure of a topsides metering pump. There is starting to be
significant volumes of chemical being inadvertently injected into
subsea wells and flowlines from these platforms, and this problem
will increase in the coming years. Even in this topsides pump
application, positive displacement control valve 30 would be an
improvement over conventional technology.
[0026] Subsea services may comprise preventing auto-siphoning of
the fluid through a chemical metering pump in applications where
the discharge pressure is lower than the suction pressure. One
advantage of the disclosed method is to prevent auto-siphoning of
fluid through a chemical metering pump in applications where the
discharge pressure is lower than the suction pressure.
Additionally, subsea services may comprise using positive
displacement control valve 30 where a pressure of a subsea
production is lower than the minimum possible controllable delivery
pressure of a topsides metering pump. Further, subsea services may
include chemical injection into a fluid flowline, chemical
metering, hydraulic fluid supply and power, pressure management,
integrity testing, blockage remediation, or the like, or a
combination thereof.
[0027] Subsea pump 2 is typically disposed subsea. As described
herein, positive displacement control valve 30 is disposed in the
pumping circuit and comprises two internal valve circuits 31,33
that act to alternately open and close the pump suction and
discharge circuits in sync with the suction and discharge pump
strokes.
[0028] Design of subsea pump 2 may be substantially not limited by
compression ratio. Moreover, positive displacement control valve 30
may be configured to perform where conditions at inlet valve 21 or
outlet valve 23 are above or below ambient pressures in any
combination. Positive displacement control valve 30 may be operated
hydraulically, electrically, or mechanically such as through a
linkage to the pump drive mechanism.
[0029] Subsea pump 2 may be used to move fluid from the suction
side, e.g. suction valves 31-32, to the discharge side of subsea
pump 2, e.g. discharge valves 33-34. In an embodiment this process
comprises fully opening the suction circuit to pump cylinders 11,13
and fully closing the pump discharge circuit during a pump suction
stroke and fully closing the suction circuit, e.g. 25, and fully
opening the pump discharge circuit, e.g. 26, to a downstream
circuit during a pump discharge stroke.
[0030] During the pump suction stroke, fluid may be allowed to flow
through pump suction port 35 into pump cylinder 13, drawing the
fluid from local reservoir 100 or supply conduit by the movement of
pump piston 14. Additionally, during the pump discharge stroke,
fluid may be pushed within pump cylinder 13 out of subsea pump 2 by
pump piston 13, allowing the fluid to exit through pump discharge
port 36.
[0031] Fluid may then be pumped without the fluid passing through a
valve spring loaded check valve. Exiting fluid may be routed to a
different location such as pipeline 110 or a tank or the like.
[0032] In certain operations, the operation of positive
displacement control valve 30 may be synchronized with the pump
operation. There are various methods of synchronizing the operation
of positive displacement control valve 30 with the pump operation.
For example, positive displacement control valve 30 may be operated
hydraulically, electrically, or even mechanically through a linkage
to the pump drive mechanism. The improvements realized from the use
of such positive displacement control valve 30 in pump 2 in subsea
applications are independent of the particular method used to
synchronize the operation with pump 2.
[0033] In certain embodiments, suction pressure may be reduced
without needing to overcome a spring force in the suction check
valve.
[0034] The foregoing disclosure and description of the inventions
are illustrative and explanatory. Various changes in the size,
shape, and materials, as well as in the details of the illustrative
construction and/or a illustrative method may be made without
departing from the spirit of the invention.
* * * * *