U.S. patent application number 13/504931 was filed with the patent office on 2012-11-08 for subsea pumping system.
This patent application is currently assigned to FMC Kongsberg Subsea AS. Invention is credited to Leif Arne Tonnessen.
Application Number | 20120282116 13/504931 |
Document ID | / |
Family ID | 43855960 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120282116 |
Kind Code |
A1 |
Tonnessen; Leif Arne |
November 8, 2012 |
SUBSEA PUMPING SYSTEM
Abstract
The invention concerns a subsea pumping system that comprises an
reciprocating pump such as a membrane pump or a hose pump. The
motive fluid for the pump is obtained from one of the well fluids
which is pressurized in a separate stage.
Inventors: |
Tonnessen; Leif Arne;
(Baerums Verk, NO) |
Assignee: |
FMC Kongsberg Subsea AS
Kongsberg
NO
|
Family ID: |
43855960 |
Appl. No.: |
13/504931 |
Filed: |
October 29, 2010 |
PCT Filed: |
October 29, 2010 |
PCT NO: |
PCT/EP2010/066477 |
371 Date: |
July 18, 2012 |
Current U.S.
Class: |
417/53 ;
417/375 |
Current CPC
Class: |
F17D 1/14 20130101; E21B
43/36 20130101; E21B 41/0007 20130101; E21B 43/01 20130101 |
Class at
Publication: |
417/53 ;
417/375 |
International
Class: |
F04B 47/08 20060101
F04B047/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2009 |
NO |
20093258 |
Claims
1. A subsea pumping system for use in a remote location such as a
subsea hydrocarbon production facility, the subsea pumping system
comprising: a source of high pressure fluid; and a fluid driven
reciprocating pump; wherein the high pressure fluid is used as a
motive fluid for the pump; and means for creating pressure pulses
in the motive fluid.
2. The subsea pumping system according to claim 1, wherein the
source of high pressure fluid is produced gas pressurized by a
compressor.
3. The subsea pumping system according to claim 1, wherein the
source of high pressure fluid is produced liquids pressurized by a
liquid pump.
4. The subsea pumping system according to claim 1, wherein the
source of high pressure fluid is an injection fluid provided by a
pump located at a topside facility.
5. The subsea pumping system according to claim 1, wherein the
reciprocating pump is a diaphragm pump.
6. The subsea pumping system according to claim 1, wherein the
reciprocating pump is a hose diaphragm pump.
7. The subsea pumping system according to claim 1, wherein the
reciprocating pump is a piston pump.
8. The subsea pumping system according to claim 1, wherein the
means for creating pressure pulses comprises at least one valve
arranged between the source of high pressure fluid and the
pump.
9. The subsea pumping system according to claim 8, the means for
creating pressure pulses comprises an inlet valve and an outlet
valve which are synchronized to provide the pulses.
10. The subsea pumping system according to claim 8, wherein the
means for creating pressure pulses comprises a rotating sequencing
valve.
11. The subsea pumping system according to claim 10, wherein the
rotating sequencing valve has a rotational axis which is parallel
to a pipeline axis for a pipeline in which the valve is
arranged.
12. The subsea pumping system according to claim 1, further
comprising at least one separator.
13. A method for operating a subsea reciprocating pump, the method
comprising the steps of: separating out a first fluid phase from a
well stream comprising a plurality of phases; increasing the
pressure of said first fluid phase; and using a portion of the
pressurized first fluid phase as a motive fluid for the
reciprocating pump.
14. The method according to claim 13 wherein the pressurized first
fluid phase is fed to the reciprocating pump through a sequential
valve.
15. The method according to claim 13, further comprising the step
of the regulating a pressure differential in the first fluid
phase.
16. The subsea pumping system according to claim 10, wherein the
rotating sequencing valve has a rotational axis which is transverse
to a pipeline axis for a pipeline in which the valve is arranged.
Description
[0001] The present invention relates to a pumping system for use in
a remote location such as a subsea hydrocarbon extraction facility,
comprising a source for high pressure fluid and a fluid driven
pump.
[0002] In many fields, the pressure of the hydrocarbon reservoir
will decrease as the reservoir gets depleted. Therefore, to enable
increased recovery of hydrocarbons, there has been an increased use
of boosting equipment. One example of this are gas lift systems.
Another is the so-called ESP's that is electrical submersible pumps
that are suspended in a hydrocarbon well to boost the pressure and
enable hydrocarbons to be lifted to surface. The drawback of such
installations is that each well needs a pump with the associated
power supply and control system. Another drawback is that only
liquid pumps are feasible in this situation since compressors are
more difficult to operate in wells.
[0003] There is therefore an increased interest in locating the
boosting equipment on the seabed and pump well fluids collected
from several wells. This also enables the use of separators so that
each phase of the well fluids (gas, oil or water) can be separated
from each other and transported to different locations. For example
can water be separated out from the well stream and reinjected into
the ground, thus saving space and treatment equipment on the
platform.
[0004] Added to this is the fact that new fields are found in
deeper waters and further from land. This requires long step out
systems for power supply and control.
[0005] Many subsea process plants with process boosting require
more pumps in addition to a main booster. Traditionally, subsea
pumps are large, heavy and complex units that also require electric
power supply and barrier oil supply provided over a long distance.
The electric system itself is highly complicated and costly,
including for example penetrators, connectors, cable, transformers
and motor control systems. If the host for electric power and
barrier oil is a vessel or a platform, the pump supply systems will
occupy highly valuable deck-area
[0006] Hydrocarbons coming from wells can be divided into several
types, having mainly gas with some water or oil, having mainly oil
with some water. In some instances there may be three phases, gas,
oil and water. The well stream is separated into separate phases in
a separator. The water may preferably be injected back into the
formation.
[0007] In applications with several separation stages, the
separated process medium at the later stages must be commingled
with the separated process medium at first stage.
[0008] Since the process medium looses pressure throughout the
separation stages, the later stages separated process medium must
be boosted to reach the pressure of the first stage separated
process medium. One current solution for boosting the pressure of
the later stage separated process medium is to use an ejector that
uses another pressurized medium as motion fluid. However, the
ejector solution has the disadvantages of low efficiency and mixing
of motion fluid with the driven medium.
[0009] Conventional centrifugal or screw pumps have a limited
tolerance to sand. Current solution is either to let the sand go
through the pump and use very high grade materials and coatings, or
if the sand production is very high, the sand can be separated out
upstream the pump and bypassed by means of an ejector. This ejector
system is rather complex and require high flow of motion fluid.
[0010] It is therefore a need for a different solution to boost a
fluid subsea.
[0011] The aim of the invention is to provide a simpler system that
does not require dedicated supply of utilities (e.g. electric power
and barrier fluid) from an external host, and hence will be more or
less autonomous. It is also an aim of the invention to provide a
system that is robust to sand and capable of pumping viscous sand
slurries. This is achieved by using a subsea available pressurized
fluid as a motive fluid for the pump, that the pump is a
reciprocating pump and that it comprises means for creating
pressure pulses in the motive fluid for operation of the pump.
[0012] The working principle of the autonomous pump invention is to
bleed off some process fluid from a high pressure space to a low
pressure space. In the bleed-off line it shall be fitted a valve,
or arrangement of valves (hereafter named sequencing valve) which
working task is to transform a steady fluid pressure to a pulsating
fluid pressure for excitation of a reciprocating or oscillating
pump.
[0013] Preferably the reciprocating pump is a piston type,
diaphragm type or hose diaphragm type. Especially diaphragm pumps
and hose diaphragm pumps are robust to sand and particles.
[0014] The means for providing the reciprocating driving fluid is a
sequential valve, preferably a rotating valve or a shuttle valve.
It can also be an arrangement of several valves. One sequencing
valve (or valve arrangement) can be made to operate one single pump
or multiple pumps.
[0015] In one embodiment of the invention where there is sand in
the well fluids, the sand is separated out in a de-sander and
pumped using the reciprocating pump while the clean fluid is used
as the motive fluid for the pump.
[0016] In one embodiment where the hydrocarbons are mainly gas, the
motive fluid is gas that is pressurized in a compressed and the
compressed gas is used as the motive fluid to power the pump for
the liquid phase.
[0017] In another embodiment the hydrocarbons are mainly liquids.
The hydrocarbons are separated into an oil phase and a water phase.
The oil phase can then be used as the motive fluid to increase the
pressure in the water line to enable reinjection of water into the
formation. Or vise versa, pressurized water for water injection can
be used as motive fluid for increasing the oil pressure for
transport to an oil-reception facility.
[0018] The invention shall now be described with reference to the
accompanying drawings where
[0019] FIG. 1 is a principal sketch of the invention,
[0020] FIG. 2 is a drawing of a first embodiment of the invention
comprising a compressor,
[0021] FIG. 3 is a drawing of a second embodiment of the invention
comprising a compressor,
[0022] FIG. 4 is a drawing of a first embodiment of the invention
comprising a liquid pump,
[0023] FIG. 5 is a drawing of a third embodiment of the
invention,
[0024] FIGS. 6-8 are drawings of different embodiments of
sequential valves.
[0025] Referring first to FIG. 1 there is shown a sketch of the
principle of the invention. A pump 12 is connected to a pipeline 13
to receive a fluid to be pressurized, for instance hydrocarbon
stream from one or more wells (not shown). The pump is a
reciprocating pump preferably a hose diaphragm pump, a diaphragm
pump or a piston pump. The pumped fluid is led to a pipeline 14
which transports the hydrocarbons to a receiving facility (not
shown). Another pipeline 16 conveys a fluid of higher pressure than
line 13. The fluid is led through a sequential valve 17 which in
turn is connected to the pump 12 and delivers pulsed fluid to be
the motive fluid for the pump 12.
[0026] The high pressure fluid can be served from a remote
facility. Reference can here be made to NO patent 323785 that
describes a method for generating electricity in a subsea station.
The high pressure fluid may be an injection fluid that is
transported from a land based facility that pressurizes the fluid
to a higher pressure than what is needed for the well and the
excess energy/pressure is drawn from this fluid.
[0027] In FIG. 2 there is shown a first embodiment of a practical
use of the invention where the fluids produced from one or several
subsea wells are separated into a first and second fluid phase,
where the first phase may be a gas and the second phase may be a
liquid such a condensate, oil or water or combination of those. The
hydrocarbons are transported through pipeline 20 to a separator 22.
In the separator 22 the first phase is separated from the second
phase and the first phase is led through pipeline 23 to a
compressor 24. The second phase is led through pipeline 30 to the
reciprocating pump 32. In pump 32 the liquid is pressurized up and
led into export pipeline 34. The compressor outlet is connected to
a pipeline 25 for the high pressure first phase. A pipeline 26
branches off pipeline 25 to carry some of the first phase through
sequential valve 27 and then back to the inlet pipe 23 upstream
compressor 24. Alternatively the light fluid could after sequential
valve 27 be led back to pipeline 20 or separator 22. The valve is
arranged to set up an alternating high and low pressure pulse to
drive the reciprocating pump. A reciprocating pump, works by
pulsing the pressure outside of a diaphragm or piston to set up the
pumping action. This arrangement is not describes further as such
pumps are well known in the art. Examples of sequential valves will
be shown later with reference to FIGS. 6-8.
[0028] The first and second phases may be recombined downstream of
the pump(s). In this case it is advantageous to pressurize the
second phase to a higher pressure than the first phase, to
facilitate recombination.
[0029] In FIG. 3 there is shown a second embodiment of the
invention. In this case the produced fluids from the well are three
phase fluids, i.e. gas oil and water. The hydrocarbons stream is
led through pipeline 20 to a first separator 22 that separates the
fluids into a gaseous phase that is led to pipeline 23 and a liquid
phase that is led through pipeline 30. The gas is led through a
compressor 24 and to the gas export pipeline 25. As in FIG. 2 a
branch leads the high pressure gas through sequential valve 27 that
sets up the pressure pulses for driving the reciprocating pump 32.
The liquids that are separated out in first separator 22 is led to
a second separator 40. This separates the oil from the water. The
oil is led through pipeline 41 to reciprocating pump 32 which
pressurizes up the oil and then through pipeline 42 and recombines
the oil with the gas. The water is led through pipeline 44 to
another pump 46 that pressurizes the water so that it can be
injected into the formation.
[0030] In FIG. 4 there is shown yet another embodiment of the
invention. In this case the fluids produced by the well(s) are also
a three phase fluid but may be a two phase fluid, that is, oil and
water. As in the other embodiments hydrocarbons from the well are
transported through pipeline 20 to a first separator 22. This first
separator 22 is only needed in the case where the well fluids
contain gas. The gas is led through an export pipeline 52 to a
remote facility. The liquids are led through pipeline 54 to a
second separator 56 that separates the oil from water. The water is
led through pipeline 58 to a pump 60 and then through pipeline 62.
The pipeline 62 can lead to an injection well or to another
facility. The oil is led trough pipeline 64 to reciprocating pump
66 and then to export pipeline 68. In the case of there being gas
in the well stream the gas and oil can be recombined downstream of
the reciprocating pump. A pipe 70 branches off the pipeline 62 to
convey pressurized fluid through sequential valve 27 and back
through line 71 into pipeline 58 (the pump inlet). Similar to what
is described earlier the high pressure fluids led through line 70
and sequential valve 27 sets up the pulses that make up the driving
fluid for the reciprocating pump 66.
[0031] At times well fluids may contain particles such as sand. The
sand can be very abrasive and it is normally not desirable to have
sand in contact with rotary equipment, such as rotary pumps, since
it can wear out the pump impellers and dynamic seals and bearings
very quickly. Diaphragm pumps and hose diaphragm pumps are far more
tolerant of particles since they do not have rotating parts,
dynamic seals or bearings. In FIG. 5 there is therefore shown an
embodiment where a well stream contains sand. The well fluids are
transported from the well in pipeline 20 to a de-sander 80. The
clean fluids are conveyed through pipeline 82 to pump 84 and to
export pipeline 86. The sand slurry is conveyed through line 90 to
n reciprocating pump 92. The pump 92 pressurizes the slurry to a
pressure that is equal, or preferably a little higher, than in
pipeline 86 and is recombined with the well fluids downstream of
pump 84. A line 87 branches off pipeline 86 downstream of the pump
and, as in the previous embodiments, are led through sequential
valve 27 and then through line 87 back into pipeline 82 upstream of
the pump. The sequential valve 27 sets up the pressure pulses that
drive the reciprocating pump 92.
[0032] FIGS. 6-8 show examples of a sequential valve that may be
used in the invention. In FIG. 6 there is shown a high pressure
line 101 with a first valve 102. After that there is a low pressure
line 103 with valve 104. Between the valves 102 and 104 a line 105
leads to the reciprocating pump. The valves 102 and 104 are run in
sequence corresponding with the pulsing of the reciprocating pump.
The valves may be controlled electrically or hydraulically but
ideally they are controlled by the fluid to create a fully
autonomous system.
[0033] In FIG. 7 the sequential valve is a rotating valve with its
rotational axis parallel with the pipeline axis. As the valve
rotates it will in sequence convey high pressure fluid through bore
106 to the reciprocating pump or exhaust spent fluid through bore
108. The valve can be arranged with a fixed rotational speed that
is synchronized with the oscillations of the pump or it can be
mechanically linked to the pump.
[0034] In FIG. 8 the sequential valve is a rotating valve with its
rotational axis perpendicular to the pipeline axis. The valve has a
rotating vane 110 that sequentially opens for high pressure fluid
to the pump and exhausts the spent fluids. The vane can be rotated
with an electric motor but preferably is controlled either by the
pump or by the pressurized fluid to create an autonomous
system.
[0035] Another kind of valve that may be used is the kind called a
shuttle valve. Also other types of valves and valve-arrangements
may be fit for purpose.
[0036] To achieve a fully functional system there must be a set
pressure differential between the pump strokes. The maximum
discharge pressure is set by the process pressure supplied to
autonomous pump drive in displacing sequence. This pressure can be
increased by increasing main booster discharge pressure, e.g. by
means of a restriction at main booster discharge, downstream the
branch-off to autonomous pump drive.
[0037] The pump charging sequence requires a positive differential
pressure between pumped medium in pump chamber and pump drive
medium. This differential pressure can be increased either by
increasing suction pressure to autonomous pump (e.g. by increasing
liquid column upstream pump), or by decreasing drive medium
pressure.
[0038] One method of achieving this is to increase pulsation
pressure negative amplitude by creating low pressure discharge by
means of a venturi arrangement. Pulsation pressure negative
amplitude can also be increased by means of an ejector incorporated
in the sequencing valve or sequencing valve arrangement.
[0039] By adjusting the restriction it will be possible to maintain
the correct pressure differential between the high pressure and the
low pressure. This pressure differential can therefore be used to
control the sequential valve. By adjusting the restriction the
system will be able to handle changes in the composition of the
well fluids.
[0040] A charging sequence may be determined by the pressure on the
pump inlet. If flow should be regulated, initially the frequency on
the valve must be regulated. However there is a possibility to
achieve a self-regulating pump for compressor applications as the
liquid column in the separator would determine how much the pump
will be filled during a "charging" sequence.
[0041] The invention has been described with reference to some
embodiments. A person skilled in the art will realize that there
are several other ways of utilizing the invention. The
reciprocating pump can for example be used for in a circuit for
supplying cooling fluid to a compressor. It can also be used to set
up a high pressure stream to purge a separator of accumulated sand.
Also, more than one pump can be installed in the system. In the
case of having more than one pump it is preferable to control both
pumps with one single sequential (rotating) valve.
* * * * *