U.S. patent application number 10/491882 was filed with the patent office on 2004-12-09 for system and method for injecting water into an underwater hydrocarbon reservoir.
Invention is credited to Appleford, David Eric, Lane, Brian William.
Application Number | 20040244980 10/491882 |
Document ID | / |
Family ID | 9923777 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040244980 |
Kind Code |
A1 |
Appleford, David Eric ; et
al. |
December 9, 2004 |
System and method for injecting water into an underwater
hydrocarbon reservoir
Abstract
Water is supplied from a host facility (2) to a pump (10) in a
seabed facility (5) via a connecting pipeline (6). The pump (10)
pumps the water to a higher pressure, and injects the pumped water
into a hydrocarbon reservoir at a pressure higher than the pressure
of the fluid in the reservoir so that it drives production fluid
there to the host facility (2).
Inventors: |
Appleford, David Eric;
(Essex, GB) ; Lane, Brian William; (Essex,
GB) |
Correspondence
Address: |
Summa & Allan
Suite 200
11610 North Community House Road
Charlotte
NC
28277
US
|
Family ID: |
9923777 |
Appl. No.: |
10/491882 |
Filed: |
April 7, 2004 |
PCT Filed: |
October 11, 2002 |
PCT NO: |
PCT/GB02/04628 |
Current U.S.
Class: |
166/305.1 ;
166/90.1 |
Current CPC
Class: |
E21B 43/18 20130101 |
Class at
Publication: |
166/305.1 ;
166/090.1 |
International
Class: |
E21B 043/16 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2001 |
GB |
0124616.4 |
Claims
1. A system (1) for injecting water into a hydrocarbon reservoir,
comprising a host facility (2) having water supply means (3), an
underwater pump (10) remote from the host facility (2), and
connected to the water supply means (3) by a pipeline (6), and at
least one water injection well (7) connected to the underwater pump
(10) whereby the pump (10) is arranged to pump the water received
from the pipeline (6) to the or each well (7) to inject the pumped
water into the reservoir at a pressure higher than the pressure of
the fluid in the reservoir, characterised in that said underwater
pump comprises an electric motor driven pump (10).
2. A system as claimed in claim 1, wherein the pump (10) is
connected to the at least one water injection well (7) by at least
one flowline (8) which is able to withstand conveyed fluid of a
higher pressure than the pipeline (6) between the host facility (2)
and the underwater pump (10).
3. A system as claimed in claim 1 or 2, wherein the pump (10) is
located at an underwater facility (5).
4. A system as claimed in claim 3, wherein the underwater facility
(5) includes a retrievable module (16) which incorporates the pump
(10).
5. A system as claimed in any preceding claim 1, including a power
and control umbilical (13) from the host facility (2) to the
underwater pump (10) for conveying power and control signals to the
pump.
6. A system as claimed in claim 5, wherein the power and control
umbilical (13) is arranged to convey power and control signals
required for other underwater equipment.
7. A method for injecting water into a hydrocarbon reservoir,
comprising the steps of supplying water from a host facility (2) to
an underwater pump (10) via a connecting pipeline (6), pumping the
water received by the underwater pump (10) to a higher pressure,
and injecting the pumped water into the reservoir at a pressure
higher than the pressure of the fluid in the reservoir,
characterised by the step of: driving the underwater pump (10) with
an electric motor.
Description
[0001] The present invention relates to a system and method for
injecting water into a hydrocarbon reservoir.
[0002] In an oil and/or gas field development, production fluid,
extracted from the hydrocarbon reservoir by production wells, is
driven to a host facility by the natural pressure of the reservoir.
However, the natural pressure varies from field to field and some
reservoirs may not have enough pressure to drive the production
fluid to the host facility.
[0003] A way of overcoming this problem is to boost the pressure of
the reservoir by injecting water supplied from the host facility
into it. A seabed facility pipeline connects the host facility to a
seabed facility where the pipeline is manifolded into separate well
flowlines connected to water injection wells located at the
extremities of the reservoir. Water for injection purposes is
normally chemically treated and filtered at the host facility to
ensure its suitability for injection into the hydrocarbon
reservoir. However, in some instances, dependent upon the local
seawater and the particular reservoir, it may be possible to inject
seawater into the reservoir without chemical treatment.
[0004] The water is pumped down the seabed facility pipeline and
into the reservoir via the seabed facility, the well flowlines and
the water injection wells. The injected water is pumped to a
pressure higher than the natural pressure of the reservoir so that
it drives production fluid from the reservoir up to the production
wells and on to the host facility.
[0005] The required pressure of the injected water is typically in
the region of 27.58 MPa (4000 pounds per square inch). Hence, the
pipeline and flowlines which are required to convey the injected
water to the injection wells have to have walls thick enough to
withstand the high pressure of the water. The costs of the pipeline
and flowlines themselves and the installation costs are high.
[0006] U.S. Pat. No. 4,848,471 discloses a system for injecting
water into a production well. Seawater is treated and pressurised
at a host facility before being transported in a supply line to
drive an underwater fluid driven motor. A portion of the seawater
is conveyed from the supply line for injection into the well via an
injection pump driven by the motor. Return water from the fluid
driven motor is carried in a separate return line back to the host
facility.
[0007] It is therefore an object of the present invention to
provide a system and method which overcomes at least the
above-mentioned disadvantage of the prior art.
[0008] According to one aspect of the present invention there is
provided a system for injecting water into a hydrocarbon reservoir,
comprising a host facility having water supply means, an underwater
pump remote from the host facility, and connected to the water
supply means by a pipeline, and at least one water injection well
connected to the underwater pump, whereby the pump is arranged to
pump the water received from the pipeline to the or each well to
inject the pumped water Into the reservoir at a pressure higher
than the pressure of the fluid in the reservoir, characterised: in
that
[0009] said underwater pump comprises an electric motor driven
pump.
[0010] The pump may be connected to the at least one water
injection well by at least one flowline which is able to withstand
conveyed fluid of a higher pressure than the pipeline between the
host facility and the underwater pump.
[0011] The pump is preferably located at an underwater facility
such as a seabed facility. Gravity alone may be used to convey
water to the pump at the underwater facility. In contrast, the
prior art described requires the water to be pumped to the seabed
facility. By locating the pump on the underwater facility, a
pipeline able to convey fluid at a high pressure is not required
between the host facility and the underwater facility, as water
from the host facility is only at a high pressure once it has been
pumped by the pump. Hence, the pipeline between the host facility
and the underwater facility may have its pipe wall thickness
reduced as it does not need to convey fluid at such a high
pressure. As there is a reduction in the quantity of pipe material
for this pipeline, there is a significant cost saving.
[0012] By conveying the water for injection at a lower pressure to
the underwater facility, the pressure losses due to friction in the
pipeline are reduced. Consequently, less power is required to pump
the water for injection, enabling a smaller pump and drive motor
(which is electric) to be specified at the underwater facility and,
if required, at the host facility. Hence, there is a further cost
saving as a smaller pump requires less energy to drive it. If the
host facility also has a pump for water supply, the reduction in
size of the pump and its associated drive motor provides a saving
in deck space on the host facility and in the weight to be
supported by the host facility. If water supply is by gravity
alone, no pump need be provided at the host facility.
[0013] The reduction in pipe wall thickness enables the sections of
the pipe for making up the pipeline to the underwater facility to
be welded together more easily and quickly which considerably
reduces fabrication costs. Furthermore, the reduction in pipe wall
thickness may enable the pipeline to be reeled onto a drum and be
laid from a pipe reel-lay barge which is a faster method of
installing a pipeline than other conventional methods.
[0014] The savings in pipeline costs enables longer tie-backs to
the host facility to be economically considered which may allow the
use of an existing host facility to be used for a remote field as
opposed to having to provide a new host facility. This is of
particular benefit when the field to be developed is located
beneath deep water.
[0015] The system preferably includes a power and control umbilical
from the host facility to the underwater pump for conveying power
and control signals to the pump. The power and control umbilical
may be also arranged to convey power and control signals required
for other underwater equipment such as wellhead trees and
manifolds. Minimal additional cost is incurred when providing power
to the underwater pump if the same umbilical is used for the
underwater pump and other underwater equipment.
[0016] The underwater facility may include a retrievable module
which incorporates the pump. Hence, the pump may be easily
recovered for inspection, maintenance or repair, for example. The
module may be of the type forming part of the modular system
designed by Alpha Thames Ltd of Essex, United Kingdom, and named
AlphaPRIME.
[0017] According to another aspect of the present invention there
is provided a method for injecting water into a hydrocarbon
reservoir, comprising the steps of supplying water from a host
facility to an underwater pump via a connecting pipeline, pumping
the water received by the underwater pump to a higher pressure, and
injecting the pumped water into the reservoir at a pressure higher
than the pressure of the fluid in the reservoir, characterised by
the step of:
[0018] driving the underwater pump with an electric motor.
[0019] The method may include the steps of using any of the system
components referred to above.
[0020] Embodiments of the present invention will now be described,
by way of example, with reference to the accompanying drawings, in
which:--
[0021] FIG. 1 is a schematic diagram of a system for putting the
invention into practice; and
[0022] FIG. 2 is a modified detail of FIG. 1.
[0023] Referring to FIG. 1 of the accompanying drawings, a system 1
has a host facility 2 which may be, for example, onshore or on a
fixed or floating rig. The host facility 2 has an injection water
treatment plant 3 with a connected pump 4 which is connected to a
remote seabed facility 5 by an injection water supply pipeline 6.
The seabed facility 5 is connected to a plurality of water
injection wells 7 for a hydrocarbon reservoir-whereby each well is
connected to the facility 5 by a separate supply flowline 8 which
is able to withstand conveyed water of a higher pressure than the
water supply pipeline 6.
[0024] At the seabed facility 5 the water supply pipeline 6 is
connected to an inlet 9 of a high pressure pump 10 and a conduit 11
from an outlet 12 of the pump 10 is manifolded to the flowlines 8
connected to the water injection wells 7.
[0025] The pump 10 is arranged to be supplied with power and
control signals from the host facility 2 via a power and control
umbilical 13.
[0026] The operation of the system 1 will now be described.
[0027] The water treatment plant 3 chemically treats the water for
injection so that it is suitable for injection into the hydrocarbon
reservoir and the pump 4 at the host facility 2 pumps the treated
water into the water supply pipeline 6 where gravity assists the
conveyance of the water to the seabed facility 5.
[0028] At the seabed facility 5, the water is pressure boosted by
the high pressure pump 10 and is injected into the hydrocarbon
reservoir via the well
[0029] supply flowlines 8 and the water injection wells 7. The
pressure of the injected water is higher than the pressure of the
fluid in the reservoir so that it drives the production fluid to
the host facility 2 via production wells (not shown).
[0030] A modification to the system 1 will now be described in
which parts which correspond to those shown in FIG. 1 are
designated with the same reference numerals and are not described
in detail below. In the modified system, the seabed facility 16
illustrated in FIG. 2 comprises a base structure 17 which supports
a retrievable module 18 that contains the high pressure pump 10.
The pump inlet 9 is connected to the injection water supply
pipeline 6 from the host facility 2 by a multi-ported fluid
connector 19 such as that described in GB-A-2261271 and the pump
outlet 12 is connected by the conduit 11 to the well supply
flowlines 8 via the same multi-ported fluid connector 19. This
connector 19 enables the module 18 to be isolated from the pipeline
6 and flowlines 8 connected to the base structure 17 when the
module 18 is to be retrieved.
[0031] In addition, the module 18 has a power and control pod 20
which is connected to the power and controls umbilical 13 by a
connector 21 whereby the pod 20 directs power and provides control
signals to equipment within the module 18. In particular, the pod
20 controls the high pressure pump 10 but it may be overridden by
control signals received from the host facility 2 via the umbilical
13. The pod 20 also drives the pump 10 with power received from the
host facility 2 via the umbilical 13.
[0032] In use, water from the host facility 2 is received by the
high pressure pump 10 in the module 18 via the fluid connector 19
and pressure boosted water is pumped out of the module 18 via the
fluid connector 19 and manifold conduit 11 and into the hydrocarbon
reservoir via the well supply flowlines 8 and water injection wells
7.
[0033] Whilst particular embodiments have been described, it will
be understood that various modifications may be made without
departing from the scope of the invention. For example, the pump 4
at the host facility 2 may not be required if the injection water
can flow to the remote facility 5 under the action of gravity
alone. The power and control pod 20 in the retrievable module 18 is
also optional, as power and control could be provided/controlled
externally of the module. The pipeline and flowlines described may
be of rigid or flexible construction.
[0034] Although the invention has been described in the context of
a subsea hydrocarbon field, it would also be applicable to other
areas such as swamps whereby the system including the pump 10
remote from the host facility 2, would be land based.
* * * * *