U.S. patent application number 10/492704 was filed with the patent office on 2005-01-13 for installation for the separation of fluids.
Invention is credited to Gramme, Per Eivind.
Application Number | 20050006086 10/492704 |
Document ID | / |
Family ID | 19912925 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050006086 |
Kind Code |
A1 |
Gramme, Per Eivind |
January 13, 2005 |
Installation for the separation of fluids
Abstract
An installation arranged on the sea bed for the separation of
fluids, comprising at least one separator (1) that is connected to
one or more wells, each via an associated well head (2) or similar,
and a pipeline (17). The components separated, oil, gas, water or
combinations of these substances, are fed fully or partially from
the installation to a platform, vessel, etc. on the surface or via
collecting pipelines onto shore, or are reinjected into the
formation beneath the sea bed. Each separator (1) consists of a
long pipe (pipe separator) that may form a major or minor part of
the transport pipeline (18) from the well and has a diameter that
is mainly equal to or slightly larger than the diameter of the
transport pipeline (18).
Inventors: |
Gramme, Per Eivind;
(Porsgrunn, NO) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
19912925 |
Appl. No.: |
10/492704 |
Filed: |
August 19, 2004 |
PCT Filed: |
October 14, 2002 |
PCT NO: |
PCT/NO02/00370 |
Current U.S.
Class: |
166/105.5 |
Current CPC
Class: |
B01D 17/0208 20130101;
B01D 17/06 20130101; B01D 17/044 20130101; B01D 19/0068 20130101;
E21B 43/36 20130101; B01D 19/00 20130101; B01D 17/045 20130101 |
Class at
Publication: |
166/105.5 |
International
Class: |
E21B 043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 17, 2001 |
NO |
2001 5048 |
Claims
1. An installation arranged on the sea bed for the separation of
fluids, comprising at least one separator (1) that is connected to
one or more wells, each via an associated well head (2) or similar,
and a pipeline, in which the components separated, oil, gas, water
or combinations of these substances, are fed fully or partially
from the installation to a platform, vessel, etc. on the surface or
via collecting pipelines onto shore, or are reinjected into the
formation beneath the sea bed, wherein each separator (1) consists
of a long pipe (pipe separator) that may form a major or minor part
of the transport pipeline (18) from the well and has a diameter
that is mainly equal to or slightly larger than the diameter of the
transport pipeline (18).
2. An installation in accordance with claim 1, wherein a first
separator (1), which is designed to separate gas and liquid, where
the gas separated is fed via a pipeline (3) to the surface/shore,
while the liquid separated is fed to a second pipe separator (8)
for oil and water, after which the oil separated is fed to the
surface/shore via a pump (5) and pipeline (4), while the water
separated is reinjected into the reservoir by means of a pump (7)
via a pipeline (6).
3. An installation in accordance with claim 1, wherein a compact
electrostatic coalescer (9) is arranged between the first and
second pipe separators (1 and 3).
4. An installation in accordance with claim 1, wherein a gas
dehydration unit (11) and a subsequent gas/liquid separator (12)
are arranged at the gas outlet from the first separator (11),
whereby glycol is added via a pipeline (13) to the dehydration unit
(11), while gas separated is fed from the separator (12) to the
surface via a pipeline (14) and glycol separated is fed to the
surface by means of a pump (16) via a pipeline (15).
5. An installation in accordance with claim 2, wherein a compact
electrostatic coalescer (9) is arranged between the first and
second pipe separators (1 and 3).
6. An installation in accordance with claim 2, wherein a gas
dehydration unit (11) and a subsequent gas/liquid separator (12)
are arranged at the gas outlet from the first separator (11),
whereby glycol is added via a pipeline (13) to the dehydration unit
(11), while gas separated is fed from the separator (12) to the
surface via a pipeline (14) and glycol separated is fed to the
surface by means of a pump (16) via a pipeline (15).
7. An installation in accordance with claim 3, wherein a gas
dehydration unit (11) and a subsequent gas/liquid separator (12)
are arranged at the gas outlet from the first separator (11),
whereby glycol is added via a pipeline (13) to the dehydration unit
(11), while gas separated is fed from the separator (12) to the
surface via a pipeline (14) and glycol separated is fed to the
surface by means of a pump (16) via a pipeline (15).
Description
[0001] The present invention concerns an installation arranged on
the sea bed for the separation of fluids.
[0002] Fluids in this context means oil, gas and water or mixtures
of these substances, possibly containing particles of sand, that
are produced in connection with the extraction of oil/gas from
wells in geological formations beneath the sea bed.
[0003] PCT/NO98/00085 concerns the separation of fluids in pipe
separators in horizontal sections of wells.
[0004] The main reason why it is possible to achieve quantitative
oil and water separation in a pipe separator installed in a
horizontal well is related to the good separation properties of the
well fluid. The main reason for the good separation properties in
the well is that the interface between the oil and water is
relatively free of surfactants that can stabilise the interface and
thus impede drop growth and the formation of a free aqueous phase
in connection with coalescence. This is what makes it possible to
use such separation solutions in the well, where controlled use of
a de-emulsifier is very complicated or virtually impossible.
[0005] In many cases, it may be desirable to carry out the
separation on the sea bed instead of in the wells. On the sea bed,
chemical destabilisation of the crude oil using a de-emulsifier is
a much simpler and absolutely realistic solution. Chemical
destabilisation of the fluid can improve the separation properties
of the fluid so that they are almost as good as down-hole
conditions. This makes it possible to use pipe separator technology
on the sea bed in connection with sea bed processing plants. With a
sea bed installation, there is also greater freedom with regard to
the choice of separator diameter than with a down-hole
installation.
[0006] Conventional gravitation separators are characterised by
large tank diameters. This limits the application of the technology
to relatively shallow waters. Long, thin separators with high UD
ratios are favourable for use at large sea depths.
[0007] Under typical sea bed conditions, the separation properties
of the oil/water fluid will always be poorer than under down-hole
conditions. This difference can be compensated for by placing the
separator upstream of the choke when using a de-emulsifier or
ultrasound. This makes it possible to use pipe separators on the
sea bed. In practice, the pipe separator can be a transport
pipeline designed with a slightly larger diameter than necessary or
as an extended section of the transport pipeline. The pipe
separator is an effective solution to the design problem caused by
high external liquid pressure at large sea depths. The technology
can be combined with CEC (Compact Electrostatic Coalescer) concepts
based on pipe coalescers, which allows it to be used at larger sea
depths. For fluids that are more difficult to separate, a CEC is
necessary to achieve the product specifications of the oil phase
and to eliminate downstream hydrate precipitation problems in this
flow.
[0008] The advantages of using a pipe separator in a sea bed
processing plant are, among other things, that it allows:
[0009] bulk gas/oil/water separation
[0010] removal of water from crude oil to product
specifications
[0011] purification of production water to a quality that allows
reinjection
[0012] purification of production water to a quality that allows it
to be discharged
[0013] chemical-free hydrate control in connection with the
transport of crude oil and gas.
[0014] In the main, the pipe separator produces bulk oil/water
separation. For lighter, simpler crude oil systems, the separator
will be able to separate the fluid down to product specifications.
In this case, no further separation unit is required in the
process. The pipe separator is designed as follows. The last part
of the transport pipeline from the well head to the processing
template is designed as a long, thin pipe separator. On account of
its small pipe diameter (in the order of 0.5 m), the separator can
be operated at high external pressure and low internal pressure.
The separator is therefore particularly well suited for large sea
depths. It is important for the water quality from the separator to
be as good as possible in order to avoid, as far as possible, any
further purification before injection/discharge. The separator can
therefore be fitted with a mechanical ultrasound-based emulsion
destabilisation system instead of using a chemical de-emulsifier.
This solution will be able to produce a water quality that is
suitable for reinjection (<<1000 ppm) and possibly for
discharge into the sea (<40 ppm). A particularly favourable
position for the pipe separator will be at the well head before any
pressure relief.
[0015] The separator is designed as a three-phase separator with
configuration options that allow for separate removal of gas, oil
and water or, alternatively, gas/oil as a common flow and water as
a separate flow. In addition, it must also be possible to design
the separator as a two-phase oil/water separator for use downstream
from a CEC (Compact Electrostatic Coalescer).
[0016] The separator can be fitted with an ultrasound-based
destabilisation system for the emulsion layer at the oil/water
interface (as an alternative to the use of chemicals to break up
emulsions). The separator is also fitted with a double set of level
profile meters (alternatives: gamma, capacitance and ultrasound).
The end of the pipe separator is connected to the template either
directly or via flexible hoses.
[0017] The present invention will be described in further detail in
the following by means of examples and figures, where:
[0018] FIG. 1 shows an installation on the sea bed with a pipe
separator for gas/liquid separation.
[0019] FIG. 2 shows a first alternative embodiment of an
installation with a pipe separator for gas/oil/water
separation.
[0020] FIG. 3 shows a second alternative embodiment of an
installation with two pipe separators in series, the first for
gas/liquid separation and the second for oil/water separation.
[0021] FIG. 4 shows a third alternative embodiment of an
installation with a pipe separator for gas/oil/water separation
followed by a compact electrostatic coalescer and subsequently a
pipe separator for oil/water separation.
[0022] FIG. 5 shows a fourth alternative installation with a pipe
separator for gas/oil/water separation followed by a compact
electrostatic coalescer and subsequently a pipe separator for
oil/water separation. In addition, there is a gas dehydration unit
consisting of a pipe contactor and a gas/liquid separator in
connection with the first pipe separator.
[0023] FIG. 6 shows a fifth embodiment which is based on the
solution shown in FIG. 4, but which is adapted for situations in
which two or more wells produce different quantities of
oil/water/gas.
[0024] FIG. 1 shows an installation arranged on the sea bed with a
separator in the form of a pipe (pipe separator) 1 for gas/liquid
separation that is connected to a well head 2. This is a simple
solution designed for use for oil/gas wells in which small
quantities of water are produced. The separated gas is removed in a
pipe 3 and fed up to a platform, a production ship, etc. on the
surface of the sea or a collecting pipeline that feeds the gas onto
shore. The liquid is removed in a pipe 4, and a pump 5 pumps it up
to the surface or onto shore as for the gas.
[0025] FIG. 2 shows a similar installation to that in FIG. 1.
However, in addition to gas and oil, the separator here also
separates out water that is fed via a pipe 6 to a pump 7 and back
to the reservoir.
[0026] FIG. 3 shows a sea bed installation designed for conditions
with a lot of gas in relation to liquid. The solution is like that
in FIG. 1 but the liquid (oil and water) that is separated out in a
first separator 1 is fed to a second separator 8 where the oil is
fed to the surface via the pipe 4 and the pump 5, while the water
is reinjected by means of the pump 7 via the pipe 6.
[0027] FIG. 4 shows a sea bed processing plant designed for heavier
oils and represents a further development of the installation shown
in FIG. 3. The pipe separator 1, which, in this case, is designed
for gas/oil/water separation, is connected to the well head 2. The
gas is removed in the pipe 3 and fed to the surface. The oil and
water proceed to a compact electrostatic coalescer (CEC) 9 that
increases the drop size of the water. The oil and water are then
separated in a second pipe separator 8 for oil/water separation.
The oil is removed in the pipe 4 and pumped to the surface by the
oil pump 5, while the water is reinjected via the pipe 6 and the
reinjection pump 7.
[0028] FIG. 5 shows a sea bed installation that, in addition to
that which is shown in FIG. 4, has a gas dehydration unit. The gas
that is separated out in the first separator 1 is fed first to a
gas dehydration reactor 11. Here, glycol is added that "reacts
with" the water in the gas. The gas and the liquid (water dissolved
in glycol) are then fed to a third separator 12, which, in turn,
separates out the gas, which is fed to the surface via a pipe 14,
while the liquid is fed to a pump 16 and on to the surface.
[0029] FIG. 6 shows an example based on the solution shown in FIG.
4, but which is adapted for a situation in which different
quantities of oil, gas and water are produced in different ratios
from two or more wells. From well 2, oil/gas/water are separated in
a first separator 1 and oil/water in a second separator 12 with an
intermediate coalescer 9, as explained previously.
[0030] Down-hole separation takes place in a second well 20. Water
separated out from the first separator 2, the second separator 12
and the down-hole separator 18 is fed via respective pipes 21, 22,
23 to a buffer tank 18 for reinjection water. The water in the tank
18 is reinjected into the reservoir by means of a pump 19 via the
pipe/well 6.
[0031] The present invention, as it is shown and described in the
present application, offers several advantages:
[0032] 1. The pipe separator tolerates high internal and external
pressure and therefore allows the following processing tasks to
take place at large sea depths:
[0033] Bulk gas/oil/water or oil/water separation.
[0034] Removal of water from crude oil to product
specifications.
[0035] A pipe separator in combination with a Compact Electrostatic
Coalescer (Kvaerner technology).
[0036] A pipe separator in combination with a Pect C Coalescer
(Cyclotech technology).
[0037] Gas dehydration by means of a combination of gas dehydration
technology (Minox technology) and a pipe separator.
[0038] 2. It produces a quality of aqueous phase that allows
reinjection.
[0039] 3. Low water content in the oil and gas flows, thus allowing
chemical-free hydrate control in connection with transport to
downstream installations.
[0040] 4. The pipe separator tolerates a high internal process
pressure and can therefore be installed to advantage upstream of a
choke valve on the well head. The high process pressure will
improve the phase separation properties and allow reduced use of
de-emulsifier or chemical-free separation, depending on the fluid
properties.
[0041] 5. For fields with acid oil and the potential for calcium
naphthenate precipitation, sea bed processing with removal of water
to 0.5%, performed at a high system pressure (i.e. lower pH in the
aqueous phase on account of more CO in the aqueous phase), will
eliminate problematic precipitation of calcium naphthenate or
expensive topside installations designed to handle calcium
naphthenate precipitation.
* * * * *