U.S. patent application number 14/895580 was filed with the patent office on 2016-05-12 for subsea production cooler.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Gregory John HATTON, Claud Eugene LACY, Howard Steven LITTELL, Andrew ONSTAD, John Lucas PEARSON, Scott Edward STOMIEROWSKI, George John ZABARAS.
Application Number | 20160130913 14/895580 |
Document ID | / |
Family ID | 52008557 |
Filed Date | 2016-05-12 |
United States Patent
Application |
20160130913 |
Kind Code |
A1 |
HATTON; Gregory John ; et
al. |
May 12, 2016 |
SUBSEA PRODUCTION COOLER
Abstract
A subsea production cooler module comprising: a core; a coiled
tubing disposed around the core, wherein the coiled tubing
comprises an inlet and an outlet; and a shroud at least partially
encasing the core and the coiled tubing.
Inventors: |
HATTON; Gregory John;
(Houston, TX) ; LACY; Claud Eugene; (Sugar Land,
TX) ; LITTELL; Howard Steven; (Houston, TX) ;
ONSTAD; Andrew; (New Orleans, LA) ; PEARSON; John
Lucas; (Katy, TX) ; STOMIEROWSKI; Scott Edward;
(Fulshear, TX) ; ZABARAS; George John; (Houston,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
52008557 |
Appl. No.: |
14/895580 |
Filed: |
June 4, 2014 |
PCT Filed: |
June 4, 2014 |
PCT NO: |
PCT/US2014/040864 |
371 Date: |
December 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61831880 |
Jun 6, 2013 |
|
|
|
Current U.S.
Class: |
166/302 ;
166/57 |
Current CPC
Class: |
Y02E 60/14 20130101;
F28D 7/022 20130101; Y02E 60/142 20130101; E21B 47/001 20200501;
F28D 7/024 20130101; F28D 20/00 20130101; E21B 36/001 20130101 |
International
Class: |
E21B 36/00 20060101
E21B036/00 |
Claims
1. A subsea production cooler module comprising: a core; a coiled
tubing disposed around the core, wherein the coiled tubing
comprises an inlet and an outlet; and a shroud at least partially
encasing the core and the coiled tubing.
2. The subsea production cooler module of claim 1, further
comprising a control valve at the top of the shroud capable of
regulating the flow of fluid through the shroud.
3. The subsea production cooler module of claim 1, wherein the core
and the shroud are insulated.
4. The subsea production cooler module of claim 1, wherein the
shroud comprises a conical roof.
5. The subsea production cooler module of claim 1, wherein the
coiled tubing comprises an inner coating and an outer coating.
6. The subsea production cooler module of claim 1, wherein the
coiled tubing comprises multiple coils of tubing in close proximity
to each other.
7. The subsea production cooler module of claim 1, wherein the
coiled tubing comprises an inner coil and an outer coil spiraled
around the core in opposite directions.
8. The subsea production cooler module of claim 1, further
comprising a thermal reservoir disposed in a cavity defined by the
coiled tubing.
9. The subsea production cooler module of claim 1, further
comprising a cooling fluid chiller disposed about a top portion of
the core.
10. The subsea production cooler module of claim 9, wherein the
fluid chiller comprises a chiller tubing and a chiller shroud
11. The subsea production cooler module of claim 1, wherein the
shroud is removable.
12. A subsea production cooler comprising: a subsea production
cooler module; wherein the subsea production cooler module
comprises: a core; a coiled tubing disposed around the core,
wherein the coiled tubing comprises an inlet and an outlet; and a
shroud at least partially encasing the core and the coiled tubing;
a base; and a piping system.
13. The subsea production cooler of claim 12, wherein the subsea
production cooler comprises multiple subsea production cooler
modules arranged in series.
14. The subsea production cooler of claim 12, wherein the subsea
production cooler comprises multiple subsea production cooler
modules arranged in parallel.
15. The subsea production cooler module of claim 12, wherein the
piping system comprises a separator comprising a hot production
line, a hot liquid line, and a hot gas line comprising a flow
control valve.
16. A method of cooling a subsea production stream, the method
comprising: providing a subsea production stream and cooling the
subsea production stream with a subsea production cooler module,
wherein the subsea production cooler module comprises: a core; a
coiled tubing disposed around the core, wherein the coiled tubing
comprises an inlet and an outlet; and a shroud at least partially
encasing the core and the coiled tubing.
17. The method of claim 16, wherein cooling the subsea production
stream with the subsea production cooler module comprises:
separating the subsea production stream into a hot liquid stream
and a hot gas stream; cooling the hot liquid stream with the subsea
production cooler module thereby forming a cooled liquid stream;
and combining the cooled liquid stream and the hot gas stream to
form a cooled subsea production stream.
18. The method of claim 16, wherein cooling the subsea production
stream with the subsea production cooler comprises flowing the
production stream upward through the coiled tubing.
19. The method of claim 18, wherein cooling the subsea production
stream with the subsea production cooler further comprises allowing
cooling fluid to naturally convect within the shroud.
20. The method of claim 19, wherein cooling the subsea production
stream with a subsea production cooler is performed without pumping
the subsea production stream or the cooling fluid.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/831,880, filed Jun. 6, 2013, which is
incorporated herein by reference.
BACKGROUND
[0002] The present disclosure relates generally to subsea
production coolers. More specifically, in certain embodiments the
present disclosure relates to subsea production coolers that
utilize natural convection and associated methods.
[0003] Crude oil and other fluids produced from production wells
are sometimes produced at temperatures too high for handling by
available subsea hardware, for example at temperatures at or above
400.degree. F. These high temperatures may create a thermal strain
on hardware on the seafloor and often may require additional
cooling of the fluid on the topsides. As a result, it is desirable
to cool these fluids to temperatures in the range of 180.degree. F.
to 300.degree. F. before they are transported along or from the
seafloor.
[0004] Conventional subsea cooling techniques utilize un-insulated
production piping arranged in sets of hairpin turns or other
configurations such as a pyramid convecting freely to the
surroundings. Typically, these conventional subsea cooling
techniques have very limited ability to adapt to changing flow
rates or temperatures of the produced fluids. This may result in
excessive cooling, which may be problematic in fluids that are not
fully inhibited against hydrate blockage by chemicals.
[0005] It is desirable to develop a method of subsea cooling that
provides a means of reliable cooling with an ability to adapt to
changing flow rates and temperatures. It is also desirable to
develop a method of subsea cooling that uses sea water at
40.degree. F., with consideration given to excessive cooling and
unacceptably cold piping surface temperatures.
SUMMARY
[0006] The present disclosure relates generally to subsea
production coolers. More specifically, in certain embodiments the
present disclosure relates to subsea production coolers that
utilize natural convection and associated methods.
[0007] In one embodiment, the present disclosure provides a subsea
production cooler module comprising: a core; a coiled tubing
disposed around the core, wherein the coiled tubing comprises an
inlet and an outlet; and a shroud at least partially encasing the
core and the coiled tubing.
[0008] In another embodiment, the present disclosure provides a
subsea production cooler comprising: a subsea production cooler
module comprising: a core; a coiled tubing disposed around the
core, wherein the coiled tubing comprises an inlet and an outlet;
and a shroud at least partially encasing the core and the coiled
tubing; a base; and a piping system.
[0009] In another embodiment, the present disclosure provides a
method of cooling a subsea production stream comprising: providing
a subsea production stream and cooling the subsea production stream
with a subsea production cooler module, wherein the subsea
production cooler module comprises: a core; a coiled tubing
disposed around the core, wherein the coiled tubing comprises an
inlet and an outlet; and a shroud at least partially encasing the
core and the coiled tubing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A more complete and thorough understanding of the present
embodiments and advantages thereof may be acquired by referring to
the following description taken in conjunction with the
accompanying drawings.
[0011] FIGS. 1A and 1B are illustrations of a subsea production
cooler module in accordance with certain embodiments of the present
disclosure.
[0012] FIG. 2 is an illustration of a subsea production cooler
module in accordance with certain embodiments of the present
disclosure.
[0013] FIG. 3 is an illustration of a subsea production cooler
module in accordance with certain embodiments of the present
disclosure.
[0014] FIG. 4 is an illustration of a subsea production cooler in
accordance with certain embodiments of the present disclosure.
[0015] The features and advantages of the present disclosure will
be readily apparent to those skilled in the art. While numerous
changes may be made by those skilled in the art, such changes are
within the spirit of the disclosure.
DETAILED DESCRIPTION
[0016] The description that follows includes exemplary apparatuses,
methods, techniques, and instruction sequences that embody
techniques of the inventive subject matter. However, it is
understood that the described embodiments may be practiced without
these specific details.
[0017] In certain embodiments, the present disclosure relates to
techniques for cooling production fluids produced from subsea
wells. Such cooling may involve utilizing natural convection. In
certain embodiments, the cooling may be accomplished without using
pumps to circulate the production fluids or cooling fluid within
the subsea production coolers.
[0018] Produced fluid exiting a wellhead on an ocean floor may flow
through a series of coils in a production cooler where it is cooled
by cold sea water or other cooling fluid. The cold sea water or
other cooling fluid may be heated by the coils, become less dense,
and rise away from the coils due to natural convection. As the
heated sea water or other cooling fluid rises away it may be
replaced by colder, denser seawater from the surrounding area in a
continuous flow or by cooled cooling fluid. Because the flow of the
produced fluid through the coils may be due to well pressure and
the flow of seawater or other cooling fluid may be driven by
buoyancy, in certain embodiments the pumping of fluids is not be
required.
[0019] Some desirable attributes of the subsea production coolers
discussed herein may include: predictable performance for both
design and operational monitoring; the ability to adjust heat
transfer to maintain desired outlet temperature; the ability to
tolerate changes in production flow rate and maintain desired
outlet temperature; a cool down time similar to the insulated
flowline system; robust piping capable of withstanding multiphase
flow; functionality to distribute multiphase flow and produce even
cooling; by-passable; minimization of both internal and external
fouling; the ability to maintain interior wall temperature greater
than the wax deposition temperature (e.g. 110.degree. F. at all
times); the ability to maintain exterior wall temperature less than
the seawater scale formation temperature (e.g. 130.degree. F. at
all times); the ability to allow sea water side cleaning by
remotely operated vehicles, and the ability to control circulation
of the sea water to meeting cooling demand.
[0020] Referring now to FIG. 1, FIG. 1 illustrates a subsea
production cooler module 101 in accordance with certain embodiments
of the present disclosure. In certain embodiments, subsea
production cooler module 101 may comprise a core 110, coiled tubing
120, shroud 130, and a control valve 140.
[0021] In certain embodiments, core 110 may generally have a
cylindrical shape. Core 110 may be sized to efficiently cool a
variety of production temperatures and flow rates. In certain
embodiments, core 110 may be from 3 feet to 15 feet in diameter
and/or from 10 feet to about 100 feet in height. Core 110 may be
constructed out of any material suitable for in a deepwater
environment. Examples of suitable materials include steel, glass
reinforced plastic, and/or a variety of composite materials. In
certain embodiments, an outside surface 111 of core 110 may
comprise a coating 112. Examples of suitable coating materials
include solid glass reinforced plastics, epoxy coatings,
specialized paints, and insulating materials. Coating 112 may be
structural, semi-structural, or non-structural in order to achieve
a desired shape, geometry, or surface characteristic. In certain
embodiments, the thickness of coating 112 may be determined by its
desired properties. In certain embodiments, coating 112 may be from
about 0.005 inches thick to 0.020 inches thick. In other
embodiments, coating 112 may be from about from 0.1 inches thick to
0.4 inches thick. In other embodiments, coating 112 may be from
0.02 inches thick to 0.05 inches thick. In certain embodiments,
coating 112 may prevent the warmed cooling fluid retained in subsea
production cooler module 101 from rapidly cooling during unexpected
shutdowns. In certain embodiments, core 110 may have a hollow
center. In other embodiments, the subsea production cooler module
101 may have no core.
[0022] In certain embodiments, coiled tubing 120 may comprise any
suitable tubing material in a coil formation. In certain
embodiments, coiled tubing 120 may comprise a single coil of tubing
or multiple coils of tubing. For example, coiled tubing 120 may
comprise one, two, three, four, or five or more individual coils of
tubing. In certain embodiments, each individual coil of tubing may
have its own inlet and outlet. When subsea production cooler module
101 comprises a core 110, coiled tubing 120 may be coiled around
core 110. In embodiments where subsea production cooler module 101
does not comprise a core 110, coiled tubing 120 may define a
cavity.
[0023] In certain embodiments, coiled tubing 120 may have a coil
geometry comprising one or more inner coils and one or more outer
coils. In certain embodiments, the one or more inner coils may be
disposed around core 110 and the one or more outer coils may be
disposed around the one or more inner coils. In certain
embodiments, the inner and outer coils may be spiraled in the same
direction. In other embodiments, the inner and outer coils may be
spiraled in opposite directions. In embodiments where the inner and
outer coils are spiraled in opposite directions, torsion present in
the inner and out outer coil in coiled tubing 120 may be arranged
to balance each other, which may in turn decrease the overall
structural strength required to manage the force and movement of
coiled tubing 120 under production pressures and temperatures.
[0024] In certain embodiments, the geometry of coiled tubing 120
may maximize the beneficial effect of creating flow through two
independent, but complimentary effects. First, by having multiple
individual coils of tubing transferring heat to the same fluid
multiplies the temperature rise and the subsequent coolant buoyancy
that creates the natural convection heat transfer. Second, by
placing the coils in close proximity to each other and the surfaces
of core 110 and/or shroud 130, there may be an additional
enhancement of heat transfer at certain operating conditions due to
fluid flow effects. For example, in certain embodiments, the coils
may be spaced about core 110 such that the distance between the
center of coiled tubing 120 in each coil is from 1.5 to 2 times the
diameter of coiled tubing 120.
[0025] In certain embodiments, the geometry of coiled tubing 120
may allow the avoidance of sudden turns that occur in standard
elbows or hairpin turns, reducing the localized accumulation of
solids on the interior wall of coiled tubing 120 through enhanced
deposition that is believed to be due to low velocity areas created
in the fluid stream by the turning actions and the cold spots that
can occur due to the non-uniform flow field.
[0026] Coiled tubing 120 may be constructed out of any suitable
tubing material. Examples of suitable tubing materials comprise
carbon steel, stainless steel, titanium, nickel alloys, and
composite materials. In certain embodiments, the composite
materials may comprise different materials arranged to give certain
beneficial properties to the surfaces of the coil 120 that may be
different than the properties of the bulk of the tube wall. In
certain embodiments, coiled tubing 120 may comprise an inner
diameter of from one inch to six inches.
[0027] In certain embodiments, an inner surface 121 of coiled
tubing 120 may comprise an inner coating 122. Inner surface 121 may
be completely or partially coated with inner coating 122. In
certain embodiments, inner coating 122 may comprise ceramic enamel
or a diamond-like coating. In certain embodiments, inner coating
122 may be from 2 to 30 microns thick. In other embodiments, inner
coating 122 may be from 5 to 10 microns thick.
[0028] In certain embodiments, an outer surface 123 of coiled
tubing 120 may comprise an outer coating 124. Outer surface 123 may
be completely or partially coated with outer coating 124. In
certain embodiments, outer coating 124 may comprise ceramic enamel,
ethylene copolymer such as Halar, a thermoset polymer, a
diamond-like coating, or a phenolic coating. In certain
embodiments, outer 124 coating may be from 2 microns thick to 400
microns thick. In other embodiments, outer coating 124 may be from
10 microns thick to 50 microns thick.
[0029] The selection of material and thickness for coiling tubing
120 may be critical in controlling the surface temperatures both on
the inside and the outside of coiled tubing 120. In certain
embodiments, it may be desirable to keep the coil surface
temperatures in safe limits by designing the appropriate fluid
velocities and heat transfer coefficients. In certain embodiments,
the temperature of inner surface 121 or inner coating 122 of coiled
tubing 120, as appropriate, should be maintained above a minimum
value because of the concern of wax deposits. In certain
embodiments, the temperature of inner surface 121 or inner coating
122 of coiled tubing 120 should be maintained at a temperature
greater than 110.degree. F. In certain embodiments, the temperature
of outer surface 123 or outer coating 124 of coiled tubing 120, as
appropriate, should be maintained below a maximum value because of
concerns with corrosion and sea water scaling. In certain
embodiments, the temperature of outer surface 123 or outer coating
124 of coiled tubing 120, as appropriate, should be maintained at a
temperature less than 150.degree. F. In other embodiments, the
temperature of outer surface 123 or outer coating 124 of coiled
tubing 120, as appropriate, should be maintained at a temperature
less than 130.degree. F.
[0030] In certain embodiments, coiled tubing 120 may comprise an
inlet 125 and an outlet 126. In certain embodiments, inlet 125 may
be located near the bottom of core 110 and outlet 126 may be
located near the top of core 110. Inlet 125 may be connected to a
hot production fluid line 127. Outlet 126 may be connected to a
vertical discharge line 128. In certain embodiments, hot production
fluid line 127 and/or vertical discharge line 128 may disposed
within a hollow center of core 110. In other embodiments, hot
production fluid line 127 and/or vertical discharge line 128 may be
disposed within the cavity defined by coiled tubing 120. In other
embodiments, hot production fluid line 127 and/or vertical
discharge line 128 may be disposed on an outside surface 111 of
core 110.
[0031] In certain embodiments, coiled tubing 120 may comprise one
or more bypass lines 129 allowing the fluid to short circuit the
production fluid path to the outlet 126, and allow production fluid
to flow into the vertical discharge line 128. In certain
embodiments, bypass line 129 may have a valve 160 installed to
manage the volume of flow directed through bypass line 129.
[0032] During operation, a production fluid may flow into the
subsea production cooler module 101 through hot production fluid
line 127, through the coiled tubing 120 where it is cooled, and out
of the subsea production cooler module 101 through vertical
discharge line 128. The flowrate of the production fluid entering
the subsea production cooler module 101 may be determined by the
particular production well supplying the production fluid to subsea
production cooler module 101. This flowrate vary considerably,
particularly during conditions when the production well is brought
back online after being shut off.
[0033] The production rates that the subsea production cooler
module 101 may efficiently cool to desired outlet temperatures may
be in the range from 2000 barrels/day to 50,000 barrels/day. Any
number of combinations of flowrate, pressure, temperature, fluid
thermodynamic state, and compositional details may exist at the
inlet 125 and outlet 126 of subsea production cooler module 101.
This possible variation of many operating parameters is well known
to those skilled in the art. In certain embodiments, the production
fluid entering the subsea production cooler may be at a temperature
of from 250.degree. F. to 450.degree. F. In certain embodiments,
production fluid leaving the subsea production cooler module may at
a temperature of from 150.degree. F. to 250.degree. F.
[0034] In certain embodiments, the production fluid may flow upward
through the coiled tubing 120 while it is cooled. Although this
upward flow may be atypical, it is believed that this upward flow
may be advantageous, particularly when the production fluid is a
multiphase fluid. By directing the flow upward, a multiphase flow
regime will tend towards slugging flow, which will continually move
the gas along and intermittently wet inner surface 121 of coiled
tubing 120. This may help eliminate cold spots on inner surface 121
of coiled tubing 120 which could become nucleation sites for solid
deposits such as paraffins. Also, the inner surface of coiled
tubing 120 may warmed by the liquid flow allowing for a more
uniform and efficient heat transfer. One or more valves 160 may
regulate the flow of production fluids through the hot production
fluid line 127 and the vertical discharge line 128.
[0035] In certain embodiments, shroud 130 may be disposed around
core 110 and coiled tubing 120. In certain embodiments, shroud 130
may be a hollow structure with generally cylindrical shape. Shroud
130 may be constructed out of any material suitable for in a
deepwater environment. Examples of suitable materials include
steel, glass reinforced plastic, and various composite materials.
In certain embodiments, shroud 130 may comprise a coating 135. In
certain embodiments, coating 135 may comprise a solid glass
reinforced plastic, epoxy coatings, specialized paints, and a range
of insulating materials. Coating 135 may be structural,
semi-structural, or non-structural to achieve a desired shape,
geometry, or surface characteristic. In certain embodiments, the
shroud 130 may be heavily insulated so that during an unexpected
shutdown, the warmed cooling fluid retained in the subsea
production cooler module 101 will cool slowly to limit the
formation of hydrates in the production fluids.
[0036] In certain embodiments, the thickness of coating 135 may be
determined by its desired properties. In certain embodiments, the
coating may be from about 0.005 inches thick to 0.020 inches thick.
In other embodiments, the coating may be from about from 0.1 inches
thick to 0.4 inches thick. In other embodiments, the coating may be
from 0.02 inches thick to 0.05 inches thick.
[0037] In certain embodiments shroud 130 may be sized to envelope
the coiled tubing 120, with a clearance gap so it does not contact
coiled tubing 120, which may require the shroud internal dimensions
and shape exceed that of coiled tubing 120. In certain embodiments,
shroud 130 may be cylindrical with a diameter of between 3 feet and
15 feet and/or a length of between 10 feet to about 100 feet.
[0038] In certain embodiments, shroud 130 may comprise an inlet 131
and an outlet 132. Inlet 131 may be located at the bottom of shroud
130 and outlet 132 may be located near the top of shroud 130. In
certain embodiments, inlet 131 may have a cross sectional area of
from 10 square feet to 100 square feet. In other embodiments, inlet
131 may have a cross sectional area of from about 20 square feet to
50 square feet. In certain embodiments, outlet 132 may be a single
opening with a cross sectional area of from about 0.25 square feet
to 20 square feet or multiple openings having similar aggregate
cross sectional area. In certain embodiments, sea water or other
cooling fluids may flow into shroud 130 via inlet 131 and flow out
of shroud 130 via outlet 132.
[0039] In certain embodiments, control valve 140 may regulate the
flow of the sea water or other cooling fluid through outlet 132 of
shroud 130. In certain embodiments, the flow of sea water through
shroud 130 may be as low as 50 gallons per minute to as large as
3000 gallons per minute. The setting of control valve 140 may be
adjusted to maintain a given production fluid outlet temperature
set point based upon production flow rate and inlet temperature. By
manipulating control valve 140, an operator, or a control system,
can monitor and adjust the amount of heat being removed from the
production stream to produce a desirable outlet temperature as well
as purposefully halt the main process of heat transfer and retain
the heat of the production stream in the cooler in the event of an
unexpected flow shutdown.
[0040] In certain embodiments, shroud 130 may further comprise one
or more support structures 135. Support structure 135 may be
located on a base 136 of shroud 130. In certain embodiments,
support structure 135 may be porous to allow the flow of cooling
fluid into shroud 130, thus forming the shroud inlet 131. Support
structure 135 may be integral and an extension of the material used
to construct the shroud 130, and may comprise structural beams or
other components that support shroud 130. Support structure 135 may
be a separate component than shroud 130, and may be permanently
attached to shroud 130. Support structure 135 may be constructed of
different materials than shroud 130 and may be designed to provide
a relatively heavy base to aid installation and may provide high
structural integrity at the base of the shroud to ensure its
robustness.
[0041] In certain embodiments, shroud 130 may be removable. In
certain embodiments, shroud 130 may comprise one or more lift
points 137 whose position can be adjusted so that the net lift
force vector passes through the center of gravity. In certain
embodiments, shroud 130 may be lifted upward from its normal
position around core 110 and coiled tubing 120. Once clear of the
core 110, a robotic submarine (a Remotely Operated Vehicle, or ROV)
could inspect and/or test properties of any external fouling
present, and cleaning could be performed, either with tools
attached to the ROV, or by a dedicated semi-automated walking
device similar to a swimming pool cleaner moving on or near the
coils.
[0042] In certain embodiments, shroud 130 may comprise a conical
roof 138. The conical roof 138 may help to deflect falling sediment
from entering the subsea production cooler module 101 during
non-operational periods.
[0043] The basic design of subsea production cooler module 101
creates a large amount of pipe surface that is exposed to cold sea
water or other cooling fluid. By encasing the coiled tubing 120 in
a shroud 130, the velocity at which the natural convection of the
cooling fluid flows around the coiled tubing 120 may be increased,
enhancing the heat transfer abilities of the subsea production
cooler module 101.
[0044] During unplanned shutdowns, control valve 140 may be
completely closed to trap warm sea water or other cooling fluid
within subsea production cooler module 101. The warmest cooling
fluid may rise to the top of subsea production cooler module 101,
potentially exposing the bottom portion of coiled tubing 120 to
excessive cooling. In order to prevent the bottom coils from
excessive cooling, subsea production cooler module 101 may comprise
an electric heater or a thermal reservoir 150, located below the
lowest portion of the coiled tubing 120.
[0045] In certain embodiments, thermal reservoir 150 may comprise a
storage tank 151, an inlet 152, an outlet 153, a valve 154, and
coiled tubing 155. Storage tank 151 may be capable of storing
several hundred gallons of warmed cooling fluid. In certain
embodiments, storage tank 151 may be disposed within a hollow
center of core 110. In certain embodiments, storage tank 151 may be
disposed in a cavity defined by coiled tubing 120. In certain
embodiments, storage tank 151 may be disposed in a cavity defined
by coiled tubing 155. In certain embodiments, coiled tubing 155 may
be coiled around a bottom portion of core 110. Valve 154 may
regulate the flow of warmed cooling fluid through inlet 152, outlet
153, and coils 155. In certain embodiments, coiled tubing 155 may
have the same material construction of coiled tubing 120.
[0046] During shutdowns, valve 154 may be opened to allow the
warmed cooling fluid to flow through inlet 152, outlet 153, and
coils 155. This warmed cooling fluid may heat the cooling fluid in
the bottom portion of the subsea production cooler module 101 and
allow for the heating of the bottom portion of coiled tubing 120.
In certain embodiments, storage tank 151 may comprise an expansion
chamber 156 to allow for the warmed cooling fluid to swell and
shrink, depending on its temperature. During normal operation of
the subsea production cooler module 101, the warmed cooling fluid
in storage tank 151 may be warmed to the outlet temperature of the
production fluid flowing through vertical discharge line 128 by
passage of the discharge line through the storage tank 151,
allowing the contents to be heated by the production fluid until
their respective temperatures are nearly the same.
[0047] In certain embodiments, subsea production module 101 may
comprise a running tool. The running tool may be a
permanently-mounted or removable running tool. In certain
embodiments, the running tool may be attached to shroud 130. The
running tool may allow for a true vertical removal path for shroud
130 so that interference with the core 110 and coiled tubing 120 is
minimized In certain embodiments, one or more centralizers may
ensure that the shroud does not contact coiled tubing 120 during
removal or operation.
[0048] Referring now to FIG. 2, FIG. 2 illustrates a partial solid
model rendering of a subsea production cooler module 201 in
accordance with certain embodiments of the present disclosure.
Similar to subsea production cooler module 101 illustrated in FIG.
1, subsea production cooler module 201 may comprise a core 210,
coiled tubing 220, and a shroud 230. In FIG. 2, coiled tubing 220
is shown to comprise four individual coils of tubing. Hot
production fluid line 227 and vertical discharge line 228 are shown
to be within a hollow center of core 210.
[0049] Referring now to FIG. 3, FIG. 3 illustrates an alternative
concept of a subsea prosecution cooler module 301. While in certain
embodiments subsea production cooler module 301 may share each of
the same features of subsea production cooler modules 101 and 201,
for example, subsea production cooler module 301 may comprise a
core 310, coiled tubing 320 comprising an inlet 325 connected to a
hot production fluid line 327 and outlet 326 connected to a
vertical discharge line 328, one or more valves 360, shroud 330
with an inlet 331 and an outlet 332, and a control valve 340,
several key differences between subsea production cooler module 301
and subsea production cooler modules 101 may exist.
[0050] One difference between subsea production module 301 and
subsea production module 101, is that while the bottom of shroud
130 of subsea production cooler module 101 may be open to seawater,
the bottom portion of shroud 330 is not open to seawater. Rather,
shroud 330 completely encases a bottom portion 315 of core 310
isolating it from contact with the seawater. Instead, inlets 331
and outlet 332 of shroud 330 may be fluidly connected to a cooling
fluid chiller 370.
[0051] In certain embodiments, cooling fluid chiller 370 may
surround a top portion 316 of core 310. In certain embodiments,
cooling fluid chiller 370 may comprise chiller tubing 371 and
chiller shroud 376.
[0052] In certain embodiments, chiller tubing 371 may comprise the
same features of coiled tubing 120. In certain embodiments, chiller
tubing 371 may be coiled around a top portion 316 of core 310. In
certain embodiments, chiller tubing 371 may comprise an inlet 372
and an outlet 373. In certain embodiments, inlet 372 may be
connected to outlet 332 of shroud 330 by means of a warm coolant
line 374. In certain embodiments, outlet 373 may be connected to
inlet 331 of shroud 330 by means of a cold coolant line 375. In
certain embodiments, a coolant expansion chamber 356 may be
connected to the cold coolant line 375.
[0053] In certain embodiments, chiller shroud 376 may be disposed
around top portion 316 of core 310 and chiller tubing 371. In
certain embodiments, chiller shroud 376 may share similar
characteristics of shroud 130. In certain embodiments, a valve 377
may regulate the flow of sea water through inlet 378 and outlet 379
of chiller shroud 376.
[0054] In certain embodiments, chiller shroud 376 may further
comprise one or more support structures 380. Support structure 380
may be located on a base 381 of chiller shroud 376 and attach
chiller shroud 376 to shroud 330. In certain embodiments, support
structure 380 may be porous to allow the flow of cooling fluid into
chiller shroud 376, thus forming the inlet 378. Support structure
380 may share common characteristics with support structures
135.
[0055] During operation, warmed coolant from outlet 332 of shroud
330 may flow upward into chiller tubing 371 of cooling fluid
chiller 370. The warmed coolant may be cooled by surrounding sea
water flowing into the chiller shroud 376 through inlet 378. As the
warmed coolant is cooled, it may flow downward through chiller
tubing 371 where it is further cooled by seawater flowing upward
through chiller shroud 376. The cooled coolant may then exit
cooling fluid chiller 370 via cold coolant line 375 and re-enter
the bottom of shroud 330. One or more valves 360 may regulate the
flow of cooling fluid through the warm coolant line 374 and the
cold coolant line 375 and one or more valves 340 may regulate the
flow of sea water through inlet 378 and outlet 379.
[0056] Referring now to FIG. 4, FIG. 4 illustrates subsea
production cooler 400 comprising subsea production cooler modules
401, base 485, and piping system 490.
[0057] Subsea production cooler modules 401 may comprise any of the
components of subsea production cooler modules discussed
previously.
[0058] Base 485 may be designed to contain piping system 490 and to
provide one or more sites 486 to install the one or more subsea
production cooler modules 401. FIG. 4 illustrates a subsea
production cooler comprising 4 subsea production cooler modules 401
installed on base 485 with 5 sites 486.
[0059] In certain embodiments base 485 may be constructed mainly of
steel, similarly to other subsea equipment such as piping manifold,
subsea pumping systems, etc. The base 485 may be (when viewed from
above) roughly 40 feet wide, 100 feet long, and 20 feet tall. The
base 485 may be set on the seafloor itself using a mudmat. The base
485 may be set onto one or more subsea pilings designed to resist
not only the weight of the base, but also to predictably resist any
moment created by the rather tall subsea production cooler modules
401, or by uneven or imbalanced loading created by various
combinations of filled or empty sites 486. In certain embodiments
sites 486 may comprise a multibore connector. In certain
embodiments, sites 486 may support the forces and moments generated
by the presence of subsea production cooler module 401 via the
multibore connector, or support for the subsea production cooler
may be supported by contact of one or more structural members of
the subsea production cooler resting on the base 485. In certain
embodiments, sites 486 may support the subsea production cooler
module 401 by a combination of the multibore connector and separate
structural members.
[0060] Piping system 490 may comprise a hot multiphase production
line 491, a separator 492, a hot gas line 493, a hot liquid line
494, a cooled liquid line 495, and a cooled multiphase production
line 496. In certain embodiments, separator 492 may comprise an
arrangement of piping components arranged so as to slow the
multiphase mixture and allow gravity separation of liquids and gas,
while simultaneously providing flowpaths for both liquid-rich
streams and gas-rich streams. Separator 492 may separate the fluid
from hot multiphase production line 491 into hot gas line 493 and
hot liquid line 494. At typical operating condition, when entering
separator 492, the temperature of the fluid in hot multiphase
production line 491 may be from 300.degree. F. to 450.degree. F.,
the pressure may be in the range of from 1500 psia to 7000 psia,
and the gas volume fraction may be in the range of from about 0% to
about 80%. The particular operating conditions are dependent on the
producing wells and the manner in which the system is operated, and
can vary considerably, so these parameters are intended only to
illustrate, not to limit the operational envelope of the system
being described.
[0061] When exiting the separator, the fluid in hot liquid line 494
may be mostly liquid with a minor amount of gas. In certain
embodiments, the fluid in hot liquid line 494 may have a gas volume
fraction of from about 0% to about 10% at very nearly the same
pressure and temperature of the fluid in hot multiphase production
line 491. In certain embodiments, the fluid in hot gas line 493 may
be mostly gas with a minor amount of liquid. In certain
embodiments, the fluid in hot gas line 493 may have a gas volume
from of from 90% to about 100% at very nearly the same pressure and
temperature of the fluid in hot multiphase production line 491.
[0062] The flowrate of fluid in hot gas line 493 may controlled by
flow control valve 497, that may simply match, or nearly match, the
pressure drop created by various piping and subsea production
cooler modules 401. Further, in certain embodiments, manipulation
of the temperature of fluid in cooled multiphase production line
496 in relation to the temperature of the fluid in cooled liquid
line 495 may be implemented by flow control valve 497. In certain
embodiments, this control may be utilized to ensure that a certain
thermal mass flowrate exists in hot gas line 493, so that in mixing
with fluid in cool liquid 495, a certain higher temperature is
maintained in cooled multiphase production line 496.
[0063] The fluid in hot liquid line 494 may flow into a single
subsea production cooler module 401 or multiple subsea production
cooler modules 401 arranged in series or in parallel. Cooled liquid
line 495 may be a single stream flowing from a subsea product
production cooler, or multiple streams flowing from multiple
coolers combined. Fluid from cooled liquid line 495 may be combined
with the fluid in hot gas line 493 to form the cooled multiphase
production line 496. The fluid in cooled multiphase production line
496 may be nearly the same gas volume fraction as that in hot
multiphase production line 491, or by effect of the cooling have
attained a gas volume fraction of zero. The temperature of fluid in
cooled multiphase production line 496 may be between 150.degree. F.
and 300.degree. F. The pressure of fluid in cooled multiphase
production line 496 may be near to, but somewhat less than the
pressure in hot multiphase production line 491, or it may be
considerably lower due to pressure drop in separator 492 and subsea
production cooler modules 401.
[0064] In certain embodiments, the subsea production coolers
discussed herein may have a wide range of operating conditions. In
certain embodiments, an operator or a control system can monitor
and adjust the amount of heat being removed to produce a desirable
outlet temperature as well as purposefully halt the main process of
heat transfer and retain the heat of the production in the cooler
in the event of an unexpected flow shutdown. In certain
embodiments, the subsea production coolers discussed herein are
capable of cooling production streams utilizing natural convection
and do not require the pumping of cooling fluids.
[0065] While the embodiments are described with reference to
various implementations and exploitations, it will be understood
that these embodiments are illustrative and that the scope of the
inventive subject matter is not limited to them. Many variations,
modifications, additions and improvements are possible.
[0066] Plural instances may be provided for components, operations
or structures described herein as a single instance. In general,
structures and functionality presented as separate components in
the exemplary configurations may be implemented as a combined
structure or component. Similarly, structures and functionality
presented as a single component may be implemented as separate
components. These and other variations, modifications, additions,
and improvements may fall within the scope of the inventive subject
matter.
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