U.S. patent application number 14/018031 was filed with the patent office on 2014-03-06 for direct steam generation co2 output control.
This patent application is currently assigned to CONOCOPHILLIPS COMPANY. The applicant listed for this patent is CONOCOPHILLIPS COMPANY. Invention is credited to Scott MACADAM, James SEABA.
Application Number | 20140060825 14/018031 |
Document ID | / |
Family ID | 50185817 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140060825 |
Kind Code |
A1 |
MACADAM; Scott ; et
al. |
March 6, 2014 |
DIRECT STEAM GENERATION CO2 OUTPUT CONTROL
Abstract
Methods and systems generate steam and carbon dioxide mixtures
suitable for injection to assist in recovering hydrocarbons from
oil sands based on concentration of the carbon dioxide in the
mixtures as influenced by temperature of water introduced into a
direct steam generator. Increasing temperature of the water to
above 200.degree. C. before introduction into the direct steam
generator may utilize heat from an electrical power generation
unit. Enthalpy of this preheated water impacts amount of fuel
needed to burn in the direct steam generator and hence the
concentration of the carbon dioxide, which may be below 11% by mass
percent of the steam.
Inventors: |
MACADAM; Scott; (Calgary,
CA) ; SEABA; James; (Calgary, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONOCOPHILLIPS COMPANY |
Houston |
TX |
US |
|
|
Assignee: |
CONOCOPHILLIPS COMPANY
Houston
TX
|
Family ID: |
50185817 |
Appl. No.: |
14/018031 |
Filed: |
September 4, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61697026 |
Sep 5, 2012 |
|
|
|
Current U.S.
Class: |
166/272.3 ;
110/203; 122/28; 122/412; 432/29 |
Current CPC
Class: |
F01K 21/04 20130101;
F22D 1/40 20130101; E21B 43/164 20130101; Y02E 20/344 20130101;
E21B 43/2406 20130101; F22B 1/26 20130101; F22D 1/16 20130101; Y02E
20/34 20130101 |
Class at
Publication: |
166/272.3 ;
122/412; 122/28; 432/29; 110/203 |
International
Class: |
F22D 1/40 20060101
F22D001/40; E21B 43/24 20060101 E21B043/24; E21B 43/16 20060101
E21B043/16; F22D 1/16 20060101 F22D001/16 |
Claims
1. A method of generating a mixture of steam and carbon dioxide,
comprising: supplying fuel and oxidant into a direct steam
generator; heating water to above 200.degree. C. for introducing in
liquid phase into the direct steam generator; and combusting the
fuel and oxidant in the direct steam generator as the water that is
preheated is introduced to produce the mixture that includes the
steam and combustion products and that has a carbon dioxide level
in mass percent of the steam below 11 percent.
2. The method according to claim 1, wherein the heating of the
water includes heat exchange with heat from an electrical power
generation unit.
3. The method according to claim 1, wherein the heating of the
water includes heat exchange with fluids recovered from a
hydrocarbon production well and then with heat from an electrical
power generation unit.
4. The method according to claim 1, wherein a portion of the water
is introduced into the direct steam generator at a temperature
below 200.degree. C. in an area of the direct steam generator
upstream from where the water above 200.degree. C. is
introduced.
5. The method according to claim 1, wherein the water is above
250.degree. C. and at a pressure above 6000 kilopascals when
introduced into the direct steam generator.
6. The method according to claim 1, wherein the water is supplied
by recycling condensate of the steam recovered following injection
of the mixture into a formation.
7. The method according to claim 1, further comprising injecting
the mixture into a formation to assist recovery of
hydrocarbons.
8. The method according to claim 1, wherein the fuel includes
hydrocarbons and the carbon dioxide level in mass percent of steam
is below 10 percent.
9. The method according to claim 1, wherein the fuel is natural gas
and the oxidant is oxygen separated from air.
10. The method according to claim 1, wherein the water is
introduced into the direct steam generator at more than 30.degree.
C. below a temperature of the mixture output.
11. The method according to claim 1, wherein the water is between
250.degree. C. and 280.degree. C. when introduced into the direct
steam generator and the mixture is output from the direct steam
generator above 280.degree. C. and at least 6000 kilopascals.
12. A system for generating a mixture of steam and carbon dioxide,
comprising: a device for heating water and configured for
outputting the water in liquid phase at a temperature above
200.degree. C.; and a direct steam generator coupled in fluid
communication with an output of the device for heating the water
and configured to combust fuel and oxidant as the water from the
output of the device is introduced into the direct steam generator
to produce the mixture that includes the steam and combustion
products and has a carbon dioxide level in mass percent of steam
below 11 percent.
13. The system according to claim 12, wherein the device for
heating the water includes a heat exchanger to transfer heat from
an electrical power generation unit.
14. The system according to claim 12, wherein the device for
heating the water includes a first heat exchanger for transferring
heat from fluids recovered from a hydrocarbon production well and a
second heat exchanger for transferring heat from an electrical
power generation unit.
15. The system according to claim 12, further comprising an
injection well in fluid communication with the mixture output from
the direct steam generator.
16. The system according to claim 12, wherein the device for
heating the water is configured to heat the water to between
250.degree. C. and 300.degree. C.
17. The system according to claim 12, wherein the direct steam
generator is operable to provide the carbon dioxide level in mass
percent of steam below 10 percent and combust the fuel that
includes hydrocarbons.
18. The system according to claim 12, wherein the direct steam
generator is coupled to receive a portion of the water at a
temperature below 200.degree. C. in an area of the direct steam
generator upstream from where the water above 200.degree. C. is
introduced.
19. A method of generating a mixture of steam and carbon dioxide,
comprising: combusting fuel and oxidant in a direct steam generator
as water that is heated to above 200.degree. C. and in liquid phase
is introduced into the direct steam generator to produce the
mixture that includes the steam and combustion products and has a
carbon dioxide level in mass percent of steam below 11 percent;
introducing the mixture into a formation; and recovering a
hydrocarbon emulsion containing a condensate of the steam that is
recycled for resupplying of the water heated before entering the
direct steam generator.
20. The method according to claim 19, wherein the introducing of
the mixture into the formation is through a horizontal injection
well above a horizontal production well through which the emulsion
is recovered in a steam assisted gravity drainage process.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a non-provisional application which
claims benefit under 35 USC .sctn.119(e) to U.S. Provisional
Application Ser. No. 61/697,026 filed Sep. 5, 2012, entitled
"DIRECT STEAM GENERATION CO2 OUTPUT CONTROL," which is incorporated
herein in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None.
FIELD OF THE INVENTION
[0003] Embodiments of the invention relate to generating a stream
containing steam and carbon dioxide for injection during steam
assisted hydrocarbon recovery processes.
BACKGROUND OF THE INVENTION
[0004] Steam assisted gravity drainage (SAGD) provides an exemplary
steam assisted recovery process for producing bitumen within oil
sands. During SAGD operations, steam introduced into a reservoir
through a horizontal injector well transfers heat to the bitumen
upon condensation. The bitumen with reduced viscosity due to this
heating drains together with steam condensate and is recovered via
a producer well disposed parallel and beneath the injector
well.
[0005] Steam generation costs limit economic returns of the SAGD.
Relative to boiler or once through steam generation approaches,
direct steam generation may facilitate lowering these costs due to
improvements in efficiency, inherent makeup water replacement and
reduced fouling issues. The direct steam generation operates by
burning a fuel in a combustor and quenching resulting combustion
products with water to produce a mixture of steam and the
combustion products including carbon dioxide for injection.
[0006] The carbon dioxide may benefit the SAGD operations by
lowering the steam to oil ratio. However, desired concentrations of
the carbon dioxide within the steam to achieve such benefits for
any particular SAGD application may not coincide with output from
the direct steam generation. Dilution with pure steam can provide
the desired concentrations but introduces expenses associated with
boilers and steam transport.
[0007] Therefore, a need exists for methods and systems for
generating steam and carbon dioxide mixtures for injection to
assist in recovering hydrocarbons from oil sands.
BRIEF SUMMARY OF THE DISCLOSURE
[0008] In one embodiment, a method of generating a mixture of steam
and carbon dioxide includes supplying fuel and oxidant into a
direct steam generator. The method further includes heating water
to above 200.degree. C. for introducing in liquid phase into the
direct steam generator. Combusting the fuel and oxidant in the
direct steam generator as the water that is preheated is introduced
produces the mixture that includes the steam and combustion
products and that has a carbon dioxide level in mass percent of
steam below 11 percent.
[0009] According to one embodiment, a system for generating a
mixture of steam and carbon dioxide includes a device for heating
water and a direct steam generator coupled in fluid communication
with an output of the device for heating the water. The device for
heating the water outputs the water in liquid phase at a
temperature above 200.degree. C. The direct steam generator
combusts fuel and oxidant as the water from the output of the
device is introduced into the direct steam generator to produce the
mixture that includes the steam and combustion products and has a
carbon dioxide level in mass percent of steam below 11 percent.
[0010] For one embodiment, a method of generating a mixture of
steam and carbon dioxide includes combusting fuel and oxidant in a
direct steam generator as water that is heated to above 200.degree.
C. and in liquid phase is introduced into the direct steam
generator to produce the mixture that includes the steam and
combustion products and has a carbon dioxide level in mass percent
of steam below 11 percent. The method further includes introducing
the mixture into a formation and recovering a hydrocarbon emulsion.
The emulsion contains a condensate of the steam that is recycled
for resupplying of the water heated before entering the direct
steam generator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A more complete understanding of the present invention and
benefits thereof may be acquired by referring to the follow
description taken in conjunction with the accompanying
drawings.
[0012] FIG. 1 is a schematic with a direct steam generator
producing an injection mixture of steam and carbon dioxide at a
concentration controlled by temperature of the water fed to the
generator, according to one embodiment of the invention.
[0013] FIG. 2 is a graph of the temperature of the water fed to the
generator versus the concentration of the carbon dioxide in the
mixture produced by the generator, according to one embodiment of
the invention.
DETAILED DESCRIPTION
[0014] Turning now to the detailed description of the preferred
arrangement or arrangements of the present invention, it should be
understood that the inventive features and concepts may be
manifested in other arrangements and that the scope of the
invention is not limited to the embodiments described or
illustrated. The scope of the invention is intended only to be
limited by the scope of the claims that follow.
[0015] For some embodiments, methods and systems generate steam and
carbon dioxide mixtures suitable for injection to assist in
recovering hydrocarbons from oil sands based on concentration of
the carbon dioxide in the mixtures as influenced by temperature of
water introduced into a direct steam generator. Increasing
temperature of the water to above 200.degree. C. before
introduction into the direct steam generator may utilize heat from
an electrical power generation unit. Enthalpy of this preheated
water impacts amount of fuel needed to burn in the direct steam
generator and hence the concentration of the carbon dioxide, which
may be below 11 percent by mass percent of the steam (i.e., mass of
the carbon dioxide/mass of the carbon dioxide and steam expressed
as a percentage).
[0016] FIG. 1 illustrates a direct steam generator (DSG) 100 that
produces a mixture 101 of steam and carbon dioxide. The steam
generator 100 may integrate with a steam assisted production
process used in connection with an injection well 102 and a
production well 104. An output of the steam generator 100 couples
to the injection well 102 to convey the mixture 101 into a
formation.
[0017] In an exemplary steam assisted production operation, the
injection well 102 and production well 104 each include horizontal
lengths that pass through the formation and may be disposed
parallel to one another with the horizontal length of the injection
well 102 above the production well 104. This configuration of the
injection well 102 and the production well 104 exemplifies a
conventional steam assisted gravity drainage (SAGD) well pair. The
steam in the mixture 101 condenses and transfers heat to
hydrocarbons in the formation that then drain with condensate of
the steam by gravity to the production well 104 for recovery.
[0018] An emulsion 106 of the hydrocarbons and the condensate
recovered from the production well 104 upon separation provides
products and part or all of feed water 108 to the steam generator
100. The water 108 pumped to the steam generator 100 may need
additional treatment if being recycled depending on configuration
of the steam generator 100. In some embodiments, separation of the
emulsion 106 occurs without significant heat loss from the water
108 relative to when recovered from the production well 104.
[0019] For some embodiments, one or more heat exchangers, such as a
first heat exchanger 110, transfers heat to the water 108 from any
components of the emulsion 106 recovered through the production
well 104. The water 108 exits the first heat exchanger 110 through
a heater input conduit 112 coupled to a device, such as a second
heat exchanger 114, for heating the water 108 to a temperature
above 200.degree. C. prior to being introduced into the steam
generator 100.
[0020] Depending on how much heat is lost and/or recovered, initial
temperature of the water 108 upon introduction into the second heat
exchanger 114 thus may range from ambient up to a temperature, such
as 200.degree. C., corresponding to temperature of the emulsion
coming from the production well 104. In some embodiments, the
second heat exchanger 114 transfers heat from an electrical power
generation unit 116 to the water 108 increasing the temperature of
the water 108 to above 200.degree. C. For example, the electrical
power generation unit 116 may utilize a gas turbine burning natural
gas with resulting exhaust used by the second heat exchanger 114
instead of, or in addition to, a second cycle to increase
electricity production.
[0021] The second heat exchanger 114 may not rely only on waste
heat from the electrical power generation unit 116 since the heat
in common practice would otherwise raise steam production for the
second cycle. Increasing size and firing rate of the gas turbine
compensates for the heat removed by the second heat exchanger 114.
However, resulting fuel savings in the steam generator 100
outweighs additional fuel burned in the electrical power generation
unit 116, as shown in Table 1 herein.
[0022] Location of the electrical power generation unit 116 on-site
enables employing the second heat exchanger 114 with the steam
generator 100. With respect to being on-site, the electrical power
generation unit 116 supplies power needs of a facility supporting
the steam assisted production process. Demand for the power comes
from associated equipment including an air separation unit,
evaporator and/or carbon dioxide conditioning/compression
system.
[0023] A heater output conduit 118 conveys the water 108 from the
second heat exchanger 114 for introduction into the steam generator
100 under sufficient pressure to be in liquid phase. In operation,
fuel 120, such as hydrocarbons including natural gas, and an
oxidant 121, such as oxygen separated from air, supplied to the
steam generator 100 combust inside the steam generator 100 as the
water 108 is introduced. The water 108 makes direct quenching
contact with resulting combustion products and is thereby vaporized
into steam. This steam in combination with the combustion products
produces the mixture 101 output from the steam generator 100.
[0024] In some embodiments, a portion of the water 108 (e.g., from
the heater input conduit 112 as shown) enters into the steam
generator 100 at a temperature below 200.degree. C. in an area of
the steam generator 100 upstream from where the water 108 above
200.degree. C. is introduced. The water 108 that is below
200.degree. C. when entering the steam generator 100 may ensure
sufficient cooling in a head of the steam generator 100 where
temperatures may be highest in the steam generator 100. The head
also includes injectors of the fuel 120 and the oxidant 121 and is
most susceptible to thermal damage.
[0025] For some embodiments, the second heat exchanger 114
increases temperature of the water 108 such that the water 108 is
above 250.degree. C., between 250.degree. C. and 300.degree. C., or
between 250.degree. C. and 280.degree. C. and at a pressure above
6000 kilopascals when output from the second heat exchanger 114
and/or introduced into the steam generator 100. Further, the water
108 may enter the steam generator 100 at more than 30.degree. C.
below a temperature of the mixture 101 output. For example, the
mixture 101 may exit from the steam generator 100 above 280.degree.
C. and at least 6000 kilopascals for introduction into the
formation through the injection well 102.
[0026] FIG. 2 shows a graph with a line plotting the temperature of
the water 108 fed to the steam generator 100 versus the
concentration of the carbon dioxide in the mixture 101 produced by
the steam generator 100. Depending on the temperature of the water
108, the mixture may thus contain a carbon dioxide level in mass
percent of the steam below 11 percent or below 10 percent. In some
embodiments, controlling temperature of the water 108 fed to the
steam generator 100 adjusts the carbon dioxide level to a selected
value to achieve a threshold steam to oil ratio.
[0027] In addition to providing control of the carbon dioxide level
in the mixture 101, approaches described herein may reduce
operating and capital expenses compared to similar approaches that
lack the second heat exchanger 114 used to increase the temperature
of the water 108 above 200.degree. C. The Table 1 shows this
comparison made with process models for a 90,000 barrel per day
facility. As shown in the Table 1, firing rate of the steam
generator 100 decreases by 16 percent when the second heat
exchanger 114 is employed as described herein. This reduction
enables using fewer steam generators along with smaller air
separation units and carbon dioxide processing systems per given
amount of steam output. Total fuel usage also drops with use of the
second heat exchanger 114.
TABLE-US-00001 TABLE 1 without 2.sup.nd with 2.sup.nd heat
exchanger heat exchanger DSG head H20 temperature 170.degree. C
170.degree. C DSG non-head H20 temperature 170.degree. C
280.degree. C CO2 mass % of steam 11.4% 9.5% H2O flowrate
(tonne/hr) 1148 1166 O2 flowrate (tonne/hr) 210.7 175.6 Total power
(MW.sub.e) 216.8 199.3 Fuel- DSG(tonne/hr) 53.7 44.8 Fuel- power
generation (tonne/hr) 35.8 38.8 Total fuel (tonne/hr) 89.5 83.6
[0028] In closing, it should be noted that the discussion of any
reference is not an admission that it is prior art to the present
invention, especially any reference that may have a publication
date after the priority date of this application. At the same time,
each and every claim below is hereby incorporated into this
detailed description or specification as an additional embodiment
of the present invention.
[0029] Although the systems and processes described herein have
been described in detail, it should be understood that various
changes, substitutions, and alterations can be made without
departing from the spirit and scope of the invention as defined by
the following claims. Those skilled in the art may be able to study
the preferred embodiments and identify other ways to practice the
invention that are not exactly as described herein. It is the
intent of the inventors that variations and equivalents of the
invention are within the scope of the claims, while the
description, abstract and drawings are not to be used to limit the
scope of the invention. The invention is specifically intended to
be as broad as the claims below and their equivalents.
* * * * *