U.S. patent application number 15/728380 was filed with the patent office on 2018-03-15 for oilfield application of solar energy collection.
The applicant listed for this patent is GlassPoint Solar, Inc.. Invention is credited to Stuart M. Heisler, David Bruce Jackson, John Setel O'Donnell, Peter Emery von Behrens.
Application Number | 20180073777 15/728380 |
Document ID | / |
Family ID | 45441765 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180073777 |
Kind Code |
A1 |
O'Donnell; John Setel ; et
al. |
March 15, 2018 |
OILFIELD APPLICATION OF SOLAR ENERGY COLLECTION
Abstract
Solar energy is collected and used for various industrial
processes, such as oilfield applications, e.g. generating steam
that is injected downhole, enabling enhanced oil recovery. Solar
energy is indirectly collected using a heal transfer fluid in a
solar collector, delivering heat to a heat exchanger that in turn
delivers heal into oilfield feedwater, producing hotter water or
steam. Solar energy is directly collected by directly generating
steam with solar collectors, and then injecting the steam downhole.
Solar energy is collected to preheat water that is then fed into
fuel-fired steam generators that in turn produce steam for downhole
injection. Solar energy is collected to produce electricity via a
Rankine cycle turbine generator, and rejected heat warms feedwater
for fuel-fired steam generators. Solar energy is collected
(directly or indirectly) to deliver heat to a heater-treater, with
optional fuel-fired additional heat generation.
Inventors: |
O'Donnell; John Setel;
(Oakland, CA) ; von Behrens; Peter Emery; (Menlo
Park, CA) ; Heisler; Stuart M.; (Bakersfield, CA)
; Jackson; David Bruce; (Bakersfield, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GlassPoint Solar, Inc. |
Fremont |
CA |
US |
|
|
Family ID: |
45441765 |
Appl. No.: |
15/728380 |
Filed: |
October 9, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14194919 |
Mar 3, 2014 |
9810451 |
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15728380 |
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13576623 |
Aug 1, 2012 |
8701773 |
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PCT/US2011/042907 |
Jul 3, 2011 |
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14194919 |
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61361507 |
Jul 5, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24S 23/74 20180501;
F24S 20/20 20180501; F24S 10/70 20180501; F01K 13/02 20130101; Y02E
10/47 20130101; E21B 43/24 20130101; Y02E 20/14 20130101; F24S
30/425 20180501; Y02E 10/40 20130101; Y02P 80/20 20151101; F22B
33/18 20130101; F01K 17/04 20130101; F22B 1/006 20130101; F24S
2023/834 20180501; F24S 90/00 20180501 |
International
Class: |
F24J 2/42 20060101
F24J002/42; E21B 43/24 20060101 E21B043/24 |
Claims
1-26. (canceled)
27. An oil recovery system, comprising: a solar collector,
including: a reflector positioned to receive and redirect solar
radiation; and a receiver positioned to receive radiation
redirected by the reflector; a turbine generator having an inlet
and an outlet, the inlet being thermally coupled to the receiver to
receive heat collected at the receiver; a heat exchanger thermally
coupled to the outlet and to a source of feed water to transfer
heat from the outlet to the feed water; a fuel-fired steam
generator operatively coupled to the heat exchanger to heat the
feed water; and a steam distribution system operatively coupled to
the fuel-fired steam generator to receive steam from the fuel-fired
steam generator, the steam distribution system being coupled to at
least one oilfield steam injection well.
28. The system of claim 27, further comprising a heat transfer
fluid carried by the receiver and wherein the inlet of the turbine
generator is coupled to the receiver to receive the heat transfer
fluid.
29. The system of claim 28 wherein the heat transfer fluid includes
water.
30. The system of claim 27 wherein the heat exchanger is a first
heat exchanger, and wherein the system further comprises: a first
heat transfer fluid carried by the receiver; a second heat transfer
fluid carried by the turbine generator; and a second heat exchanger
coupled between the receiver and the turbine generator to transfer
heat from the first heat transfer fluid to the second heat transfer
fluid.
31. The system of claim 30 wherein the first heat transfer fluid
includes a synthetic oil.
32. The system of claim 30 wherein the first heat transfer fluid
includes a molten salt.
33. The system of claim 30 wherein the second heat transfer fluid
includes an organic fluid.
34. The system of claim 27 wherein the turbine generator is a
Rankine cycle generator.
35. The system of claim 27 wherein the reflector includes a
parabolic trough reflector, and wherein the receiver incudes an
elongated conduit.
36. A method for extracting oil, comprising: concentrating solar
energy to generate heat; directing at least a first portion of the
heat to a turbine generator; rejecting at least a second portion of
the heat from the turbine generator; heating feed water with at
least some of the second portion of the heat rejected from the
turbine generator; further heating the feed water with a fuel fired
steam generator; and directing the further heated feed water to at
least one oilfield injection well.
37. The method of claim 36 wherein concentrating solar energy
includes focusing the solar energy with a parabolic trough
reflector onto a linear conduit.
38. The method of claim 36 wherein directing at least the first
portion of the heat to the turbine generator includes directing a
heat transfer fluid from a solar collector into the turbine
generator.
39. The method of claim 36 wherein the heat transfer fluid includes
water.
40. The method of claim 36 wherein directing at least the first
portion of the heat to the turbine generator includes: directing a
first heat transfer fluid from a solar concentrator to a heat
exchanger; transferring heat from the first heat transfer fluid to
a second heat transfer fluid at the heat exchanger; and directing
the second heat transfer fluid into the turbine generator.
41. The method of claim 40 wherein the first heat transfer fluid
includes a synthetic oil.
42. The method of claim 40 wherein the first heat transfer fluid
includes a molten salt.
43. The method of claim 40 wherein the second heat transfer fluid
includes an organic liquid.
44. The method of claim 36 wherein heating feed water with at least
some of the second portion of the heat rejected from the turbine
generator includes heating the feed water at a heat exchanger.
45. An oil recovery system, comprising: a solar collector,
including: a reflector positioned to receive and redirect solar
radiation; and a receiver positioned to receive radiation
redirected by the reflector; and a heater-treater unit coupled to
the solar collector to receive heat from the solar collector.
46. The system of claim 45 wherein the heater-treater unit is
configured to heat constituents of a fluid mixture extracted from
an oil field during an enhanced oil recovery operation, and wherein
the system further comprises a steam distribution system
operatively coupled to at least one oilfield production well to
receive the fluid mixture and direct the liquid mixture to the
heater-treater unit.
47. The system of claim 45, further comprising a fuel-fired heater
coupled to at least one of the heater-treater or the solar
collector to supplement heat generated by the solar collector.
48. The system of claim 47 wherein the fuel-fired heater includes a
firetube heater.
49. The system of claim 45, further comprising a heat transfer
fluid carried by the receiver and wherein the heater-treater unit
is coupled to the receiver to receive the heat transfer fluid.
50. The system of claim 49 wherein the heat transfer fluid includes
water.
51. The system of claim 45, further comprising: a first heat
transfer fluid carried by the receiver; a second heat transfer
fluid carried by the heater-treater unit; and a heat exchanger
coupled between the receiver and the heater-treater unit to
transfer heat from the first heat transfer fluid to the second heat
transfer fluid.
52. The system of claim 51 wherein the first heat transfer fluid
includes a synthetic oil.
53. The system of claim 51 wherein the first heat transfer fluid
includes a molten salt.
54. The system of claim 51 wherein the second heat transfer fluid
includes an organic fluid.
55. The system of claim 45, further comprising a thermal energy
storage system coupled to the solar collector to store heat
generated by the solar collector.
56. A method for processing extracted oil, comprising:
concentrating solar energy via a solar collector to generate heat;
and directing at least one portion of the heat to a heater-treater
unit.
57. The method of claim 56, further comprising: directing an
oil-containing mixture from an oil extraction well to the
heater-treater unit; and at the heater-treater unit, separating oil
from the oil-containing mixture using the at least one portion of
heat
58. The method of claim 57 wherein separating includes separating
the oil from water.
59. The method of claim 57 wherein separating includes separating
the oil from a gas.
60. The method of claim 57, further comprising heating the
oil-containing mixture with a fuel-fired heater.
61. The method of claim 57, further comprising storing at least
some of the heat generated at the solar collector, at a thermal
energy storage system.
62. The method of claim 57 wherein separating oil from the
oil-containing mixture is performed without combusting fuel to heat
the oil-containing mixture.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Priority benefit claims for this application are made in the
accompanying Application Data Sheet, Request, or Transmittal (as
appropriate, if any). To the extent permitted by the type of the
instant application, this application incorporates by reference for
all purposes the following applications, all commonly owned with
the instant application at the time the invention was made:
U.S. Provisional Application (Docket No. 310618-2001 and Ser. No.
61/149,292), filed Feb 02, 2009, first named inventor Rod
MacGregor, and entitled Concentrating Solar Power with Glasshouses;
U.S. Provisional Application (Docket No. CLEN-002/00US 310618-2002
and Ser. No. 61/176,041), filed May 06, 2009, first named inventor
Peter Von Behrens, and entitled Concentrating PhotoVoltaics with
Glasshouses; PCT Application (Docket No. GP-09-01PCT and Serial No.
PCT/US10/22780), filed Feb. 01, 2010, first named inventor Roderick
MacGregor, and entitled Concentrating Solar Power with Glasshouses;
U.S. Provisional Application (Docket No. GP-10-02 and Ser. No.
61/361,509), filed Jul. 05, 2010, first named inventor Peter Von
Behrens, and entitled Concentrating Solar Power with Glasshouses;
U.S. Provisional Application (Docket No. GP-40-04 and Se. No.
61/361,512), filed Jul. 05, 2010, first named inventor John Setel
O'Donnell, and entitled Direct Solar Oilfield Steam Generation;
U.S. Provisional Application (Docket No. GP-10-04A and Ser. No.
61/445,545), filed Feb. 23, 2011, first named inventor John Setel
O'Donnell, and entitled Direct Solar Oilfield Steam Generation;
U.S. Provisional Application (Docket No. GP-10-08 and Ser. No.
61/361,507), filed Jul. 05, 2010, first named inventor John Setel
O'Donnell, and entitled Oilfield Application of Solar Energy
Collection; PCT Application (Docket No. GP-10-02PCT and Serial No
PCT/US11/42891), filed Jul. 02, 2011, first named inventor Peter
Von Behrens, and entitled Concentrating Solar Power with
Glasshouses; and PCT Application (Docket No. GP-10-04APCT and
Serial No. PCT/US11/42906), filed Jul. 03, 2011, first named
inventor John Setel O'Donnell, and entitled Direct Solar Oilfield
Steam Generation.
BACKGROUND
Field
[0002] Advancements in solar energy collection and use thereof are
needed to provide improvements in performance, efficiency, and
utility of use.
Related Art
[0003] Unless expressly identified as being publicly or well known,
mention herein of techniques and concepts, including for context,
definitions, or comparison purposes, should not be construed as an
admission that such techniques and concepts are previously publicly
known or otherwise part of the prior art. All references cited
herein (if any), including patents, patent applications, and
publications, are hereby incorporated by reference in their
entireties, whether specifically incorporated or not, for all
purposes.
[0004] Concentrated solar power systems use minors, known as
concentrators, to gather solar energy over a large space and aim
and focus the energy at receivers that convert incoming solar
energy to another form, such as heat or electricity. There are
several advantages, in some usage scenarios, to concentrated
systems over simpler systems that directly use incident solar
energy. One advantage is that more concentrated solar energy is
more efficiently transformed to heat or electricity than less
concentrated solar energy. Thermal and photovoltaic solar receivers
operate more efficiently at higher incident solar energy levels.
Another advantage is that non-concentrated solar energy receivers
are, in some usage scenarios, more expensive than mirror systems
used to concentrate sunlight. Thus, by building a system with
mirrors, total cost of gathering sunlight over a given area and
converting the gathered sunlight to useful energy is reduced.
[0005] Concentrated solar energy, collection systems, in some
contexts, are divided into four types based on whether the solar
energy is concentrated into a line-focus receiver or a point-focus
receiver and whether the concentrators are single monolithic
reflectors or multiple reflectors arranged as a Fresnel reflector
to approximate a monolithic reflector.
[0006] A line-focus receiver is a receiver with a target that is a
relatively long straight line, like a pipe. A line-focus
concentrator is a reflector that receives sunlight over a two
dimensional space and concentrates the sunlight into a
significantly smaller focal point in one dimension (width) while
reflecting the sunlight without concentration in the other
dimension (length) thus creating a focal line. A line-focus
concentrator with a line-focus receiver at its focal line is a
basic trough system. The concentrator is optionally rotated in one
dimension around its focal line to track daily movement of the sun
to improve total energy capture and conversion.
[0007] A point-focus receiver is a receiver target that is
essentially a point, but in various approaches is a panel, window,
spot, ball, or other target shape, generally more equal in width
and length than a line-focus receiver. A point-focus concentrator
is a reflector (made up of a single smooth reflective surface,
multiple fixed facets, or multiple movable Fresnel facets) that
receives sunlight over a two-dimensional space and concentrates the
sunlight into a significantly smaller focal point in two dimensions
(width and length). A monolithic point-focus concentrator with a
point-focus receiver at its focal point is a basic dish
concentrated solar system. The monolithic concentrator is
optionally rotated in two dimensions to rotate its focal axis
around its focal point to track daily and seasonal movement of the
sun to improve total energy capture and conversion.
[0008] A parabolic trough system is a line concentrating system
using a monolithic reflector shaped like a large half pipe. The
reflector has a 1-dimensional curvature to focus sunlight onto a
line-focus receiver or approximates such curvature through multiple
facets fixed relative to each other.
[0009] A concentrating Fresnel reflector is a line concentrating
system similar to the parabolic trough replacing the trough with a
series of mirrors, each the length of a receiver, that are flat or
alternatively slightly curved in their width. Each mirror is
individually rotated about its long axis to aim incident sunlight
onto the line-focus receiver.
[0010] A parabolic dish system is a point concentrating system
using a monolithic reflector shaped like a howl. The reflector has
a 2-dimensional curvature to focus sunlight onto a point-focus
receiver or approximates such curvature through multiple flat or
alternatively curved facets fixed relative to each other.
[0011] A solar power tower is a point concentrating system similar
to the parabolic dish, replacing the dish with a 2-dimensional
array of mirrors that are flat or alternatively curved. Each minor
(heliostat) is individually rotated in two dimensions to aim
incident sunlight onto a point-focus receiver. The individual
mirrors and an associated control system comprise a point-focus
concentrator whose focal axis rotates around its focal point.
[0012] In solar thermal systems, the receiver is a light to heat
transducer. The receiver absorbs solar energy. transforming it to
heat and transmitting the heat to a thermal transport medium such
as water, steam, oil, or molten salt. The receiver converts solar
energy to heat and minimizes and/or reduces heat loss due to
thermal radiation.
SYNOPSIS
[0013] The invention may be implemented in numerous ways, including
as a process, an article of manufacture, an apparatus, a system,
and a composition of matter. In this specification, these
implementations, or any other form that the invention may take, may
be referred to as techniques. The Detailed Description provides an
exposition of one or more embodiments of the invention that enable
improvements in performance, efficiency, and utility of use in the
field identified above. The Detailed Description includes an
Introduction to facilitate the more rapid understanding of the
remainder of the Detailed Description. As is discussed in more
detail in the Conclusions, the invention encompasses all possible
modifications and variations within the scope of the issued
claims.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 illustrates various details of an embodiment of an
oilfield application of solar energy collection.
[0015] FIG. 2 illustrates various details of continuous
constant-rate steam injection via hybrid gas-solar steaming.
[0016] FIG. 3 illustrates various details of continuous
variable-rate steam injection via hybrid gas-solar steaming.
[0017] FIG. 4 illustrates various details of an embodiment of a
solar heated heater-treater.
DETAILED DESCRIPTION
[0018] A detailed description of one or more embodiments of the
invention is provided below along with accompanying figures
illustrating selected details of the invention. The invention is
described in connection with the embodiments. The embodiments
herein are understood to be merely exemplary, the invention is
expressly not limited to or by any or all of the embodiments
herein, and the invention encompasses numerous alternatives,
modifications, and equivalents. To avoid monotony in the
exposition, a variety of word labels (including but not limited to:
first, last, certain, various, further, other, particular, select,
some, and notable) may be applied to separate sets of embodiments;
as used herein such labels are expressly not meant to convey
quality, or any form of preference or prejudice, but merely to
conveniently distinguish among the separate sets. The order of some
operations of disclosed processes is alterable within the scope of
the invention. Wherever multiple embodiments serve to describe
variations in process, method, and/or features, other embodiments
are contemplated that in accordance with a predetermined or a
dynamically determined criterion perform static and/or dynamic
selection of one of a plurality of modes of operation corresponding
respectively to a plurality of the multiple embodiments. Numerous
specific details are set forth in the following description to
provide a thorough understanding of the invention. The details are
provided for the purpose of example and the invention may be
practiced according to the claims without some or all of the
details. For the purpose of clarity, technical material that is
known in the technical fields related to the invention has not been
described in detail so that the invention is not unnecessarily
obscured.
INTRODUCTION
[0019] This introduction is included only to facilitate the more
rapid understanding of the Detailed Description; the invention is
not limited to the concepts presented in the introduction
(Including explicit examples, if any), as the paragraphs of any
introduction are necessarily an abridged view of the entire subject
and are not meant to be an exhaustive or restrictive description.
For example, the introduction that follows provides overview
information limited by space and organization to only certain
embodiments. There are many other embodiments, including those to
which claims will ultimately be drawn, discussed throughout the
balance of the specification.
[0020] Thermal techniques for enhanced oil recovery enable
improvements for current and future oil production around the
world. For example, steam injection provides nearly half of
California's oil production, and improvements in ongoing expansion
of steamflood and steam stimulation systems enable a more nearly
stable energy supply.
[0021] Injected steam expands oil production through several
mechanisms. By raising the temperature of oil and the surrounding
formation, viscosity of the oil is reduced, thus expediting its
flow. In some embodiments, steam flow and resulting condensed water
flow sweep oil along towards production wells. Other
characteristics, such as reservoir pressure and rock wettability,
are affected by steam injection as well.
[0022] In some embodiments, steam used in oilfield operations is
injected at temperatures ranging from 300F to 700F or 750F, and
pressures at up to 1500 or 2500 PSI, where particular temperatures
and pressures are determined by specifics of the oil formation and
production approach. In some embodiments, steam for oilfield
injection is produced in once-through steam generators. In some
embodiments, the steam generators are heated by fuel combustion.
Fuel combustion carries many costs, such as the cost of fuel, the
costs of complying with regulatory regimes regarding air quality
and disposal of combustion products, and coming regimes that impose
costs for emitting CO2. In some embodiments, solar-heated steam
generators are used to produce steam for oilfield operations.
Solar-heated steam generators use little or no fuel, and thus emit
little or no combustion products or CO2.
[0023] In some embodiments, point-focus "power tower" steam
generation based solar apparatus systems deliver steam into an
oilfield via a "reboiler." a heat exchanger that condenses
high-purity, high-pressure steam that is generated by the solar
apparatus, and heat feed water or generate steam using lower-purify
oilfield feed water. In some embodiments, a limited amount of solar
steam as a percentage of daytime oilfield steam is used; small
solar collectors feeding energy into lame steam distribution
systems make little difference in total flow rate. In some
embodiments and/or usage scenarios, one or more of the techniques
described herein, such as solar steam injection and automatic
control systems, enable higher fractions of solar steam use, in
some situations, extending above 90% in both daytime and annual
steam use. In some embodiments and/or usage scenarios, one or more
of the techniques described herein enable line-focus solar
collectors for oilfield steam generation that are relatively lower
cost than some power tower solar apparatus based
implementations.
[0024] Solar energy is collected and used for various oilfield
applications. Collected solar energy is used to generate steam to
teed an industrial process, such as downhole injection, enabling
enhanced oil recovery. Solar energy is optionally indirectly
collected using a heat transfer fluid in a solar collector. The
heat transfer fluid delivers heat to a heat exchanger (such as a
tube-in-tube heat exchanger) that in turn delivers heat into
oilfield feed water, producing hotter water or steam. Solar energy
is optionally directly collected by directly generating steam with
solar collectors, and then injecting the steam downhole. Solar
energy is optionally collected and used to preheat water that is
then fed into fuel-fired steam generators that in turn produce
steam for downhole injection. Solar energy is optionally collected
and used to produce electricity via a Rankine cycle turbine
generator, and rejected heat warms feed water for fuel-fired steam
generators. Solar energy is optionally collected and used (directly
or indirectly) to deliver heat to a heater-treater, with optional
fuel-fired additional heat generation.
Injection of Solar Steam for Enhanced Oil Recovery Applications
[0025] In some embodiments, "steamflood" operations involve a
pattern of multiple steam injection wells and multiple oil
production wells, arranged so that injected steam causes increased
production at the producer wells. While a "five-spot" pattern is
common, many other arrangements of injection and production wells
are contemplated using techniques taught herein. In some
embodiments, "huff-and-puff" or "cyclic stimulation" steam
injection operations involve periodically injecting steam into each
well for a period of one or inure days, then shutting steam supply
to the well and producing oil from the well for a period of one or
more weeks. In some embodiments, a steam distribution system of
piping and flow control devices interconnects one or more steam
generators to a plurality of steam injection wells that operate
concurrently, in a steamflood configuration, a cyclic stimulation
configuration, or some other suitable configuration. In some
embodiments, applicable to "steamflood", "cyclic stimulation", and
other suitable configurations of oilfield steaming, a plurality of
concentrating solar thermal collectors gather solar energy for
steam generation. Solar reflectors track the sun and direct solar
radiation to thermal energy receivers, that directly or indirectly
heat water and generate steam that is fed into the steam
distribution system and injected downhole. In some embodiments,
solar-generated steam provides the majority of total steam supply
for the injection, and injection rate varies based on currently
available sunshine. In some embodiments of "solar majority" steam
injection, fuel-fired steam generators operate at night and during
other periods of low solar radiation to provide enough steam to
maintain temperature of the steam injection system and wells above
ambient temperature, without contributing significant steam flow
into the formation. In some embodiments of "solar majority"
injection, fuel-fired steam generators operate continuously,
providing a portion of daytime steam injection and continuing
overnight and during periods of low solar radiation to maintain
system temperature at lower flow rates.
[0026] FIG. 1 illustrates various details of an embodiment of an
oilfield application of solar energy collection. In some
embodiments, solar steam generators 38 are interconnected to steam
distribution system 7 that also is supplied with steam from
fuel-fired steam generators 9, and solar heat provides a portion of
steam supply. In some embodiments, solar-generated steam provides a
large portion of daytime steam. In some embodiments, an automatic
control system (not illustrated) that automatically communicates
with solar field controls and controls for fuel-fired steam
generators, enables solar heat to provide a large portion of
daytime steam.
[0027] FIG. 2 illustrates various details of a continuous
constant-rate steam injection embodiment and/or mode of operation
of the automatic control system. A "balancing" control unit (that
is part of the automatic control system) communicates with solar
field controls and issues commands to fuel-fired steam generator
units, so that as solar steam output rate 10c rises, the firing
rate in fuel-fired generators is adjusted downwards lowering
fuel-generated steam rate 12c to maintain desired total steam
injection rate 11c. In some embodiments, the desired steam
infection rate is nearly constant day and night, with flow rate
varying approximately 10% about a target rate.
[0028] FIG. 3, illustrates various details of a continuous
variable-rate steam injection embodiment and/or mode of operation
of the automatic control system that provides control of fuel-fired
generators to enable overall steam injection rate 11v to vary as
much as 50% from an "average" steam injection rate 13. Note in that
as illustrated in FIG. 3, overall steam injection rate 11v is
enabled to vary an hourly basis depending on solar steam rate 10v;
in this mode of operation, solar energy is thus enabled to deliver
a higher fraction of total daily steam production than in the
constant-rate case illustrated in FIG. 2. In some usage scenarios,
not illustrated, automated "turndown" of fuel firing rates and feed
water rates in fuel-fired generators producing variable
fuel-generated steam rates 12v, enables solar steam 10v to deliver
up to 100% of daytime steam flow while maintaining any desired
total steam flow pattern.
[0029] In some embodiments, fuel-fired generator turndown strategy
is designed to minimize annual cost of maintaining fuel burners and
proving compliance with applicable standards for emissions of
criteria pollutants. Solar radiation varies continuously, rising
smoothly or discontinuously from dawn until noon. In some
embodiments, an oilfield steam distribution system has multiple
fuel-fired steam generators interconnected to a common steam
distribution system. In some embodiments, to reduce or minimize a
number of burner operating points to be measured and witnessed by
regulatory authorities, a control system turns down burners by
fixed amounts, to two or three fixed firing points; "full" and
"minimum", or "full," "medium," and "minimum" firing rates. In an
operating regime for a solar steam generation system with
approximately constant steam flow, as solar radiation and
solar-fired steam production changes, individual fuel-fired burners
are automatically commanded to move from "full" to "minimum", or
"full" to "medium" and then "medium" to "minimum". By independently
automatically controlling multiple fuel-fired burners, the control
system delivers approximately constant steam flow rates. In some
embodiments, oilfield control systems alter an order that
fuel-fired generators are commanded to turn down as solar radiation
rises, or an order that fuel-fired generators are ordered to return
to full output as solar radiation falls, to reduce or minimize
operating costs. In some embodiments and/or usage scenarios, some
steam generators are more efficient in fuel combustion than others
and some steam generators experience higher maintenance costs
associated with varying fuel firing rates. The control system's
ordering of generator firing commands is implemented taking into
account the characteristics of particular steam generators.
Indirect Steam Generation for Enhanced Recovery Applications
[0030] In some embodiments of solar steam generation for enhanced
oil recovery, solar heat is collected using a heat transfer fluid
that gathers heat in solar collectors and delivers heat to a heat
exchanger. The heat exchanger delivers heat into oilfield feed
water, producing hotter water or steam that in turn is fed into an
oilfield feed water or steam distribution system. In some
embodiments of indirect steam generation, the heat transfer fluid
is a synthetic oil, such as Therminol or Dowtherm. In some
embodiments of indirect steam generation, the heat transfer fluid
is a blend of inorganic salts that circulate as molten salt. In
some embodiments of indirect steam generation, the heat transfer
fluid is high-purity pressurized water that circulates and boils in
a solar field and condenses in the heat exchanger.
Tube-in-Tube Heat Exchanger for Indirect Solar Steam Generation for
Enhanced Oil Recovery Applications
[0031] In some embodiments of indirect solar steam generation, a
heat exchanger is designed as a "tube-in-tube" type exchanger,
where an interior tube carries high-pressure oilfield feed water
that is being converted to steam, and an outer tube carries a heat
transfer fluid heated by solar collectors. Because liquid water is
evaporated as it proceeds through steam generator piping, residual
contaminants carried in feed water concentrate as liquid volume
drops, progressively rising as liquid converts to vapor phase. The
term "steam quality" refers to the percentage of inlet water mass
that has been converted to vapor phase; thus 70% steam quality
would have only 30% of original water in liquid phase, and
contaminants would be concentrated by more than threefold from the
original feed water.
[0032] In some embodiments, an ideal oilfield steam generator
delivers the highest possible steam quality for a given feed water
quality. Higher steam quality delivers more energy per pound of
water injected. However, if steam quality exceeds limits imposed by
water contaminant concentration, corrosion and scaling begin to
occur at unacceptably high rates, causing fouling, plugging, and
potential failure or burnout of steam generator tubing. In some
embodiments, economical operation occurs when steam quality is
tightly controlled, such as within a 5% to 10% range. In sonic
embodiments and/or usage scenarios, a serpentine horizontal
arrangement of tube-in-tube apparatus enables economical operation,
due in part to an extended horizontal boiling zone that limits
mineral deposits, and in part to a capability to periodically clean
collection tube interiors with acids and mechanical scrubbers known
as "pigs".
[0033] In some embodiments, fuel-fired steam generators maintain
steam quality within a desired range by measuring inlet air and
water temperatures, and controlling fuel firing rate and water feed
rate appropriately. In some embodiments, a tube-in-tube heat
exchanger for indirect solar steam generation measures incoming
heat transfer fluid temperature and flow rate. Automatic controls
adjust inlet valves and pumps as well as outlet valves to manage
outlet steam quality by modulating feed water flow in a manner
proportional to heat carried in a heat transfer fluid. Automatic
controls shut a steam outlet valve when heat flow from a solar
field is inadequate to make target steam quality. A control system
for the tube-in-tube heat exchanger communicates with a master
control and/or directly with controls for other fuel-fired steam
generators (such as described above) to maintain overall desired
steam flow rates.
Direct Steam Generation for Enhanced Oil Recovery Applications
[0034] In some embodiments of solar steam generation for enhanced
oil recovery, oilfield feed water is fed directly into solar
collectors, in an arrangement similar to a feed water system for
fuel-fired steam generators, and as se alar heat is collected, the
collected solar heat directly generates steam that in turn is fed
into an oilfield feed water or steam distribution system. In some
embodiments and/or usage scenarios, line-focus solar collectors
enable economical operation in oilfield steam generators, due in
part to an extended horizontal boiling zone that limits mineral
deposits, and in part to a capability to periodically clean
collection tube interiors with acids and mechanical scrubbers known
as "pigs".
Solar Water Preheating for Enhanced Oil Recovery Applications
[0035] In some embodiments of solar steam generation for enhanced
oil recovery, oilfield feed water is fed directly into solar
collectors, and is raised in temperature by solar heat without
boiling (without conversion from liquid to vapor phase). The heated
water is then fed from solar collectors into one or more fuel-fired
steam generators. In some embodiments, a contribution of solar heat
increases a rate of steam production by a fuel-fired steam
generator for constant fuel firing rate. In some embodiments, a
contribution of solar heat reduces a fuel firing rate for a
fuel-fired steam generator while maintaining a constant steam
production rate.
Solar Cogeneration of Heat and Electric Power for Enhanced Oil
Recovery Applications
[0036] In some embodiments of solar water preheating for enhanced
oil recovery, oilfield water is directly heated via circulation in
solar collectors. In some embodiments, oilfield water is preheated
via a heat exchanger in a "solar cogeneration" configuration. In
some cogeneration embodiments, solar collectors gather solar heat
that drives a Rankine cycle turbine generator. Rejected heat from
the Rankine generator warms feed water through a heat exchanger,
feeding the warmed feed water to one or more fuel-fired steam
generators. In some embodiments, a heat transfer fluid flows
through a solar field, and generates high-purity high-pressure
vapor in a heat exchanger. In some, embodiments, a solar field
directly generates high-purity, high-pressure vapor to drive a
turbine. The high pressure vapor runs a Rankine cycle turbine.
Turbine exhaust is condensed in a heat exchanger, giving up latent
heat of vaporization to oilfield feed water flowing through the
heat exchanger. In some embodiments, vapor/liquid in a Rankine
cycle turbine is steam/water. In some embodiments, vapor/liquid in
the Rankine cycle turbine is an organic fluid such as toluene or
pentane. In some embodiments, heat transfer fluid flowing through a
solar field is a synthetic oil such as Therminol or Dowtherm. In
some embodiments, heat transfer fluid flowing through a solar field
is a molten salt mixture. In some embodiments and/or usage
scenarios, a configuration where a solar field directly generates
high-pressure high-purity steam that flows through a steam turbine,
producing electric power, and is condensed in a heat exchanger that
heats oilfield steam generator feed water, is implemented with a
reduced or lowest cost compared to other implementations.
Solar Heating for Produced Oil Treatment
[0037] In some embodiments, product flowing from oil wells is a
mixture of petroleum, water, gas, and various contaminants.
Separating oil and water economically is desirable, in some usage
scenarios. In some embodiments, such as illustrated in FIG. 4,
"heater-treater" units 14 separate oil 16, water 20, and gas 19,
using a combination of chemicals and heat to break oil-water
emulsions. The heater-treater units, in some embodiments, comprise
one or more of drain 21, mist extractor 22, gas equalizer 23, and
during operation in some scenarios contain oil/water interface 24.
In some embodiments, firetube heaters 17 are used in
heater-treaters, delivering heat front fuel combustion into an
oil-water-gas mixture. In some embodiments, a plurality of
concentrating solar thermal collectors (e.g. solar steam generators
38) gather solar energy as heat. Solar reflectors 16 track the sun
and direct solar radiation to thermal energy receivers that
directly or indirectly provide heat to one or more heater-treater
units. In some embodiments, heat transfer fluid circulates,
gathering heat in a solar field, and delivers the gathered heat
into a heater-treater via heat exchanger tube element 18. In some
embodiments, the heat transfer fluid is a synthetic oil such as
Therminol or Dowtherm. In some embodiments, the heat transfer fluid
is a molten salt mixture. In some embodiments, pressurized water is
circulated in a solar field, delivering heat as steam that is
recondensed in a heat exchanger tube in a heater-treater. In some
embodiments, solar oil heat treatment optionally operates
intermittently, using solar radiation as available. In some
embodiments, a heater-treater unit optionally includes a fuel
burner (such as firetube heaters 17) as well as a solar heat
exchanger, enabling the heater-treater unit to operate
continuously, with solar energy providing a portion of annual
energy. In some embodiments (not illustrated), a thermal energy
storage system collects solar heat during the day and provides
extended-hour or continuous heat delivery to a heater-treater unit,
enabling continuous operation without fuel combustion.
CONCLUSION
[0038] Certain choices have been made in the description merely for
convenience in preparing the text and drawings and unless there is
an indication to the contrary the choices should not be construed
per se as conveying additional information regarding structure or
operation of the embodiments described. Examples of the choices
include: the particular organization or assignment of the
designations used for the figure numbering and the particular
organization or assignment of the element identifiers (the callouts
or numerical designators, e.g.) used to identify and reference the
features and elements of the embodiments.
[0039] The words "includes" or "including" are specifically
intended to be construed as abstractions describing logical sets of
open-ended scope and are not meant to convey physical containment
unless explicitly followed by the word "within."
[0040] Although the foregoing embodiments have been described in
sonic detail for purposes of clarity of description and
understanding, the invention is not limited to the details
provided. There are many embodiments of the invention. The
disclosed embodiments are exemplary and not restrictive.
[0041] It will be understood that many variations in construction,
arrangement, and use are possible, consistent with the description,
and are within the scope of the claims of the issued patent. The
names given to elements are merely exemplary, and should not be
construed as limiting the concepts described. Also, unless
specifically stated to the contrary, value ranges specified,
maximum and minimum values used, or other particular
specifications, are merely those of the described embodiments, are
expected to track improvements and changes in implementation
technology, and should not be construed as limitations.
[0042] Functionally equivalent techniques known in the art are
employable instead of those described to implement various
components, sub-systems, operations, functions, or portions
thereof.
[0043] The embodiments have been described with detail and
environmental context well beyond that required for a minimal
implementation of many aspects of the embodiments described. Those
of ordinary skill in the art will recognize that some embodiments
omit disclosed components or features without altering the basic
cooperation among the remaining elements. It is thus understood
that much of the details disclosed are not required to implement
various aspects of the embodiments described. To the extent that
the remaining elements are distinguishable from the prior art,
components and features that are omitted are not limiting on the
concepts described herein,
[0044] All such variations in design are insubstantial changes over
the teachings conveyed by the described embodiments. It is also
understood that the embodiments described herein have broad
applicability to other applications, and are not limited to the
particular application or industry of the described embodiments.
The invention is thus to be construed as including all possible
modifications and variations encompassed within the scope of the
claims of the issued patent.
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