U.S. patent application number 09/925788 was filed with the patent office on 2003-02-13 for apparatus, method and system for single well solution-mining.
This patent application is currently assigned to Anadarko Petroleum Company. Invention is credited to Brown, Neil, Nesselrode, Karl.
Application Number | 20030029617 09/925788 |
Document ID | / |
Family ID | 25452248 |
Filed Date | 2003-02-13 |
United States Patent
Application |
20030029617 |
Kind Code |
A1 |
Brown, Neil ; et
al. |
February 13, 2003 |
Apparatus, method and system for single well solution-mining
Abstract
The claimed invention is a method, system and apparatus for
solution-mining of subterranean materials such as trona, nahcolite,
thermonatrite, pirssonite, natron, dawsonite, wegscheiderite,
gaylussite, shortite, halite, and other salts, minerals, and so
forth. The method comprises injecting a fluid into an elbow well,
the fluid forming a subterranean mixture with the subterranean
material, and collecting the subterranean mixture from the elbow
well. The system comprises a means for injecting a fluid into an
elbow well, the fluid forming a subterranean mixture with the
subterranean material, and a means for collecting the subterranean
mixture from the elbow well. The apparatus further comprises a
production casing, wherein the production casing has a production
casing inner diameter of sufficient size to allow for production of
a subterranean mixture of the fluid and the subterranean material
between an outer surface of the injection tube and an inner surface
of the production casing.
Inventors: |
Brown, Neil; (The Woodlands,
TX) ; Nesselrode, Karl; (The Woodlands, TX) |
Correspondence
Address: |
Erik J. Osterrieder
2603 Augusta Drive, Suite 800
Houston
TX
77019
US
|
Assignee: |
Anadarko Petroleum Company
200 Timberloch Place
The Woodlands
TX
77380
|
Family ID: |
25452248 |
Appl. No.: |
09/925788 |
Filed: |
August 9, 2001 |
Current U.S.
Class: |
299/5 ; 166/369;
299/17 |
Current CPC
Class: |
E21B 43/28 20130101 |
Class at
Publication: |
166/305.1 ;
166/369; 299/17 |
International
Class: |
E21B 043/16 |
Claims
What is claimed is:
1. A method for solution-mining of a subterranean material, the
method comprising: injecting a fluid into an elbow well, the fluid
forming a subterranean mixture with the subterranean material; and
collecting the subterranean mixture from the elbow well.
2. The method of claim 1, wherein the subterranean material
comprises trona.
3. The method of claim 1, further comprising making the elbow
well.
4. The method of claim 3, wherein making the elbow well comprises
drilling an elbow well into a bed comprising the subterranean
material.
5. The method of claim 1, wherein the method comprises casing the
elbow well.
6. The method of claim 1, wherein said injecting the fluid further
comprises injecting the fluid into an injection tube located in the
elbow well.
7. The method of claim 1, wherein the method further comprises
creating a cavity, wherein the cavity comprises the subterranean
material.
8. The method of claim 7, wherein the cavity comprises the
subterranean material mixture after said injecting the fluid.
9. The method of claim 1, wherein the subterranean mixture
comprises a subterranean solution.
10. The method of claim 1, wherein the fluid comprises water.
11. The method of claim 1, wherein the fluid comprises a caustic
mixture.
12. The method of claim 1, wherein the method further comprises
heating the fluid.
13. The method of claim 1, wherein said collecting the subterranean
mixture further comprises collecting the subterranean mixture
through a production tube located in the elbow well.
14. The method of claim 1, wherein said collecting the subterranean
mixture comprises pumping the subterranean mixture.
15. The method of claim 14, wherein said pumping the subterranean
mixture comprises lifting the subterranean mixture through the
production tube.
16. The method of claim 15, wherein the method further comprises
delivering the subterranean mixture to a collection location.
17. The method of claim 16, wherein the collection location
comprises the earth's surface.
18. The method of claim 14, wherein the method further comprises
placing a pump in the elbow well.
19. The method of claim 1, wherein the method occurs at ambient
well pressure.
20. The method of claim 1, wherein the method further comprises
processing the subterranean mixture after said collecting the
subterranean mixture.
21. A system for solution-mining of a subterranean material, the
system comprising: means for injecting a fluid into an elbow well,
the fluid forming a subterranean mixture with the subterranean
material; and means for collecting the subterranean mixture from
the elbow well.
22. The system of claim 21, wherein the subterranean material
comprises trona.
23. The system of claim 21, further comprising means for making the
elbow well.
24. The system of claim 23, wherein said means for making the elbow
well comprises means for drilling the elbow well into a bed
comprising the subterranean material.
25. The system of claim 21, wherein the system comprises means for
casing the elbow well.
26. The system of claim 21, wherein said means for injecting the
fluid further comprises an injection tube located in the elbow
well.
27. The system of claim 21, wherein the subterranean mixture
comprises a subterranean solution.
28. The system of claim 21, wherein the fluid comprises water.
29. The system of claim 21, wherein the fluid comprises a caustic
mixture.
30. The system of claim 21, wherein the system further comprises
means for heating the fluid.
31. The system of claim 21, wherein said means for collecting the
subterranean mixture comprises means for pumping the subterranean
mixture.
32. The system of claim 31, wherein the system further comprises
means for placing a pump in the elbow well.
33. The system of claim 31, wherein the system further comprises
means for delivering the subterranean mixture to a collection
location.
34. The system of claim 33, wherein the collection location
comprises the earth's surface.
35. The system of claim 21, wherein the system occurs at ambient
well pressure.
36. The system of claim 21, wherein the system further comprises
means for processing the subterranean mixture after said means for
collecting the subterranean mixture.
37. An apparatus for solution-mining of a subterranean material,
the apparatus comprising: an injection tube, wherein the injection
tube has an injection tube inner diameter of sufficient size to
allow for injection of a fluid for mining of a subterranean
material; and a production casing, wherein the production casing
has a production casing inner diameter of sufficient size to allow
for production of a subterranean mixture of the fluid and the
subterranean material between an outer surface of the injection
tube and an inner surface of the production casing.
38. The apparatus of claim 37, further comprising a production tube
for collecting the subterranean mixture.
39. The apparatus of claim 38, further comprising a pump connected
to the production tube.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to solution-mining of subterranean
materials. The following discusses the disclosed solution-mining
invention as applied to trona, but it is understood that this
solution-mining invention applies to all subterranean
materials.
[0002] The subterranean material trona, also known as natural soda
ash, is a crystalline form of sodium carbonate and sodium
bicarbonate, known as sodium sesquicarbonate, having the formula
Na.sub.2CO.sub.3.multidot.NaHC- O.sub.3.multidot.2H.sub.2O.
Worldwide, deposits of natural trona are rare, but the world's
largest known deposit is located in the Green River Basin of
southwestern Wyoming. Smaller deposits of trona are found near
Memphis, Egypt and the Lower Nile Valley, widely throughout the
soda lakes of Africa, Armenia, and Iran, and in the alkali deserts
of Mongolia and Tibet. From natural trona, the primary end product
is soda ash. In fact, Wyoming produces 90% of the processed soda
ash in the United States and 30% of the world's supply. Other
end-products from trona include sodium bicarbonate, caustic soda,
sodium sulfite, sodium cyanide and sodium phosphate. Improved and
cheaper processes for mining trona from natural deposits are
desired.
[0003] Mining is an age-old approach for removing subterranean
materials, e.g., trona, nahcolite, dawsonite, wegscheiderite,
thermonatrite, pirssonite, natron, gaylussite, shortite, halite,
and other salts, minerals, and so forth. Many deposits of
subterranean materials, however, do not permit commercially viable
extraction, whether through underground mechanical mining or
solution-mining. For example, not even 10% of known trona deposits
permit commercially viable underground mechanical mining, and trona
solution-mining has not been economical.
[0004] Underground mechanical mining requires deep shafts to remove
the subterranean material, and ever-deeper shafts are used as more
material is extracted. In addition, mechanical mining is
people-intensive. This creates a dangerous operating
environment.
[0005] After lifting the material to the surface, the material is
calcined to expel volatile components, such as carbon dioxide.
Calcination is an energy-intensive processing step that affects the
economics of mechanical mining. After calcination, the calcined
material is recrystallized in aqueous solution, collected, dried
and ready for further processing or shipping.
[0006] Solution-mining is a touted alternative to mechanical
mining, but solution-mining has not proven as economical as
desired. Solution-mining of subterranean materials, in particular,
trona, is possible using hot water or alkaline solutions. For
example, U.S. Pat. No. 2,388,009 (Pike) discloses the use of a hot
water or hot carbonate solution as the mining fluid. See also U.S.
Pat. Nos. 2,625,384 (Pike et al.); 2,847,202 (Pullen); 2,979,315
(Bays); 3,018,095 (Redlinger); 3,050,290 (Caldwell et al.);
3,086,760 (Bays); U.S. Pat. No. 3,184,287 (Gancy); 3,405,974
(Handley et al.); U.S. Pat. No. 3,952,073 (Kube); U.S. Pat. No.
4,283,372 (Frint et al.); 4,288,419 (Copenhafer et al.); and U.S.
Pat. No. 4,344,650 (Pinsky et al.), all of which are incorporated
herein by reference. These disclosures, and other documented
solution-mining processes, reveal use of two or more of the
following economic drains on commercial viability: high
temperatures, high pressure calcination, hydraulic fracturing
("fracturing"), and two wells, wherein one well is for injection
and one well is for production, see e.g., U.S. Pat. No. 4,815,790,
Rosar, et al.; U.S. Pat. No. 4,344,650, Pinsky, et al.; U.S. Pat.
No. 4,252,781, Fujita, et al.; U.S. Pat. No. 4,022,868, Poncha, et
al.; U.S. Pat. No. 4,021,526, Gancy et al.; and U.S. Pat. No.
4,021,525, Poncha, all of which are incorporated herein by
reference. Fracturing rarely fractures only the material to be
removed, so injecting hot water or alkaline solution dissolves
other materials, including salts, and contaminates the subterranean
material product collected from the production well. Collection of
contaminated subterranean materials is yet another economic drain
to commercial viable solution-mining processes.
[0007] In addition to solution-mining of trona, various U.S.
patents disclose solution-mining of nahcolite (predominantly
NaHCO.sub.3). For example, U.S. Pat. No. 3,779,602 (Beard et al.)
and U.S. Pat. Nos. 3,792,902 (Towell et al.), and U.S. Pat. No.
3,952,073 (Cube) and U.S. Pat. No. 4,283,372 (Frint, et al.)
disclose basic solution-mining of nahcolite and wegscheiderite
(predominately Na.sub.2CO.sub.3.multidot.3Na- HCO.sub.3), all of
which are incorporated herein by reference. Like the trona
solution-mining processes, however, these nahcolite and
wegscheiderite solution-recovery processes also possess economic
drains on commercial viability.
[0008] A need, therefore, exists for improved solution-mining of
subterranean materials through improved, more efficient methods and
systems.
SUMMARY OF THE INVENTION
[0009] The claimed invention is a method, system, and apparatus for
solution-mining of subterranean materials. According to a first
aspect of the invention, a method is provided for solution-mining
of a subterranean material, the method comprising injecting a fluid
into an elbow well, the fluid forming a subterranean mixture with
the subterranean material, and collecting the subterranean mixture
from the elbow well. According to another aspect of the invention,
a system is provided for solution-mining of a subterranean
material, the system comprising a means for injecting a fluid into
an elbow well, the fluid forming a subterranean mixture with the
subterranean material, and a means for collecting the subterranean
mixture from the elbow well. According to still another aspect of
the invention, an apparatus is provided for solution-mining of a
subterranean material, the apparatus comprising an injection tube,
wherein the injection tube has an injection tube inner diameter of
sufficient size to allow for injection of a fluid for mining of a
subterranean material. The apparatus further comprises a production
casing, wherein the production casing has a production casing inner
diameter of sufficient size to allow for production of a
subterranean mixture of the fluid and the subterranean material
between an outer surface of the injection tube and an inner surface
of the production casing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic of the cased elbow well drilled into a
bed of a subterranean material, wherein the elbow well comprises an
injection tube, a production casing, and a production tube that is
connected to a pump to help lift the subterranean mixture in the
cavity to a collection location, here, the earth's surface.
[0011] FIG. 2 is a cross-sectional view of the initial cavity in
the elbow well.
[0012] FIG. 3 is a cross-sectional view of the cavity in the elbow
well, wherein the cavity is larger than in FIG. 2.
[0013] FIG. 4 is a cross-sectional view of the cavity in the elbow
well, wherein the cavity is larger than in FIG. 3.
DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION
[0014] The disclosed solution-mining invention is a device, method,
and system for solution-mining of subterranean materials, such as
trona, nahcolite, dawsonite, wegscheiderite, thermonatrite,
pirssonite, natron, gaylussite, shortite, halite, and other salts,
minerals, and so forth. Although this detailed disclosure focuses
on the subterranean material trona, it is understood that the
disclosed device, method, and system for solution-mining applies to
all solution-minable subterranean materials.
[0015] In one example embodiment of the claimed invention, seen in
FIG. 1, an elbow well 15 is drilled into a bed 30 of the
subterranean material 25 being mined. An elbow well 15 is a well
that begins at the earth's surface 70, and first penetrates
vertically before penetrating horizontally. Although the elbow well
15 does not necessarily resemble the shape of a human elbow, there
is a vertical portion that eventually turns to a horizontal
portion. For trona, the estimated depth 160 for mining is 2000 feet
below the earth's surface 70. Both an injection tube 45 and a
production tube 60a are located in the elbow well 15, wherein
3-1/2" J55 tubing is used in one example for the injection tube 45,
but other sizes and types of tubing will occur to those of skill in
the art without departing from the scope of the present invention.
A fluid 10 is injected into the injection tube 45, wherein the
fluid 10 reacts with the subterranean material 25 to create a
mixture 55 (e.g., a solution) and a cavity 50. The mixture 55 flows
between the injection tube 45 and the production casing 60b. In
another example embodiment, a pump 140 is attached to the
production tube 60a to help lift the mixture 55 to the collection
point 65 (here, the earth's surface 70).
[0016] Fracturing is unnecessary in many embodiments of the
invention, because the injection tube 45, production casing 60b,
and production tube 60a are in the same well 15. The elbow well 15,
in some embodiments, is over 3000 linear feet in length 155 within
the bed 30 of the subterranean material 25.
[0017] According to another embodiment of the invention, seen in
FIGS. 2-4, the cavity 50 expands as more fluid 10 is injected into
the well 15 dissolving more subterranean material 25. The cavity 50
expands outward from the end of the elbow well 15, and therefore
the cavity 50 propagates back to the well 15. In the event that a
collapse of the cavity 50, or other obstruction, reduces the flow
of the mixture 55, the injection tube 45 is perforated in some
embodiments to permit further amounts of the mixture 55 to be
collected. Alternatively, rather than perforation, the injection
tube 45 is withdrawn, partially, until debris from the collapse is
clear and flow of the mixture 55 is raised to an acceptable
level.
[0018] High pressures of operation may cause the material 25 in the
mixture 55 to escape before collection of the subterranean material
mixture 55. Low pressures of operation, however, reduce the total
collection of the subterranean material 25, because the cavity 50
may collapse prematurely. Selection of the well pressure to avoid
these problems should be observed. At present, there is no known
empirical method to make such selection other than trial and error.
It is believed, however, that the following pressures and flow
rates are acceptable, at least for trona: at 2000 feet deep, the
pressure is 800-900 psi in the cavity 50 and the flow rate is
200-300 gal/min.
[0019] In further example embodiments of the invention, the
subterranean material 25 is selected from a group consisting
essentially of trona, dawsonite, wegscheiderite, nahcolite,
thermonatrite, pirssonite, natron, gaylussite, shortite, halite,
and other salts, minerals, and so forth.
[0020] In various example embodiments, the fluid 10 is selected
from a group consisting essentially of water, a caustic mixture, a
sodium carbonate solution, or any other fluid 10 capable of
mechanically and/or chemically reacting with the subterranean
material 25 to be mined so as to produce a mixture 55 capable of
being removed from the production casing 60b through a production
tube 60a. Such fluids 10 will occur to those of skill in the art.
In some embodiments, the fluid 10 is heated.
[0021] In a further example embodiment, the mixture 55 is lifted,
for example, by pumping with a pump 140 connected to the production
tube 60a, and the mixture 55 is delivered to a collection location
65, such as the earth's surface 70. According to one example
embodiment, an acceptable pump 140 comprises an electric
submersible centrifugal pump, 140 such as those manufactured by
Baker Hughes Centrilift. In addition, placement of the pump 140 is
above the bed 30 of subterranean mineral 25, that is, above the
mining areas. For example, with trona, the pump 140 is placed in
some embodiments about 1100 feet below the earth's surface 70 in
the elbow well 15. Other pumps 140 acceptable for use with the
claimed invention include piston/cylinder pumps, driven by sucks
rods from the surface 70. Still other pumps 140 acceptable for use
with the claimed invention will occur to those of skill in the
art.
[0022] Having thus described exemplary embodiments of the
invention, it will be apparent that various alterations,
modifications and improvements will readily occur to those skilled
in the art. Such alterations, modifications and improvements,
though not expressly described above, are nevertheless within the
spirit and scope of the invention. Accordingly, the foregoing
discussion is intended to be illustrative only, and not limiting;
the invention is limited and defined by the following claims and
equivalents thereto.
* * * * *