U.S. patent application number 14/931535 was filed with the patent office on 2016-05-05 for in-situ mining of ores from subsurface formations.
This patent application is currently assigned to BAKER HUGHES INCORPORATED. The applicant listed for this patent is Emily Crose, Rocco DiFoggio, Scott Donald, Edwin Jong, Derek Mathieson, Dan Moos, Rudolf Carl Pessier. Invention is credited to Emily Crose, Rocco DiFoggio, Scott Donald, Edwin Jong, Derek Mathieson, Dan Moos, Rudolf Carl Pessier.
Application Number | 20160123096 14/931535 |
Document ID | / |
Family ID | 55852106 |
Filed Date | 2016-05-05 |
United States Patent
Application |
20160123096 |
Kind Code |
A1 |
Mathieson; Derek ; et
al. |
May 5, 2016 |
IN-SITU MINING OF ORES FROM SUBSURFACE FORMATIONS
Abstract
An in situ method of mining is disclosed. In one non-limiting
embodiment, the method includes: defining an ore volume; drilling a
large number of vertical boreholes; forming lateral boreholes from
at least some of the vertical boreholes; transporting the ore cut
during drilling of the vertical and lateral boreholes to a surface
location; and separating the ore received at the surface from other
materials. Additional ore may be extracted fracturing and/or
leaching the formation surrounding the drilled boreholes. The
residual ore at the surface may be disposed by pumping it into
already drilled boreholes or underground storage facilities.
Inventors: |
Mathieson; Derek; (The
Woodlands, TX) ; Pessier; Rudolf Carl; (Houston,
TX) ; DiFoggio; Rocco; (Houston, TX) ; Donald;
Scott; (Spring, TX) ; Jong; Edwin; (Houston,
TX) ; Crose; Emily; (Houston, TX) ; Moos;
Dan; (Palo Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mathieson; Derek
Pessier; Rudolf Carl
DiFoggio; Rocco
Donald; Scott
Jong; Edwin
Crose; Emily
Moos; Dan |
The Woodlands
Houston
Houston
Spring
Houston
Houston
Palo Alto |
TX
TX
TX
TX
TX
TX
CA |
US
US
US
US
US
US
US |
|
|
Assignee: |
BAKER HUGHES INCORPORATED
Houston
TX
|
Family ID: |
55852106 |
Appl. No.: |
14/931535 |
Filed: |
November 3, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62074493 |
Nov 3, 2014 |
|
|
|
Current U.S.
Class: |
299/7 ; 175/206;
175/50 |
Current CPC
Class: |
E21C 41/16 20130101;
E21B 41/0035 20130101 |
International
Class: |
E21B 21/06 20060101
E21B021/06; E21B 7/04 20060101 E21B007/04; E21B 49/00 20060101
E21B049/00; E21B 3/00 20060101 E21B003/00 |
Claims
1. A method of in-situ mining of ore from below the earth surface
without removing overburden, the method comprising: defining an ore
volume below the surface of the earth; drilling a plurality of
boreholes from a surface location through the ore volume to
disintegrates the ore volume, wherein each wellbore is drilled by a
rotating a drill bit attached at bottom of a drill string and
wherein a fluid is circulated through the drill string and the
wellbore fluid returning ("return fluid") to the surface carries
therewith the ore disintegrated by the drill bit; and processing
the return fluid at the surface location to recover a selected
element present in the ore in the return fluid.
2. The method of claim 1 further comprising defining the ore volume
using at least one of: seismic survey of earth subsurface that
includes the ore volume; information relating to previously drilled
boreholes; and acoustic ranging.
3. The method of claim 1, wherein drilling the plurality of
boreholes includes maintaining in place the overburden above the
ore volume.
4. The method of claim 1, wherein the plurality of boreholes are
drilled using pad drilling, wherein each borehole in the plurality
of boreholes is drilled from a common surface location and the ore
volume from all the return fluid is processed at the common surface
location.
5. The method of claim 1, wherein drilling the plurality of
boreholes comprises: drilling a plurality of main boreholes; and
drilling one or more lateral boreholes for at least some of the
main boreholes.
6. The method of claim 1, the method further comprising: fracturing
formation surrounding at least some of the boreholes in the
plurality of boreholes; and extracting ore from the fractured
formation.
7. The method of claim 1 further comprising; leaching formation
surrounding at least some of the boreholes in the plurality of
boreholes to produce fluid that contains the ore; and extracting an
element of interest from the fluid that contains the ore to the
surface.
8. The method of claim 1, wherein the ore field is more than 5000
feet deep and the plurality of boreholes includes at least one
hundred boreholes, wherein each borehole is spaced less than one
hundred feet from an adjacent borehole.
9. The method of claim 1, wherein each borehole is between five
feet and twenty five feet from at least one borehole.
10. The method of claim 1, wherein the plurality of boreholes
includes a first plurality of vertical boreholes, each such
borehole being larger than 28 inches in diameter; at least one
lateral wellbore formed from at least some of the main boreholes,
each such lateral bore hole being larger than eighteen inches in
diameter.
11. The method of claim 1, wherein the ore volume is an isolated
section formed by fracture planes created by fracturing of the
earth subsurface.
12. The method of claim 1 further comprising identifying an element
of interest in the ore volume during drilling of at least one
borehole in the plurality of boreholes using one of: a pulsed
neutron sensor calibrated for a peak relating to a mineral of
interest.
13. The method of claim 14, wherein the element of interest is
selected from a group consisting of: copper; uranium; gold;
platinum; nickel; and manganese.
14. The method of claim 1 further comprising determining quantity
of an element of interest from the ore separated from the return
fluid.
15. The method of claim 1 further comprising maintaining drilling
of a particular borehole in the plurality of boreholes a selected
distance from any other borehole already drilled.
16. The method of claim 15, wherein maintaining the selected
distance comprising using one of: acoustic logging while drilling;
and magnetic ranging while drilling.
17. The method of claim 1 further comprising disposing ore
remaining after processing ("residue") as one of: pumping the
residue with a fluid into one or more boreholes already drilled;
pumping the residue with cement into one or more boles already
drilled; and storing the residue in underground storage units.
18. A method of in-situ mining of an ore from below the earth
surface from a vein containing a metal of interest, the method
comprising; defining the vein containing the metal of interest;
drilling a borehole from a rig site through the vein to
disintegrate ore in the vein into cuttings by circulating a fluid
through the borehole; geosteering the drilling of the borehole
using an electrical measurements of surrounding the borehole during
drilling to maintain the borehole within the vein; receiving a
return fluid from the borehole containing the cuttings; separating
the cuttings from the return fluid; and processing the cuttings at
the rig site to recover the metal of interest from the
cuttings.
19. The method of claim 18, wherein the electrical measurements are
responsive to metallic elements present in the formation
surrounding the borehole and the formation in front of the
borehole.
20. A system for in-situ mining of ore from an ore volume below the
earth surface without removing overburden, the system comprising: a
drilling system for drilling a plurality of boreholes from a rig
site that uses a fluid to drill the plurality of boreholes and
receives a return fluid from each such borehole that includes
cuttings of the ore therein; a separator at the rig site that
separates the ore cuttings from the return fluid; and a processing
unit at the rig site that processes the separated ore cutting to
recover an element of interest from the ore cuttings.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application takes priority from U.S. Provisional
application Ser. No. 62/074,493, filed on Nov. 3, 2014, which is
incorporated herein in its entirety by reference.
BACKGROUND
[0002] 1. Field of the Disclosure
[0003] The disclosure herein relates to in situ mining of ores from
subsurface formations.
[0004] 2. Background of the Art
[0005] Many high quality ore bodies are located at depths at which
traditional mining methods, such as removal of overburden to
extract the ore or creating mine stopes and shafts and using mining
equipment or deploying humans are not feasible due to harsh
environment or not economical to build open pits or underground
mines. Also, a vast majority of the ore extracted, crushed and
processed does not contain adequate amounts of the desired
minerals. Also, current in situ leaching methods are limited to
recover copper and uranium from ores. Also, very little sampling is
currently performed in real-time. Such lack of information often
results in ore rock being treated as waste. Many of the current
mining methods also are not environmentally friendly.
[0006] This disclosure provides in situ methods of extracting ores
from subsurface formations by drilling a large number of
articulated boreholes through ore volumes and recovering additional
ore from around the drilled boreholes utilizing fracturing and
leaching of ores from around such boreholes.
SUMMARY
[0007] In one aspect, the disclosure provides a method of
extracting ores from a subsurface location or an ore deposit
without removing the overburden. In one embodiment the method
includes: defining an ore volume; drilling a large number of
mother-bores and forming lateral boreholes from the mother-bores;
transporting the ore cut during drilling to the surface; separating
the ore received at the surface; and extracting minerals from the
separated ore at the surface. In another embodiment, the method
further includes fracturing the drilled boreholes to recover
additional ore. In another embodiment, the method further includes
supplying a leaching fluid into drilled borehole to leach the ore
surrounding the already drilled borehole and transporting the
leached ore to the surface for recovery of the minerals contained
therein.
[0008] Examples of the more important features of in situ mining
have been summarized rather broadly in order that the detailed
description thereof that follows may be better understood, and in
order that the contributions to the art may be appreciated. There
are, of course, additional features that will be described
hereinafter and which will form the subject of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a detailed understanding of the apparatus and methods
disclosed herein, reference should be made to the accompanying
drawings and the detailed description thereof, wherein like
elements are generally given same numerals and wherein:
[0010] FIG. 1A shows an in situ mining system utilizing a large
number of boreholes for mining ore from a subsurface deposit or ore
field;
[0011] FIG. 1B shows a plan view of another exemplary layout of
large boreholes for mining ore;
[0012] FIG. 2 shows a schematic diagram of an exemplary drilling
system that may be utilized for in situ mining of ores;
[0013] FIG. 3 shows an exemplary fracturing system for use with the
in situ mining systems, including systems shown in FIGS. 1A and
1B;
[0014] FIG. 4 shows an exemplary leaching system for use with in
situ mining systems, including systems shown in FIGS. 1A, 1B and 3;
and
[0015] FIG. 5 shows an exemplary isolated subsurface ore bearing
volume for mining ore therefrom according to the various methods of
this disclosure.
DETAILED DESCRIPTION OF THE DRAWINGS
[0016] In general, the disclosure herein provides methods of
defining or identifying an ore field located below the earth
surface that includes an element of interest, extracting the ore by
drilling a large number of boreholes through the ore field and
processing of the extracted ore at the drill site to recover the
element of interest from the extracted ore. FIG. 1A shows a
borehole (or wellbore) system 100 that includes a large number of
main or primary boreholes 102a (also referred to as mother bores or
mother wellbores) formed from the surface 101 through an overburden
104 and into an ore field or ore volume 106 (area or field or
volume of interest) situated below or underneath the overburden 104
for the mining of ores (also referred to as minerals) from the ore
field 106. The overburden 104 is the earth volume above the ore
field 106. The boreholes 102a may be formed in the area of interest
106 in any suitable pattern that would enable in situ mining of a
substantial amount of ore from the ore field 106. In certain
embodiments, the number of mother-bores may be very large, such as
hundreds or thousands of boreholes, including vertical and
non-vertical boreholes. In an exemplary embodiment, boreholes 102a
are shown as vertical boreholes drilled or formed from the surface
101 through the overburden 104 and into the ore field 106. Drilling
through the overburden 104 avoids removal of the overburden 104 as
typically done in conventional mining methods. Accordingly, in situ
mining operations, i.e., mining without removing the overburden,
compared to conventional mining where overburden is first removed,
has less environmental impact and incur lower operational costs.
Further, the use of in situ mining may allow for mining of ore or
minerals from locations that are at depths, such as over 5000 feet,
wherein conventional mining methods, such as forming mine shafts
and employing large mining equipment therein to extract ore, is not
practical or feasible due to high temperatures or excessive
cost.
[0017] In some ore fields, the ore desired to be extracted 106 may
be present in the form of distributed deposits. In other ore
fields, the ore desired to be extracted may be deposited in veins.
The methods described herein may be used to extract ore from all
such deposits. In the exemplary ore field 106, some boreholes 102a
are shown to further include a number of lateral boreholes 108a
branched off from boreholes 102a. Certain lateral boreholes 108a
further include one or more sub-lateral boreholes 110a. Boreholes
102a, lateral boreholes 108a and sub-lateral boreholes 110a may
include boreholes of any suitable orientation, including vertical
boreholes, deviated boreholes and horizontal boreholes formed in
any direction. In aspects, the use of a large number of boreholes
102a in conjunction with directional drilling, multiple kickoffs,
trenchless drilling, and controlled drilling allow pin pointing
deposits and veins containing desired elements and mining from such
areas that were previously inaccessible for mining by conventional
methods. Information from seismic surveys and pilot boreholes
drilled through the ore field may be utilized to define an ore
field, such as ore field 106. Defining an ore field may include
developing the boundaries of the ore field 106 to develop a plan
for the boreholes 102a, 108a and 110a to maximize recovery of the
ore from the ore field 106. Any borehole pattern may be utilized
for in situ extraction of the ore from the ore field 106.
[0018] FIG. 1B shows a plan view of another borehole system 150,
wherein vertical or main boreholes 152a are formed according to a
predetermined symmetric manner. Horizontal boreholes 154a may be
formed out from the vertical boreholes 152a inside an ore field
116. Several horizontal boreholes 154a may be formed from a single
main borehole at different depths in the ore field 116, thereby
forming a large number of horizontal lateral boreholes in the ore
field 116 for in situ recovery of the ore. Any other borehole
pattern containing a large number of boreholes may be utilized for
the in situ ore recovery according to the methods described herein.
Referring to FIGS. 1A and 1B, the main boreholes 102a, 152a may be
relatively large, such as 28 inches or larger in diameter, lateral
boreholes 108a, 154a may be 20 inches or larger in diameter, while
sub-lateral boreholes 110a may be 16 inches or larger in diameter.
The spacing between adjacent boreholes may be selected to maximize
the ore recovery while assuring stability of the boreholes being
drilled and the boreholes already drilled. The stability criterion
may be met if the bores do not collapse. In one aspect, the
boreholes may be placed apart three times or more the diameter of
the hole being drilled or the adjacent hole already drilled. In
another aspect, the boreholes may be greater than five feet apart.
The spacing between the boreholes may be selected based on the type
of formation and the depth of the boreholes. Typically, a casing is
installed at an upper section of each main borehole for surface
stability for each main borehole. The main boreholes may be smaller
as the wellbore depth increases. The methods disclosed herein
enable recovery of ore from great depths, such as more than 15,000
feet, which is not feasible from conventional mining due to very
high temperature and pressure at such depths. The methods described
herein are useful for extracting ores that contain a variety of
elements, including, but not limited to gold, silver, platinum, and
copper. Sometimes, such elements are present in relatively narrow
veins in subsurface formations. Such veins may be mapped using
seismic images and pilot holes drilled. Boreholes may then be
drilled through such veins using navigation techniques described
later. Any suitable method of maintaining a desired distance
between adjacent boreholes may be used, including magnetic ranging
and acoustic ranging, known in the art.
[0019] FIG. 2 shows a schematic diagram of an exemplary drilling
system 200 for drilling boreholes, such as boreholes 102a, 108a and
110a shown in FIG. 1A for in situ mining of ores. The system 200 is
shown drilling an exemplary borehole 202 by a drill bit 220
conveyed by drill string 228. The drill string 228 includes a
drilling assembly 210 at a bottom of a tubular 212, such as made
from connecting drill pipes or coiled tubing. The drill bit 220 is
attached to the bottom of the drilling assembly 210 (also referred
to as bottomhole assembly or "BHA"). The drilling assembly 210
includes a steering device 222 and a number of sensors commonly
denoted by numeral 224 for steering the drill bit 220 along desired
or selected borehole paths, such as borehole paths 108a and 110a.
Such drilling is also referred to herein as "geosteering". The
drill bit 220 is rotated by a motor at the surface and/or by a
drilling motor (not shown) in the drilling assembly 210 to drill
the borehole 202 through an overburden 204 to an ore field or
deposit 206. The drill bit 220 may be any suitable available drill
bit. During drilling, the drill bit 220 cuts the deposit 206,
creating ore cuttings ("ore") 240. A drilling fluid 232 is supplied
from the surface into the tubular 212, which fluid discharges at
the bottom of the drill bit 220 and returns to the surface via
annulus 214 between the drill string 228 and the borehole 202. The
returning fluid ("return fluid") 242 moves the cuttings 240 to the
surface 201. Thus, the return fluid 242 is a mixture of the
drilling fluid 232 and ore 240. As the drilling operations
continue, cuttings 240 are continuously extracted from the ore
field 206 and moved to the surface 201 by the return fluid 242.
Thus, in the system 200, the ore 240 is broken underground (in
situ) and moved to the surface without removing the overburden 204.
The fluid flow 232 may be supplied into tubular 212 via fluid
supply 230 facilities. Fluid 232 may include any suitable drilling
fluid and may include lubricants and additives to facilitate the
drilling and to transfer cuttings 240 to the surface 201.
[0020] In a non-limiting exemplary embodiment, drill bit 220 is
steered by a steering device 222. The steering device 222 may
include any available steering device, including, but not limited
to, a device that includes a number of force application members
that apply force on the inside of the borehole 202 to steer the
drill bit 220 in the desired direction. In aspects, the sensors 224
provide information about the location of the drill bit 220 in the
ore field 206 relative to a known location, such as true north. An
operator and/or a control circuit or controller 260 in the drilling
assembly 210 and/or a control circuit or controller 290 at the
surface 201 may direct the steering device 222 to steer or maintain
the drill bit 220 along the desired path. The controllers 260 and
290 may include processors, such as microprocessors, memory devices
and programmed instructions for geosteering and to perform other
downhole functions in real time. The controllers also may include
circuits for processing measurements from the various sensors 224
to determine in real time the various properties of the
constituents of the materials in the ore field 206. The sensors 224
also may provide information that enables the operator and/or the
controllers 260 and/or 290 to maintain the drill bit 220 in the ore
field 206. Thus, the sensors 224 provide information about elements
in the ore and distances from the boundaries from subsurface faults
and previously drilled boreholes. Such information may be utilized
to maintain the drill bit in the desired ore zone and a desired
distance from the previously drilled boreholes.
[0021] Sensors 224 may include a variety of sensors, including, but
not limited to, accelerometers and magnetometers for providing the
location and orientation of the drilling assembly 210 for
geosteering. Sensors 224 may further include logging-while drilling
sensors, including, but not limited to electrical sensors (such as
resistivity sensors), electromagnetic sensors, acoustic sensors,
nuclear logging sensors, elemental spectroscopy sensors, and pulsed
neutron sensors. The sensors 224 may be characterized for a
particular mineral or element of interest. For example, for a
pulsed neutron sensor, peaks may be calibrated based on the mineral
or element of interest in a particular ore field 206, such as
copper, uranium, gold, manganese, nickel, and rare earths to
provide optimal detection of such minerals. Downhole logging tools
exist that perform pulsed neutron elemental analysis wherein the
formation is temporarily irradiated with neutrons, which strike the
nuclei of elements, which subsequently emit radiation including
gamma rays of various energies whose unique spectral fingerprints
then allow identification and quantification of those elements.
Even when there is spectral overlap, it is possible to distinguish
one spectrum from another because different radioisotopes have
different half-lives so one can wait to collect spectral data until
after radiation from an interfering species has decayed away. The
sensitivity of this technique depends upon the element. Tables of
sensitivities for various elements are well known. Therefore,
operators can geosteer along a vein of a precious metal or some
other element by performing real time elemental analysis. Downhole
elemental analysis might also be performed by focusing a laser or a
spark on cuttings lying just outside of an optical window analogous
to the elemental analysis of a fluid by laser induced breakdown
spectroscopy (LIBS) and spark-induced breakdown spectroscopy (SIBS)
described in U.S. Pat. No. 7,530,265, which is incorporated herein
by reference in its entirety. In another method of drilling a
borehole through an identified vein containing a metal, such as
gold, platinum, etc., a resistivity sensor in the BHA may be used
to determine in real time the resistivity of the formation
surrounding the borehole and in front of the drill bit. Such
sensors can provide relatively accurate information relating to the
presence of metals and concentrations levels in the ore. This
information may be utilized to maintain the drill bit 220 in the
vein containing the selected ore. In other embodiments, alternative
sensors may be used to find other materials, such as platinum and
diamonds. Information from sensors 224 may also provide rock type
identification and correlation, rock mass characterization,
litho-stratigraphic interpretation, ore body delineation, grade
estimation, etc. The measurements from the sensors 224 may be
processed by the downhole controller 260 to determine the various
properties of the ore and the rock and to take actions, such as
geosteering. Alternatively, or in addition thereto, information
from the sensors 224 may be telemetered to the surface controller
290, which may process such information and take actions. Any
suitable telemetry system may be used, including, but not limited
to mud pulse telemetry, electromagnetic telemetry, or electrical
conductors or optical fibers in the drill string 228. A telemetry
device 292 in the drilling assembly 210 may provide two-way
communication between the controllers 260 and 290. For ore
processing at well site, small conventional smelting or leaching
units may or more environmentally friendly bioleaching units may be
set up at the rig site.
[0022] As the return fluid 238 is received at surface 201, the ore
240 (cuttings) may be separated from the fluid 232 and processed or
partially processed near the rig site 201. In an exemplary
embodiment, a separator 234 separates the ore 240 from fluid 232.
An ore processor 236 may further refine the separated ore 240 into
a material or form suitable for transportation away from in situ
mining system 200. The ore processor may include a smelter, for
example, for extracting a metal from the ore, a chemical processing
unit for leaching the desired element from the ore or any other
facility suitable for extracting the desired elements from the ore
240. In general, the amount of the desired element in the ore is
often less than one percent by weight or volume. The ore or
material remaining after processing (the "discarded material" or
"residue ore") may be disposed in any suitable manner. In certain
embodiments, a disposal unit 238 receives and stores residue ore.
In certain other embodiments, a disposal unit 238 recycles or
reintroduces the residue ore into one or more boreholes already
drilled or into an underground facility formed to store such
undesired material. The ore residue may be mixed with a suitable
fluid, such as water and pumped into the boreholes or storage
facilities or contained by other known disposal methods including
pumping cement and residual cuttings back into the boreholes. The
ore recovery methods described in reference to system 100 of FIGS.
1A and 1B and system 200 of FIG. 2 enable in situ recovery of ores
during drilling of boreholes 102a, 108a and 110a through the ore
field or volume 106. The remaining ore in the field 106 or a
portion thereof may recovered by secondary operations or methods
that may include leaching the ore surrounding some or all boreholes
102a. 108a and 110a or fracturing the ore around such boreholes and
then leaching the fractured ore, as described in more detail in
reference to FIGS. 3 and 4.
[0023] FIG. 3 shows an exemplary non-limiting system 300 for
fracturing (also referred to as fracing) for use with in situ
mining systems, including system 100 of FIG. 1A and system 150 of
FIG. 1B. In aspects, the use of the fracturing system 300 with in
situ mining systems, such as system 100 enables recovery of
additional ore from the mineral deposit or ore field 106. For
simplicity, the system 300 is shown to include a single main
borehole 351 formed in an ore field 306 and lateral boreholes 353a
and 353b formed from the main borehole 351. In general, an area or
a zone around a borehole may be fractured by supplying a treatment
fluid (also referred to as the frac fluid) 349 from a source 350
under pressure to create the fractures in such zone. The fluid 349
may contain a proppant, such as sand or synthetic beads. In the
non-limiting exemplary system 300, to fracture a zone Z around the
borehole 353a, perforations 352 may be created to facilitate the
fracing operations. Perforations 352 may be created by any suitable
method, mechanism or technique, including, but not limited to,
perforating guns. Perforations 352 may facilitate cracking or
fracturing of the formation around the borehole 353a. In certain
embodiments, zones of interest to be fractured may be isolated with
isolation devices 356 prior to fracing operations. Isolation
devices 356 enable the fluid 349 to be contained between the
isolation devices 356 and create fractures 354 in a desired area.
Isolation devices 356 may further isolate other downhole fluids
from migrating to other areas, as well as preventing frac fluid 349
from migrating to other areas. In an exemplary embodiment, frac
fluid 349 is pumped from a frac fluid source 350 to exert pressure
upon deposit 306 and perforations 352. The frac fluid 349 may be
any suitable treatment fluid, and may include components such as
water, sand, guar, synthetic beads, lubricants, and other
additives. As the frac fluid 349 pressure builds up in the wellbore
353a, fractures 354 tend to propagate through the deposit 306.
Fractures 354 allow removal of more of the deposit 306 because they
create a greater surface area to be exposed for leaching operations
described herein. In other embodiments, explosives are utilized to
fracture ores surrounding the boreholes.
[0024] FIG. 4 shows an exemplary non-limiting leaching system 400
for use with an in situ mining system, such as system 100 of FIG.
1A. The system 400 is shown to include a main borehole 451 formed
in an ore field 406 and lateral boreholes 408a and 408b formed from
the main borehole 451. In the system 400, to leach a section of a
borehole, such as borehole 408a, a leaching fluid 466 is supplied
into borehole 408a via a tubing (not shown). The leaching fluid
flow 466 may be supplied into borehole 408a from a leaching fluid
source 464 at the surface 401. Leaching fluid source 464 may supply
any suitable fluid including any suitable chemicals for leaching
the particular underground deposits, including appropriate
lixiviates for various materials, such as copper, uranium, and
other suitable materials. As leaching fluid 466 is introduced to
deposit 406 and corresponding ore, leaching fluid 466 liquefies
deposit 406 which dissolves in the leaching fluid 466. Thus, the
leaching fluid 466 becomes impregnated with the chemically reacted
ore deposit 406 and allows greater yields and movement of the ore.
In certain embodiments, borehole 402 is fractured via a fracturing
process (as previously described) to allow leaching fluid 466 to
interact with fractures 454. The fractures 454 allow a greater
surface area for interaction with leaching fluid 466. In other
embodiments, leaching may be performed without prior fracturing of
the boreholes. The impregnated leaching fluid 468 may be brought to
the surface 401 by any suitable method, including by natural
pressure differential or artificial lift mechanisms. Recovered
fluid 468 may be received by a leaching fluid processor 462. In an
exemplary embodiment, leaching fluid processor 462 removes the
dissolved or liquefied deposits 406 from the impregnated solution
468. In certain embodiments, the leaching fluid processor 462
removes all or a portion of the desired material from the fluid
468. In certain embodiments, the recovered fluid 468 is stored in
leaching fluid storage 460. The stored fluid may be isolated,
partially isolated, chemically altered or otherwise processed.
[0025] FIG. 5 shows an exemplary non-limiting isolation system 500
for use with in situ mining or other mining systems. In an
exemplary embodiment, isolation system 500 utilizes naturally
occurring or preexisting fracture planes 570 to create isolation
volumes 510. In certain embodiments, preexisting fracture planes
570 are created during prior fracturing operations, such as those
described in system 300. In certain embodiments, fracture planes
570 are found via seismic surveys. In other embodiments, acoustic
measurements from downhole sensors may be utilized to confirm and
determine the location of fracture planes 570. In an exemplary
embodiment, computer simulations and other methods may be utilized
to place fractures 554 and locate fracture operations to allow for
desirable fracture propagation 572. Fracture propagation 572 allows
for isolated volumes to be formed. In an exemplary embodiment,
isolated volumes along propagated fractures 572 allows for volumes
to be isolated for future fracture operations, such as those
described in FIG. 3 In an exemplary embodiment, fracture operations
are facilitated as described in FIG. 3, by providing adequate fluid
pressure from fluid source 550.
[0026] In one embodiment, the isolated volume may be subjected to
additional operations. The isolated volume may be subjected to in
situ mining methods, fracturing methods, and leaching methods as
described above. In certain other embodiments, traditional mining
methods are used. In an exemplary embodiment, mine shaft 574 is
formed and utilized to allow the ore inside to be retrieved. In
alternative embodiments, in situ mining methods are utilized.
[0027] Thus in some aspects, the disclosure provides various
methods of extracting ores from a subsurface location or the ore
field without removing the overburden, i.e., without removing the
earth material from above the ore field. In one method the ore
volume or field may be defined or mapped from seismic surveys
and/or from pilot or test wells drilled into the subsurface. The
ore field may be several hundreds of feet (such as over 500 feet)
or several thousand feet (such as over ten thousand feet) below the
surface. The ore field may be relatively large, such more than ten
miles wide, more than 20 miles long and more than 1,000 feet deep.
In one non-limiting embodiment the method may further include
developing a well plan that may include a very large number of
vertical wells, such as a few hundred to a few thousand wells, some
or all of the wells further including one or several lateral wells.
The wells (vertical wells and lateral wells) are formed using
drilling assemblies that include a drill bit, a steering device,
sensors for providing the location of the drill bit, sensors for
providing information about the ore desired to be recovered while
drilling and a telemetry device that allows real time communication
between the drilling assembly and a surface location. The wells are
drilled by circulating a drilling fluid that discharges at the
drill bit bottom and returns to the surface via an annulus between
the drill string and the well. The ore drilled or disintegrated by
the drill bit travels to the surface with the drilling fluid. The
ore in the returning fluid is separated from the drilling at the
surface. If a very large number of wells (such as several thousand)
are drilled into the ore field, a substantial volume of the ore
from the ore field may be recovered from the ore field without
reducing or eliminating the overburden. Such a method is safe
relative to conventional mining methods as it does not involve
forming large shafts and transporting mining equipment or persons
into the mines. Measurements from the sensors are used to geosteer,
i.e., drill the wellbores along desired paths. In other method,
some or all drilled wellbores may be treated, such as fractured
and/or leached to recover additional ore from the ore field. In
another aspect, a subsurface zone containing a desired ore may be
isolated. Such zone may then be fractured and used for in situ
mining according to the methods described herein and/or traditional
mining methods, such as using mine shafts.
[0028] The foregoing disclosure is directed to the certain
exemplary non-limiting embodiments of in situ mining methods and
systems. Various modifications will be apparent to those skilled in
the art. It is intended that all such modifications within the
scope of the appended claims be embraced by the foregoing
disclosure. The words "comprising" and "comprises" as used in the
claims are to be interpreted to mean "including but not limited
to". Also, the abstract is not to be used to limit the scope of the
claims.
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