Note: Descriptions are shown in the official language in which they were submitted.
DOWNHOLE HEATING METHODS FOR SOLUTION MINING
Field of the Invention
The present invention relates to subterranean solution mining, and
specifically to heating
methods for solution mining.
Background of the Invention
It is known in the mining industry that heat is useful for evaporite solution
mining operations that
employ an injected solvent. Typically, more desired minerals can be dissolved
in a solvent when
solvent temperatures are increased. Employing heated injected brine for
solution mining, for
example, allows for a more concentrated production brine (saturated or super-
saturated) and
lower processing costs. However, many mineral host formations are cooler than
the optimum
formation temperature required to achieve maximum solubility of the evaporite
minerals in the
solvent brine, thus having a natural cooling effect upon the injected heated
solvent brine.
To overcome the above-mentioned impediments to solution mining, solvent brine
employed for
secondary recovery (i.e., selective solution mining) is heated on the surface
and injected at an
elevated temperature into an injection wellbore and into the mining beds. The
solvent brine,
however, must be heated on surface to temperatures sufficiently high to also
account for the heat
loss that can occur not only while being pumped on surface, but also while
being injected into
the injection wellbore and into a mining / dissolution zone.
Heat loss can occur in a formation containing the evaporite minerals to be
mined, as the host
formation is typically cooler than the temperature required to maintain
maximum solubility of
evaporite minerals in the solvent brine. Heat loss can also occur during the
dissolution process
itself due to endothermic processes occurring. It is estimated that this heat
loss can be over 40
degrees C, suggesting that in order to recover a saturated mineral brine
solution that is over 40
degrees C in temperature, the brine must be heated to over 80 degrees C on
surface prior to
injection into the wellbore in order for the brine to be at 40 degrees C once
it reaches the
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dissolution zone, as it will further cool during the dissolution process
before being produced to
surface. For some solution mining operations, such as those located in
Saskatchewan, Canada,
brine may need to be heated to 100 degrees C on surface before injection to
compensate for
anticipated heat loss. Such processes are inefficient and waste a considerable
amount of energy.
This is especially a problem in regions having long and cold winters, such as
Saskatchewan,
Canada.
It is therefore contemplated that for solution mining operations that employ
surface brine
heating, brine must be heated about 20 degrees C to 60 degrees C warmer than
the temperature
otherwise required for mineral dissolution at the mining zone. This is due to
heat loss of the brine
occurring while being pumped to the mining zone and the endothermic nature of
potash
dissolution. During the cold winter months, heat transfer from the brine to
the atmosphere and
surface casing can also be considerable, as the solvent brine may be exposed
to surface ambient
temperatures ranging from -20 degrees C to -30 degrees C.
Summary of the Invention
Heating means such as brine heaters can be employed downhole in an injection
well for heating a
mining solvent, such as brine, within the well but before the solvent enters
the mineral zone.
Downhole heating means can also be employed in a production well for heating
mining solutions
before the solution is produced to the surface from the mineral zone. Such
heating means can
also be useful in production wells to re-heat the formed mineral solution so
that minerals, such as
potassium chloride, do not crystallize out of solution as a result of
temperature loss occurring at a
production wellbore casing or during piping to a processing facility. The
heating means can be
in one or any combination of the injection well, the production well and the
mining solvent
source well (described below). The heating means can also be physically
located outside the
wellbore(s) but operative to effect a temperature increase of the target
fluids within the
wellbore(s).
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A methods for heating a mining solvent, such as brine, employed for solution
mining before
entering a mining zone and/or a mining solution before being produced to the
surface from the
mining zone is provided. Underground solvent heating can reduce heat loss as
compared to
previous contemplated surface brine heating methods.
According to a first aspect, there is provided a method for mining soluble
minerals from a
subterranean deposit containing the soluble minerals, the method comprising
the steps of:
a. providing an injection wellbore contacting the subterranean deposit;
b. providing heating means in the injection wellbore;
c. injecting a mining solvent into the injection wellbore;
d. allowing the heating means to heat the mining solvent while inside the
injection wellbore
to form a heated mining solvent;
e. allowing the heated mining solvent to enter into the subterranean deposit
and dissolve a
portion of the soluble minerals from the subterranean deposit, thereby forming
a mineral
solution comprising the heated mining solvent and the portion of the soluble
minerals;
and
f producing the mineral solution to surface.
In a further aspect, the method can include, before producing the mineral
solution to the surface,
the step of allowing the heating means to heat the mineral solution. Where the
step of producing
the mineral solution to surface comprises use of a production wellbore, the
method may
comprise providing a second heating means in the production wellbore.
In a further aspect, the injection wellbore comprises at least one of: a
vertical section; and a
horizontal section. The method may further comprise the step of allowing the
heating means to
heat the mining solvent while inside the at least one of: a vertical section;
and a horizontal
section.
In a second aspect, there is provided a method for producing liquid fluid from
a subterranean
deposit containing soluble minerals, the method comprising the steps of:
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a. providing a production wellbore contacting the deposit;
b. providing heating means in the production wellbore;
c. allowing the liquid fluid to flow into the production wellbore;
d. allowing the heating means to heat the liquid fluid while inside the
production wellbore
to form a heated fluid; and
e. producing the heated fluid to surface.
In a further aspect, the liquid fluid is a mining solution comprising mined
soluble minerals from
the subterranean deposit.
In a further aspect, the production wellbore comprises at least one of: a
vertical section; and a
horizontal section. The method may further comprise the step of allowing the
heating means to
heat the liquid fluid while inside the at least one of: a vertical section;
and a horizontal section.
According to a third aspect, there is provided a method for mining soluble
minerals from a
subterranean deposit, the method comprising the steps of:
a. providing an injection wellbore contacting the subterranean deposit;
b. providing a production wellbore contacting the subterranean deposit;
c. providing first heating means in the injection wellbore;
d. providing second heating means in the production wellbore;
e. injecting a mining solvent into the injection wellbore;
f allowing the first heating means to heat the mining solvent while inside the
injection
wellbore to form a heated mining solvent;
g. allowing the heated mining solvent to enter into the subterranean deposit
and dissolve a
portion of the soluble minerals in the subterranean deposit, thereby forming a
mineral
solution comprising the heated mining solvent and the portion of the soluble
minerals;
h. allowing the mineral solution to flow into the production wellbore;
i. allowing the second heating means to heat the mineral solution while inside
the
production wellbore to form a heated mineral solution; and
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j. producing the heated mineral solution to surface.
In a further aspect, the injection wellbore comprises at least one of: a
vertical section; and a
horizontal section. The method may further comprise the step of allowing the
first heating means
to heat the mining solvent while inside the at least one of: a vertical
section; and a horizontal
section of the injection wellbore.
In a third aspect, the production wellbore comprises at least one of: a
vertical section; and a
horizontal section. The method may further comprise the step of allowing the
second heating
means to heat the mineral solution while inside the at least one of: a
vertical section; and a
horizontal section of the production wellbore.
According to a fourth aspect, there is provided a method for producing liquid
fluid from a
subterranean region containing the liquid fluid, the method comprising the
steps of:
a. providing a production wellbore contacting the subterranean region;
b. providing heating means in the production wellbore;
c. allowing the liquid fluid to flow into the production wellbore;
d. allowing the heating means to heat the liquid fluid while inside the
production wellbore
to form a heated fluid; and
e. producing the heated fluid to surface.
In a further aspect, the fluid is a mining solvent comprising water.
In a further aspect, the production wellbore comprises at least one of: a
vertical section; and a
horizontal section. The method may further comprise the step of allowing the
heating means to
heat the liquid fluid while inside the at least one of: a vertical section;
and a horizontal section.
A detailed description of exemplary embodiments of the present invention is
given in the
following. It is to be understood, however, that the invention is not to be
construed as being
limited to these embodiments. The exemplary embodiments are directed to
particular
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applications of the present invention, while it will be clear to those skilled
in the art that the
present invention has applicability beyond the exemplary embodiments set forth
herein.
Brief Description of the Drawings
In the accompanying drawings, which illustrate embodiments of the present
invention:
Figure la is a simplified schematic view of a first embodiment of the present
invention;
Figure lb is a simplified schematic view of a second embodiment of the present
invention;
Figure 2 is a simplified schematic view of a third embodiment of the present
invention;
and
Figure 3 is a simplified schematic view of a fourth embodiment of the present
invention.
Exemplary embodiments of the present invention will now be described with
reference to the
accompanying drawings.
Detailed Description of Exemplary Embodiments
Throughout the following description specific details are set forth in order
to provide a more
thorough understanding to persons skilled in the art. However, well known
elements may not
have been shown or described in detail to avoid unnecessarily obscuring the
disclosure. The
following description of examples of the technology is not intended to be
exhaustive or to limit
the invention to the precise form of any exemplary embodiment. Accordingly,
the description
and drawings are to be regarded in an illustrative, rather than a restrictive,
sense.
Throughout the following description, the terms "solvent brine", "solvent" or
"mining solvent"
should be interpreted to include aqueous solvents such as, but not limited to,
fresh water, process
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water, salt water, brackish water, saturated brine, brine saturated with
potassium chloride, brine
and any other solvent that could be employed for solution mining operations,
as would be
apparent to a person skilled in the art.
Throughout the following description, the terms "mining solution" and "mineral
solution" should
be interpreted to include solutions such as, but not limited to, solutions
created wherein a mining
solvent or solvent has dissolved minerals from a subterranean deposit that may
be ultimately
produced to surface, as would be apparent to a person skilled in the art.
Throughout the following description, the terms "mining zone" or "mineral
zone" should be
interpreted to include, but not be limited to, areas within a subterranean
deposit wherein minerals
can be mined.
Throughout the following description, the term "mining solvent source" should
be interpreted to
include, but not be limited to, a subterranean source of mining solvent.
The methods can involve downhole heating of solvent employed for solution
mining, whereby
the solvent is heated within the wellbore, thus potentially augmenting the
naturally occurring
geothermal temperature allowing for the possibility of a consistent and warmer
solvent
temperature at the depth of the minerals to be mined. The methods can also
involve downhole
heating of fluids, such as mining solutions, as they travel inside a
production wellbore to the
surface.
The downhole heating means can be employed for heating a mining solvent and/or
mining
solution while inside generally vertical injection and/or production
wellbores. Perforations or
ports along the injection wellbore may be provided allowing the injected
heated mining solvent
to enter into a subterranean deposit and dissolve some of the soluble minerals
from the deposit,
thereby forming a mineral solution that is produced to the surface.
The downhole heating means can be employed for heating a mining solvent and/or
mining
solution while inside generally horizontal portions of injection and/or
production wellbores. As
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described below, the horizontal portion of the injection wellbore may comprise
perforations or
injection ports to ensure even amounts of mining solvent are injected into the
targeted mining
zone through each of the injection ports. Such solution mining well
arrangements are well known
in the art.
By heating of the mining solvent in the wellbore and at the mining bed depth
rather than at
surface, the heat loss can be reduced from the solvent, and can re-heat the
mining solution in the
production well before it is produced and piped to a processing plant. A
consistent temperature
regime can be produced in a wellbore and at the mining level that is
significantly warmer than
the surface ambient temperature, as opposed to the typical practice in the
solution mining
industry whereby the solvent fluid is heated at surface either in close
proximity to the injection
wellbore or at the processing plant.
Heat loss found in conventional surface solvent-heating systems caused by
convection and heat
transfer between the hot solvent fluid and the typically cool ambient surface
temperatures at the
near surface wellbore regions can also be reduced. The heat energy lost to the
formation during
the dissolution of soluble minerals, such as evaporite minerals, may also be
used to replaced as
dissolution is typically an endothermic process.
Means for heating The mining solvent/solution within an injection and/or
production wellbore
can be heated with a variety of devices including, but are not limited to,
mineral insulated
heating cables, other heating cables, heating devices employing
electromagnetic energy, heating
devices employing radiofrequency energy, electric heating devices, or other
types of heating or
heat conduction systems that would be well suited for solution mining using a
wellbore that has
at least one vertical section and preferably also a horizontal section.
The mining solvent can be heated just before entering the mining zone by using
a mineral-
insulated ("MI") cable such as those manufactured and described by MCAAA Ltd.
(http ://www.mc a an . eu).
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MI cable can be used to heat the solvent near the mining zone so that heat
loss can be controlled
and reduced due to a more consistent geothermal temperature regime in the
wellbore, at depth. In
some embodiments, MI cable can be provided in 2,000 meter spools so that cable
can be run as a
continuous string into injector wells or production wells to augment, and take
advantage of, the
naturally occurring geothermal temperature at the mining depth, which should
minimize the
energy needed to keep the brine at an optimal temperature.
Controlled downhole heating through the use of the downhole heating means,
such as a MI
cable, can heat the injected mining solvent travelling down an injection
wellbore until
immediately before the solvent reaches the mining zone. In cases where both
the injection and
production wellbores are both being heated, heat may be transferred to the
mining zone helping
to ensure that the solvent brine is at, or above, the geothermal formation
temperature so that the
efficiency of the mineral dissolution process is maximized.
Soluble minerals or mineral compounds with the aid of a suitable solvent brine
heated downhole
can be mined with use of a heating means, such as a MI cable placed within the
horizontal and/or
vertical injection and/or production well as required. This can facilitate the
recovery of chloric,
nitric and sulphatic minerals, and particularly potassium chloride (potash)
minerals such as
sylvinite/sylvite or earnallite.
For conventional techniques that provide heating to the solvent brine only at
the surface, the
solvent brine is typically heated to temperatures well above the geothermal
temperature of the
mining zone to compensate for the anticipated conductive heat loss to be
experienced by the
solvent as it travels from the surface down to the mining zone. Similarly,
fluids, such as mining
solution, can experience heat loss as they are produced to the surface from
the mining zone. This
can be quite costly in colder climates like those found in Saskatchewan,
Canada. Previous
heating techniques also compensate for the anticipated heat loss caused by the
dissolution
processes, occurring in the mining zone, as these processes are typically
endothermic when, for
example, sylvite or carnallite minerals are dissolved.
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The present process can be used to help reduce recrystallization of sylvite,
carnallite, or sodium
chloride in an injection/production wellbore and above-surface piping.
Recrystallization of such
minerals can reduce the flow of liquid fluids into and out of the mining zone.
This is often
caused by the cooling of a saturated or super-saturated mining solution as it
is being withdrawn
from the mining zone and transported to the processing facility. This
unintended recrystallization
can have a detrimental effect on the mining process by further cooling the
brine and mining
solution, restricting flow in dissolution cavities or the mining plane/zone,
and causing crystal
build-up and flow restrictions within the production and injection wells and
production piping
system.
Non-selective or selective solution mining can be carried out by a continuous
injection of a
heated solvent, such as water or brine, more particularly of a brackish to
saline brine type, into a
potash-bearing stratum. The amount of water or brine that is required to be
injected and its
capability to dissolve minerals from the host rock is dependent on the ratio
of soluble minerals
within the host rock, the naturally occurring geothermal temperature of the
host rock, and the
temperature of the injected water or brine. Downhole heating can be an
efficient method to
control the temperature of the injected water or brine thereby potentially
increasing the
efficiency of the dissolution process.
Following the principles of thermodynamics, the methods can involve running a
MI cable with
up to 2000 meters of continuous cable (i.e., no splices) into an injection
wellbore so that once a
certain temperature is achieved within the wellbore, the MI cable can easily
maintain the
temperature of a heated injected solvent or process brine so that the desired
dissolution
temperature is achieved and maintained within the mining zone. A MI cable
downhole heating
means can also be installed in the vertical and/or horizontal portions of a
production well so that
the mining solution produced from the mining zone through the production well
is at an
appropriate temperature before being piped to a refinery plant to reduce the
risk or amount of
recrystallization.
.. The injected mining solvent may be composed of a combination of fresh brine
from deeper
deposits and spent plant effluent. The ratio of the components forming the
mining solvent may
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be adjusted according to the prevailing ore ratio in the mineral bed to be
mined. The heat content
of the injected solvent may be determined by considering the relative
proportions of the
components used to form the injected solvent and their temperatures. The
amount of downhole
heating required to cause an injected solvent temperature to be at or greater
than the geothermal
formation temperature at the mining zone can then be determined based on the
determined heat
content of the injected solvent.
While the heat content of the process brine employed in most cases is equal to
or higher than the
geothermal temperature of the mining horizon, the heat content of a mixture
with effluent may be
either higher than, equal to, or lower than that of the mineral stratum to be
mined. A downhole
MI cable heater can be used to more consistently regulate the temperature of
the mining solvent
(composed, for example, of process brine and effluent) being injected from the
injection
wellbore into the mining zone and control the temperature of the mining
solution as it is
produced from the mining zone to the surface and sent to a refinery plant.
Brine, solvent or process water can be heated in the wellbore before being
injected from the
wellbore and into the mining zone containing the desired minerals to be
solution-mined, such as
desired evaporite minerals. This can be achieved by placing a MI cable into a
coil tubing string
or other suitable tubing string and allowing the MI cable to be inside the
coil tubing string as it is
inserted into a vertical or horizontal injection well to a desired location.
Alternatively, a coil
tubing sting or suitable tubing string may also be already run inside the
well. In such cases, the
MI cable may be pushed or pulled to the end of the wellbore with the
assistance from an injected
solvent.
The use of a coil tubing string can protect the MI cable from wear and tear as
the cable is
inserted inside a wellbore. A coil tubing string also allows for a MI cable to
be safely placed
inside either a generally vertical and/or generally horizontal portion of an
injection and/or
production well. The MI cable is allowed to increase in temperature thereby
heating the solvent
or solution inside the coil tubing string that has been inserted inside the
injection or production
well. The heated injected solvent inside the coil tubing string is allowed to
be injected from the
wellbore (through ports, perforations or other suitable means) into the mining
zone.
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A number of suitable arrangements for employing a coil tubing string within a
well casing can be
used. For example, a tubing string can be inserted inside a vertical wellbore
casing and
positioned above the perforations or frack ports on the casing which are
positioned along the
well casing portion that is inside the mining zone. The tubing string can be
held in place with a
packer or series of packers that also prevents the injected mining solvent
from entering into the
annulus between the tubing string and the casing. In some embodiments, a
packer or series of
packers may be employed on a horizontal wellbore for preventing the injected
mining solvent
from entering the annulus between the string and the casing, and instead
ensuring that the mining
solvent is injected directly into the mining zone through the injection ports
on the casing. Such
an arrangement may be employed with an injection control device as would be
known to those
skilled in the art.
The solvent that is heated can be derived from subterranean sources of
naturally occurring
brackish to saline water, refinery plant effluent brine, or mixtures thereof,
that is derived mainly
from:
a subterranean source located close to the strata of the embedded soluble
minerals,
a subterranean source located under the strata of the embedded soluble
minerals,
a subterranean source located above the strata of the embedded soluble
minerals, and
a subterranean source located at or near the strata of the embedded soluble
minerals, and
is either a saturated or under-saturated salt solution or brine.
The solvent, such as mining solvent, can also be heated while being produced
from a
subterranean source (i.e., mining solvent source) such as, but not limited to,
those described
above.
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The voltage of the heating means, such as a MI cable, and the mining solvent
injection rate can
be adjusted to ensure that the desired temperature of the mining solvent is
obtained. This solvent
temperature may further be customized in the same way as previously described
above.
In one aspect, the heated solvent can be injected through the mining zone to
recover the desired
minerals, such as potash (specifically the minerals that make up Potash), from
the produced
mineral solution and then repeating this procedure until the deposit is
substantially exhausted.
For example, a mineral selected from a group consisting of sylvite and
carnallite can be
recovered from subterranean deposits by injecting a solvent brine (i.e.,
mining solvent) into a
wellbore that may be initially heated geothermally and/or by
artificial/mechanical means, and is
(further) heated by a downhole heating means to a heat content equal to or
higher than the
naturally occurring heat of the mineral-bearing stratum. The solvent brine is
then pumped (or
injected) out through multiple injection points/ports along a wellbore while
still being heated by
the MI cable to ensure that all of the solvent brine exits the horizontal or
vertical wellbore at
virtually the same temperature along the wellbore.
The injected solvent can be retained inside a mining zone for a time period
required for the
injected solvent to reach saturation of the desired minerals, and then
recovering the saturated
solution by means of production wells that are in fluid communication with the
injection wells. A
MI cable can also be run into the entire producing well to heat the solution
before recovery at
surface.
Turning to Figure la, a first embodiment is illustrated. In this first
arrangement, a MI cable 106
is employed for heating the injected mining solvent inside the injection
wellbore, and more
specifically inside a coil tubing string 105 positioned inside a well casing
104 of an injection
wellbore. The coil tubing string 105 is configured to allow the injected
mining solvent to flow
out the end of the string 105 and into the annulus between the string 104 and
the casing 105. A
packer or series of packers (not shown) may be employed to hold the injected
mining solvent
within the annulus that is within the mining zone.
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Other suitable arrangements for employing a coil tubing string within a well
casing could be
used. For example, a tubing string can be inserted inside a vertical wellbore
casing and
positioned above the perforations or frack ports on the casing which are
positioned along the
well casing portion that is inside the mining zone. The tubing string can be
held in place with a
packer or series of packers that also prevents the injected mining solvent
from entering into the
annulus between the tubing string and the casing (i.e., bullhead injection).
In some embodiments,
a packer or series of packers may be employed on a horizontal wellbore for
preventing the
injected mining solvent from entering the annulus between the string and the
casing, and instead
ensure that the mining solvent is injected directly into the mining zone
through the injection
ports on the casing (i.e., zonal isolation injection). Such an arrangement may
be employed with
an injection control device ('ICD"), as would be known to those skilled in the
art.
A power supply transformer 101 is provided above surface in the vicinity of
the vertical or
horizontal wellbore. The power supply 101 is connected to a frequency supply
device 102, which
is connected to the wellhead 103 and a MI cable 106.
Power from the power transformer 101 is supplied to the frequency supply
device 102 and
converted to a frequency supply that is grounded by the wellhead 103 allowing
the MI cable 106
to increase in temperature. The MI cable 106 increases to a temperature
capable of heating the
brine or water (i.e., the mining solvent) inside the coil tubing string 105,
at the concentrated
heating zone 108, to a temperature greater than the geothermal temperature of
the mining zone.
The MI cable 106 shown is inserted into a coil tubing string 105 or
equivalent, which is
contained inside the wellbore casing 104. The coil tubing 105 may be run
inside a wellbore
comprising a limited entry injection system (not shown) or ICD (not shown),
comprising a series
of packers, to ensure that an even amount of brine or water is injected into
the targeted mining
zone through the injection ports 107 positioned along the wellbore casing 104.
Such limited
entry injection systems have been manufactured and sold by Packers Plus
(http ://packersplus.com/).
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As shown in Figure la, a concentrated heating zone 108 is created in the
generally horizontal
portion of the wellbore to heat up the brine or water contained within it to a
temperature that is at
or exceeds the targeted mining zone's geothermal temperature.
Turning to Figure lb, a second embodiment is illustrated that is generally
akin to that described
with respect to the first arrangement. In this second arrangement, the heating
zone 108 is created
in both the generally vertical and horizontal portions of the wellbore.
As discussed above, the MI cable 106 can also be inserted into a vertical
and/or horizontal
production well to heat the mining solution before it is recovered to the
surface.
Turning to Figure 2, a third embodiment is illustrated. In this third
arrangement, a MI cable 206
is employed for heating the mining solvent while inside a coil tubing string
205 positioned inside
a well casing 204 of a production wellbore comprising an open-hole portion
completion (i.e., no
casing or cement) as shown in Figure 2. A packer may be employed to ensure
that the mining
solvent and solution flows into the coil tubing string 205 when being produced
and does not flow
into the annulus between the tubing string 205 and well casing 204.
A power supply transformer 201 is provided above surface in the vicinity of
the vertical or
horizontal wellbore. The power supply 201 is connected to a frequency supply
device 202, which
is connected to the wellhead 203 and a MI cable 206.
Power from the power transformer 201 is supplied to the frequency supply
device 202 and
converted to a frequency supply that is grounded by the wellhead 203 allowing
the MI cable 206
to increase in temperature. The MI cable 206 increases to a temperature
capable of heating the
brine or water (i.e., the mining solvent) inside the coil tubing string 205,
at the concentrated
heating zone 208, to a temperature greater than the geothermal temperature of
the mining
horizon.
The MI cable 206 shown is inserted into a coil tubing string 205 or
equivalent, which is
contained inside the casing 204 of the wellbore.
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As shown in Figure 2, a concentrated heating zone 208 is created in the
generally vertical
portions of the wellbore to heat up the brine, water and/or solution
containing mined minerals
contained within the wellbore to a temperature that is at or exceeding the
targeted mining zone's
geothermal temperature.
Turning to Figure 3, a fourth embodiment is illustrated that is generally akin
to that described
with respect to the other arrangements above, however, it employs microwave
emitters as a
heating means instead of a MI cable.
In the fourth embodiment, a microwave downhole heating system employs a radio
frequency
source 301 to provide microwave frequency energy to microwave emitters or
antennas 305,
positioned along a vertical and/or horizontal wellbore, within a fluid that
allows RF energy to be
emitted from the emitters 305. The radio frequency source 301 provides energy
to the microwave
emitters or antennas 305 causing radiation to be produced which subsequently
produces heat to
increase the temperature of the mining solvent inside the casing 303 of an
adjacent well and the
mining zone.
A coaxial cable 304 is provided, run inside the adjacent well, for
repositioning where the energy
travels. This can be advantageous when horizontal wells are employed. The
coaxial cable 304
may also allow for changes in how the configuration of the energy is emitted
and may assist in
ensuring that the wellbore is being heated as desired. The coaxial cable 304
may further allow
for heat to radiate out into the mining zone, allowing for further heating of
the mining solvent
once the solvent has been injected into the mining plane/zone.
A wellhead 302 is provided that acts as a ground and can be employed for
controlling the flow of
certain fluids into and out of the wellbore which may assist in maintaining a
desired temperature
inside the wellbore.
Unless the context clearly requires otherwise, throughout the description and
the claims:
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= "comprise", "comprising", and the like are to be construed in an
inclusive sense, as opposed to
an exclusive or exhaustive sense; that is to say, in the sense of "including,
but not limited to".
= "connected", "coupled", or any variant thereof, means any connection or
coupling, either direct
or indirect, between two or more elements; the coupling or connection between
the elements can
be physical, logical, or a combination thereof
= "herein", "above", "below", and words of similar import, when used to
describe this
specification shall refer to this specification as a whole and not to any
particular portions of this
specification.
= "or", in reference to a list of two or more items, covers all of the
following interpretations of
the word: any of the items in the list, all of the items in the list, and any
combination of the items
in the list.
= the singular forms "a", "an" and "the" also include the meaning of any
appropriate plural
forms.
Words that indicate directions such as "vertical", "transverse", "horizontal",
"upward",
"downward", "forward", "backward", "inward", "outward", "vertical",
"transverse", "left",
"right", "front", "back", "top", "bottom", "below", "above", "under", and the
like, used in this
description and any accompanying claims (where present) depend on the specific
orientation of
the apparatus described and illustrated. The subject matter described herein
may assume various
alternative orientations. Accordingly, these directional terms are not
strictly defined and should
not be interpreted narrowly.
Where a component (e.g. a circuit, module, assembly, device, drill string
component, drill rig
system etc.) is referred to herein, unless otherwise indicated, reference to
that component
(including a reference to a "means") should be interpreted as including as
equivalents of that
component any component which performs the function of the described component
(i.e., that is
functionally equivalent), including components which are not structurally
equivalent to the
disclosed structure which performs the function in the illustrated exemplary
embodiments of the
invention.
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Specific examples of methods and apparatus have been described herein for
purposes of
illustration. These are only examples. The technology provided herein can be
applied to contexts
other than the exemplary contexts described above. Many alterations,
modifications, additions,
omissions and permutations are possible within the practice of this invention.
This invention
.. includes variations on described embodiments that would be apparent to the
skilled person,
including variations obtained by: replacing features, elements and/or acts
with equivalent
features, elements and/or acts; mixing and matching of features, elements
and/or acts from
different embodiments; combining features, elements and/or acts from
embodiments as described
herein with features, elements and/or acts of other technology; and/or
omitting combining
features, elements and/or acts from described embodiments.
The foregoing is considered as illustrative only of the principles of the
invention. The scope of
the claims should not be limited by the exemplary embodiments set forth in the
foregoing, but
should be given the broadest interpretation consistent with the specification
as a whole.
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