Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
METHOD FUR RECOVERING MINERAL VALUES EROS A
SUBTERRANEAN FORMATION THROUGH WHEELBASE
_ PENETRATING THE FORMATION FROM TUNNELS
This invention relates to processes for the recovery
of mineral values from a subterranean formation by the use of
mining techniques in combination with drilling techniques.
This invention further relates to the recovery of
mineral values from a subterranean formation by the use of
wheelbarrows penetrating the subterranean formation from tunnels.
This invention further relates to the recovery of
mineral values from a subterranean formation by the use of well-
bores penetrating the subterranean formation from tunnels and
the use of injected fluids to enhance the recovery of mineral
values from the subterranean formation.
Many deposits of minerals are known which are not
readily recovered by the use of conventional mining techniques
or by conventional drilling techniques. Such deposits may be
metal ore deposits, hydrocarbon deposits and the like. The
factors inhibiting the recovery of -these mineral values from
such subterranean formations may be economic, technical and/or
environmental. For instance, it may be impractical from an
economic or technical point of view to actually remove material
from the subterranean formation for processing either under-
ground or at the surface to recover mineral values from the
material. Such impracticality may arise for a variety of
reasons, such as the relative value of the mineral recovered,
the cost of the removal and recovery step, the quantities of
mineral contained in the reserve, the grade of the metal ore
and the like. In other instances, it may be extremely undesir
able that the surface be disturbed above the subterranean
deposit. In such instances, drilling from the surface is
impractical Further, in many instances, when the injection of
to Jo
a fluid to enhance recovery of the mineral values is required
the well spacings required for the effective use of the fluid
may be so close as to he prohibitively expensive. In some
environments such as in Alaska and other areas where permafrost
is present, the difficulty in positioning, maintaining and
operating drilled wells is well known. While such can be
accomplished, it tends to be relatively expensive. As a result
of these and other factors, many deposits are known which are
not readily mined or produced by either conventional mining or
by conventional drilling techniques.
Mineral reserves which may be recovered by -the use of
an injected fluid to enhance recovery are metals such as gold,
silver, uranium, copper and the like which may be recovered from
subterranean formations by leaching or other fluid contact with
the formation, oils such as crude oil, heavy crude oils carbon
Nazis material from tar sands, shale oils and the like, Such
deposits are known in a variety of locations and the reasons
for the difficulty in the recovery of the mineral values from
such deposits are as varied as are the number of deposits. The
difficulties may arise from the location of the formation, such
as in a difficultly accessible area, the depth of the formation,
the neology of the particular region, special surface conditions
such as permafrost, water, ice, ice floes and the like.
Efforts have been made in some instances to recover
mineral values from such subterranean deposits by processes
which are described in various publications referring to oil
mining. These articles refer to the recovery of oil by various
techniques which seek to combine mining and conventional
drilling techniques. considerable effort has been directed to
the development of such methods and a variety of such methods
are shown in the following references which were considered in
the preparation of this application:
~;~3~9~
US Patent No
1,506j920 issued September I 1924 to DeChambrier
1,63~,235 issued June 28, 1~27 to Ryan
1,S34,236 issued June OR 9 1927 to Ryan
1,660,187 issued February I 1928 to Erupt
1,667~269 issued April I 1928 to Ryan
1,722,679 issued July 30, 1929 to Ryan
1,735,481 issued November 127 1929 to Urn
1,811,560 issued June 23, 1931 to Ryan
1,811,561 issued June 23, 1931 to Ryan
17812,305 issued June 30, 1931 to Ryan
1,851,446 issued March 29, 1932 to Ryan
1,935,643 issued November 21, 1933 to Laughlin
2,331,072 issued October 5, 1943 to Hansen et at.
2,989,294 issued June 20, 1961 to Coyer
4,099,783 issued July 11, 1978 to erupt et at.
4,165,903 issued August 28, 1979 to Combs
~,201,420 issued May I 19~0 to Luckily en at.
4,227~743 issued October 14, 1980 to Ruin en alto
4,265,485 issued May 5, 1981 to Boxer man en alp
4,283~088 issued August 11, 1981 to Tabakov e and
toil Mining A Technical and Economic Feasibility
Study of Oil Production by Mining Methods r Final
Report on Contract Jo. Joy (USE Department of
the Interior, Bureau of Mines colder Associates,
October 1978.
mining for Petroleum: Feasibility Study Final
Report on Contract No J0275002 Us department of
the Interior Bureau of Mines) Energy Department
Consultant Inc., July 1978.
toil Mining, WIFE. Reed Jar Junk 1~79, FE-2468-42
(available from NITS
kern River Hot Plate Project Launched, I. Williams,
Oil and Gas Journey August 23~ 1982.
While these references show a variety
of processes utilizing a combination of mining and drilling
techniques for the recovery of oil from subterranean formations
there has been little commercial use of such techniques and a
continuing search has been directed to the development of imp
proved techniques of this type which may be efficiently and
effectively used to recover mineral values from subterranean
formations.
According to the present invention 7 such mineral
values may be recovered from such mineral bearing subterranean
Lo
formations by a method consisting essentially of pa) positioning
a shaft from the surface to a subterranean formation, the sub-
terranean formation being positioned generally parallel to the
mineral bearing subterranean formation; (b) positioning at
least two tunnels in the subterranean formation, the tunnels
being spaced apart a selected distance and in communication
with the shaft; (c) positioning wheelbarrows to penetrate the
mineral bearing subterranean formation from the tunnels; (d)
injecting a fluid through at least a portion of the wheelbarrows
penetrating the mineral bearing subterranean formation from a
first tunnel to enhance the recovery of mineral values from
the mineral bearing subterranean formation via at least a
portion of the wheelbarrows penetrating the mineral bearing sub-
terranean formation from a second tunnel; and (e) recovering
mineral values from at least a portion of the wheelbarrows penes
treating the mineral wearing subterranean formation Eros the
second tunnel.
Such methods are particularly effective when the
mineral values to be recovered are hydrocarbonaceous materials
such as crude oil, heavy oils, carbonaceous materials from tar
sands and the like.
Figure 1 is a cross-sectional schematic diagram of
an embodiment of the present invention;
Figure 2 is a topographical schematic diagram of the
embodiment of the present invention shown in Figure l; and
Figure 3 is a topographical schematic diagram of
wheelbarrows positioned in selected tunnels from the embodiment
shown in Figure 2.
In the discussion of the Figures, the same numbers
will be used throughout to refer to the same or similar combo-
nonwhites
I
The invention will be discussed by reference to the
recovery of oil from an oil wearing subterranean formation,
although it will be readily understood that the invention is
also useful for the recovery of other mineral values from
subterranean formations containing such mineral values, as will
be discussed hereinafter.
In Figure 1, a shaft 24 is positioned from the surface
12 through a permafrost zone 14, overburden 18, and an oil
bearing formation 10 into a non-oil bearing formation 20. A
main tunnel I joins shaft I at its lower end and extends
horizontally into formation OWE A plurality of access tunnels
I intersect main tunnel 26 at substantially right angles and
a plurality of wells 3Q are drilled into oil bearing formation
10 from tunnels 34. As shown in Figure 1, a second oil bearing
formation 22 lies beneath formation 20. Oil can be recovered
from formation 22 via a plurality of wheelbarrows 32 which are
drilled to penetrate second oil bearing formation 22 from
tunnels 34. It will be appreciated that the method of the
present invention is equally applicable to the recovery of oil
from oil bearing formations which lie above or below the format
lion in which the tunnels are positioned. Desirably, formation
20, in which the tunnels are positioned, is a consolidated or
semi consolidated formation and preferably contains no oil.
While the method of the present invention could be used even
if oil was present in formation 20, it is greatly preferred
that formation 20 contain substantially no oil. While it is
preferable that formation 20 be consolidated, various mine con-
struction techniques such as shields, pressure tunnel linings
and the like can be used i-F formation 20 is not consolidated.
Such techniques are considered to be well known to those
skilled in the art and will not be discussed further.
In Figure 2, a topographical view of an embodiment of
the present invention is shown. Shaft 24 is a main shaft for
access to the oil mining operation. Main tunnel 26 and a lateral
main tunnel 28 extend from shaft 24 with a plurality of access
tunnels 34 being positioned at substantially tight angles to
main tunnel 26 at desired spacings. Outer access tunnels 36 and
additional vent shafts 38 are provided for both safety and
ventilation reasons. The arrangement of the main shaft, main
tunnels, access tunnels and ventilation shafts can vary widely
depending upon the size of the particular oil mining operation
and a variety of other considerations as known to those skilled
in the art. For instance, more than one main shaft may be used.
The primary considerations are operating access, safety access
to an escape shaft from all points in the oil mining area and
adequate ventilation in the tunnels. Fire doors for isolating
sections of the mine in emergencies etc. are desirably positioned
at strategic locations in the mine as known to those skilled in
the art While a rectangular layout is shown, it should be
appreciated that the method of the present invention can equally
well be used with a variety of configurations although it is
preferred that tunnels 34 be substantially parallel.
In the practice of the method of the present invention
for crude oil recovery from formation 10, an injection fluid
may be injected from the wells in a first tunnel, for instance,
injection wheelbarrows 48 positioned in a tunnel I as shown in
Figure 3. The spacing of injection wells I in tunnel I is
shown in Figure 3 as well as the spacing of production wells 50
in a tunnel 42. It will be recognized that the use of fluid
injection to recover oil from subterranean formation 10 can be
accomplished in a variety of ways once access to formation 10
has been achieved. In general, fluid is injected into injection
wells I to enhance the recovery of crude oil from production
wells 50. When injection wells 48 are closely spaced, a goner-
ally flat front of injection fluid sweeps through the area of
formation 10 between tunnels 40 and 42 pushing oil toward pro-
diction wells 50 from which it is recovered. When the recovery
of oil from production wells 50 declines indicating at least
partial depletion of the oil contained in formation 10 between
tunnels I and 42, production wells 50 may be closed in and
injection continued through injection wells 48 to enhance the
recovery of crude oil from production wells 52 in tunnel 44.
Crude oil may also be recovered from production wells 50 and 52
simultaneously. This sequence of operations could be continued
by switching the injection to injection wells 54 in tunnel 46
when the oil has been depleted between tunnels 40 and 44. In a
further variation, production could be continued from product
lion wells 50 as fluid is injected through injection wells I
Optionally, fluid could continue to be injected through inject
lion wells 48 thereby continuing production at reduced levels
from production wells 50. A variety of such production tech-
piques can be used.
In the use of production techniques which initiate
oil recovery from the ends of the zone of formation 10 to be
produced from the tunnels, drilling and piping work is normally
performed beneath zones which have not yet been produced, i.e.
heated.
Some advantages of the present method are that with
the tunnels positioned a relatively short distance from the
oil bearing formation, a large number of wells can be drilled
relatively inexpensively so that the injected fluid can be
effectively injected into substantially the entire formation
to enhance the recovery of oil. this permits the use of a flat
I
front sweeping effect between the tunnels Such techniques are
known to be effective in the recovery of oil from subterranean
formations, In some instances, it may be found that no such
fluid injection is required, at least initially, for the
recovery of oil from formation 10. In such instances, the oil
may be allowed to flow naturally from formation 10 through
both the injection and the production wheelbarrows until such
time as enhanced recovery is required. Enhanced recovery may
be accomplished as discussed above or by a variety of other
techniques known to those skilled in the art.
The present method involves a minimal number of shafts
passing from the surface to the production zone, i.e. shafts
I and I Such is extremely advantageous when operations in
permafrost regions are considered For instance, the injection
of hot fluids or the recovery ox hot fluids from a subterranean
formation tends to cause the permafrost to melt and collapse in
the vicinity of the Wilbur While techniques are known for
minimizing or preventing such melting and collapse in per ma-
frost zones, they involve added expense and may be prohibitively
expensive when close well spacings are necessary In the
present method, any pipes which carry warm fluid in communication
with the surface can be insulated and positioned inside one of
the shafts so that no direct contact with the permafrost is
necessary. Even if such lines are positioned through the per ma-
frost, the insulation of a few such lines is a much simpler
matter than is the insulation of a large number of wheelbarrows.
The use of a minimal number of shafts is also advantageous when
the surface above the mineral bearing formation is underwater,
subject to ice, ice floes and the like
The fluid injected may be water, steam, COY, heated
gas, hydrocarbon gases, flue gases, aqueous surfactant solutions
96
muzzler solutions or the like alone or in conjunction with
saline solutions, thickened water and other materials known to
those skilled in the art for use in secondary and tertiary
recovery of oil from subterranean formations By the method of
the present invention, access to the subterranean oil bearing
formation is accomplished so that such methods may be practiced
using close well spacings.
As discussed, it is desirable that tunnels 34 be
substantially parallel, although such is not required. Goner-
ally, when parallel access tunnels are used, it is anticipated that substantially uniform conditions prevail in formation 10
between the parallel access tunnels so that relatively uniform
sweeping action is accomplished. If such is not the case, the
tunnels can be spaced in other configurations and the like as
required to effectively recover oil from the particular format
lions from which oil is to be produced.
The wheelbarrows are desirably positioned at a plurality
of spaced-apart locations in the tunnels. The positioning of the
wheelbarrows can vary widely so long as the penetration of the oil
bearing formation is at the desired locations.
By the use of tunnels as discussed above, close well
spacings can be used. Close well spacings are necessary in many
instances to insure adequate injected fluid contact with the oil
bearing formation. Well spacings will vary widely dependent upon
the particular formation. Typically, the well spacing along the
tunnels will be at least about 100 feet, although closer spacings
can be used if necessary or desirable. The tunnel spacings may
also vary widely dependent upon the particular formation.
Typically, the tunnels will be at least about 1000 feet
apart, although closer spacings can be used if necessary or
desirable The determination of proper well and tunnel spacings
for the specific fluid injected and method used for a part-
cuter formation is considered to be within the skill of those
in the art when access to the formation has been accomplished.
The wheelbarrows may be drilled, cased and completed
using standard drilling and casing techniques, including the
use of blowout preventers and the like as necessary. The
casings are cemented, grouted or the like to prevent the leakage
of oil or fluids into tunnels I Suitable valving and piping
is provided to inject or recover fluids or oil from the well-
bores in the sequences desired. Such operations are considered to be known to the art and will not be discussed further except
to note that a closed system is desirably used for drilling wells
upwardly into formation 10 from the tunnels.
When heavy oil is to be recovered, a variation in the
above process may be desirable. heavy oil as used in this
discussion generally refers to petroliferous materials which
are so viscous that they do not drain from or move readily
within the formation in which they are contained at the temper
azure at which they naturally exist. Clearly, if such heavy
oils are to be recovered, some sort of enhanced recovery is
necessary. In a preferred embodiment of the present method,
fluid injection is initiated in injection wells pa and oil is
recovered from injection wells 48 until a portion of the oil in
zones 56 above tunnel I is recovered Such processes are known
to the art and may be accomplished by the use of separate fluid
injection and production lines through each Wilbur; by the
use of huff-and-puff techniques or the like. Such oil recovery
from zones 56 may be accomplished by injecting fluid through
alternate injection wheelbarrows 48 and recovering heavy oil from
the other injection wheelbarrows. A variety of such techniques
can be used to recover at least a portion of the oil from the
--10--
I
area above tunnel 40. The objective of such recovery is to
increase the apparent permeability of oil bearing formation 10
above tunnel 40. Similar techniques may be used to recover at
least a portion of the oil from the area above tunnel I if de-
sired. After a portion of the heavy oil sufficient to increase
the apparent permeability above tunnel 40 has been removed from
formation 10 above tunnel 40, fluid injection can be initiated
and a flat front can be used to sweep the area between tunnels
I and I as discussed previously. The increased apparent per-
mobility in the area above tunnel 40 tends to facilitate Eluidmovement from the area above tunnel 40 toward tunnel I as a
flat front. If the heavy oil is not removed at least in part
from the area of formation 10 above tunnel 40, an irregular
sweep front may result with resulting reduced efficiency in the
recovery of heavy oil from subterranean formation 10. As noted
previously, it may also be despicable to remove a portion ox the
heavy oil from the area above tunnel 42 prior to the use of the
fluid sweep. The recovery of heavy oil from remaining sections
of the formation may be accomplished as discussed previously by
a variety of techniques known to those skilled in the art. For
instance in the recovery of heavy oils, the use of healed fluids
is common with steam being a particularly preferred fluid. Other
fluids such as flue gases carbon dioxide, light hydrocarbons
and the like can also be used. In some instances, in situ come
bastion may be used. Such techniques are considered well known
to those skilled in the art and suitable for use in the practice
of the method of the present invention.
As will be appreciated by those skilled in the art,
the use of such methods as discussed above is extremely Defoe-
cult unless the subterranean formation can be reached by well-
bores on a relatively close spacing.
~fd32~9~i
As discussed above the fluids used may be water,
steam, COY, heated gas hydrocarbon gases flue gases, aqueous
surfactant slurries, muzzler solutions and the like, either
alone or in conjunction with saline solutions, hackneyed water
and other materials known to those skilled in the art for use
in secondary and tertiary recovery of oil f rum subterranean
formations.
The shafts may be formed by freeze drilling by blind
hole boring and the like and cased and/or otherwise completed
as known to those skilled in the mining arts. The tunnels may
also be formed by conventional mining techniques including
mine construction techniques such as shields "linings of various
types for the tunnels and the like especially in the event that
formation 20 is not consolidated,
Other minerals may also be recovered by the method of
the present invention using suitable injection fluids. Fur
instance, in the recovery of uranium the injection fluid typic
gaily comprises an aqueous solution containing ammonium, sodium
or potassium carbonates and/or bicarbonates in conjunction with
an oxidant such as air, oxygen hydrogen peroxide and the like.
Some such surface leaching processes for uranium leaching are
disclosed in US. Patents 4,066,297; r4,082,359; 4,083,6~3; and
4,105,~53,
When copper it recovered, the fluid may comprise
aqueous solutions containing mineral acids such as sulfuric
acid, ammonium carbonate,~ferric sulfate eureka chloride
bacterial leaching with oxygen and the like. When gold or
silver it recovered Thor 9 cyanides and the like may be
used. The practice of the method is substantially the same as
that described above for the recovery of oil from subterranean
formations. It will be appreciated that a variety of methods
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~32~
and tunnel configurations can be used to optimize the effective-
news of the fluid contact with the subterranean formation once
access to the mineral bearing formation is achieved by the
present method.
As shown in Figure 1, tunnels I may be above or
below or between subterranean mineral bearing formations. The
practice of the present method is substantially the same in
either event. In other words, the method is practiced equally
well when the mineral bearing formation is above access tunnels
34 or below access tunnels 34, or in some instances, above and
below.
As discussed previously, the wells may be drilled and
cased as necessary by conventional well drilling techniques and
may include the use of blowout preventers and the like Such
techniques are considered to be well known to those skilled in
the art and need not be discussed in detail
While Figure 1 has shown a permafrost zone, it should
be appreciated that the use of the present method is not so
limited.
The injected fluid used may be produced, recovered
and/or recycled by treating facilities in the subterranean zone
or by facilities at the surface. For instance, if steam is used,
it may be desirable to produce the steam in a subterranean
chamber and in some instances, it may be desirable to inject
the flue gas into formation 10 as well as the steam. Such
variations are subject to a number of considerations known to
those skilled in the art and need not be discussed in detail.
rho method of the present invention is not dependent upon the
source of the injected fluid. Similarly, the produced oil may
be piped to a storage or treating facility in a subterranean
zone or directly to the surface and storage facilities or
transportation. The method of the present invention is not
dependent upon the method chosen for the handling of the oil
so produced.
Having thus described the present invention by refer-
once to its preferred embodiments, it is pointed out that the
embodiments described are illustrative rather than limiting in
nature and that many variations and modifications are possible
within the scope of the present invention. Many such variations
and modifications may be considered obvious and desirable by
those skilled in the art upon a review of the foregoing
description of preferred embodiments.
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