Note: Descriptions are shown in the official language in which they were submitted.
7~9
This invention relates to methods and apparatus for
mining, and more particularly ~o novel methods and apparatus
for combination hydraulic and simultaneous mechanical mining
in situ of solid or semi-solid subterranean carbonaceous
deposits, for example bitumen, heavy oil and coal. One
specific field to which the present invention relates is the
mining of deposits to recover the values therefrom in situ.
A specific application of the invention is the mining of
mineral-bi~umen deposits, e.g. tar sands and heavy oils, for
extraction and separation of the oil values therefrom below
ground, whilst leaving at- least a major proportion of
inorganic component of such deposits within the in situ cavity.
The most familiar example of mineral-bitumen deposits
are the tar sands, located in parts of Northern Alberta, and
referred to commonly as the Athabasca Tar Sands. These
Athabasca Tar Sands are estimated to contain many billion
barrels of crude oil reserves. Intensive studies and
investigations are underway to develop suitable technology
whereby oil can be extracted from tar sands economically,
refined to useful petroleum products and transported to
industrial markets.
The composition of the Athabasca Tar Sands is widely
variable from location to location. The components of the
tar sands include minerals, oil, water and gas. The components
have been deposited at various geological times and under
various geological conditions, to form in effect variable
fine-to-coarse agglomerate particles of clay, silt and
quartz sand, each individually surrounded by rings of thin
films of connate water, leaving voids between their irregular
1~678~
shapes containing a dense thick tarry asphalt base oil, and
gas, in varying amounts up to an average 20~.
The oil content of the tar sands~ on a pexcent by
volume basis, is quite ~ariable, being generally less than
about 25%. The oil generally has a high specific gravity,
and a small water content~ The oil becomes thinner
progressively as it is heated. The balance of the
composition is mainly mineral, and is predominantly uniform
white quartz sand, the remainder being essentially clay fines
with traces of associated minerals. The trace minerals are
pxesent at least in part as metal porphyrins, primarily
vanadium porphyrin and nickel porphyrin, and sulphur. Some
of these trace minerals can however form dangerous pollutants.
ParticuIarly dangerous are vanadium compounds, especially
when found and processed in combination with other compounds
and processes.
One co~nercial method which has been developed and
used involves removing the tar sand deposit from below
ground by open pit mining, and then conducting an extract
process above ground to recover the oil from the associated
inorganic components of the deposit. It is clearly
undesirable to have to raise from underground deposit 100
units by weight of material when only about 10-20 units by
weight is useful product. Open pit mining, in particular,
entails the removal of large tracts of land from other
surface uses for extended periods of time. Such surface
operations axe adversely effected by severe frosts encountered
in the tar sands area, which vastly effect the cost of
operations, labour required and life of equipment. The cost
~t;7~3 IL9
of returnin~ the ground to useful condition, and the
difficulties of compacting the replaced ground, are also very
considerable.
Surface processing of mined tar sands, to separate
the organic bitumen or oil from the inorganic content, has
many attendant problems. The bitumen contains traces of
minerals and rare earth elements. When the bitumen is
processed above ground, for separation from sand, the
minerals and rare earth elements, along with sulphur and
~races of vanadium, form nuclei on which coke particles
deposit, in ~ubsequent distillation.
The resulting coke, although in theory a high
carbon content material, is rendexed practically worthless as
a fuel because of its high corrosive mineral content.
Burning of this coke gives effluents having high concentration
of pollutants, causing prohibitive sulphur contents in stack
gases and prohibitive breakdown of boilers. One of the
minerals commonly found in the bitumen of the tar sands is
vanadium, in various compound forms. Vanadium in combination
with sulphur is a dangerous pollutant. The coke product of
such a process must therefore be discarded, or burnt in
limited quantities in small supplementary equipment, or used
as fill.
Other previously proposed and used tar sand
extraction and separation processes involve hot or cold water
washing to separate the organic components from the inorganic
components. One such process is an in situ method, generally
known as the steam~drive method, and sets out to make the oil
flow without moving the sand. An injection well and
~06~8~
adjacent production wells are dxilled in a 5 spot arrangement
into the tar sand deposit, and fractures of the tar sand are
shock induced between the ~ells. ~hen high pressure steam
and aqueous alkaline solutions are injected into the
injection well, and reverse, so as to emulsify the bitumen
and cause it to float for eventual separation from the sand,
and the liquid aqueous emulsion is recovered from alternate
adjacent production wells. Then the bitumen must be
separated from the aqueous emulsion.
Such processes, due to temperatures and pressures
used, form imper~ious coke enveloped paths limiting any
further diameter expansion, and hence limit production.
The use of high pressures below ground in the
steam drive process effectively limits its applicability to
areas where the overburden is of substantial depth, such as
500 feet or greater, because of the risk of blow-outs to
the surface. In addition, it tends to accelerate undesirable
carboni~ation blockage.
In total, in situ separation processes, if efficient,
have the substantial advantage that the non-useful, sand
component of the tar sands does not have to be raised to the
surface and subsequently replaced. Only the efficiencies of
various methods can be questioned.
The present invention provides, in one embodiment,
a novel process for in situ separation of oil and sand from
tar sand deposits, in which a high proportion of the
separated sand is left down hole, and not brought to the
surface at all. As much as 95~ plus of the bitumen in the
deposit can be separated and extracted to the surface~ The
10678R~
process o~ the invention can be operated with a minimum of
disturbance to the overburden and suxface ground layers.
The process ~ery materially reduces the environmental
problems experienced with previously proposed and operated
tar sands extraction processes. The invention also provides
a novel mining apparatus for in situ extraction and
separation of oil or bitumen rom tar sand deposits, and
various other mining operations as described herein, without
putting men underground in toxic areas, requiring ventilation
for human safety, and requiring the forcing of air underground
to induce possibly explosive atmospheres.
Thus according to one aspect of the present
invention, there is provided a process for the mining of sub-
terranean carbonaceous deposits, which comprises:
subjecting the carbonaceous deposit in situ to the
substantially simultaneous action of circulating high pressure
jets of heated mining fluid and circulating mechanical mining
teeth, said fluid jets and said mining teeth being circulated
together so act substantially simultaneously upon a given
portion of surface of the in situ carbonaceous deposit, so as
to reduce the subjected deposit to finely divided form;
the mining fluid comprising water in admixture with
at least one normally gaseous hydrocarbon;
the temperature difference between the in situ
deposit and the mining fluid immediately prior to issue from
the jets heing at least 60~F;
upwardly displacing carbonaceous components of the
finely divided deposits so formed, and
mechanically agitating the aqueous slurry of residual
mining fluid remaining underground, to cause downward settling
of other components of the finely divided deposits so formed.
:~L0~7~
According to another aspect of the present
invention, there is pxovided a process for extracting car-
bonaceous material from a subterranean deposit thereof by
in situ treatment with mining fluid and simultaneous mechnical
grinding thereof, which compri.ses:
drilling a pilot hole of relatively narrow diame~er
from the ground surface, through the overburden and the deposit
and a distance of no~ less than the depth of the deposit layer
: into the sub-deposit formation located beneath the deposit;
enlarging the pilot hole below the deposit to form
a sub-deposit cavern and extracting the mined materials from
said sub-deposit cavern to the ground surface through said
pilot hole;
filling the sub-deposit cavern with aqueous liquid;
enlarging the pilot hole radially in the deposit
by treating the deposit with circulating high pressure jets of
heated mining fluid comprising a mixture of water and normally
gaseous hydrocarbons, the temperature difference between the
in situ deposit and the mining fluid immediately prior to
issue from the jets being at least 60F, to cause break up of
the deposit and interaction of the carbonaceous content thereof
with gases of the mining fluid, and to form a cavern in said
deposit;
agitating the liquid slurry formed in the cavern
in said deposit to wash and cause downward settling of non-
carbonaceous components thereof;
and upwardly displacing the carbonaceous component
to the ground surface.
-- 6 --
~31678~
The process of the invention is useful for
drilling and recovering heavy oils, from sand deposits
thereof and the like. Conventional oil drilling processes
have in the past only recovered a maximum 30% of the oil
present in the subterranean formation. During the life of
production the initial ~ottom hole pressure has been
depleted until flow has ceased or is no longer economical.
Some further recovery can be achieved by pumping down hole
with a conventional cylinder and sucker rods arrangement, but
eventually the point is reached where the permeability of
the medium in which the oil is located decreases to the
extent that no more oil is pumped out. This is commonly
caused by wax-up of the interstices of the medium.
The present invention provides a method and
appaxatus for recovering additional quantities of oil from
conventionally drilled and "exhausted" oil deposits.
According to the invention, new production holes are bored
adjacent abandoned wells, and oil extracted by the combined
hydraulic/mechanical mining process as described herein for
use with tar sand deposits. The wax is effectively melted
out by the heated mining fluid supplied below ground, and
separation of the oil values from the sand deposits takes
place in situ below ground, as described in connection with
the extraction and separation of bitumen from tar sand
deposits.
In the process of the present invention as applied
to tar sand mining, substantially only the bitumen portion of
the tar sands is brought to the surface. This material,
which is obtained in the form of a water/oil emulsion, is
~ 7 -
~7~
readily processed at the surface in known, conventional
hydrocarbon separation, cracking and ref~ning processes and
apparatus All the remaining inorganic constituents such as
rock, shale, sand~ gravel and the like, remain below ground.
To the extent that such potentially pollutant material is
contained in the bitumen/oil fractions, these are readily
dealt with in the conventional surface processing equipments
of refining and cracking, according to well established
refinery procedures.
The conditions of treatment of the tar sand deposit
in situ according to the process of the present invention
are chosen in combination to give a maximum recovery of the
bitumen content, together with fast and efficient separation
of the bitumen content from the inorganic, mainly sand,
components of the tar sands. These conditions involve the
use of combination hydraulic and rnechanical mining, whereby
the tar sand deposit is treated with a mechanical grinding
action and a high velocity, high pressure hydraulic mining
fluid, the fluid containing normally gaseous hydrocarbons
which, on contacting the tar sands at high pressures, interact
with the bitumen portion of the tar sand to reduce its
specific gravity, and cause frothing thereof, effectively
forming a frothed, bitumen-rich aqueous bouyant emulsion.
This emulsion is lighter than the aqueous phase formed by the
rest of the mining fluid. As the mining process continues, a
hole or cavern is formed in the tar sand deposit, which
gradually fills with the aqueous liquid, The separated sand
sinks through the aqueous "pond" formed in the cavern, and is
subjected to agitation therein by the mining tool and
~ - ~
78~L~
associated structure, This agitation has a ball milling
effect upon the sand, thoroughly polishing it so as to
release oil skin from the sand and thoroughly to wash the
sand. This polishing effect can be enhanced by maintaining
aqueous mining fluid pH in the alkaline range. As a result,
clean sand sinks to the bottom of the cavern so formed, with
the bitumen component due to its gas induced bouyancy rising
to the surface.
A preferred method of conducting the process of
the present invention is to mine the cavern in the tar sand
layer from bottom to top of the deposit, using a rotating
mining tool having arms with cutters and jets thereon, the
arms extending radially outwardly and downwardly from a
central shaft. As a result, the tool cuts an inverted
conical shape in the deposit, the centre of the cone being an
aperture to the ground surface. Vacuum can be applied to the
central aperture, to draw lighter material, i.e. the mined,
frothed bitumen/water emulsion up to the surface.
The drilling motion of the cone upwardly more than
counteracts centrifuging while at the same time the volume of
the annular slowly vertically rising return water to surface
promotes a vertical movement up the frustrum of the cone,
whereas the four arms in path at 90~ permit a wide space for
non bouyant separated material to slide downwardly between
spokes, so that the majority of the sand by virtue of being
non-bouyant and wetted (lubricated by oil) slides down the
frustrum of the cone to enter the pool at its ascending base.
The Athabaska Tar Sand deposits are commonly found
below an overburden, which varies in depth from location to
71~
location~ At places, the overburden has been removed by
glacial drift, Elsewhere the overburden has a depth of up
to about 2,100 feet. Certain deposits in the Bakersfield,
California region, have 1000 feet thic~. tar sand layer. The
composition of the overburden of the Athabaska Tar Sands
generally comprises shales, sands and gravels, in various
amounts. The process of the present invention can be operated
in the presence of overburdens of depths from about 20 feet
to about 2100 feet.
One problem which an in situ tar sand extraction
process has to overcome, especially one using an aqueous
extraction medium, is the factor of swell. When treated with
water under conditions of shear, the sand portion of the tar
sand increases in volume by a factor of from about 2 to about
2 1/2 times an average. The extraction of the bitumen
content and its removal above grotmd does not provide
sufficient extra volume below ground to allow for this
volume expansion. One feature of the process of the present
invention is the prov~sion of a cavern below the tar sand
deposit into which a major proportion of the separated sand
will settle, thereby allowing for this volume expansion
factor.
A first step in the extraction process of the
present invention is the rotary drilling of a pilot hole, from
the ground surface, through the overburden, through the tar
sand deposit and down into the sub~tar sand formation located
beneath the tar sand deposit. If circulation is lost at any
point in transverse described above, drilling is immediately
stopped, tools withdrawn, casing run to bottom, perforated at
-- 10 --
~713~3
last circulation point and suitable d~illin~ muds or cement
are fed through the perforations, ~or example by the
Haliburton method, with ~ast set fluids, until gauges
indicate the ~ormation is permanently sealed. Then drilling
is resumed, ~hilst this pilo~ hole is of very small diameter
in comparison with the diameter of the subterranean caverns
subsequently to be mined, it can nevertheless be of substantial
diameter, such as 2-20 feet. The diameter is selected with
a view to overburden depth, desired diameter extension, and
lG a economic balance between maximum pay zone, expansion and
number of holes to be drilled, and accommodating the passage
therethrough of the mining tools to be used in the
subsequent process stages. Thus the size of the pilot hole
; should have regard to the planned size of the expanded hole
subsequently to be drilled in the tar sand deposit for
production purposes, which will in part determine production
rates. The thickness and consistency of the overburden
layer is also significant in this respect. Normally, a well
casing is inserted in the pilot hole for the depth of the
overburden, to prevent washout of overburden from the solvent
action of the liquids returning to the surface therethrough.
It is important that steps be taken to prevent clay, shale or
the like from the overburden from mixing with the bitumen
being extracted
The characteristics of the various subterranean
formations through which the drilling passes as it proceeds
do~mwardly, should be recorded carefully in a well log, to
gather information useful in adjusting subsequent process
conditions.
~67~
The pilot hole is con~inued to the base of the tar
sand layer, with note being taken of the depth of this layer
and its physical characteristics, As the pilot hole is
drilled, the extracted material is brought to the surface in
the conventional manner and put to one side, for later
replacement.
There is normally, but not invariably, found below
the tar sand layer a stratum of base rock of variable
thickness, underneath which is sub-base rock strata which may
be of clay, sand, limestone etc. When the pilot hole is
drilled to the base rock layer, the pilot hole is cased to
that level by continuing a slightly smaller diameter well
casing from the overburden to the top of the base rock layer.
Drilling of the pilot hole is continued through the base rock
layer, and into the sub-base rock strata. It is preferred to
continue the pilot hole a distance into the sub-base rock
layer which is not less than the depth of the tar sand layer,
and most preferably from about 2 to 2 lf2 times the depth of
the tar sand layer. The material removed from the base rock
and sub-base rock strata is extracted to the surface and put
to one side.
When this drilling of the pilot hole has been
completed to the necessary depth, the standard rotary drilling
rig is removed to the surface. The pilot hole may if desired
be swabbed and flushed ~ith clean water to remove loose
extracted material.
The next step in the process of the present
invention is the radial and vertical enlargement of the pilot
hole in the sub-base rock strata, to form the sub-tar sand
1~7~
cavern. The sub~tar s~nd cavern is formed by the use of the
novel radially expandable mining tool described in more detail
hereinafter. In essence, the tool is a combined mechanical
and hydraulic mining tool, equipped with mining teeth and
hydraulic jet outlets near its radial extremities.
Where necessary, a drill bushing may be installed
in the cement cap on a top bearing. Next the novel mining or
hole expanding tool is mounted on the end of the kelly and
lowered to the bottom of the hole. The hole expanding tool
includes a fluid actuated cylinder and piston arrangement
connected by a drill string to a source of ~luid pressure
above ground, and a plurality of articulated ~ining arms,
typically four in number, having an umbrella-like action,
; pivotally connected at their lower end to the piston so as to
expand and contract radially as the piston is raised and
lowered in response to fluid pressure in the cylinder. The
articulated mining arms are connected to a source of mining
fluid located above ground, and are provided with high
pressure outlet jets and mechanical mining teeth along their
upper surfaces, for upward drilling, and/or along their
lower surfaces, for top-to-bottom hole drilling. The jets
and teeth effect a combination of hydraulic and ~echanical
mining.
The hole expanding tool is thus lowered through the
pilot hole, in its radially contracted position, to the
bottom portion of the pilot hole in the sub~base rock layer.
Rotation of the mining tool, supply of mining fluid to the
jets therein and gradual radial e~pansion of the tool by
supply of fluid pressure to the fluid actuated cylinder then
~ 13 ~
7~3~g
commences, so that the sub~base rock layer is mined and the
hole expanded, until the mining tool reaches its radially
extended position, with t~e arms making an angle of about 60
for example, with the vertical If desired, the pilot hole
can be extended further down at this stage also, The mining
fluid is supplied to the mining arm interiors under high
pressures, of the order of 1000-5000 psi, so that it issues
at high speed from the jets. The jets are directed rearwardly
and upwardly with respect to the rotation of the tool, so as
to provide rotational thrust thereto. Then the mining tool
is gradually raised, whilst continuing the rotation of the
tool in the radially extended position and supply of high
pressure, heated mining fluid thereto, by raising of the
drill string from akove ground. This continues until the
mining tool comes into the proximity of the base rock layer,
when the excavating of the sub-base rock cavern is complete.
The mate-ial mined from the sub-base rock cavern in
the process of the present invention is raised to the ground
surface and put to one ~ide, for later return to the ground
when the tar sand layer has been mined. The raising of the
mined material is accomplished hydraulically, the supply o~
mining fluid to the rotary hole enlarging tool under high
pressure forcing the material to the ground by simple fluid
displacement, up the kelly tube or drill string which extends
down the pilot hole.
The mining fluid used for enlarging and excavating
the sub-base rock cavern is aqueous, most suitably water.
After the sub-base rock cavern has been fully
excavated in this manner, the mining tool is collapsed to its
14 -
~0~7~9
radially contracted position, b~ release of fluid pressure
from the cylinder, and the cavern is filled, to the base of
the base rock layer, with water. If, however, during the
excavation of the su~base cavern, porous zones, underground
streams and the like are encountered, it is advantageous to
seal these until abandonment under 5000 psi is completed, at
the termination of the process. This can be accomplished by
applying drilling muds, such as sealing "Baroids" of suitable
consistency~ or any of the other special purpose fluids
available on the market for such purposes, squeezing them
into the appropriate zone to effect sealing, by known
techniques such as the Haliburton system or other.
It will be appreciated that the precise method
adopted for the formation of the sub-tar sand layer cavern is
not critical to the operation of the process of the invention,
provided it is of sufficient size t:o accommodate the
expanded volumes of materials obtained from the subsequent
tar sand extraction process, and i5 located below the tar
sand layer to be mined, and communicates therewith. It is
preferred to drill the sub-tar sand layer cavern by the
process outlined above, using the same apparatus as will
subsequently be used to mine the tar sand cavern and cause
separation of the bitumen from the tar sand down hole.
In the next stage of the process, the tar sand is
excavated, by enlarging the pilot hole in the tar sand layer
radially and vertically by processes similar to those
described above, for drilling the sub~tar sand layer.
Next, the expandable mining tool, mounted on the
end of the kelly, and positioned at the bottom of the tar
~ 15 -
i78:~L9
sand layer. It is positioned in the pilot hole in its radially
contracted position, and then rotation thereof is commenced,
with supply of high pressure mining fluid to the jets in ~he
articulated mining arms of the hole enlarging or mining tool.
Fluid pressure is supplied to the cylinder, so as to raise
the piston and cause gradual radial extension of the mining
arms, as they are rotated and supplied with mining fluid. By
a combination of hydraulic and mechanical mining, as the tool
rotates, the mining tool enlarges the pilot hole at the base
of the tar sand layer, until the mining tool reaches its_full
radial extension. The mining of the tar sand is continued
from this point, by gradual upward movement of the rotating
mining tool and its associated structure, from power means
located at the surface, with the m:ining tool in its fully
radially expanded position. This drawing upward continues
until the upper mining portions of the mining tool reach the
top of the tar sand layer and the bottom of the overburden.
Then the mining is stopped, to ensure that clay and the like
material from the overburden is not mined and mixed with the
; 20 bitumen being extracted from the tar sand layer by the process
of the invention. The depth of the overburden and thickness
of the tar sand layer, and hence the position of the mining
tool when rotation thereof and supply of hydraulic mining
liquid thereto should cease, are readily determined from the
records kept during the initial drilling of the pilot hole.
In this process of mining the tar sand layer, the
tar sand is subjected to both mechanical mining, caused by
~a~
mining teeth, such as Hughes saddle ~Q~ cutters, located on
the upper surfaces of the radially extended arms of the
- 16 -
~67~
rotating mining tool, and hydraulic mining by being subjected
to high pressure jets of mining flu~d, The mining fluid
which is used is a mixture of water and normally gaseous
hydrocarbons, such as natural gas. Preferably~ the mining
fluid is made slightly alkaline, pH 7.5~9.5, by addition
thereto of a suitabie alkali such as caustic soda, This
serves to accelerate the down hole separation process of the
bitumen from the sand, by enhancing the emulsification
abilities of the mining fluid on the bitumen. The mining
fluid is used at elevated temperatures, normally between
100F and 200F. The use of such elevated temperatures
assists in the separation of the tar sand deposit from its
geological formation, and in separation of the bitumen from
- the sand content. Such high temperatures are used again to
offset the 8.1 specific heat ratio of bitumen to water plus
the cooling effect occasioned by the expansion of the gas as
it is emitted under pressure through the jets. The viscosity
of the bitumen .LS also reduced by rai.sing its temperature,
and emulsification of the bitumen in the dilute aqueous
alkali is promoted. The actual temperature of the mining
fluid which is used should be adjusted, in combination with
the drilling speed, rate of extraction, and shearing strength
of the deposit, so that the temperature of the bitumen water
emulsion issuing to the surface through the cased hole in the
overburden is at least 70F for ease of surface processing of
the bitumen. The gas content of the drilling fluid, which is
volume cut and adjusted to prevent drop in processing
efficiency, issues from the jets on the mining arms, forming
a gas envelope (as in underwater flame cutting) thereby
~ 17 -
7~9
greatly accelerating the rate of flow of the liquid and
turbulating the flow from the jet to the deposit being mined.
Natural gas is available from tar sand deposits themselves
and can be used to supplement that used in the mining fluid.
Mechanical pressure exerted on the mining tool,
normally in a generally upwardly direction, against the face
of the bitumen deposit, forces the rotating mining teeth into
the deposit. These mining teeth grind the deposit, destroying
the structure of the tar sand particles, to promote
emulsification of the bitumen with the warm alkaline fluid.
The high pressure, high velocity mining fluid impinging upon
the oil sand particles causes frothing of the bitumen/oil,
forming a frothed bitumen/oil-rich aqueous emulsion which is
lighter than water. Hence the frothed bitumen/oil emulsion
floats, moving upwardly along the mining tool and eventually
to the ground surface. The sand component of the tar sand
deposit and the remainder of the aqueous drilling fluid
moves downwardly over the mining booms, serving to wash them
as they rotate.
The sand separated from this frothed bitumen/oil
remains contaminated with an oil skin which it is desirable
to remove. This contaminated sand is effectively polished by
the rotating mining tcol down hole in the pool of alkaline
water accumulating and gradually filling the hole. By this
agitation, an oil rich aqueous emulsion of bitumen is formed.
floating as a layer on the surface of the aqueous effervescing
pond, and gradually rising to the surface as more mining
fluid is introduced, The sand is substantially totally freed
of bitumen by this process, the polished sand sinking to the
- 18 -
~067~
bottom of the tar sand cavern, and down into the sub~base
rock cavern, displacing water therefrom as it does so.
The down hole separation of the process o~ the
present invention can thus be considered as a multi-stage
separation process. In a first stage, the tar sand deposit
is subjected to warm mining fluid, containing natural gas,
and prefera~ly alkaline under high pressure and with
mechanical action, to free it from the deposit, grind it and
have the bitumen part subjected to the action of the natural
gas, forming a frothed emulsion thereof. A subsequent stage
involves (1~ separation by sand washing and (2) separation by
a type of "ball mill cleaning" as the sand settles in the
rotating water pond. Oil froth flotation occurs as oil froth
rises in the fluid pond and is forced upward through the
annulus between the kelly and the bore hole to the surface,
at the same time effecting a degree of lubrication of the
mechanism and cutter. Subsequently an oil emulsion in water
floats upwardly and is received at the surface.
Individual conditions of the bi~umen deposit mining
process according to the present invention are adjusted during
the conducting of the process, so as to achieve the most
efficient and rapid separation down hole, and recovery of
bitumen at the surface. Thus, the pressure at which the
mining fluid is supplied, and the speed at which the mining
.~.... . .
tool is rotated and drawn upwardly, as well as the alkalinity
of the mining fluid and the temperature at which the mining
fluid is supplied, will be quite widely variable, and may
need adjustment on site according to varying conditions
experienced. The optimum combination of such conditions will
~ 19 -
~06~
depend to some e~tent upon the nature of the tar sand deposit
at the location at which it ~s ~e~ng mined, its thickness,
composition, compressive strength, depth, and the like.
However, these are operat~ng adjustments and lie within the
skill of the mining engineers in the field.
When using a screening apparatus at the surface to
separate the oil ~mulsion from the aqueous portion containing
sand and clay, it is important to ensure that the temperature
of the liquids striking the screen is 70F or higher, to
lQ prevent plugging. Thus if the liquid issuing from down hole
is too cold, there is a risk it will plug the screen and
necessitate shutting down of the process.
The oil values thus recovered are conveniently
collected at the surface in a mobile surface separator where
the aqueous portion is recovered, along with any sand and
clay fines which have been removed with the oil emulsion, and
returned down the hole. The ~race minerals which would
otherwise cause pollution problems are left down hole in the
aqueou~ portion, or returned down hole with the water and
fines which are separated and returned from the surface
separator. Any pollution causing minerals in the bitumen/oil
phase are removed before refining, according to known
procedures.
The process of the invention can be operated on a
large scale, enlarging the cavern in the tar sand layer to a
diameter of from 10 to 300 yards~ ~or example, when the
cavern has a diameter of about 25 yards, and the tar sand
deposit has a depth of 240 feet, about 19,500 cubic yards of
tar sand are treated in one hole by the process of the
- 20
~7~
in~ention. On averager the tar sand yields about l barrel of
bitumen per cu~ic yard, so that a single hole can produce
19,500 barrels of bitl~en or oil by the process of the
invent~on.
The process can be operated in the presence or
absence of an overburden overlying the tar sand deposit. It
will be appreciated that heavy, massive equipment has to be
provided on the ground surface overlying the location to be
drilled and excavated. When a "shell" or cap roc~ is not
present, to support the weight of the overburden and surface
located mining equipment, during the processing and refilling
cycle of the process of the invention, a large diameter
sur*ace cavity can be bored and then poured with concrete to
form a support dome.
The surface operations associated with the process
include initial levelling and dyking of the surface area
immediately surrounding the location of the pilot hole.
Suitably surface terrain in a unit rectangular area is
bulldozed to a depth of 2-3 feet to each side and rearwardly.
This forms dykes suitable for containment of pilot hole
cuttings and sub-tar sand cavern cuttings, for a temporary
period, until they are replaced down the bore hole at the
conclusion of the process.
The levelled and dyked area is suitably sized to
accommodate several oil extraction units, to which the
extracted bitumen is fed, as well as to accommodate the
necessary surface power means and drilling rig components.
At the conclusion of the process, the hole is left
sealed, to prevent the escape to the atmosphere of gaseous
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~lLlD~7~319
hydrocarbons ~grat~ng from down hole.
A feature of the preferrea process of the invention
; is that the process can be repeated at successive locations
of the tar sand deposit~ The surface equipment Gan be mobile,
so that, one drilling and excavation of one tar sand hole is
complete, and all the tar sand therefrom treated and bitumen
extracted, the equipment can be moved to the next, adjacent
location for drilling of an adjacent production hole. Whilst
the new hole is drilled and brought into production, the
exhausted hole is refilled. In this manner, a large area of
tar sand deposit can be mined by means of successive boring,
bringing into production and then refilling of production
holes according to the process of the present invention.
Suitably, holes are drilled in pairs, two at a time, to
balance out the torques applied to the down hole driven
apparatus.
The process and apparatus of the present invention
are illustrated by way of example in the accompanying
drawings, in which:-
FIGURE 1 iS a diagrammatic perspective view of one
version of a mining tool or hole expanding tool according to
the present invention, in its radially expanded position;
FIGURE 2 is a detail of a corner joint of the tool
shown in Fig. l;
FIGURE 3 is a diagrammatic part sectional ~iew
showing the tool of Fig. 1 in a radially contracted position
in a bored pilot hole;
FIGURE 4 is a view similar to Fig. 3 but showing
the tool in its radially expanded position;
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78~
~ IGU~E 5 is a cro~s sectional ~iew of a mining arm
or boom of a tool arm of the invention~
In the drawings, like reference numerals indicate
like parts.
With reference to Fig. l, the mining tool according
to the present invention, generally designated lO, has an
"umbrella-type" action whereby it can be moved from a radially
contracted position to a radially expanded position, by up
and down movement of a lower sliding block on a central
shaft, the mining arms or booms of the tool being hingedly
connected to the lower sliding block and to a fixed block,
and having a hinge joint near the middle of their length.
Specifically, the tool 10 has four mining booms 12, 14, 16,
18 distributed equidistantly around the tool lO, and
hingedly connected to a flxed top head 20. The top head 20
is releasably secured to a square section kelly 22. The top
end of kelly 22 is pxovided with a tool joint 24 r for
securing it to a long kelly section and a drill string 26,
shown in broken lines, which can extend upwardly through the
pilot hole in practice, to powex sources and fluid supply
sources above ground. The top head 20 is provided with four
vertically extending channels such as 26, sized so as to
receive therein the ends of the respective mining boom 12 etc.,
in a pivotal manner. Each channel 26 etc. is provided with a
pivot pin such as 28 extending transversely through the side
structures of the channels 26 and ends of the respective
mining booms 12 etc., for pivotal mounting of the booms 26
etc. therein.
The interior of kelly 22 and joint 24 is hollow, to
~o~78~9
provide fluid communication with the ground surface. Each
~ining boom 12~ 14 etc. is connected with the hollow interior
of the kelly 22 by means of flexible braid covered high
pressure hoses 30, 32 etc. By means of hoses 30, 32, fluid
can be supplied from the kelly 22 to mining booms 12, 14, 16,
18.
In the radially expanded position of the tool 10
shown in Fig. 1, the four mining booms 12, 14, 16, 18 are
disposed in a pyramid configuration, around the kelly 22 at
the centre, the kelly 22 extending a substantial distance *
below top head 20. At its radially outer lower extremity,
each mining boom 12 etc. is hingedly connected to a
respective radially outwardly extending spoke 38, 40, 42, 44
by means of respective pivot pins 46, 48, 50, 52. At their
inner ends, the spokes 38, 40, 42 and 44 are pivotally
mounted on a slidable bottom head 54 which is slidable upon
the square section kelly 22 for up and down movement. To
receive the inner ends of spokes 38, 40, 42 and 44, the
upper part of bottom head 54 is provided with appropriately
sized channels such as 56, and pivot pins such as 58
extending through aligned apertures in the side structures of
channels 56 and in the ends of spokes 38 etc.
Close to its radially outer end, each mining boom
12, 14 etc. is provided with an integral mounting formation
such as 60 or 62, to which are hingedly connected the ends
of two hinged struts. Thus there are four such hinged
struts 64, 66, 68, 70, which, in the radially expanded
position of the tool 10, substantially define the four sides
of the base of the pyramid configuration, extending between
- 24 -
1~67~l9
adjacent ones of the spokes 38, 40, 42, 44. The struts are
of shallow channel configuration, and are provided with
respective hinges 72, 74, 76, 78, at the approximate mid-
point of their lengths,
The detail of the hinge connection of a strut 64
to a mounting formation 62 of the mining boom 14 is shown in
Fig. 2. The integral mounting formation 62 has a protrusion
80 extending towards the strut 64~ to the end face o which
is pivotally connected the base of a U-bracket 82, by means
of a pivot pin 84. A second pivot pin 86 extends through
; aligned apertures in the side walls of U-bracke~ 82 and in
the side walls of channel shaped strut 64. Thus strut 64 is
hingedly connected to the mining boom 14 for pivotal
movement with respect thereto about two mutually perpendicular
axes. An essentially similar pivotal connection is
provided on the other side of boom 14 to connect strut 66 to
mining boom 14 for hinge movement about two mutually
perpendicular axes.
Each mining arm or boom 12, 14 etc. is provided on
its surface with sets of cutting teeth 88 at intervals along
its length, and down at its radial extremities to come in
contact with a mine and mechanically grind the deposit as the
tool rotates in its expanded condition. The arms also have
jets 90 in their rotationally trailing faces, for issue of
high pressure mining fluid to cause separation and extraction
- of the mined material, and impart rotational thrust to the
tool 10~ The jets are directed upwardly from the rear ~ace
of the mining boom.
The lower sliding block 54 is mounted on a piston
- 25
~678~1
92 slidably received in a cylinder 94 $upplied with fluid
pressure from above ground, to raise and lower piston 92
therein and hence raise and lower block 54 to radially
expand and contract the arms 12 etc.
~ ig. 3 shows the tool 10 in a radially contracted
position inside a narrow (e.g. 30 inch diameter~ pilot hole
prior to radial expansion and mining. It will be seen that
- the cylinder starts at the bottom of the hole. When pressure
is supplied to cylinder 94, piston 92 rises and arms 12 etc.
expand radially. With the tool 10 rotating, this causes the
teeth 88 and jets 90 to mine the deposit and cut a conical
shaped cavity as shown in Fig. 4. Then the tool, including
the cylinder 94 and piston 92, is gradually raised with
continued rotation to mine out the expanded hole from top to
bottom, wi~h down hole in situ separation as previously
described.
Fig. 5 shows in section an alternative and
preferred mining arm, which has a generally square, hollow
section but a rotationally leading edge 100 of conversely
curved configuration for added strength. The trailing edge
is provided with jets such as 102, directed upwardly. On
the top edge, cutter wheels 104 are mounted. Typically, the
arm is about 10 inches square, with 2 inch wall thicknesses.
The arm is provided along its length with alternating 2 foot
sections of cutter wheels and jets, the jets having larger
diameter nearer the central shaft.
The process and apparatus of the invention is also
useful for mining coal, as previously described, as well as
various other mineral ores. In the case of coal, no
~ 26 -
1~78~
subs~antial amount of in situ separation of coal from other
materials is necessary, although this does beneficially occur
down hole. The coal obtained according to the present
invention is ground to powder down hole by the action of the
jets and the cutter wheels. It is obtained as a powdered
slurry or emulsion, at the surface, being forced up the
mining boom by the supply of high pressure mining fluidæ in
large volumes down hole through the mining took, in
essentially the same manner as the oil/bitumen emulsion is
obtained from the tar sand deposits, and the oil emulsion is
obtained from oil deposits, according to the invention.
';
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