Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 2668784 201/-03-07
=TROD ARD_APPARATUB roR RLECTROKINNTIC =TRACTION OF HEAVr
OIL
This invention is in the field of oil extraction and more
particularly in-situ electrical extraction of oil.
BACKGROUND
Heavy oil and extra-heavy oil (bitumen) is a type of crude
that does not flow easily or at all in ambient conditions.
It can be made up of naphthenee, paraffins, aromatics, and
asphaltenes and frequently also contains other COnStituents
such as sulphur, nitrogen and metals.
Heavy oil is dense and viscous with Canadian extra-heavy
crude often having a viscosity the same as molasses or even
higher. The high viscosity of heavy and extra-heavy oil
compared to more conventional light oil requires more
complex and costly methods of extraction than conventional
light oil. The makeup of heavy oil also often requires a
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certain amount of refining before it can be shipped. This
makes light oil the favored of the two to find and extract.
However, heavy oil is much more prevalent in the world than
conventional light crude oil., Some estimates have only S-
s ist of all in place oil being recoverable using
conventional techniques, leaving an enormous amount of
untapped resources in the form of heavy oil throughout the
world.
Is Previous systems for extraction of heavy oil have required
vast amounts of capital infrastructure investment. Some
forms of heavy oil extraction from bitumen entail removal
of the bitumen from the Earth to a processing facility from
which using heat, steam, solvents or other methods the oil
15 was removed from the sand or substrate. Other in Earth
methods of extraction use significant quantities of
solvents or are otherwise difficult or expensive to use.
20 OUKKARY OF MR INVIOITION
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It is an object of the present invention to provide a
system and method for extracting heavy oil that overcomes
problems in the prior art.
S A system is provided for extracting heavy oil from beneath
a ground surface. A single horizontal electrode is created
by horizontally boring a bole running under the ground
surface. An electrically conductive pipe is then provided
in the horizontally bored hole. The pipe contains
apertures passing through the pipe into the interior of the
pipe. A progressive cavity pump or other suitable pump is
installed in the pipe to carry liquid collected in the pipe
up to the ground surface.
Is With the horizontal electrode in place, a number of
vertical electrodes can be placed on either side of the
horizontal electrode and power supplies connected between
each of the vertical electrodes and the single horizontal
electrode. The power supplies are
used to positively
charge the vertical electrodes with the horizontal
electrode being negatively charged,
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In operation, as power is supplied between each of the
vertical electrodes and the horizontal electrode and water
is injected down the vertical electrodes, electric fields
are created between the positive vertical electrodes and
the negative horizontal electrode. The electric field
created across the formation between the vertical
electrodes and the horizontal electrode creates a number of
soil kinetic reactions that cause oil and water in the
formation to move towards and collect in the horizontal
W electrode.
The soil kinetic reactions created in the formation by the
electrical field include electroosmosis, eloctromigration,
electrophoresis and electrical resistive heating_
Is Electrooemosie is the induced motion of water and
hydrocarbons from the anodes (the vertical electrodes) to
the cathode (the horizontal electrode) resulting in a net
flow in the formation from the anodes to the cathode.
Electromigration involves the movement of ions toward the
20 respective anodes and cathodes. The electric field induced
through the formation between the anodes and cathode,
molecules in the formation are separated into their
positive ions and negative ions. The electrical field
=
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pull the free positive ions in the direction of the
negative electrode and the free negative ions in the
direction of the positive electrode. This creates an
acidic plume at the cathode the horizontal electrode) and
basic plumes at the anodes (the vertical electrodes).
Through the continuous use of free radicals such as
hydrogen ions and hydroxyl, the kinetic movement pushes
forward reducing viscosity of the hydrocarbons, as well as
decreasing the numerous unsolicited elements such as
sulfur/sulfides within the removed hydrocarbon mix
extracted from the cathode. Electrophoresis will occur ae
a result that many if not all of the dispersed particles
will have an electric surface charge on them. This charge
can be manipulated through the application of the electric
field and allow these charged particles to be moved through
the formation between the anodes and the cathode. Finally,
electrically resistive heating of the formation between the
anodes and the cathode will occur by the application of the
electric field in the formation between them. This heating
of the soil and other materials in the formation will lower
the viscosity of the oil present in the formation making it
easier for the oil to flow through the formation.
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One of the factors leading to heavy crude oil's "heaviness"
is the large number of carbon atoms making up the oil
itself; in some cases, 60 carbon atoms or more. The
electric field induced between the anodes and the cathode
heats the soil and can "crack" these long chain
hydrocarbons, resulting in oil with fewer carbon atoms and
therefore Less viscosity. The application of steady heat,
pressure created in the formation between the anodes and
cathode, and the increase in hydrogen allows the bitumen
fractions to breakdown into lighter ends, resulting in a
higher quantity and quality of hydrocarbons in the oil
being extracted in addition to allowing the oil to flow
better through the formation.
As a result of the soil kinetic reactions, oil and water
move towards the horizontal electrode where it passes
through the apertures in the pipe making up the horizontal
electrode. Once collected in the pipe, the oil and water
mixture can be pumped to the ground surface.
DESCRIPTION OF THE DRAWINOS
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While the invention is claimed in the concluding portions
hereof, preferred embodiments are provided in the
accompanying detailed description which may be best
understood in conjunction with the accompanying diagrams
where like parts in each of the several diagrams are
=
labeled with like numbers. and where:
Fig. 1 is a schematic illustration of a heavy oil
extraction/collection system;
Fig. 2 is a schematic illustration of a horizontal
electrode;
Fig. 3 is a schematic illustration of a vertical
electrode; and
Fig. 4 is a schematic illustration of a replenishable
vertical electrode in a further aspect.
DETAILED DESCRIPTION OF TEE ILLUSTRATED EMBODIMENTS
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System:
There are numerous components to the electrokinetic
extraction system of the present invention which we will
now address. The system comprises at least one horizontal
subterranean electrode Which contains a porous conduit into
which oil or other fluids from the ground formation can
migrate for evacuation to the ground surface. In addition
to the at least one horizontal subterranean electrode there
are also at least two vertical subterranean electrodes,
disposed on opposing sides of the horizontal electrode.
Generically the final elements of the system of the present
invention which allow for the evacuation of heavy oil and
electrokinetic method to the ground surface are in
extraction apparatus which is connected in some way to the
horizontal electrode -- this might in most circumstances
comprise the recovery pipe and the pump which would allow I ?
for the suction of oil from the ground formation through
the apertures in the porous extraction pipe.
Fig. 1 illustrates a heavy oil extraction/collection system
100. A horizontal eleCtrode 110 is provided running under
the ground surface 10 in the subsurface formation 20
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through a formation containiag a heavy oil deposit 50. As
outlined elsewhere herein, the system of the present
invention would require at least one horizontal electrode
in the subsurface formation that in a larger installation
or application it will be understood that more than one
horizontal electrode 110 might be used, with the likely
corresponding increase in the number of vertical
electrodes, and that systems of varying sizes including any
specific number of horizontal subterranean electrodes 110
JO are contemplated within the scope here of.
A number of vertical electrodes 120 are positioned on
either side of the horizontal electrode 110. At least two
vertical subterranean electrodes 120 are contemplated to be
required for the method of the present invention to
function properly. As in the cane of the
horizontal
subterranean electrode outlined above, the number of
vertical electrodes 120 is also contemplated to be
variable, either in an application using a single
subterranean horizontal electrode or in a larger
application or system with more than one horizontal
electrode. The number and location
of the vertical
electrodes 120 in an array in proximity or relation to the
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at least one horizontal subterranean electrode 110 will be
understood to vary and necessary Changes or modifications
to the system of the present invention as will be obvious
to one skilled in the art in order to accomplish this
objective are all contemplated within the scope hereof.
Fig. 2 illustrates a schematic illustration of a section of
the horizontal electrode 110. A horizontal bore hole 210 =
is created and a long porous conduit 220 of electrically
conductive material such as steel is inserted in the
horizontal bore hoie 210 to form the horizontal electrode
llo. The extraction pipe 220 contains a number of
apertures 230 positioned along a length of the pipe 220 to
provide access into an interior of the pipe 220. The
horizontal bore hole 210 can be made to any practical
length allowing the horizontal electrode 110 to be made to
any practical length. The extraction pipe 220 would then
be electrified by the application of electrical energy from
a power source, described in further detail elsewhere
herein.
Referring again to Fig. 1, a progressive cavity pump 250 or
other suitable device is provided in the interior of the
CA 2668784 201/-03-07
pipe 220 in the portion that is running horizontally to
pump fluid up the bore hole 210 to the ground surface 10.
Fig. 3 illustrates one embodiment of a vertical electrode
$ 120. A vertical bore hole 310 is created passing through
the ground surface 10 into subsurface formation 20. An
electrically conductive rod 320 such as a carbon rod is
inserted down the vertical bore hole 310 to form the
vertical electrode 120.
The conductive rod 320 is placed down the vertical bore
hole 310 so that the conductive rod 320 forms a vertical
electrode 120 in the ground at substantially the same depth
as the horizontal electrode 110, shown in Pig. A.
Alternatively. in a further aspect granular carbon or some
other electrically conductive particulate material might be
placed in the vertical bore bole 310 to form the vertical
electrode 120.
Referring again to Fig. 1, to create the system 100, a
number of vertical electrodes 120 are used, each created by
boring a vertical bole through the ground surface 10 down
through the formation 20 to either side of the horizontal
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electrode 110. because the horizontal electrode 1/0 can be
quite long, if vertical electrodes 120 are not originally
provided along the entire length of the horizontal portion
of the horizontal electrode 110, the vertical electrodes
120 will typically be clustered around a portion of the
length of the horizontal electrode 110.
At least one power supply 150 is then provided between each
of the vertical electrodes 120 and the horizontal electrode
110. Although fewer power supplies 150 could be used with
one power supply ISO connecting more than one vertical
electrode I20 to the horizontal electrode 110 in parallel,
in this embodiment each power supply 150 is connected
between a single vertical electrode 120 and the horizontal
is electrode 110 so that the vertical electrode 120 is
supplied with -a positive charge and the horizontal
electrode 110 is provided with a negative charge. In this
manner, an electric field can be induced in the soil
between the vertical electrodes 120 and the horizontal
electrode 110 with the vertical electrodes 120 acting as
anodes and the horizontal electrode 120 acting as a
cathode.
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Method of extractions
In operation, voltage and current are supplied between each
of the vertical electrodes 120 and the horizontal electrode
110 so that the vertical electrodes 120 are positively
charged and the horizontal electrode 110 is negatively
charged creating an electric field in. the formation 20
between the vertical electrodes 120 and the horizontal
electrode 110. Water can be injected down the vertical
electrodes 120 and out into the ground surrounding the
vertical electrodes 120.
The creation of an electrical field between the anode and
.15 cathode electrodes causes soil kinetic reactions to occur
in the formation 20 between the vertical electrodes 120 and
the horizontal electrode 110, Specifically, electrooamosia,
electromigration, electrophoresis and electrical resistive
heating. zlectroosmosis causes
the uniform movement of
water and hydrocarbon from the anodes (vertical electrodes
120) towards the cathode (the horizontal electrode 110)
causing a net flow of water and hydrocarbons from the anode
to the cathode. Electromigration will cause ions In the
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formation 20 to move towards the vertical electrodes 120
and horizontal electrode 110. This electromigration of
ions reduces the viscosity of the hydrocarbons as well as
decreasing a number of undesired elements such as
sulfur/sulfides from the collected oil. Electrophoresis
will alter the surface charge on dispersed particles in the
formation 20 allowing the charged particles to be moved
through the formation 20_ Electrical resistive
heating
increases the temperature of the formation 20 between the
vertical electrodes 120 and the horizontal electrode /10,
which, in addition to decreasing the viecoeity of the oil
in the formation 20, along with the increased pressure and
additional hydrogen from the other kinetiC reaction serves
to 'crack" the long chain carbons of the hydrocarbons,
allowing the hydrocarbons to more easily flow through the
formation 20 and improving the quality of the extracted oil
collected from the horizontal electrode 110.
The result of these kinematic reactions is a net flow of
oil and water towards to the horizontal electrode 110
acting as a cathode. Referring again to Fig. 2, as this
flow of oil and water moves towards the horizontal
electrode 110, it will pass through the apertures 230 in
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the pipe 220 and collect in the interior of the pipe 220.
The oil/water mixture collecting in the interior of the
pipe 220 can then be pumped to the ground surface 10 by the
progressive cavity pimp 250, where it can be gathered and
further treated.
Because of the ongoing need to inject water down the
vertical electrodes 120 and into the formation 20 as the
system 100 is in use, in one aspect, the oil/water mixture
extracted from the horizontal electrode 110 and pumped up
to the ground surface 10 by the progressive cavity pump 150
is separated into oil and water at the ground surface 10.
The separated water is then redirected back to the vertical
electrodes 120 to once again be injected down the vertical
electrodes 120 and into the formation 20. In this manner,
the water injected down the vertical electrodes 120 and
recovered with the collected oil can be reused for the
process, reducing the total amount of water that is
necessary for the process.
In a further aspect, the water being injected down the
vertical electrodes 120 can have a small amount of oxidant
such as hydrogen peroxide added to the water being injected
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to aid in the flow induced by the anode/cathode reaction in
the coil 20.
Each power supply 150 is connected across the horizontal
electrode 110 to only one of the vertical electrodes 120.
When a positive voltage is applied to the vertical
electrodes 120 by each of the power supplies 150, the
vertical electrodes 120 act as anodes with the single
horizontal electrode 110 acting as a cathode. By providing
M a power supply 150 for each vertical electrode 120, the
voltage and current supplied to each vertical electrode 120
can be varied independently from the other vertical
electrodes 120 allowing the electric field at different
points along the horizontal electrode 110 to be altered to
account for differences in the make up of the formation 20.
If the formation 20 between one of the vertical electrodes
120 and the horizontal electrode 110 differs in the makeup,
density, moisture content, etc. from the formation 20
between another of the vertical electrodes 120 and the
horizontal electrodes 110, different voltages and/or
current can be supplied by the respective power supplies
150 to account for the differences in the soil 20. In this
manner, different soil conditions between different
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vertical electrodes 120 paired with the horizontal
electrode 110 can be taken into account at the same time.
Once the heavy oil in the formation 20 between the vertical
electrodes 120 and the horizontal electrode 110 has been
sufficiently extracted from the formation 20, the previous
vertical electrodes 120 can be abandoned and new vertical
electrodes 120 created further along the length of the
horizontal electrode 110 allowing heavy oil to be extracted
from formation 20 surrounding the horizontal electrode 110
further along the length of the horizontal electrode 110.
In this manner, a single horizontal electrode 110 can be
used over and over again as vertical electrodes 120 are
created along the length of the single horizontal electrode
l5 110.
Because the application of voltage and current across the
vertical electrodes 120 and the horizontal electrode 110
results in an anode/cathode reaction with the vertical
electrodes 120 acting as anodes, the electrically
conductive material making up the vertical electrodes 120
will breakdown and degrade over time. Typically, this
requires the vertical electrode 120 to be maintained or
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replaced periodically. Providing maintenance on
or
replacing one of the vertical electrodes 120 is much
simpler and less costly then replacing the horizontal
electrode 110 because the cost of horizontal drilling and
the assembly of the horizontal electrode 110 is costly.
Additionally, because the horizontal electrode 110 is
functioning as the cathode, it will not degrade over time
like the anode (in fact it will be cathodically protected),
causing the horizontal electrode 110 not to require the
same amount of maintenance and replacement as the vertical
electrodes 120.
Ac a portion of the formation 20 around the horizontal
electrode 110 is depleted of oil, new vertical electrodes
120 can be made surrounding the same horizontal electrode
110 further down the length of the horizontal electrode
110. This allows the single horizontal electrode 110 to be
repeatedly used with numerous vertical electrodes 120 and
allowing oil to be extracted along the entire length of the
horizontal electrode 110 as new vertical electrodes 1.20 are
installed along the length of the horizontal electrode 110.
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Repleniehable vertical subterranean electrode:
Beyond the system and method of extraction of subterranean
heavy oil outlined herein one of the other key aspects of
the present invention as outlined in claims in the
remainder of this specification is the invention of a
replenishable vertical electrode for subterranean
applications, as well as a method for its manufacture.
io One of the previous issues with the use of subterranean
electrodes in electrOkinetic applications is at the
electrodes degrade after a period of time and need to
potentially be extracted or replaced where for example a
conductive rod or the like is used -- the cost of
replacement of the electrodes from time to time drives up
the cost of their use in various electrdkinetic
subterranean applications and it is a desired Object of the
present invention to provide a replenishable subterranean
electrode for use in the vertical application that would
.20 not require the complete removal and replacement of for
example a conductive rod or the like. Certain applications
will still require the use of a rod or a conduit if the
conduit is being used also for the carriage of fluids or
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the like to particular locations down the ground for but in
certain applications where the pipe was not necessary for
= other uses in addition to the electrode application, the
replenishable vertical electrode outlined herein will
provide significant benefits in cost and simplicity of
manufacture for use in this as well as other electrokinetic
applications.
In a further aspect, the vertical electrodes 120 are
replenishable. Fig. 4 is a schematic illustration of a
repleniahable vertical electrode 120. A vertical bore hole
410 is drilled and a casing 415 of a non-conductive
material such as fiberglass in used to line the vertical
bore hole 410 down to the desired depth in the soil 20 so
that the vertical electrode 120 is at the same depth as the
horizontal electrode 110. Electrically conductive liquid
420, such as liquid graphite, is then inserted down the
bore hole 410 contacting the soil 20 where the casing 415
is not present. A conductor 436 such as an electrically
conductive wire is then fed down the vertical bore hole 410
into the electrically conductive liquid 420.
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In operation, voltage and current is passed to the vertical
electrode 120 down conductor 430 to electrically charge the
electrically conductive liquid 420. As the electrically
conductive liquid 420 degrades as a result of the
anode/cathode reaction, more electrically conductive liquid
420 can be supplied down the vertical bore hole 410. In
one aspect, a bead of electrically conductive liquid 420
can be kept in the casing 415. Mn this manner, the head
creates pressure in the electrically conductive liquid 420
in contact with the formation 20, automatically
replenishing the electrically conductive liquid 420 as it
degrades.
Water can be injected down the vertical electrode 120 by
maintaining a significant head of water in the vertical
bore hole 410 causing the water to mix with the
electrically conductive liquid 420 and pass out into the
formation 20 surrounding the vertical bore hole 410 below
the casing 415.
Alternatively a hollow pipe 440 can be provided passing
through the electrically Conductive liquid 420 with branch
conduits 445 extending from the hollow pipe 440 to the
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interior surface of the vertical bore hole 410.
Pressurized water can then be injected down the hollow pipe
440 and out the branch conduits 445 into the formation 20
surrounding the vertical bore hole 41g. In this manner,
the amount of water injected into the formation 20 can be
somewhat controllable. .
A. horizontal subterranean electrode which was replenishable
could also be generated or manufactured in accordance with
the method of the present invention albeit in that
circumstance it would be difficult when the electrically
conductive fluid was placed within the horizontal bore to
provide an interior conduit therein for evacuation or
extraction of oil. It will however be understood that in
certain circumstances this could be overcome, and another
circumstances where a horizontal subterranean electrode was
required without the need for a porous extraction pipe or
other interior extraction mechanism the method of
manufacture of the replenishable electrodes outlined herein
could be used very effectively by simply pouring the
electrically conductive fluid in question down the
horizontal bore hole and placing an. electrical conductor
therein. Insofar as subterranean horizontal electrodes of
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this nature would be useful in certain applications without
the need even for a central or porous extraction pipe
therein, it will be understood that the manufacturer of a
horizontal subterranean electrode in accordance with the
3 same type of a method as is outlined herein with respect to
a vertical subterranean electrode is also contemplated
within the scope of the present invention.
The foregoing is considered as illustrative only of the
principles of the invention. Further, since numerous
changes and modifications will readily occur to those
skilled in the art, it is not desired to limit the
Invention to the exact construction and operation shown and
Is described, and accordingly, all such suitable changes or
modifications in structure or operation which may be
resorted to are intended to fall within the scope of the
claimed invention.
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