Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR PROCESSING HYDROCARBONS
This invention concerns improvements in and relating to the processing of
matrices
and/or the contents of matrices, in particular but not exclusively the
treatment of
geological structures, such as hydrocarbon containing reservoirs, and/or
compounds, such
as hydrocarbons either whilst within such structures and/or after extraction
by human
activity.
In a variety of situations, hydrocarbons are known to exist within the matrix
formed
by a geological structure. The geological structure may be a relatively
shallow one such as
encountered with some oil sands. The geological structure may be a relatively
deep one
beneath the surface, such as an offshore oil containing reservoir. Some forms
of
hydrocarbons, particularly light oils, are more readily extracted than other
forms, such as
heavy oils or bituminous hydrocarbons. Existing processing approaches can face
difficulties
in extracting such hydrocarbons or difficulties because of the costs of doing
so.
Even once extracted by human activity, some hydrocarbons are more commercially
valuable than others. Lighter oils which are closer to the high demand
gasoline format of
hydrocarbons are typically more valuable that heavier oils and/or sour oils
which contain
contaminants such as heavy metals or sulphur.
Existing approaches to the treatment of such compounds formed of less
commercially valuable hydrocarbons are time consuming, expensive in terms of
capital
equipment and expensive in terms of operation, for instance power consumption
or the
need to blend the hydrocarbon with lighter oils.
The present invention has amongst its potential aims to provide a method and
apparatus which offers a beneficial approach to breaking down compounds,
typically
hydrocarbons, through oxidation. This aim may relate to the compounds whilst
still in-situ
and/or after extraction by human activity from the location where they
occurred.
The present invention has amongst its potential aims to provide a method and
apparatus which allow a wider range of compounds, particularly hydrocarbons,
to have
commercial value or increased commercial value through the treatment of such
hydrocarbons after extraction by human activity.
The present invention has amongst its potential aims to provide a low power
consumption process and apparatus for the processing of geological structures,
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hydrocarbons below the surface of the ground or other hydrocarbon containing
locations in
matrix form, particularly to reduce the viscosity of the compounds present
and/or to reduce
the carbon chain length of the compounds present and/or to reduce the level of
contamination present within those compounds, for instance contamination by
sulphur
and/or chlorides and/or heavy metals and/or water.
According to a first aspect of the invention there is provided a method for
the processing of
hydrocarbons within a location, the method including:
a) introducing at least two electrodes into the location, the location
containing the
hydrocarbons;
b) providing connections between a voltage source and the at least two
electrodes;
c) applying a voltage of a first polarity to the connections for a first
period of time,
under the control of a voltage controller;
d) applying a voltage of a second, reversed, polarity to the connections for a
second
period of time, under the control of the voltage controller;
e) repeating steps c) and d) a plurality of times;
steps c), d) and e) promoting a reduction in the length of the carbon chain
for one of
more species present in the hydrocarbon and/or a reduction in the sulphur
content of the
hydrocarbons and/or a reduction in the heavy metal content of the
hydrocarbons.
The processing of the hydrocarbons may be to reduce the viscosity of the
hydrocarbons, for instance within the location. The processing of the
hydrocarbons may be
to reduce the size of the average hydrocarbon molecule present and/or the size
of the
larger hydrocarbon molecules present. The processing may be to convert one or
more of the
heavier hydrocarbons present to one or more light hydrocarbons. The processing
may be to
reduce the level of one or more contaminants in the hydrocarbons, such as the
sulphur level
and/or heavy metal level.
The hydrocarbons may be within a volume of material, with the volume of
material
being a matrix, for instance a matrix which is a mixture of liquid and solid,
such as the
hydrocarbons and the surrounding rock. This includes all situations where the
hydrocarbons
are present below the surface of the ground in a matrix awaiting extraction.
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The location may be man-made location for hydrocarbons extracted by human
activity. The location may be a location built to contain the hydrocarbons.
The location may
be a storage location. The location may be a transport location. The location
may be a
processing location. The location may be a location where the hydrocarbons
occur naturally
in-situ.
The location may be a tank or other form of container for hydrocarbons
extracted by
human activity. The tank or other form of container may be provided with an
inlet for the
hydrocarbons. The tank or other form of container may be provided with an
outlet for the
hydrocarbons. A pump or other means for moving the hydrocarbons may be
provided,
particularly to provide circulation and/or mixing of the hydrocarbons. The
location may be a
pre-existing location to which the method is applied, for instance a storage
location. The
location may be a location to which hydrocarbons are conveyed for the
application of the
method. The one or more electrodes may include one or more walls of the tank
or other
form of container, or parts thereof. The one or more electrodes may be
provided within the
tank or other form of container.
The location may be a conduit through which hydrocarbons pass after extraction
by
human activity. The conduit may be a pipe. The pipe may extend between a first
site and a
second site. The first site and the second site may be at least 1 km apart and
may be at least
km apart. The first site may be a site at which hydrocarbons are extracted
from an in-situ
location. The second site may be a storage site or a processing site for
hydrocarbons. The
one or more electrodes may extend into the pipe, for instance across a part of
the cross-
section of the pipe. The one or more electrodes may be provided as a grid. The
one or more
electrodes may extend across a part of the cross-section of the pipe,
potentially in different
orientations along the length of the pipe. The location may be a naturally
occurring location
below ground. The location may be a geological structure, for instance one or
more strata
within a geological structure or parts thereof. The location may be a location
at which
hydrocarbons have been formed naturally below ground and/or a location to
which
naturally formed hydrocarbons have moved after extraction.
One or more outlets, preferably man made, may be provided to allow
hydrocarbons
to leave the geological structure, for instance one or more drilled extraction
wells. One or
more inlets, preferably man made, may be provided to allow one or more
materials to be
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introduced to the geological structure, preferably to assist in the extraction
of
hydrocarbons.
The hydrocarbons may be introduced to the location, for instance by being
extracted
and removed to the location or for instance by being directed to the location
by a prior
process, such as flowing to the location.
The hydrocarbons may be already at the location below ground, for instance by
being naturally occurring at the location and/or by being found at the
location by
investigations.
The hydrocarbons may be classified as heavy crude oil. The hydrocarbon may be
classified as heavy crude oil due to having an API gravity of less than 22.3.
The hydrocarbons
may be classified as extra heavy crude oil. The hydrocarbons may be classified
as extra
heavy crude oil due to having an API of less than 10. Potentially the
hydrocarbons may be
classified as light crude oil. The hydrocarbon may be classified as light
crude oil due to
having an API of greater than 31.1 and/or due to originating from US and
having an API of
37 to 42 and/or due to being non-US originating and having an API of 32 to 42
degrees. The
hydrocarbon may be classified as medium crude oil. The hydrocarbon may be
classified as
medium crude oil due to having an API of 22.3 to 31.1. For reference, Brent
crude has an API
38.06 and water has an API of 10.
The reduction of the length of the carbon chain for one or more species in the
hydrocarbons may cause a change in the API value for the hydrocarbons and/or a
change in
viscosity for the hydrocarbons.
The hydrocarbon may have a first API value, for instance at a first time. The
hydrocarbon may have a second API value, for instance at a second time which
is after the
first time. The time period between the first time and the second time may be
between 20
hours and 2000 hours, potentially between 30 hours and 1000 hours, preferably
between
60 hours and 400 hours and ideally between 75 hours and 300 hours. The second
API value
may be greater than the first API value. The second API value may be at least
25%, possibly
at least 50%, potentially at least 75% and preferably at least 100% higher
that the first API
value.
The hydrocarbon may have a second API value which is greater than the first
API
value, without the addition of any further hydrocarbons having a greater API
to the
hydrocarbon being treated. The hydrocarbon may have a second API value which
is greater
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than the first API value, without the hydrocarbon being blended and/or mixed
and/or
contact with any further hydrocarbons of a different composition.
The hydrocarbon may have a second API value which causes the hydrocarbon to be
classified as a different grade of crude oil compare with the classification
caused by the first
API value. For instance, an extra heavy crude oil at the first time may be
classified as a heavy
crude oil at the second time. The API considerations are made at the same
temperature at
the first time and the second time.
The hydrocarbon may have a first viscosity value, for instance at a first
time. The
hydrocarbon may have a second viscosity value, for instance at a second time
which is after
the first time. The time period between the first time and the second time may
be between
20 hours and 2000 hours, potentially between 30 hours and 1000 hours,
preferably
between 60 hours and 400 hours and ideally between 75 hours and 300 hours. The
second
viscosity value may be less than 60% the first viscosity value. The second
viscosity value may
be less than 30%, possibly less than 20%, potentially less than 15% and
preferably at less
than 10% of the first viscosity value.
The hydrocarbon may have a second viscosity value which is less than the first
viscosity value, without the addition of any further hydrocarbons having a
lower viscosity to
the hydrocarbon being treated. The hydrocarbon may have a second viscosity
value which is
less than the first viscosity value, without the hydrocarbon being blended
and/or mixed
and/or contact with any further hydrocarbons of a different composition.
The hydrocarbon may have a second viscosity value which causes the hydrocarbon
to be classified as a different, lighter, grade of crude oil compare with the
classification
caused by the first viscosity value. For instance, an extra heavy crude oil at
the first time
may be classified as a heavy crude oil at the second time. The viscosity
considerations are
made at the same temperature at the first time and the second time.
The reduction in the sulphur content of the hydrocarbons may arise together
with a
reduction in the carbon chain length for one or more species in the
hydrocarbons.
The hydrocarbons may be classified as a sweet crude oil. The hydrocarbon may
be
classified as a sweet crude oil due to having a sulphur content of less than
0.5% by weight.
The hydrocarbons may be classified as a sour crude oil. The hydrocarbons may
be classified
as a sour crude oil due to having a sulphur content of 0.5% or more by weight.
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hydrocarbon may have a sulphur content at a first time of greater than 1%,
possibly greater
than 2%, potentially greater than 3% and even possibly greater than 4%.
The hydrocarbon may have a first sulphur content, for instance at a first
time. The
hydrocarbon may have a second sulphur content, for instance at a second time
which is
after the first time. The time period between the first time and the second
time may be
between 20 hours and 2000 hours, potentially between 30 hours and 1000 hours,
preferably between 60 hours and 400 hours and ideally between 75 hours and 300
hours.
The second sulphur content may be less than the first sulphur content. The
second sulphur
content may be 25% or more less than, possibly 50% or more less than,
potentially 75% or
more less than, and preferably 85% or more less than the first sulphur
content.
The hydrocarbon may have a second sulphur value which is less than the first
sulphur value, without the addition of any further hydrocarbons having a lower
sulphur
content to the hydrocarbon being treated. The hydrocarbon may have a second
sulphur
content which is less than the first sulphur content, without the hydrocarbon
being blended
and/or mixed and/or contact with any further hydrocarbons of a different
composition.
The hydrocarbon may have a second sulphur content which causes the hydrocarbon
to be classified as a sweet crude oil compared with a classification of sour
crude oil caused
by the first sulphur content value.
The reduction in the heavy metal content of the hydrocarbons may arise
together
with a reduction in the carbon chain length for one or more species in the
hydrocarbons.
The hydrocarbon may have a first heavy metal content, for instance at a first
time.
The hydrocarbon may have a second heavy metal content, for instance at a
second time
which is after the first time. The time period between the first time and the
second time
may be between 20 hours and 2000 hours, potentially between 30 hours and 1000
hours,
preferably between 60 hours and 400 hours and ideally between 75 hours and 300
hours.
The second heavy metal content may be less than the first heavy metal content.
The second
heavy metal content may be 15% or more less than, possibly 25% or more less
than,
potentially 50% or more less than, and preferably 65% or more less than the
first heavy
metal content. The heavy metal content may consider one or more or all of:
nickel,
vanadium, copper cadmium or lead. The heavy metal content may consider, or may
further
consider in combination with the species above, one or more or all of e
content with respect
to cadmium, zinc, manganese, iron,
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The hydrocarbon may have a second heavy metal content value which is less than
the first heavy metal content value, without the addition of any further
hydrocarbons
having a lower heavy metal content to the hydrocarbon being treated. The
hydrocarbon
may have a second heavy metal content which is less than the first heavy metal
content,
without the hydrocarbon being blended and/or mixed and/or contact with any
further
hydrocarbons of a different composition.
The two or more electrodes, particularly when provided in a naturally
occurring
location such as a geological structure, may have a length of over 25m, for
instance over
50m, possibly over 100m and potentially over 250m. The two or more electrodes,
particularly when provided in a naturally occurring location such as a
geological structure,
may have a length of less than 2000m, for instance less than 1000m, possibly
less than
500m and potentially less than 250m.
The two or more electrodes may have a length of over 0.25m, for instance over
1m,
possibly over 5m and potentially over 10m. The two or more electrodes may have
a length
of less than 30m, for instance less than 15m, possibly less than 10m and
potentially less
than 5m.
The two or more electrodes, particularly when provided in a storage location
such as
a tank or other container, may have a length of over 1m, for instance over 2m,
possibly over
3m and potentially over 5m. The two or more electrodes, particularly when
provided in a
storage location such as a tank or other container, may have a length of less
than 20m, for
instance less than 10m, possibly less than 7m and potentially less than 5m.
The two or more electrodes, particularly when provided in a conduit such as a
pipe,
may have a length of over 0.1m, for instance over 0.3m, possibly over 0.5m and
potentially
over 1m. The two or more electrodes, particularly when provided in a conduit
such as a
pipe, may have a length of less than 2m, for instance less than 1m, possibly
less than 0.75m
and potentially less than 0.5m.
The two or more electrodes may be of titanium, particularly titanium provided
with
a mixed metal oxide surface or coating. The two or more electrodes may be of
steel.
The two or more electrodes may be spaced along the length of the location. The
two
or more electrodes may be spaced along the width of a location. The length and
width of
the location may be provided with an array of electrodes, for instance a
regular array of
electrodes. The spacing of the electrodes may be a common spacing between one
electrode
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and the next across the width of the location. The spacing of the electrodes
may be a
common spacing across the length of the location. The spacing may be the same
across the
width as along the length of the location.
The spacing may be lower or higher across the width of the location when
compared
with the length of the location.
More electrodes may be provided in one or more parts of the location being
treated
compared with one or more other parts. The one or more parts may include the
edges of
the location being treated. The one or more parts may include the central 30%
of the
location being treated, considered by volume or considered by distance
relative to the
distance between one electrode at one extremity of the location and the
electrode further
away from that electrode. The one or more other parts may include the edges of
the
location being treated. The one or more other parts may include the central
30% of the
location being treated, considered by volume or considered by distance
relative to the
distance between one electrode at one extremity of the location and the
electrode further
away from that electrode.
The electrodes, particularly when provided in a naturally occurring location
such as a
geological structure, may have a spacing greater than 25m, for instance
greater than 50m,
possibly greater than 100m and potentially greater than 250m. The electrodes,
particularly
when provided in a naturally occurring location such as a geological
structure, may have a
spacing less than 5000m, for instance less than 2500m, possibly less than
1000m and
potentially less than 500m.
The electrodes may have a spacing greater than 1m, for instance greater than
2m,
possibly greater than 5m and possibly greater than 10m. The electrodes may
have a spacing
less than 50m, for instance less than 25m, possibly less than 15m and possibly
less than
10m.
The electrodes, particularly when provided in a storage location such as a
tank or
other container, may have a spacing greater than 0.1m, for instance greater
than 0.5m,
potentially greater than 2m and possibly greater than 5m. The electrodes,
particularly when
provided in a storage location such as a tank or other container, may have a
spacing less
than 15m, for instance less than 10m, potentially less than 5m and possibly
less than 2m.
The electrodes, particularly when provided in a conduit such as a pipe, may
have a
spacing of greater than 0.01m, for instance greater than 0.05m, possibly
greater than 0.1M
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and potentially greater than 0.3m. The electrodes, particularly when provided
in a conduit
such as a pipe, may have a spacing of less than 1m, for instance less than
0.5m, possibly less
than 0.3m and potentially less than 0.2.
The electrodes may have an extent into the depth, particularly when provided
in a
naturally occurring location such as a geological structure, of greater than
10m, for instance
greater than 50m, possibly greater than 100m and potentially greater than
250m. The
electrodes may have an extent into the depth, particularly when provided in a
naturally
occurring location such as a geological structure, of less than 1000m, for
instance less than
500m, possibly less than 200m and potentially less than 100m.
The electrodes may have an extent into the depth for instance greater than
0.7m,
possibly greater than 2m and potentially greater than 5m. The electrodes may
have an
extent into the depth of less than 10m, for instance less than 5m, possibly
less than 2m and
potentially less than 1m.
The electrodes may have an extent into the depth, particularly when provided
in a
storage location such as a tank or other container, of greater than 0.5m, for
instance greater
than 1.5m, possibly greater than 4m and potentially greater than 8m. The
electrodes may
have an extent into the depth, particularly when provided in a storage
location such as a
tank or other container, of less than 20m, for instance less than 10m,
possibly less than 5m
and potentially less than 2m.
The electrodes may have an extent into the depth, particularly when provided
in a
conduit such as a pipe, of greater than 0.1m, for instance greater than 0.5m,
possibly
greater than 1m and potentially greater than 2m. The electrodes may have an
extent into
the depth, particularly when provided in a conduit such as a pipe, of less
than 3m, for
instance less than 2m, possibly less than 1m and potentially less than 0.5m.
The electrodes may have an extent into the depth of the location which is at
least
20% of the depth of the location being treated, more preferably at least 50%
of the depth of
the location being treated.
A gap may exist between the top of the electrodes and the surface of the
structure
they are provided in. The gap may be bridged by the electrical conductor, for
instance wire,
used to connect the electrodes to the surface and/or power supply.
The electrodes may be generally vertically provided, for instance +/- 20
degrees to
the vertical, ideally +/- 5 degrees to the vertical. The generally vertically
provided electrode
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may provide only a section of the overall electrode. The generally vertically
provided
electrode may be present in combination with a generally horizontal section of
electrode to
provide an overall electrode. Inclined, curved, spiral and other shapes for
the electrode may
be provided. For instance a drill, subsequently used as an electrode, or an
electrode inserted
into a drill hole may extend down into the location and then turn and extend
out into the
location with various directions and inclinations for different sections.
The electrodes may be inserted into apertures formed within the volume of
material.
The apertures may be formed by drilling into the volume of material. The
drills may
subsequently be used as the electrodes. The apertures may be formed by driving
or
otherwise forcing an element into the volume of material. The elements may
subsequently
be used as the electrodes.
One or more material may be added to the aperture, before and/or during and/or
after drilling or driving or forcing. The one or more materials may increase
the conductivity
between the electrodes and the volume of material compared with the
conductivity when
the one or more materials are absent.
One or more pairs of alternative orientation electrodes may be provided. One
or
more sets of electrodes of alternative orientation may be provided. The
alternative
orientation may be horizontal +/- 30 degrees, preferably +/- 20 degrees and
ideally +/- 5
degrees. Such pairs or sets of electrodes may be provided in addition to the
other pairs or
sets of electrodes.
The alternative orientation pairs or sets of electrodes may be provided with
connections and/or voltage pulse profiles and/or defined current pulse
profiles and/or other
characteristics as defined elsewhere for the pairs of electrodes or sets of
electrodes.
The electrodes, particularly when provided in alternative orientations, may be
positioned within the volume of material, for instance using gravity, for
instance by allowing
the electrodes to settle within the location.
The electrodes, particularly when provided in alternative orientations, may be
flexible electrodes. The flexible electrodes may be wires and/or cables and/or
flexible rods.
The electrodes, particularly the flexible electrodes, may be bare metal
electrodes and/or be
without any insulating coating or cover.
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The connections may include the connection of the voltage source to two or
more
electrodes, those two or more electrodes forming a first set of electrodes.
The voltage
controller may provide a first set of operating conditions to the first set of
electrodes.
The method may further include providing connections between the voltage
source
and two or more second set electrodes. The voltage controller may provide a
second set of
operating conditions to the second set of electrodes.
The method may further include providing connections between the voltage
source
and one of more still further sets electrodes. The voltage controller may
provide a still
further set of operating conditions to each of the still further sets of
electrodes.
Each of the sets of operating conditions may be different from each of the
other sets
of operating conditions. Two or more of the operating conditions may be the
same as each
other. The operating conditions may include the voltage pulse profile applied,
including the
voltage pulse profile during different component parts of the voltage pulse
profile, the
magnitude of the pulse over its full cycle and during the different component
parts and the
duration of the full cycle and each of the component parts and the sequence of
the
component parts. The operating conditions may include one or more of: the
voltage pulse
profile applied; the voltage pulse profile during one or more or all of the
different
component parts of the voltage pulse profile; the magnitude of the pulse over
its full cycle
and/or during one or more or all of the different component parts; the
duration of the full
cycle and/or one or more or each of the component parts; or the sequence of
the
component parts.
Two or more of the sets of operating conditions may be the same except for the
start time of the voltage pulse profile. The start time of the voltage pulse
profile may be
offset with respect to one or more or all of the other sets of operating
conditions. The
second set of operating conditions may be offset in time with respect to the
start of its
voltage pulse profile compared with the start of the voltage pulse profile of
the first set of
operating conditions. The still further sets of operating conditions may be
provided with
their own further offsets, potentially including an offset value for one of
the still further sets
of operating conditions which cause it to have the same phase as the first set
of operating
conditions. One or more of the still further sets of operating conditions may
have a phase
matching the first set of operating conditions. One or more of the still
further sets of
operating conditions may have a phase matching the second set of operating
conditions.
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One or more of the still further sets of operating conditions may have a phase
matching one
of the other still further sets of operating conditions.
The first set of electrodes may include electrodes extending across the width
of the
location in a first set of positions, for instance in a row. The first set of
electrodes may
include electrodes extending across the width of the location at a second set
of positions,
for instance a second row. The first and second positions may be such that
there are no
intervening electrodes from other sets of electrodes. The first and second
positions may be
rows, relative to the length of the location, ideally with no rows of
electrodes from one or
more other sets of electrodes between them. In particular, the first set of
electrodes may
have a first row of electrodes and a second row of electrodes adjacent one
another.
A second set of electrodes may be provided in addition to the first set of
electrodes.
The second set of electrodes may include electrodes extending across the width
of the
location in a second set of positions, for instance in a row. The second set
of electrodes may
include electrodes extending across the width of the location at a second set
of positions,
for instance a second row. The first and second positions may be such that
there are no
intervening electrodes from other sets of electrodes. The first and second
positions may be
rows, relative to the length of the location, ideally with no rows of
electrodes from one or
more other sets of electrodes between them. In particular, the second set of
electrodes may
have a first row of electrodes and a second row of electrodes adjacent one
another. The
second set of electrodes may be provided to one side, for instance relative to
the length of
the location, the first of the still further sets of electrodes may be
provided to the other
side. The various still further sets of electrodes may be provided in
equivalent arrangements
relative to one another.
In a preferred form, the first set of electrodes may be provided in two
parallel rows,
followed by the second set of electrodes in two parallel rows, followed by a
further first set
of electrodes in two parallel rows, followed by a further second set of
electrodes in two
parallel rows, potentially with one or more further repeats of this
arrangement. Within each
set of electrodes, it is preferred that one row is of a first polarity and the
other row is of a
different polarity. Corresponding rows in different sets of electrodes may be
provided at the
same polarity at the same time.
The voltage source may be connected to a mains power supply. The voltage
source
may be connected to a discrete power supply, for instance a power supply
specific to the
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method and/or specific to the geographical location at which the method is
conducted. The
voltage source may be an AC voltage source or a DC voltage source. The voltage
source may
step down the voltage to the level required for the method. A constant voltage
output may
be provided.
The voltage may be the voltage necessary to achieve a voltage of greater than
0.2V/m across the separation between the electrode of one potential and the
electrode of a
different potential which is closest to that electrode. A voltage greater than
0.4V/m may be
so provided. A voltage greater than 0.8V/m may be so provided. The voltage
drop provided
may be greater than 1V/m, for instance greater than 1.5V/m, possibly greater
than 2V/m or
potentially greater than 3V/m. A voltage greater than 0.4V/m may be so
provided. A voltage
less than 10V/m may be so provided. The voltage drop provided may be less than
8V/m, for
instance less than 6V/m, possibly less than 4V/m or potentially less than
3V/m.
The voltage controller may determine the voltage applied to one of the at
least two
electrodes. The voltage controller may determine the voltage applied to the
electrodes in
the first position in a set of electrodes, including the first set and/or
second set and/or one
or more of the still further sets. The voltage controller may apply a zero
voltage or a
different voltage to the other of the at least one electrodes. The voltage
controller may
apply a zero voltage or a different voltage to the electrodes in the second
position in a set of
electrodes, including the first set and/or second set and/or one of more of
the still further
sets. A zero voltage or a voltage of a different polarity may be applied to
the other of the at
least one electrodes. A zero voltage or a voltage of a different polarity may
be applied to the
electrodes in the second position in a set of electrodes.
The voltage controller may determine the voltage applied to the first position
electrodes in a second set of electrodes. The voltage controller may apply a
voltage and/or a
polarity to the first position electrodes in the second set of electrodes
which is different to
the second position electrodes in the first set of electrodes. The voltage
controller may
determine the voltage applied to the first position electrodes in one or more
or all of the
still further sets of electrodes. The voltage controller may apply a voltage
and/or a polarity
to the first position electrodes in the one or more or all still further sets
of electrodes which
is different to the second position electrodes in the adjacent set of
electrodes. In a preferred
form, one row of electrodes is at a first voltage and/or first polarity, with
the adjacent row
of electrodes on one or both sides at a second voltage and/or polarity and/or
a third voltage
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and/or polarity respectively. The second voltage and/or polarity and the third
voltage
and/or polarity may be the same. A voltage difference and/or polarity
difference may be
provided between all adjacent position electrodes.
The voltage applied may be in the form of a voltage pulse profile. The voltage
pulse
may have a first section during which the voltage is at a maximum value. The
voltage pulse
profile may have a second section during which the voltage is at a maximum
value, but of
opposing polarity. The voltage pulse profile may be a square wave profile. The
duration of
the first section and the duration of the second section are preferably the
same.
In instances were transport of one or more parts of the matrix and/or one or
more
of the species being treated and/or one or more of the reaction products from
the
treatment of the one or more species is desired, then the first section and
the second
section may have different durations.
The first section and the second section are preferably adjacent one another.
Preferably the second section is followed by a further first section.
Preferably the further
first section is followed by a further second section. Preferably alternating
repeats of the
first section and the second section are provided.
In one embodiment of the invention, a third section is provided between the
first
section and the start of the second section. A fourth section may be provided
between the
second section and the start of a further first section. The sequence of first
section, third
section and second section may be repeated. The sequence of second section,
fourth
section and further first section may be repeated. The third section and/or
fourth section
may be a zero voltage section.
The first section and/or the second section may have a duration of between 1
and
500ms, for instance between 10ms and 500ms, more particularly between 20 and
200ms.
The third section and/or fourth section may have a duration of 0.5ms to 50ms.
The voltage controller may provide a voltage, particularly a voltage pulse
profile, to
the one or more pairs of electrodes so as to provide and/or seek to provide a
defined
current pulse profile. The voltage, particularly the voltage pulse profile,
may be determined
through a calibration method, for instance a calibration method according to
the third
aspect of the invention.
The defined current pulse profile may include a first section. The defined
current
pulse profile may include a second section, preferably following on directly
from the first
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section. The defined current pulse profile may include a third section,
preferably following
on directly from the second section or following on from a fourth section. The
defined
current pulse may include a first reversed section. The defined current pulse
profile may
include a second reversed section, preferably following on directly from the
first reversed
section. The defined current pulse profile may include a third reversed
section, preferably
following on directly from the second reversed section. The defined current
pulse profile
may include repeats of the sections, particularly with the first section
following on directly
from the third reversed section.
The first reversed section may have the equivalent profile shape but with a
reversed
current direction compared with the first section. The second reversed section
may have the
equivalent profile shape but with a reversed current direction compared with
the second
section. The third reversed section may have the equivalent profile shape but
with a
reversed current direction compared with the third section.
The first section may have a start current value and an end current value. The
first
section start current value may be zero. The first section end current value
may be the
maximum current for the defined current pulse profile. The first section may
last for a first
time period. The first time period may be less than 0.5ms, more preferably
less than 0.1ms
and ideally less than 0.05ms. The first reverse section may be similarly
provided.
The second section may have a start current value and an end current value.
The
second section start current value may be the maximum current for the defined
current
pulse profile. The current may decline between the start current value and the
end current
value. The end current value may be a declined current value. The declined
current value
may be the current value which occurs with the prolonged, for instance greater
than 500ms,
application of the voltage in the corresponding part of the voltage pulse
profile. The
declined current value may be the value the current declines to, from the
maximum current
value, with the passage of time but represents a steady state current reached
after a period
of time. The decline current value may continue at that declined current value
for a fourth
section of a current pulse profile, with the fourth section intermediate the
second section
and the third section of the defined current pulse profile.
In the defined current pulse profile, a fourth section may be preferred. The
fourth
section may provide the, or a part of the, pulse section during which the
volume of material
or a part of the volume of material becomes charged. The fourth section may
provide the
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charge which contributes to the second reversed section of the current pulse
profile, for
instance by contributing to the higher value of the current during the second
reversed
section of the current pulse profile. The fourth section may provide the
charge which
contributes to the first reversed section of the current pulse profile having
a higher
maximum current value that the minimum current value of the second reversed
section, for
instance by contributing to the higher value of the current during the first
reversed section
of the current pulse profile.
In the defined current pulse profile, a fourth reversed section may be
preferred. The
fourth reversed section may provide the, or a part of the, pulse section
during which the
volume of material or a part of the volume of material becomes charged. The
fourth
reversed section may provide the charge which contributes to the second
section of the
current pulse profile, for instance by contributing to the higher value of the
current during
the second section of the current pulse profile. The fourth reversed section
may provide the
charge which contributes to the first section of the current pulse profile
having a higher
maximum current value that the minimum current value of the second section,
for instance
by contributing to the higher value of the current during the first section of
the current
pulse profile.
The first section and/or second section may have a current value in excess of
the
fourth section current value due to the discharge of the charge provided to
the volume or
material or a part of the volume of material during the immediately previous
fourth
reversed section.
The first reversed section and/or second reversed section may have a current
value
in excess of the fourth reversed section current value due to the discharge of
the charge
provided to the volume or material or a part of the volume of material during
the
immediately previous fourth section.
In the defined current pulse profile it may be provided that no fourth section
is
present. It is preferred that the end of the decline in current represents the
transition point
to the third section of the defined current pulse profile.
The second section may have a generally elliptical shape, with an initial
rapid
decrease in current and then decreasing rate of current decline down to the
declined
current value. The second reverse section may be similarly provided.
Potentially there is no
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fourth reverse section between the second reverse section and the third
reverse section in
the defined current pulse profile.
The second section of the defined current pulse profile and/or the second
reverse
section of the defined current profile may have a duration of 1ms or greater,
for instance
between 1ms and 500ms, or for instance between 10ms and 500ms, more
particularly
between 20 and 200ms.
The fourth section and the fourth reverse section may be absent from the
defined
current pulse profile, but may be present with a duration of less than 5ms and
more
preferably less than 1ms and ideally less than 0.5ms. In an alternative
embodiment, the
fourth section may have a duration of at least 1ms, potentially of at least
15ms, preferably
at least 50ms, optionally at least 100ms and potentially at least 500ms. For
instance, the
duration may be between 1ms and 500ms, or for instance between 10ms and 500ms,
more
particularly between 20 and 200ms.
The third section may have a start current value and an end current value. The
third
section start current value may be less than the maximum current for the
defined current
pulse profile and/or may be the declined current value. The third section end
current value
may be zero. The third section may last for a third time period. The third
time period may be
less than 0.5ms, more preferably less than 0.1ms and ideally less than 0.05ms.
The third
reverse section may be similarly provided.
The second section and/or the second reverse section may include a current
above
the declined current value due to the voltage applied causing the one or more
of the species
to be treated and/or one or more components of the material, particularly of
the matrix, to
become charged according to the natural capacitance of the system.
The reduction in current between the start and end of the second section may
cause
and/or be indicative of the formation of free radicals within the material,
preferably with
these free radicals being involved in the oxidation reactions which treat one
or more of the
species.
The repeating of steps c) and d) a plurality of times, may include at least
1000
repetitions, more preferably at least 10,000 repetitions and ideally at least
500,000
repetitions. The repeating of steps c) and d) a plurality of times, may
include more than 5
million repetitions, possibly more than 10 million repetitions and even
possibly more than
25 million repetitions.
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The method may include one or more further processing steps. The one or more
further steps may be performed in parallel with step e) of the method. The one
or more
further steps may be provided subsequent to part or all of step e) of the
method. For
instance, one or more further processing steps may be provided which extract
hydrocarbons
from the location. Such extraction may occur in parallel with step e). Such
extraction may
occur after step e) has been in progress for a period of time but before step
e) ends. Such
extraction may occur after step e) has ended. Step e) may be stopped whilst
one or
morefurther processing steps are provided, but step e) may be recommenced.
Step e) may
recommence after the one or more further processing steps have stopped or
whilst they
continue. One or more cycles of such steps may be provided.
The one or more further steps may include extracting hydrocarbons from the
location. The extraction may be provided by pumping the hydrocarbons from the
location
and/or by displacing the hydrocarbons from the location and/or by the
application of heat
to the hydrocarbons and/or by the application of pressure to the hydrocarbons.
The hydrocarbons may be extracted from the in-situ location where they formed
or
where they accumulated below ground. The hydrocarbons may be stored at the
extraction
location or within 1 km thereof. The hydrocarbons may be transported from the
storage
location to a further storage location and/or processing location. The
hydrocarbons may be
transported to a still further storage location and/or further processing
location. The
method of processing the hydrocarbons at a location may be applied to the
hydrocarbons
whilst in-situ and/or during transportation to the extraction location and/or
at the
extraction location and/or during transportation to the storage location
and/or at the
storage location and/or during transportation to the further storage location
and/or
processing location and/or during transportation from the further storage
location and /or
processing location to a still further storage location and/or further
processing location.
The method may promote oxidisation by generating free radicals within the
location.
The method may generate the free radicals at the surface of the solid species
within the
matrix forming the location, with respect to one or more or all of those solid
species within
the matrix.
Preferably water is present in and/or is added to the location and/or the
volume of
material and/or the hydrocarbons. Preferably the hydrocarbons are in contact
with and/or
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in proximity with water. Preferably the hydrocarbons contain water, for
instance droplets of
water dispersed in the hydrocarbons, or vice versa.
Preferably solids are present in and/or are added to the location and/or the
volume
of material and/or the hydrocarbons. Preferably the hydrocarbons are in
contact with
and/or in proximity with solid material. Preferably the hydrocarbons contain
solid material,
for instance solid particles dispersed in the hydrocarbons.
Preferably the method has one or more or all of the following effects upon the
matrix and/or upon one or more of the species:
breaking down one or more species present to one or more smaller species,
preferably with reduced toxicity or reduced other undesirable characteristics
and/or
with more mobility within the matrix and/or with greater solubility;
reducing the level of contaminants present in the liquid, such as water,
drawn off the method, for instance through breakdown of those compounds or
changing their form;
changing the surface chemistry of the matrix and/or one or more of the
species, for instance in terms of their physical chemistry and/or in terms of
the ions
or other species present at the surface and/or the charge level of the
surface, for
instance so as to promote better settling of the materials or species within
it and/or
flocculation of the materials or species within it;
reduction in the volume of the material compared with its untreated form,
for instance by more than 30%, more than 40% or even 50% or more.
Preferably the method has one or more or all of the following effects upon the
matrix and/or one or more of the species between a first time at the start of
the method's
application and a second time after the method has been applied:
a reduction in the concentration of the C40 or more carbon atoms
hydrocarbons by 20% or more, potentially by 35% or more, preferably by 50% or
more, ideally by 70% or more;
an increase in the concentration of the C8 to C30 hydrocarbons by more than
100%, potentially by more than 200%, preferably by more than 500% and ideally
by
more than 700%;
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an increase in the concentration of the less than C8 hydrocarbons (or organic
compounds) by more than 25%, potentially by more than 50%, preferably by more
than 100% and ideally by more than 200%;
a reduction in the concentration of the C8 or greater hydrocarbons by 10% or
more, potentially 20% or more, preferably by 30% or more and ideally by 40% or
more.
The time period between the first time period and the second time period may
be
between 20 hours and 2000 hours, potentially between 30 hours and 1000 hours,
preferably between 60 hours and 400 hours and ideally between 75 hours and 300
hours.
The voltage pulse profile may generate electro-osmotic forces in a first
direction, and
then when the polarity is reversed, in the opposite direction for any one
species present
(depending upon its charge). The method may cause the charged contents of the
pore water
to move back and forward with the polarity changes. The method may cause
freshly formed
oxygen and hydroxyl free radicals formed in these electrochemical reactions to
move back
and forth. The method may promote the involvement of the free radicals in the
oxidisation
of the compounds present. The method may cause the free radicals to cause
hydrocarbon
chains to breakdown into lighter fractions and form carbon dioxide and water
as by
products. Water may be present and/or added to participate in formation of
oxygen and/or
hydroxyl free radicals by the electrochemical reactions.
The voltage pulse profile, particularly when the physical nature of the matrix
is one
with a moderate or low degree of compaction, means that the electrophoretic
forces
generated (which generally oppose the direction of electro-osmotic forces)
cause small
amounts of movement by the particulate material.
Optionally the method includes control of the pH of the material, particularly
the
liquid phase. Preferably the pH is greater than 3, ideally greater than 4. The
method of
control may include the introduction of pH controlling compounds or species to
the
electrodes. The method preferably seeks to maintain the pH within the range at
which any
heavy metals to be treated according to the method remain as heavy metal ions
and so are
soluble. pH control may be provided by treatment of water extracted from and
reintroduced
to and/or introduced to the electrodes. A perforated barrier, such as a tube,
may be
provided around each electrode. The barrier may define a reservoir of water
between the
electrode and the material which is of the correct pH.
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According to a second aspect of the invention there is provided apparatus for
the processing
of hydrocarbons within a location, the apparatus including:
a) at least two electrodes, the at least two electrodes being introduced into
the
location, the location containing the hydrocarbons;
b) connections between a voltage source and the at least two electrodes;
c) a voltage controller for applying a voltage of a first polarity to the
connections for
a first period of time;
d) the voltage controller applying a voltage of a second, reversed, polarity
to the
connections for a second period of time;
e) the voltage controller repeating steps c) and d) a plurality of times;
steps c), d) and e) promoting a reduction in the length of the carbon chain
for one of
more species present in the hydrocarbon and/or a reduction in the sulphur
content of the
hydrocarbons and/or a reduction in the heavy metal content of the
hydrocarbons. The
second aspect of the invention includes apparatus and component parts
therefore for
implementing and/or providing each of the features, options and possibilities
defined
elsewhere within this document, and in particular within the first aspect of
the invention.
According to a third aspect of the invention there is provided a method of
calibrating the
operating conditions to be used in a method of processing hydrocarbons within
a location,
the method including:
a) introducing at least two electrodes into the location, the location
containing a
sample of the hydrocarbons for processing;
b) providing connections between a voltage source and the at least two
electrodes;
c) applying a voltage of a first polarity to the connections for a first
period of time,
under the control of a voltage controller;
d) applying a voltage of a second, reversed, polarity to the connections for a
second
period of time, under the control of the voltage controller;
e) detecting the current arising within the sample or volume of material;
f) varying one or more characteristics of the voltage;
g) detecting the current arising within the sample or volume of material with
the
revised characteristics of the voltage;
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h) further varying one or more characteristics of the voltage until a defined
current
pulse profile is detected.
The sample could be a sample taken from the location for which processing is
to be
applied. The sample could be a sample of material believed to have or having
equivalent
properties to the volume of material.
The detected current may vary according to one or more of the circuit
resistance,
the electrical conductivity of the material, the electrical conductivity of
the matrix within the
material, the electrical conductivity of the fluid within the material and/or
one or more
species within the material, and/or the number of electrodes provided within
the material
and/or the positions and/or separations of the electrodes within the material.
The defined current pulse profile sought may include a first section. The
defined
current pulse profile may include a second section, preferably following on
directly from the
first section. The defined current pulse profile may include a third section,
preferably
following on directly from the second section or following on from a fourth
section. The
defined current pulse may include a first reversed section. The defined
current pulse profile
may include a second reversed section, preferably following on directly from
the first
reversed section. The defined current pulse profile may include a third
reversed section,
preferably following on directly from the second reversed section. The defined
current pulse
profile may include repeats of the sections, particularly with the first
section following on
directly from the third reversed section.
The first reversed section may have the equivalent profile shape but with a
reversed
current direction compared with the first section. The second reversed section
may have the
equivalent profile shape but with a reversed current direction compared with
the second
section. The third reversed section may have the equivalent profile shape but
with a
reversed current direction compared with the third section.
The first section may have a start current value and an end current value. The
first
section start current value may be zero. The first section end current value
may be the
maximum current for the defined current pulse profile. The first section may
last for a first
time period. The first time period may be less than 0.5ms, more preferably
less than 0.1ms
and ideally less than 0.05ms. The first reverse section may be similarly
provided.
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The second section may have a start current value and an end current value.
The
second section start current value may be the maximum current for the defined
current
pulse profile. The current may decline between the start current value and the
end current
value. The end current value may be a declined current value. The declined
current value
may be the current value which occurs with the prolonged, for instance greater
than 500ms,
application of the voltage in the corresponding part of the voltage pulse
profile. The
declined current value may be the value the current declines to, from the
maximum current
value, with the passage of time but represents a steady state current reached
after a period
of time. The decline current value may continue at that declined current value
for a fourth
section of a current pulse profile, with the fourth section intermediate the
second section
and the third section of the defined current pulse profile.
In the defined current pulse profile, a fourth section may be preferred. The
fourth
section may provide the, or a part of the, pulse section during which the
volume of material
or a part of the volume of material becomes charged. The fourth section may
provide the
charge which contributes to the second reversed section of the current pulse
profile, for
instance by contributing to the higher value of the current during the second
reversed
section of the current pulse profile. The fourth section may provide the
charge which
contributes to the first reversed section of the current pulse profile having
a higher
maximum current value that the minimum current value of the second reversed
section, for
instance by contributing to the higher value of the current during the first
reversed section
of the current pulse profile.
In the defined current pulse profile, a fourth reversed section may be
preferred. The
fourth reversed section may provide the, or a part of the, pulse section
during which the
volume of material or a part of the volume of material becomes charged. The
fourth
reversed section may provide the charge which contributes to the second
section of the
current pulse profile, for instance by contributing to the higher value of the
current during
the second section of the current pulse profile. The fourth reversed section
may provide the
charge which contributes to the first section of the current pulse profile
having a higher
maximum current value that the minimum current value of the second section,
for instance
by contributing to the higher value of the current during the first section of
the current
pulse profile.
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The first section and/or second section may have a current value in excess of
the
fourth section current value due to the discharge of the charge provided to
the volume or
material or a part of the volume of material during the immediately previous
fourth
reversed section.
The first reversed section and/or second reversed section may have a current
value
in excess of the fourth reversed section current value due to the discharge of
the charge
provided to the volume or material or a part of the volume of material during
the
immediately previous fourth section.
In the defined current pulse profile it may be provided that no fourth section
is
present. It may be preferred that the end of the decline in current represents
the transition
point to the third section of the defined current pulse profile.
The second section may have a generally elliptical shape, with an initial
rapid
decrease in current and then decreasing rate of current decline down to the
declined
current value. The second reverse section may be similarly provided.
Potentially there is no
fourth reverse section between the second reverse section and the third
reverse section in
the defined current pulse profile.
The second section of the defined current pulse profile and/or the second
reverse
section of the defined current profile may have a duration of between 10ms and
500ms,
more particularly between 20 and 200ms.
The fourth section and the fourth reverse section may be absent from the
defined
current pulse profile, but may be present with a duration of less than 5ms and
more
preferably less than 1ms and ideally less than 0.5ms.
The calibration method may vary the voltage to reduce the duration of and/or
eliminate the presence of the fourth section and/or provide a desired
duration. The desired
duration may be the duration which provides for a given degree of charging of
the location
and preferably the matrix therein or the surfaces of the matrix. The given
degree of charging
may be at least 70% of the natural capacitance, more preferably at least 80%
and ideally at
least 90%. The natural capacitance may be considered relative to the
electrical potential
being applied across the matrix and/or the separation of the electrodes and/or
the distance
from the electrodes.
The calibration method may vary the voltage to ensure that the declined
current
value is reached.
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The calibration method may vary one or more of the following when varying the
voltage: the duration of one or more of the above defined sections for the
voltage pulse
profile; the magnitude of the voltage; the polarity of the voltage; the shape
of the voltage
pulse profile.
The calibration method may provide iterative changes to the voltage and
consider
the current pulse profile arising, with the iterative changes continuing until
the defined
current pulse profile is reached.
The third section may have a start current value and an end current value. The
third
section start current value may be less than the maximum current for the
defined current
pulse profile and/or may be the declined current value. The third section end
current value
may be zero. The third section may last for a third time period. The third
time period may be
less than 0.5ms, more preferably less than 0.1ms and ideally less than 0.05ms.
The third
reverse section may be similarly provided.
The first and/or second and/or third aspects of the invention may include any
of the
features, options or possibilities set out elsewhere in this application,
including with the
other aspects of the invention and the description which follows.
The invention will now be described, by way of example only, and with
reference to the
accompanying drawings in which:
Figure 1 is a schematic perspective view of a volume of matrix and the
hydrocarbon
compounds contained therein being treated according to an embodiment of the
invention;
Figure 2a is an illustration of the voltage pulse shape applied to the
electrodes in the
matrix over a series of pulses, where the voltage pulse profile does not
provide the net
transport effect;
Figure 2b is an illustration of the voltage pulse shape applied to the
electrodes in the
matrix over a series of pulses, where the voltage pulse profile is to provide
at least a part of
the net transport effect;
Figure 3a is an illustration of a detailed view of a part of the current pulse
shape,
showing the preferred form of that part of the pulse in one embodiment of the
invention;
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Figure 3b is an illustration of the same detailed view of a part of the
current pulse
shape as Figure 3a, but with too long a duration before the polarity is
reversed for that
embodiment of the invention;
Figure 3c is an illustration of the same detailed view of a part of the
current pulse
shape as Figure 3a, but with too short a duration before the polarity is
reversed for that
embodiment of the invention;
Figure 4 is a schematic illustration of the progression from heavy to light to
gaseous
hydrocarbons as found in oils;
Figure 5 is a schematic illustration of a still further embodiment of the
invention
where processing is provided in a mixing tank;
Figure 6 is a schematic illustration of a yet further embodiment of the
invention used
in an oil sand example;
Figure 7 is a schematic illustration of a final further embodiment of the
invention
used in a transportation based embodiment;
Figure 8 illustrates results for the operation of the method on one mixture;
Figure 9a illustrates an alternative current pulse shape provided in an
alternative
embodiment of the invention;
Figure 9b illustrates a detail of a part of the current pulse shape of Figure
9a.
In Figure 1, a geological structure 1 is provided which contains a naturally
occurring
volume of hydrocarbons 5 in a layer of the geological structure 1. The layer
in the geological
structure 1 contains a mixture 3 that includes solids, liquids and potentially
gases, including
hydrocarbons 5. Water is a desirable component of the mixture, for instance at
the 3 to 10%
proportion by volume.
For example, the hydrocarbons 5 may be the subject of an extraction process 7
including which has provided a production well 9 and potentially an injection
well 11. The
mixture 3 may be difficult to extract or unsuitable for extraction using
existing approaches.
For instance, the mixture may contain a high level of heavy hydrocarbons and a
relatively
low level of light hydrocarbons. This renders the hydrocarbons 5 as a whole
viscous and/or
well bounded to the geological structure 1 and hence resistant to extraction.
Previous treatment attempts at the treatment of the hydrocarbons 5 have
included
the injection of steam or carbon dioxide into the geological structure 1 with
a view to using
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the heat or pressure to reduce the viscosity or form of the hydrocarbons so as
to promote
movement and hence extraction at a production well. Burning has been used to
generate
heat and hence crack the oil in-situ. The in-situ treatments can be effective,
but these all
have limitations in terms of costs and/or effectiveness and they are also time
consuming to
achieve.
The present invention provides a series of electrodes 10 arranged along the
length
12 and across the width 14 of a matrix 16 which forms a part of the geological
structure and
which contains the hydrocarbons 5. The electrodes 10 also have a depth 18
within the
matrix 16. The electrodes 10 are provided in a regular array in this example,
but other
configurations can be used.
Titanium (with a mixed oxide coating or surface, to avoid any insulating
layer) and
steel represent preferred materials for the electrodes.
The electrodes are typically 100 m to 500 m apart from each other along the
width
and the length of the regular array. The electrodes 10 will typically extend
down at least
50% of the depth of the matrix 16 being treated and may span the full depth or
more. The
electrodes typically have a diameter in excess of 5 cm. The electrodes 10 can
extend from
the surface the whole way down to the depth of the geological structure 1
being treated, or
as shown, may only be present within the geological structure 1 itself (or a
part therefor).
The wiring 20 (only shown for some electrodes) for the electrodes 10 then
provides the link
to the surface 13.
The wiring 20 for the electrodes 10 connects them as a first set 22 of
electrodes 10, a
second set 24 of electrodes 10, a third set 26 of electrodes 10, a fourth set
28 of electrodes
and so on. The potential is applied so as to generate a voltage drop between
the first set
22 of electrodes 10 and the second set 24. A voltage drop is also generated
between the
third set 26 and the fourth set 28. This also generates a voltage drop between
the second
set 24 and third set 26 and between other sets of electrodes 10. The
flexibility of the
connections provided by the wiring 20 allows for different combinations of
electrodes 10 to
be connected to form pairs.
Suitable power sources 30 and power control units 32 are provided at the
surface 13
to generate the desired voltage drops and potentials within the system, and
hence voltage
pulses. The system is driven with a constant voltage supply, typically from by
to 2500V.
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Typically voltages are used which provide between 0.5 and 5 V/m of separation
between
the electrodes; hence between 50V and 500V with a spacing between electrodes
of 100m.
The current output level depends upon the circuit resistance. The circuit
resistance is
affected by the electrical conductivity of the matrix 16, and particularly the
fluid contained
therein, as well as the number of electrodes provided and the separation
between them.
The profile of the voltages applied and the impact of the applied voltages on
the
matrix and compounds are described further below.
During the method, the process conditions are most effective when the pH is
within
certain bounds. Natural redox reactions and/or reactions caused by the
operation of the
method can cause a decrease in pH around the anode and/or an increase in pH
around the
cathode. If the pH becomes too low then electro-osmosis at the anode stops
which impairs
the operation of the process. If the pH becomes too high then that can have
deleterious
effects on the process. However, it is believed that the process is still
effective at lower pH's
than can be tolerated in electro-osmotic based processes where transportation
is being
sought, as the process is seeking to provide oxidation of organic species.
To ensure the appropriate pH, the system can include treatment apparatus, not
shown, which receives electrode electrolyte from around the electrodes 10. A
perforated
tube may be provided around each electrode 10 so as to provide a reservoir of
electrode
electrolyte in contact with the matrix 16. Pumps draw the electrode
electrolyte from the
reservoirs along pipes to the treatment apparatus. The treatment apparatus
includes a pH
adjustment stage and potentially other stages for other desirable treatments
for the
electrode electrolyte. Cleaned pH adjusted electrolyte arises from these
stages and can be
returned via pipes to the reservoirs. In this way optimum conditions are
provided within the
reservoirs and for the process as a whole.
Significantly, the power consumption with the approach of the invention is
very low.
The voltage pulse profile is illustrated in Figure 2a. As can be seen, the
voltage pulse profile
consists of alternate pulses of opposite polarities with time. The voltage
pulses are generally
square shaped pulses for both polarities and are of equal duration. Hence, the
pulses are
used to apply the voltages to the matrix 16 but have no net transport effect
on the matrix
16 or more particularly the liquid and compounds within it. The transport
effect can be
provided by the process as described below. However, where the voltage pulse
profile does
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not provide the net transport effect, then other mechanisms may be used, for
instance
injection of other materials, application of pressure or forms of
displacement.
Where the pulse profile is to provide at least a part of the net transport
effect, then
a pulse profile of the form illustrated in Figure 2b may be used. The
difference in duration of
application of the pulse with one polarity and the duration of application of
the pulse with
the opposing polarity provides the net transport effect, potentially through
electro-osmotic
and/or electro-kinetic effects. Generally the pulse operative in the direction
of travel will be
between twice and five times the duration of the opposing polarity pulse in
such cases. A
rest with no or little applied voltage may be used between polarity reversals.
The square voltage pulse profile features a rapid change from one polarity to
the
other and then back again. Thus regular square shaped pulses are provided
rather than a
sinusoidal or other gradual form of changing pulse.
Whilst the voltage pulse profile is generally square shaped, there are
important
details in the shape of the current pulse which are sought for the optimum
operation of the
invention. These apply whether the voltage pulse profile is of the Figure 2a
or Figure 2b
type. As shown in Figure 3a, when the rapid change in polarity is applied, the
current profile
rises quickly and reaches a maximum level 100. From the maximum level 100 the
level
gradually declines, for instance along an elliptical curve 102, to a reduced
consistent level
104. A short time 106 after the reduced consistent level 104 is reached, the
polarity is
reversed and the current profile quickly switches to a maximum level, not
shown, of the
opposing polarity.
Typical voltage pulse lengths are between 20 and 200ms. Short rests may be
provided to the system between pulses of one polarity and the other. The rests
may be
0.5ms to 50ms in duration.
The maximum level 100 is reached as a consequence of the voltage applied
causing
the matrix, and potentially the liquid, to become charged according to the
natural
capacitance of the system. This charge is gradually discharged overtime as
reflected in the
current pulse shape. The maximum level 100 and gradual reduction is indicative
of the
formation of free radicals within the matrix. These are very beneficial to the
overall process,
in particular these free radicals are believed to be involved in the oxidation
reactions which
treat the compounds, such as hydrocarbons. The presence of water, which
usually occurs
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naturally in-situ, is believed to be beneficial in the promotion of the
formation of free
radicals.
Beneficially the free radicals are generated exactly where they are needed for
the
method to provide the desired treatment, namely at the pore surfaces within
the matrix. As
a consequence, redox reactions are promoted at those locations too.
The duration of the pulse is beneficial in generating electro-osmotic forces
in a first
direction, and then when the polarity is reversed, in the opposite direction
for any one
species present (depending upon its charge). Thus the charged contents of the
pore water
move quickly back and forward with the polarity changes. This causes freshly
formed oxygen
and hydroxyl free radical formed in these electrochemical reactions to move
back and forth.
This also promotes their involvement in the oxidisation of the compounds
present. For
instance the free radicals can cause hydrocarbon chains to breakdown into
lighter fractions
and form carbon dioxide and water as by products. The capacitive nature of the
matrix and
reactions occur at the grain surface where the pollution is.
The physical nature of the matrix in many cases, small particulate matter with
a
moderate or low degree of compaction or with loose material within a more
fixed body of
material, means that the electrophoretic forces generated (which generally
oppose the
direction of electro-osmotic forces) cause small amounts of movement by the
particulate
material. The movement is believed to be beneficial in causing reaction
product
displacement away from the surfaces and/or pH balance.
The process conditions are optimised to give the desired current pulse profile
illustrated in Figure 3a in one embodiment. The overshoot in the level and the
current pulse
length which gives the full gradual discharge are desirable.
Figure 3b illustrates a situation where the duration before the polarity is
reversed is
potentially too long. As a consequence, the same maximum level 100 is provided
and the
same gradual decay to the reduced consistent level 104, but that level is
present for a much
longer time frame. This reduced consistent level 104 is believed to reduce the
efficiency of
the process reactions as the free radical generation has stopped or is present
at a lower rate
during this phase. However, it may assist with the charging for the reversed
polarity part
and hence with the effects desired from that reverse polarity when it too
discharges.
Figure 3c illustrates another version of the same current pulse, but with a
shorter
time period before the polarity is reversed. As a result, the maximum level
100 is present
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but the reduced consistent level 104 has not been reached by the time the
polarity is
reversed. As a result it is believe that some of the free radical generating
capacity within the
system is not exploited and instead energy must be used to reverse the
remaining natural
part of the capacitance of the system. A detrimental effect on the charging
for the reverse
polarity part may also occur as a result.
The power supply conditions needed to provide the current pulse profile of
Figure 3a
may vary from matrix to matrix and/or according to the compound to compound
situations
encountered within different hydrocarbons. However, investigative measurements
can be
conducted on the particular system to provide the power supply conditions
necessary for
the desired profile shape and hence process conditions within the matrix.
The role of the free radicals generated is to promote oxidisation reactions.
The
conditions in the matrix are optimised in the present invention, thus adding
strength of
oxidising to any other form of physical and/or chemical treatment.
Test operations have demonstrated that the process is effective to oxidise a
wide
variety of organic compounds. Examples include aliphatic organics with C10 to
C40,
benzene, toluene, ethyl benzene, xylenes, and polycyclic aromatic hydrocarbons
amongst
other compounds.
Particularly in the context of hydrocarbons in forms conventionally considered
as
oils, the process is effective in breaking down the hydrocarbons from heavy
forms to lighter
forms. This involves increasing the hydrogen to carbon ratio, normally by
reducing the
length of the average carbon chain within the hydrocarbon; obviously a variety
of different
lengths are present. The process is particularly effective in acting on
asphaltenes, which as
can be seen in Figure 4, are at the heavy end of the spectrum of hydrocarbons
encountered
in oils. Breakdown of the carbon chains, proceeding from right to left, gives
rise to smaller
and shorter carbon chains.
The process is also believed to act on sulphur present, as inorganic species
such as
hydrogen sulphide, and/or as organic species such as mercaptans and
thiophenes. The
impact of the oxidation follows a potentially complex route, but leads to less
problematic
species such as sulphuric acid and sulphates.
This breakdown to lighter forms is particularly useful in the context of heavy
crude
oils, such as those extracted in Canada and Venezuela.
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Heavy crude oil is generally considered to be oil with an API gravity of less
than 20
(where an API gravity of 10 matches the density of water). An API below 10
leads to the oil
sinking in water, and may be classified as extra heavy oils. The
classification of oils as light
oils varies with geography, but typically are US originating oils with an API
of 37 to 42 and
are non-US originating oils with an API of 32 to 42 degrees, such as Brent
crude at an API
38.06.
In general, the heavier a crude oil is, then the greater its viscosity, the
more resistant
it is to flow and the more it binds or adheres to materials it contacts
(including the matrix it
is found in).
In general, heavy crude oil also has a higher, undesirable, sulphur content
compared
with light oil; potentially as high as 4.5%. The process of the invention is
believed to have a
role in reducing the sulphur content via oxidation and/or conversion to more
readily
separable forms. In general heavy oil also typically has a higher heavy metal
content and
that too needs to be reduced. Again the process of the present invention is
believed to have
a valuable role in the oxidation and/or conversion of those species and may
easy separation.
In general, heavy crude oil needs cracking, refining and purification to make
gasoline
from it. This increased processing cost makes heavy oils less valuable than
light oils; they are
less useful and have less demand without the processing and the processing
itself is
expensive. Heavy oils are also often more expensive to extract and so have
higher
production costs too. Transportation costs are also often higher due to the
viscosity having a
negative impact upon pumping and the like. Heavy crude oil also faces
environmental
problems as the quantity of carbon dioxide released during burning is also
much higher.
The process has many beneficial effects upon the matrix and/or upon the
compounds within it. These include:
Breaking down one or more compounds present to smaller compounds ¨ these may
have increased commercial value and/or may be more mobile within the matrix;
Reducing the level of contaminants present in the water drawn off the system,
other
through breakdown those compounds or changing their form;
Changing the surface chemistry of the matrix or species which form the matrix
¨
either in terms of the physical chemistry of the matrix itself or in terms of
the ions or other
species present at the surface or the charge level of the surface ¨ these can
promote better
release of the hydrocarbons from the matrix.
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In the Figure 1 illustration, the process is shown providing in-situ
processing of the
hydrocarbon within a geological structure 1. The process can be used to treat
a wide variety
of structures or situations where hydrocarbons are present and would benefit
from a
degree of oxidation. The matrices can include soil, groundwater bearing
matrices, aquifers
or other forms of geological structure containing the hydrocarbons to those
described,
including oil sand situations. Many or even all of these situations include
naturally occurring
water within the matrices to be treated. The addition of water, in liquid,
gaseous or steam
form, before or during the proposed processing is also a possibility.
Figure 5 illustrates a further embodiment of the invention in which the
similar
principles and elements of the process are deployed in a quite different
situation again. In
this case, a tank 300 is provided which contains a volume of hydrocarbons
which are too
heavy or too sour. Rather than blend this oil with a lighter oil (potentially
imported to the
country or transported a long way within the country) to produce a blended oil
with a
higher API, the process seeks to treat the heavy oil. Blending is effective to
a degree, but
requires the mixing of large volumes of expensive light oil with the heavy oil
to reach a
commercial product. This increases the costs of reaching that commercial
product and
involves material amounts of financial capital to secure and put through the
process the
lighter oil. Many countries which have the heavy oil do not have their own
sources of light
oils. If the hydrocarbon to be treated is devoid of water or low in water,
then water may be
added before and/or during processing. The water may be added as a liquid, gas
or steam
form.
In Figure 5, the electrodes 302 are provided near the walls 304 of the tank
300. A
smaller number of electrodes 306 are placed towards the centre of the tank
300. Again,
voltage pulses, current pulses and the other features described for the
invention are
provided so as to provide the oxidation effects and breakdown the oil in the
tank 300. In an
alternative form, not shown, the walls of the tank act as one of the
electrodes or as a series
of electrodes. The tank 300 is provided with an outlet 308 which leads to a
pump and return
inlet 310 so as to circulate oil and cause the oil in the tank to mix and have
homogenous
properties. The residence time within the tank 300 is controlled so as to give
the desired
form for the oil produced from it. This light oil can be sold as is, and/or
can be used in a
subsequent blending processes, for instance to blend with volumes of untreated
heavy oil
from the same or different extraction locations. The tank 300 can be a
specifically
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constructed processing tank or could be a tank normally used for storage
purposes. The
technique is suitable for use in relatively large tanks, such as tanks which
are 30 m of more
in diameter. Suitable provision may be provided for collecting and dealing
with any off
gassing arising from the processing.
As well as the vertically arranged electrodes discussed above, further
electrodes 320
are provided in a similar regular array across the width and length of the
tank 300. In this
case a series of horizontally extending electrodes 320 are provided. These are
connected to
the same wiring system. They can be used to form pairs of electrodes amongst
themselves
and/or be combined with vertically provided electrodes 302. These electrodes
are provided
at a depth d below the surface of the volume of material. These electrodes can
be provided
in a fixed position within the tank 300 or can be raised and lowered within
the tank 300 as
desired. They are used in a similar manner to the vertical electrode operation
described
above. The combination of electrode arrangements is used to increase the
volume of
material being treated or in closer proximity to an electrode.
Tanks of the type illustrated above could be used at the extraction site, at
intermediate storage locations receiving oil from multiple extraction sites,
at initial blending
installations or at refineries where other processing is also provided.
As well as the heavy oils discussed above, the embodiment illustrated in
Figure 6
shows the invention in use at an extraction site which is concerned with oil
sands (including
tar sands and bituminous sands). Such deposits are to be found in Canada,
Russia and
Kazakhstan. They generally consists of loose sand or partially consolidated
sandstone which
contains viscous hydrocarbons (often classified as bitumen) as well as the
matrix of sand,
clay and water. In this embodiment, the array of electrodes 400 are driven
into the ground
402 over the area 404 to be treated and the same type of general processing
using the
voltage pulse profiles and current pulse profiles is provided.
The viscosity of the hydrocarbons may be too high to achieve any transport at
the
outset and so no net transport effect may be provided to begin with. With
time, the
processing breaks the hydrocarbons down and reduces the viscosity. In a
further phase, a
net transport effect may be provided, using the voltage pulse profiles of a
different form
and/or using other transport mechanisms, such as "cold heavy oil production
with sand" or
"cyclic steam stimulation" or "steam assisted gravity drainage" or "vapour
extraction" or
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"toe to heel air injection" or other such techniques for extraction assistance
which are
known in the art.
Figure 7 shows a further situation in which the treatment process is provided.
In this
case, the treatment is provided during transportation. A form of on-line
blending is
provided. However, rather than add to the pipe 500 providing the
transportation of the oil
502 different types of oil and allowing those to mix as they pass along the
pipe 500, this
embodiment of the invention applies the invention's processing during
transportation. Thus,
the pipeline 500 is provided at periodic intervals with a series of electrodes
504 inside the
pipe and in contact with the oil 502. The processing is achieved in the same
manner. A
variety of electrodes 504 can be used including elongate electrodes of the
type illustrated
above, mesh or grid style electrodes extending across the cross-section of the
pipe 500 or
others. The aim is to apply the conditions to the oil as it passes and give a
reduction in
density and in viscosity, an increase in value and easier handling, pumping
and
transportation of the oil 502. Again, if the hydrocarbon to be treated is
devoid of water or
low in water, then water may be added before and/or during processing. The
water may be
added as a liquid, gas or steam form.
Figure 8 illustrates the variation observed in a number of characteristics of
a mixture
when treated according to the method of the present invention over an extended
time (in
hours) on the x axis.
At the start of the method, the heavier hydrocarbons (black line) are present
at a
concentration of over 200,000 mg/kg of the mixture. As the method is
performed, the
method serves to breakdown the heavier hydrocarbons to lighter forms and so
the
concentration declines. The method reduces the concentration to around 1/4 of
its original
value.
At the start of the method, the lighter hydrocarbons (red line) formed a
relatively small part
of the mixture and hence the concentration is low at less than 20,000 mg/kg of
mixture. As
the process converts the heavier hydrocarbons to lighter hydrocarbons, then
this
concentration increases. The method increases the concentration to around 10
times its
original value.
Figure 9a illustrates a preferred current pulse profile for some methods. Each
cycle
includes a positive polarity triggered current part 500 and a negative
polarity triggered
reverse current part 502. The current part 500 is formed of a first section
504, second
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section 506, fourth section 508 and third section 510 which occur in that
sequence.
Matching but reversed sections are provided for reverse current part 502, such
that it has a
first reversed part 512, second reversed part 514, fourth reversed part 516
and third
reversed part 518. The next positive current part would then be present as the
cycle is
repeated over and over by the application of an appropriate voltage pulse
profile (not
shown).
Figure 9b shows the peak part of the pulse in more detail. The first section
504
shows the current increasing quickly as it is encouraged by the change in the
voltage pulse
profile. As a result the voltage induced current and the current caused by the
discharge of
the capacitance built up during the previous reversed current part (not shown)
occurs.
These two current elements rapidly cause the peak current 520 to be reached.
As the capacitance of the system is discharged, then the current element from
that
diminishes in a curved decay through the second section 506. The voltage pulse
still
maintains a current though. Once the capacitance has effectively discharged,
then the
second section 506 transitions into the fourth section 506. The steady current
occurs
through the fourth section 506 before a further change in the voltage pulse
(not shown)
causes the rapid reduction of the current to zero during the third section
508, shown in
Figure 9a. A similar or matching peak occurs for the reverse polarity part and
so on through
the cycles.
The voltage pulse profile can be used to control the shape and timing of all
of the
sections of the current pulse profile.
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