Note: Descriptions are shown in the official language in which they were submitted.
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IN-SITU UPGRADING AND RECOVERY OF HYDROCARBONS
TECHNICAL FIELD
[001] The technical field relates to treatment of a hydrocarbon reservoir with
a catalyst for in-
situ upgrading and recovery of upgraded oil or bitumen.
BACKGROUND
[002] Bitumen or heavy oil is abundant in different parts of the world,
including Canada, the
United States, Venezuela, and Brazil. However, the oil is highly viscous at
reservoir
temperatures and does not flow readily. Therefore, bitumen cannot be produced
by
conventional methods. In a number of cases, the heavy oil is thermally treated
to reduce the
viscosity and this makes it flow more easily.
[003] Currently, the most common thermal-recovery processes are steam-based
technologies,
such as steam-assisted gravity drainage (SAGD) and cyclic-steam stimulation
(CSS). In these
processes, bitumen reservoirs are heated by steam injection; the bitumen is
brought to the
surface and later diluted with condensates for pipeline transportation.
[004] Solvent injection can be used to enhance the performance of SAGD and CSS
by
introducing hydrocarbon solvent additives to the injected steam. The operating
conditions for
the solvent co-injection process are similar to SAGD.
[005] Non-thermal recovery can also be effective for some bitumens or heavy
oils. It is
potentially less energy- and capital-intensive. Non-thermal recovery includes
cold heavy oil
production with sand (CHOPS), which involves sand influx into the production
well.
[006] Even after successful production of bitumen ¨ based on either thermal or
non-thermal
recovery ¨ its viscosity is usually too high for pipeline transportation.
Diluents are used to
reduce viscosity to enable flow. In Alberta, for example, diluent cost is a
major factor for
transporting bitumen to refineries. Therefore, there is an ongoing need for at
least partially
upgrading bitumen after oil recovery, or, more ideally, in situ during oil
recovery, to minimize
or avoid use of diluent.
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[007] In-situ upgrading of bitumen and heavy oil, especially catalytic
upgrading, is currently
considered to be a desirable next-generation technology. However, no
commercially-viable
process is currently being used.
SUMMARY
[008] In general, the present specification describes methods to treat a
reservoir to recover
hydrocarbons, particularly viscous hydrocarbons. The methods include
delivering a catalyst
into a mobile water phase within the reservoir and directing electromagnetic
radiation to the
catalyst to activate the catalyst and thereby initiate bitumen-upgrading
reactions.
1009] In one implementation, there is provided a method for treating a
reservoir to recover
hydrocarbons. The method includes delivering a catalyst into the reservoir
using a mobile water
phase present in the reservoir and directing electromagnetic radiation to the
catalyst to activate
the catalyst; the activated catalyst then initiates at least one catalytic
reaction.
[010] In some aspects of the methods, the reservoir is an oil sands reservoir.
In some aspects
of the methods, the hydrocarbons include bitumen. In some aspects of the
methods, the
hydrocarbons include heavy oil. In some aspects of the methods, the
hydrocarbons include
bitumen and heavy oil.
10111 In some aspects of the methods, the catalyst is a nanocatalyst. In
further aspects of the
methods, the catalyst is a metal-based catalyst. Exemplary catalysts include,
without limitation,
vanadium, sodium, aluminum, or platinum, or a combination of more than one of
any of the
foregoing. In some aspects of the methods, the catalyst is A1/y-A1203,
ammonium Y zeolite,
zirconium dioxide (Zr02), or cordierite, or a combination of more than one of
any of the
foregoing. In further aspects of the methods, the cordierite is Mg2A14Si5018.
[012] In some aspects of the methods, the catalyst is selected such that the
catalytic reaction
operates to at least partially upgrade the hydrocarbons contained in the
reservoir. In some
aspects of the methods, partially upgrading the hydrocarbons includes reducing
the viscosity of
the hydrocarbons. In some aspects of the methods, partially upgrading the
hydrocarbons
include pyrolysis, aquathermolysis (hydrous pyrolysis), gasification,
hydrocracking,
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hydrogenation, desulphurization, denitrogenation, demetallation, or
deasphalting, or a
combination of more than one of any of the foregoing.
[013] In some aspects of the methods, an interconnected pore network of the
reservoir
contains the mobile water phase. In some aspects of the methods, the catalyst
is delivered to the
reservoir by injection through a wellbore. In some aspects of the methods,
sufficient time
passes between injection of the catalyst into the reservoir and activation of
the catalyst by the
electromagnetic radiation to permit sufficient distribution of the particles
of the catalyst within
the reservoir via the mobile water phase. In further aspects of the methods,
up to one year
passes between the injection and the activation.
10141 In some aspects of the methods, the electromagnetic radiation has a
frequency in the
range of about 60 Hz to about 1,000 GHz. In some aspects of the methods, the
electromagnetic
radiation is directed to the catalyst using an antenna. In some aspects of the
methods, the
antenna is a vertical or horizontal antenna or a phased array of mixed
geometry.
[015] In some aspects, the methods include delivering a hydrogen source to the
reservoir. In
some aspects of the methods, the hydrogen source is peroxide, dimethyl ether
(DME), light
hydrocarbons, tetralin (1,2,3,4-tetrahydronaphthalene), decalin
(decahydronaphthalene), or
naphthalene, or a combination of more than one of any of the foregoing. In
some aspects, the
methods include delivering a solvent to the reservoir.
10161 In another implementation, there is provided a method for recovering
hydrocarbons
from a hydrocarbon-containing reservoir. The method includes delivering a
nanocatalyst to the
reservoir by injection through a wellbore in the reservoir; allowing a pre-
determined period of
time to pass such that particles of the nanocatalyst are dispersed into the
reservoir via a mobile
water phase present in the reservoir; directing electromagnetic radiation to
the nanocatalyst to
activate the nanocatalyst; and, when the activated nanocatalyst has induced at
least one
chemical reaction which at least partially upgrades the hydrocarbons,
recovering the at least
partially upgraded hydrocarbons from the reservoir.
[017] In some aspects of the methods, the reservoir is an oil sands reservoir.
In some aspects
of the methods, the hydrocarbons include bitumen. In some aspects of the
methods, the
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hydrocarbons include heavy oil. In some aspects of the methods, the
hydrocarbons include
bitumen and heavy oil. In some aspects of the methods, the at least partially
upgraded
hydrocarbons are recovered from the reservoir using steam injection (SAGD or
CSS) recovery.
[018] In some aspects of the methods, partially upgrading the hydrocarbons
includes reducing
the viscosity of the hydrocarbons. In some aspects of the methods, partially
upgrading the
hydrocarbons comprises pyrolysis, aquathermolysis (hydrous pyrolysis),
gasification,
hydrocracking, hydrogenation, desulphurization, denitrogenation,
demetallation, or
deasphalting, or a combination of more than one of any of the foregoing.
10191 In some aspects, the methods include refreshing the nanocatalyst in the
reservoir by at
least one of re-injection into the wellbore, injection through a secondary
injector, and injection
along an antenna. In some aspects, the methods include renewing the
nanocatalyst in situ
through application of steam or solvent wash.
[020] In another implementation, there is provided a reservoir treated with a
catalyst for
recovery of at least partially upgraded hydrocarbons. The catalyst is
distributed through a
mobile water phase present in the reservoir and is activatable by
electromagnetic radiation. In
some aspects, the reservoir is an oil sands reservoir. In some aspects, the
hydrocarbons include
bitumen. In some aspects, the hydrocarbons include heavy oil. In some aspects,
the
hydrocarbons include bitumen and heavy oil.
[021] The methods described in this specification are advantageous over other
in-situ
upgrading methods, such as those using thermally-activated catalysts. For
example, the present
methods distinguish the energy source for activating the catalyst and
catalyzing the reactions
from the energy source for heating the bitumen, thereby increasing efficiency
of catalytic
upgrading of bitumen and reducing steam consumption. Activation of a catalyst
and initiation
of a catalytic reaction are endothermic and require energy. Where thermal
activation is
employed, the catalyst uses heat for activation from steam that is also
injected to mobilize
bitumen during a steam-assisted recovery operation. In that case, although the
catalyst is added
to enhance bitumen recovery, this addition of catalyst can initially slow down
heating of
bitumen or increase consumption of steam, due to the extra heat load of
catalyst activation or
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catalysis initiation.
[022] The present methods can also reduce certain negative effects of mobile
water in the
reservoir during thermal recovery. While it is known that hydrocarbons do not
couple well with
electromagnetic radiation due to lack of a dipole moment, water can be an
excellent candidate
for dielectric heating or electromagnetic heating. During radio-frequency
radiation of a bitumen
reservoir, for example, water in the reservoir is locally heated and can
induce thermal cracking
of bitumen. In such cases, the mobile water phase in the reservoir can
function as another
energy source for upgrading bitumen and heavy oils in accordance with the
present methods. A
synergistic effect can also arise from the combination of: (a) dispersing the
catalyst in the water
phase; and (b) activating the catalyst with radiation. As noted above, water
can absorb radiation
and provide heat to the surroundings. Thus, water can facilitate activation of
the catalyst in
addition to electromagnetic radiation.
1023] The details of one or more implementations are set forth in the
description below. Other
features and advantages will be apparent from the specification and the
claims.
BRIEF DESCRIPTION OF THE DRAWING
1024] Features and advantages of embodiments of the present application will
become
apparent from the following detailed description and the appended drawing, in
which:
[025] FIG. 1 is a flowchart exemplifying implementation of the methods
described herein for
treating a hydrocarbon reservoir with a catalyst to recover upgraded oil or
upgraded bitumen.
DETAILED DESCRIPTION
[026] The present description relates to treatment of an underground reservoir
for upgrading
hydrocarbons, particularly bitumen and heavy oil, in situ. The treatment
includes distributing or
dispersing a catalyst that is activatable (i.e., capable of or susceptible to
activation) by
electromagnetic radiation into a mobile water phase present in the reservoir.
The mobile water
phase within the reservoir can include mobile water films that wet the sand
grains within the
reservoir rock. The water films are sufficiently connected throughout the
reservoir volume due
to grain-to-grain contacts; the hydrocarbon phase is present in the pore space
between the water
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films.
10271 Mobile water in a hydrocarbon reservoir is generally considered to be
disadvantageous
to thermal recovery processes. However, as the methods described herein
illustrate, a mobile
water phase can be utilized for in-situ upgrading and recovery of
hydrocarbons, including
bitumen and/or heavy oil. A mobile water phase flows through the tiny
interconnected pore
spaces in the reservoir matrix. This continuous water network provides means
for transporting
the catalyst, especially in nanocatalyst form, throughout the reservoir at
cold reservoir
conditions.
1028] The following requirements for existing in-situ upgrading processes have
been
identified: (i) provision of a catalyst; (ii) achievement of appropriate
reaction temperature; and
(iii) mobilization of hydrocarbons over the catalyst. Most in-situ
technologies currently attempt
to carry out catalytic reactions in the production well in order to gain
better control over the
requirements. CAPRITM (catalytic upgrading process in-situ) (Archon
Technologies Ltd.) is an
example.
10291 The present methods take a different approach with respect to the
following factors:
scale of upgrading, timing of distribution and activation of the catalyst, and
delivery of
activation energy. First, a catalyst is broadly distributed throughout the
reservoir, instead of
being contained or localized within the production well. Second, the catalyst
is provided to the
reservoir prior to mobilization of the hydrocarbons, and activated
concurrently with or prior to
mobilization of the hydrocarbons. Third, activation energy is delivered to the
catalyst by
electromagnetic radiation, rather than thermal heating. Therefore, when
mobilization of
hydrocarbons commences in the reservoir using one of the recovery processes
(e. g. , SAGD,
CHOPS, solvent injection), catalytic reactions can be carried out
simultaneously in the
reservoir. As a result, permanent partial upgrading in situ and improved
recovery of
hydrocarbons can be achieved at lower energy consumption.
[030] Throughout this specification, numerous terms and expressions are used
in accordance
with their ordinary meanings. Provided below are definitions of some
additional terms and
expressions that are used in the description that follows.
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[031] "Hydrocarbon" and "hydrocarbons", as used herein, refer to hydrocarbon
molecules that
contain carbon atoms and, in many cases, attached hydrogen atoms. Examples
include bitumen
and heavy oil.
[032] "Bitumen" and "heavy oil" are normally distinguished from other
petroleums based on
their relative densities and/or viscosities, which often depend on context.
Commonly-accepted
definitions classify "heavy oil" as petroleum (the density of which is between
920 and 1,000
kg/m3) and "bitumen" as oil produced from bituminous sand formations (the
density of which is
greater than 1,000 kg/m3). For purposes of this specification, the terms
"bitumen" and "heavy
oil" are used interchangeably such that each one includes the other. For
example, where the
term "bitumen" is used alone, it includes within its scope "heavy oil".
[033] As used herein, "reservoir" refers to a subsurface formation that is
primarily composed
of a matrix of unconsolidated sand, with hydrocarbons occurring in the porous
matrix.
[034] The "mobile water phase" is a continuous water network that can be
formed by
interstitial water present in the porous matrix of a hydrocarbon reservoir and
can allow reservoir
water to flow throughout the reservoir.
[035] As used herein, "electromagnetic radiation" refers to radiation
encompassing microwave
and radio-frequency radiation, particularly with frequencies anywhere in the
range of about 60
Hz to about 1,000 GHz.
[036] The "metal-based catalyst" described herein is a catalyst that includes
at least one metal
element and optionally one or more components of non-metal elements (e.g., C,
N, 0, Si, P. S,
etc.). For example, the metal-based catalyst can be a pure metal catalyst or a
metal-oxide
catalyst (e.g., nickel or nickel oxide). The "metal-based catalyst" described
herein includes a
catalyst with a support (e.g., Pt/y-A1203, Al/y-A1203, etc.).
[037] The "natural reservoir temperature" or "reservoir temperature" is an
ambient temperature
of a cold or unheated reservoir.
[038] The terms "upgrading" and "at least partially upgrading", which are used
interchangeably herein, refer to any treatment of oil or bitumen that
increases its value. The
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minimum objective is to reduce the viscosity of oil, and the maximum objective
is to obtain a
crude oil substitute of higher quality. Upgrading includes a number of
processes, such as
pyrolysis, aquathermolysis (hydrous pyrolysis), gasification, hydrocracking,
hydrogenation,
desulphurization, denitrogenation, demetallation, and deasphalting, or a
combination of more
than one of the foregoing.
[039] "Cracking" means the breaking down of larger hydrocarbon chains into
smaller-chained
compounds. In other words, a long-chain hydrocarbon will break up into smaller-
chain
hydrocarbons.
[040] The term "hydrogenation" is used herein to refer to an addition or
substitution reaction
in which hydrogen is consumed; a non-limiting example of hydrogenation is
hydrocracking.
[041] "Hydrocracking" means a hydrogenation reaction which utilizes hydrogen
as a reagent
and chemically converts hydrocarbons to relatively lighter hydrocarbons.
Additional reactions,
including olefin and aromatic saturation and heteroatom (e.g., oxygen,
nitrogen, sulfur, halogen)
removal, can also occur during hydrocracking.
[042] The term "in situ" refers to the environment of a subsurface hydrocarbon
reservoir.
10431 "Nanoscale" or "nano" means smaller than microscopic in scale. The term
"nanocatalyst" is used herein to refer to a particulate catalyst, the particle
size of which is less
than 1,000 nm.
[044] FIG. 1 illustrates an implementation of the present methods for treating
a hydrocarbon
reservoir in which heavy oil or bitumen is recovered by SAGD techniques (100).
In this
implementation, a catalyst is injected into at least one of an injection well
and a production well
drilled in a hydrocarbon reservoir (110). The catalyst reaches the reservoir
through the well(s),
and is dispersed into a mobile water phase within the reservoir (130).
Optionally, a hydrogen
source and/or a solvent can be injected along with the catalyst through the
injection well (120).
After a period of time, the catalyst is sufficiently distributed within the
reservoir. To activate
the catalyst, electromagnetic (EM) radiation is directed to the catalyst in
the reservoir (140).
After sufficient exposure to radiation, one or more catalytic reactions
initiate in-situ upgrading
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of the bitumen (150). In the SAGD recovery process, steam is injected into the
reservoir
through the injection well to mobilize the hydrocarbons (160). The timing of
the steam
injection can be varied and flexible. Steam injection can commence shortly
before step 140,
anytime between step 140 and step 150, or shortly after step 150; any
appropriate timing or
duration of steam injection can be determined by a skilled person. Upgraded
oil or upgraded
bitumen is recovered from the reservoir through a production well (170). The
process (100) can
be repeated from step 110 if a second recovery operation is desired.
1045] Specific examples of the present methods are described below. Details
are provided for
the purpose of illustration, and the methods can be practiced without some or
all of the features
discussed herein. For clarity, technical materials that are known in the
fields relevant to the
present methods are not discussed in detail.
A. Delivery of Catalyst to Hydrocarbon Reservoir
[046] The present methods utilize a catalyst that can be activated by
electromagnetic radiation.
The catalyst can be a metal-based catalyst, such as a vanadium-, sodium-, or
platinum-based
catalyst. The catalyst can also be a supported catalyst, such as alumina-
supported platinum or
alumina-supported aluminum. Examples of the catalyst include, without
limitation, ammonium
Y zeolite, aluminum-based crystallite (e.g., Al/y-A1203), zirconium oxide
(Zr02), and cordierite
(Mg2A14Si5018).
[047] The catalyst can be delivered to the reservoir through a variety of
methods commonly
known in the art. Typical methods used in the art include injecting a liquid
containing catalytic
particles (e.g., aqueous dispersion) through a wellbore drilled in the
reservoir. The wellbore can
be for an injection or production well for a hydrocarbon recovery process.
[048] In general, the catalyst is first dispersed in an aqueous (water) phase
on the surface prior
to introduction into the reservoir. The catalyst is then injected into the
reservoir in the water
phase. The catalyst flows through mobile water films that wet the sand grains
in the reservoir.
Since the water is mobile, the catalyst that is dispersed within the aqueous
phase moves freely
through the water films in the reservoir under pressure or gravity. In this
manner, the catalyst
moves and spreads throughout the reservoir, thereby improving its ability to
contact the
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hydrocarbons in the reservoir.
[049] Once the catalyst is injected to the reservoir, the catalytic particles
distribute or disperse
through a mobile water phase in the reservoir. The catalyst particles are
small enough that they
can permeate through the porous matrix of the reservoir without significant
retention.
Preferably, the size of the catalytic particles is at nanoscale. Nanoparticles
have high mobility
in porous media and can easily transport through the matrix pores of
relatively tight
hydrocarbon reservoirs.
[050] In one implementation, injection of the catalyst can be carried out
prior to production of
hydrocarbons from the reservoir. In other implementations, injection of the
catalyst can also be
carried out during the production phase. In the latter case, the catalyst is
injected into the
reservoir before commencing recovery or during recovery of remaining
hydrocarbons from the
reservoir.
[051] By way of example, an aqueous dispersion of the catalyst is injected
into the reservoir
for a period of time prior to direction of electromagnetic radiation into the
reservoir. In this
manner, the catalyst is positioned throughout the reservoir in the water films
prior to
hydrocarbon production. In such a case, the method catalyzes upgrading of the
hydrocarbons in
the reservoir throughout the volume of the reservoir that is irradiated by the
electromagnetic
energy. Hydrocarbons further from the well undergo longer exposure to the
catalyst (which is
activated by the electromagnetic energy) before being produced; thus, the
degree of
hydrocarbon upgrading increases as the reservoir is produced ¨ as long as the
hydrocarbons
produced were exposed to the catalyst.
10521 In another example, the aqueous dispersion of the catalyst is injected
into the reservoir
concurrent with direction of electromagnetic radiation into the reservoir. In
this example, the
upgrading zone within the reservoir grows as the recovery process evolves. The
aqueous
dispersion of the catalyst can also be injected into the reservoir prior to
direction of
electromagnetic radiation into the reservoir, but then continue after the
electromagnetic
irradiation has occurred.
[053] A sufficient or pre-determined period of time can be allowed to pass to
permit
CA 02884849 2015-03-11
distribution or dispersal of the catalytic particles through a mobile water
phase in the reservoir
to an extent sufficient to accomplish purposes described herein. Using
techniques known to one
of skill in the art, an appropriate or sufficient period of time can be
determined on the basis of
the desired degree or type of in-situ upgrading, the size of the hydrocarbon
bearing zone,
porosity and permeability of the reservoir, physical/chemical properties of
the catalyst, and/or
any other factors considered relevant by the skilled person.
[054] In addition to the catalyst, the reservoir can be provided with a
hydrogen source, such as
organic or inorganic peroxide, tetralin (1,2,3,4-tetrahydronaphthalene),
decalin
(decahydronaphthalene), naphthalene, dimethyl ether (DME), light hydrocarbons
(e.g., C3-C10),
and the like, or a combination of more than one of any of the foregoing, in
order to facilitate in-
situ chemical reactions with bitumen (e.g., hydrocracking,
hydrodesulfurization, etc.). The
hydrogen source can be injected to the reservoir, for example, through at
least one injection
and/or production well.
[055] Furthermore, the reservoir can be provided with a solvent, such as
toluene, diesel,
propane, butane, pentane, hexane, heptane, xylene, diluent, condensate, and
the like, or any
component or mixture thereof, in order to improve reservoir conformance and
hydrocarbon
recovery. The solvent can also be injected to the reservoir, for example,
through at least one
injection and/or production well.
B. Pre-production Process
10561 A pre-production process can be commenced as required for a given
hydrocarbon-
recovery methodology. Exemplary recovery methodologies include, without
limitation, steam
assisted gravity drainage (SAGD), cold heavy oil production with sand (CHOPS),
cyclic steam
stimulation (CSS), and solvent injection. In the case of SAGD, high pressure
steam is
continuously injected into the upper wellbore to create a steam chamber in the
oil reservoir, so
that heavy oil can be heated and mobilized for production. In the case of
CHOPS, sand ingress
or influx is initiated such that a mixture of sand and oil can be sustained
throughout primary oil
production.
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C. Directing Electromagnetic Radiation
1057] Electromagnetic radiation or frequencies can come from a frequency
generator that is
located above or below ground. An antenna system can be set up and directed
towards the
reservoir to deliver electromagnetic radiation to the catalyst spread in the
mobile water phase.
The antenna system can be a single vertical or horizontal antenna, phased
array of mixed
geometry, or some other configuration. The antenna system can also be placed
above or below
ground (e.g., placed in a well), or in a combination thereof A skilled
operator can determine
the optimal placement and/or configuration of a given antenna system to
maximize activation of
the catalyst in the reservoir.
10581 Electromagnetic radiation has a frequency anywhere between 60 Hz and
1,000 GHz.
This frequency range includes both radio and microwave frequencies. One
skilled in the art can
match the appropriate electromagnetic frequency and intensity of radiation to
the selected
catalyst(s) in order to achieve effective catalysis.
10591 The catalyst can be activated and catalysis initiated before,
concurrently with, or after
the pre-production process is commenced.
D. In-situ Upgrading and Recovery of Hydrocarbons
1060] After sufficient exposure to radiation, upgrading of the bitumen or oil
in contact with the
activated catalyst will commence. The in-situ catalytic reactions crack large
molecules in the
hydrocarbons into smaller molecules, thereby decreasing viscosity. The
reactions can also
include, without limitation, pyrolysis, aquathermolysis (hydrous pyrolysis),
gasification,
hydrocracking, hydrogenation, desulphurization, denitrogenation,
demetallation, or
deasphalting, or a combination of more than one of any of the foregoing.
10611 The catalytic upgrading of hydrocarbons involves heat, the presence of a
catalyst, the
hydrocarbons themselves, and other components that can enable hydrogen
production. In the
case of petroleum reservoirs, the components enabling hydrogen production are
the petroleum
itself and water. In the absence of oxygen, the reactions that occur at
elevated temperatures
within the reservoir include pyrolysis (thermal cracking), aquathermolysis
(hydrous pyrolysis or
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thermal cracking reactions in the presence of water), and gasification
reactions.
[062] When the catalyst is irradiated with electromagnetic waves, for example,
the water
phase heats up and, due to elevated temperatures, the hydrocarbons undergo
pyrolysis and
aquathermolysis. In the presence of the catalyst, these reactions are enabled
at lower
temperatures than would be the case if the catalyst were not present. The
reactions crack the
hydrocarbons into smaller molecular weight species. As a result of
interactions between the
hydrocarbons and water, hydrogen, hydrogen sulphide, and carbon oxides are
produced during
aquathermolysis reactions. Additionally, as a result of gasification reactions
which arise due to
heating, the water-gas shift reaction will convert excess steam and carbon
monoxide into
additional hydrogen. Consequently, all of the required conditions for
upgrading are present,
including the catalyst, the heat, the hydrocarbons, and the hydrogen.
[063] Nanocatalysts are beneficial in the present methods. Nanoscale particles
have a large
surface-to-volume ratio, and, therefore, exhibit increased contact area and
enhanced catalytic
activity. Smaller-sized particles can achieve efficiency of the chemical
aspects of the upgrading
process. By way of example, nanoscale catalysts show asphaltene adsorption
properties that
enhance catalytic cracking of heavy oil within a reservoir.
[064] In the presence of a hydrogen source, hydrocracking can occur. As noted
above, the
hydrogen source can be provided to the reservoir externally or by a water-
splitting reaction in
the reservoir. Bitumen typically contains various metallic components which
can add to the
catalytic effect, if precipitated in situ.
[065] The hydrocarbon product resulting from the present methods can include
medium-heavy
oil, which typically exhibits a density of 870 to 920 kg/m3. Such medium-heavy
oil is usually
mobile at reservoir conditions.
E. Refreshing or Renewing the Catalyst
[066] The catalyst can be refreshed in the reservoir as needed by re-injection
into one of the
injection or production wells, through a second injector, or along the
antenna. In addition, the
catalyst can be renewed in situ through application of steam or solvent wash.
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10671 Although the present specification has described particular embodiments
and examples
of the methods and treatments discussed herein, it will be apparent to persons
skilled in the art
that modifications can be made to the embodiments without departing from the
scope of the
appended claims.
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