Note: Descriptions are shown in the official language in which they were submitted.
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B&P File No. 16546-7
TITLE: Drilling Fluid Comprising Surfactants
FIELD OF THE DISCLOSURE
The present disclosure relates to drilling fluid compositions
comprising surfactants for use in bitumen recovery from oil sands, and a
method and use of said compositions to encapsulate bitumen.
BACKGROUND OF THE DISCLOSURE
In Canada, South America and China, there are very large oil
sands deposits known as oil-rich bitumen sands. These oil sands consist of a
mixture of crude bitumen (a semi-solid form of crude oil), silica sand, clay
minerals, and water. The Canadian oil sand deposits cover over about
141,000 square kilometers and have about 28 billion cubic meters (174 billion
barrels) of economically recoverable crude bitumen. There are two ways to
recover the crude bitumen from these oil sand deposits. One way is mining
and the other, is in-situ operations. In Canada, approximately 15.6 billion
cubic meters (98 billion barrels) of crude bitumen deposit can be recovered
via in-situ operations. Steam Assisted Gravity Drainage (SAGD) is the main
in-situ operation to recover crude bitumen from these oil sand deposits. SAGD
uses dual horizontal wells, situated one on top of another, to recover the
crude bitumen from these oil sand deposits. The main challenge of drilling the
horizontal wells through these oil sand deposits is the bitumen sticking to
the
drilling components. The mixture of the crude bitumen or heavy oil, often
referred to as tar sands, makes the drilling cuttings from these formations
malleable and sticky. Bitumen is a mixture of hydrocarbon compounds
containing the other elements of nitrogen, sulfur, oxygen, metals and the
like.
Bitumen is known to have, overall, an anionic charge and hydrophobic
surfaces. When the conventional water-base drilling fluids are used to drill
through the oil sand deposits, the anionic polymer additives in the drilling
fluids increase the anionic surface charge of bitumen particles, causing
bitumen to disperse into the drilling fluids. The dispersed bitumen particles
in
the drilling fluids re-aggregate on the surfaces of metal or plastic or oil-
like
substances, which have very strong affinity for the bitumen or heavy oil. The
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re-aggregated bitumen sticks to oil sand cuttings and causes the bitumen
accretion or sticking problem known to occur while drilling oil sands
deposits.
Bitumen accretion causes many drilling problems, such as high torque and
drag, slow travel, blinding of the shakers while drilling oil sand deposits
and
getting the liners stuck while running in the liners.
SUMMARY
The present disclosure relates to drilling fluid compositions
comprising surfactants, wherein the surfactants have hydrophilic-lipophilic
balance (HLB) values of less than about 7.0, which prevents the bitumen from
dispersing into the drilling fluid. In addition, the surfactants in the
drilling fluid
reduce the friction coefficient of the drilling fluid. The compositions also
include one or more hydrophobically associating polymers, wherein the
hydrophobically associating polymers are anionic, non-ionic, cationic and/or
ampholytic polymers. The hydrophobic group of hydrophobically associating
polymers strongly adsorbs on the bitumen surfaces through its affinity for
oil,
and the hydrophilic groups of the hydrophobically associating polymers make
the bitumen surface water wet and provides less sticking. Further, the
hydrophobically associating polymers also help to prevent the bitumen from
dispersing. Accordingly, these compositions comprising a surfactant with an
HLB value of less than about 7.0 and hydrophobically associating polymers
are excellent bitumen and/or tar, flocculent and sticking inhibitors. As the
hydrophobically associating polymers only have negative charges or very
small amount of ampholytic charges, they are compatible with conventional
drilling fluid additives, which normally possess a negative charge. Therefore,
hydrophobically associating polymers, when used in drilling fluid systems to
drill oil sand formations, will inhibit bitumen sticking and be compatible
with
conventional anionic drilling fluid additives.
Accordingly, the present disclosure includes a drilling fluid
composition comprising:
(a) one or more hydrophobically associating polymers;
(b) one or more surfactants having a hydrophilic-lipophilic
balance value of less than about 7.0;
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(c) a water continuous phase comprising clay minerals; and
(d) one or more conventional drilling fluid additives.
In another embodiment, the surfactants are present in an
amount effective to inhibit dispersion of bitumen during bitumen recovery from
oil sands. In another embodiment, the surfactants are present in an amount
effective to reduce the friction coefficient of the drilling fluid. In another
embodiment therefore, the drilling fluid further comprises oil sands. In
another
embodiment, the friction coefficient of the drilling fluids is between 0.01
and
0.15, optionally between 0.02 and 0.10, or about 0.02 and 0.05.
In another embodiment of the disclosure, the surfactants are
nonionic, anionic, cationic or ampholytic surfactants with Hydrophile-
Lipophile
Balance (HLB) values less than 7.0, optionally less than about 6.5, or less
than about 6.0, or less than about 5Ø In another embodiment of the
disclosure, the surfactants are nonionic, anionic, cationic or ampholytic
surfactants with Hydrophile-Lipophile Balance (HLB) values between 1.0 and
7.0, optionally 1.0 and 5Ø In a further embodiment, the concentration of the
surfactant is in the range of about 0.1 to about 50 kilograms per cubic meter
of drilling fluid composition. In another embodiment, the concentration of the
surfactant is about 1 to about 5 kilograms per cubic meter of drilling fluid
composition.
In one embodiment, the surfactant is any compound that lowers
the surface tension of a liquid, allowing easier spreading, and lowering of
the
interfacial tension between two liquids, or between a liquid and a solid.
Surfactants may act as: detergents, wetting agents, emulsifiers, foaming
agents, de-foaming agents, dispersants, and lubricants, and examples of
surfactants include, but are not limited to, alkyl benzene sulfonates,
polyethylene oxides, polypropylene oxides, siloxane defoamers / lubricants,
carboxylates (fatty acids or salts). In another embodiment, the surfactant is
a
fatty acid, for example, long, branched or unbranched, aliphatic chain
carboxylic acids or carboxylates (CO2- or CO2H) containing between about 4
to about 28 carbon atoms. In another embodiment, the fatty acid is esterified.
In another embodiment, the surfactant is a long chain fatty acid containing
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between 8 and 24 carbon atoms (C8-C24-carboxylic acid), wherein long
aliphatic chain is either saturated or unsaturated.
In another embodiment of the disclosure, the one or more
hydrophobically associating polymers include anionic and ampholytic
polymers.
In a further embodiment, the hydrophobically associating
polymer is selected from homopolymers, copolymers, terpolymers,
tetrapolymers and mixtures thereof comprised of monomer units of the
following groups i)-iv):
i) vinyl monomers comprising at least one amide group;
ii) vinyl monomers comprising at least one carboxylic acid group
or carboxylate group;
iii) vinyl monomers comprising at least one of a quaternary
nitrogen atom, a quaternary nitrogen atom with an alkyl
sulfonate group, a quaternary nitrogen atom with a carboxylic
acid group or a quaternary nitrogen atom with a carboxylate
group; and
iv) vinyl monomers comprising a hydrophobic group, selected
from a C8_20alkyl group, a C8.20alkenyl group, a C8_20alkynyl
group, a C8_20alkylenearyl group and an aryl group, wherein the
aryl group is substituted by at least one C4.20alkyl group, and,
optionally, a carboxylic acid group, a carboxylate group or an
amide group.
In another embodiment, the hydrophobically associating polymer
is a tetra-polymer comprising one unit selected from each of the monomer
groups i-iv) as described above.
In another embodiment, the vinyl monomer of group (i) is
acrylamide, and the vinyl monomer of group (ii) is acrylic acid or an
acrylate.
In another embodiment of the disclosure, the vinyl monomer of
group (iii) is 2-methacryloyloxyethyltri-methylammonium chloride (DMC) or
diallyl dimethylammonium chloride (DADMAC).
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In another embodiment, the vinyl monomer of group (iv)
comprises a hydrophobic group selected from a C8_16alky1 group, a C8-
i6alkenyl group, a C8.16alkynyl group, a C8_16alkylenearyl group and an aryl
group, wherein the aryl group is substituted by at least one C4..20alkyl
group.
In a further embodiment, the vinyl monomer of group (iv) comprises a
hydrophobic group selected from C8_20alkyl methacrylate ester. In another
embodiment, the vinyl monomer of group (iv) is selected from C8_16a1ky1
methacrylate ester.
In another embodiment, the hydrophobically associating polymer
comprises
(i) acrylamide (a non-ionic monomer) present at about 87 to about
98%;
(ii) sodium acrylate (an anionic monomer) present at about 0.5 to about
5%;
(iii) a mixture of (a) dially dimethyl ammonium chloride,
(b) acryloyloxyethyl trimethyl ammonium chloride,
(c) [2-(methacryloyloxy)ethyl]trimethyl ammonium
chloride (cationic monomers)
present at about 0.5 to about 5%, and
(iv) a mixture of (a) acrylate (C8-C18)-alkyl ester,
(b) methyl acrylate (C8-C18)-alkyl ester,
(c) N-(C8-C18)-alkoxymethyl acrylamide,
(d) dimethyl ally (C8-C18)-alkyl ammonium chloride,
(e) acryloyloxyethyl dimethyl (C8-C18)-alkyl
ammonium chloride,
(f) methyl dially (C8-C18)-alkyl ammonium chloride,
(g) [2-(methacryloyloxy)ethyl]dimethyl (C8-C18)-
alkyl ammonium chloride (hydrophobic
monomers),
present at about 0.3 to about 3%.
In an embodiment, the hydrophobically associating polymer
comprises a copolymer, terpolymer or tetrapolymer comprising monomer units
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selected from (i) acrylamide, (ii) acrylic acid or an acrylate, (iii) 2-
methacryloyloxyethyltri-methylammonium chloride (DMC) or diallyl dimethyl
ammonium chloride (DADMAC), and (iv) a C8_20a1ky1 methacrylate ester.
In another embodiment, the hydrophobically associating polymer
comprises tetrapolymers comprising monomers selected from (i) acrylamide,
(ii) acrylic acid or an acrylate, (iii) and 2-methacryloyloxyethyltri-
methylammonium chloride (DMC) or diallyl dimethyl ammonium chloride
(DADMAC) and (iv) a C8_20alkyl methacrylate ester.
In another embodiment, the clay mineral comprises bentonite.
In another embodiment, the clay mineral comprises dispersible shale clay
cuttings and shale formations which are located on the top of oil sands.
In another embodiment of the disclosure, the conventional
drilling fluids additives are selected from one or more of viscosifiers,
filtrate
loss reducers, drilling fluid thinners, dispersants, shale inhibitors, clay
inhibitors, defoaming agents, bridging agents, weighting agents, pH adjusting
agents and the circulation loss materials.
In another embodiment, the composition further comprises one
or more of clay inhibitors, drilling fluid lubricants, drilling fluid bridging
agents,
drilling fluid weighting agents and/or circulation loss materials. In another
embodiment, the clay inhibitors are selected from one or more of potassium
silicate, amine, glycol and inorganic salts.
The present disclosure also includes a method of recovering
bitumen from oil sands comprising:
(a) contacting a drilling fluid composition as defined above with
the oil sands to obtain a mixture; and
(b) recovering the bitumen from the mixture, wherein the
surfactants are present in an amount effective to reduce the friction
coefficient
of the mixture.
In another embodiment of the disclosure, the contacting of the
composition is done under conditions to encapsulate the bitumen. In a further
embodiment, the conditions to encapsulate the bitumen comprise mixing the
composition with the oil sands. In another embodiment, the composition is
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contacted with the oil sands during a drilling operation using drilling
components. In another embodiment, the composition inhibits sticking of the
bitumen to the drilling components. In a further embodiment, the drilling
operation is a steam assisted gravity drainage. In another embodiment, the
drilling operation produces oil sand cuttings which are contacted with the
composition. In another embodiment, the composition encapsulates the
bitumen in the oil sand cuttings.
The present disclosure also includes a use of a drilling fluid
composition for the encapsulation of bitumen in oil sands, the composition
comprising:
(a) one or more hydrophobically associating polymers;
(b) one or more surfactants having an HLB value of less than
about 7.0;
(c) a water continuous phase comprising clay minerals; and
(d) one or more conventional drilling fluid additives,
wherein the one or more hydrophobically associating polymers
are present in an amount effective to inhibit sticking and/or
dispersion of bitumen during bitumen recovery from oil sands.
In another embodiment, the hydrophobically associating
polymers are present in an amount effective to encapsulate the bitumen.
In another embodiment of the use, the composition is contacted
with the oil sands under conditions to encapsulate bitumen. In a further
embodiment, the conditions to encapsulate the bitumen comprise mixing the
oil sands with the composition. In a further embodiment, the composition is
contacted with the oil sands during a drilling operation using drilling
components. In another embodiment, the composition inhibits sticking of the
bitumen to the drilling components. In a further embodiment, the drilling
operation is a steam assisted gravity drainage. In another embodiment, the
drilling operation produces oil sand cuttings which are contacted with the
composition. In a further embodiment, the composition encapsulates the
bitumen in the oil sand cuttings.
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Also included within the present disclosure is a use of one or
more hydrophobically associating polymers to inhibit sticking and/or
dispersion during bitumen recovery from oil sands. Also included within the
present disclosure is a use of one or more hydrophobically associating
polymers to encapsulate bitumen during bitumen recovery from oil sands.
Further included in the present disclosure is a method of
inhibiting the sticking and/or dispersion of bitumen during bitumen recovery
from oil sands comprising contacting the oil sands with one or more
hydrophobically associating polymers. Also included in the present disclosure
is a method of encapsulating bitumen during bitumen recovery from oil sands
comprising contacting the oil sands with one or more hydrophobically
associating polymers.
Other features and advantages of the present disclosure will
become apparent from the following detailed description. It should be
understood, however, that the detailed description and the specific examples
while indicating preferred embodiments of the disclosure are given by way of
illustration only, since various changes and modifications within the spirit
and
scope of the disclosure will become apparent to those skilled in the art from
this detailed description.
DETAILED DESCRIPTION OF THE DISCLOSURE
DEFINITIONS
The term "Cm_nalkyl" as used herein means straight and/or
branched chain, saturated alkyl groups containing from "m" to "n" carbon
atoms and includes (depending on the identity of m and n) n-butyl, s-butyl,
isobutyl, t-butyl, 2,2-dimethylbutyl, n-pentyl, 2-methylpentyl, 3-
methylpentyl, 4-
methylpentyl, n-hexyl and the like, where the variable m is an integer
representing the smallest number of carbon atoms in the alkyl radical and n is
an integer representing the largest number of carbon atoms in the alkyl
radical.
The term "Cs_nalkenyl" as used herein means straight and/or
branched chain, unsaturated alkyl groups containing from 8 to "n" carbon
atoms and one or more, suitably one to five, more suitably one to three double
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bonds, and includes (depending on the identity of n), 2-methylprop-1-enyl,
but-1-enyl, but-2-enyl, but-3-enyl, 2-methylbut-1-enyl, 2-methylpent-1-enyl, 4-
methylpent-1-enyl, 4-methylpent-2-enyl, 2-methylpent-2-enyl, 4-methylpenta-
1,3-dienyl, hexen-1-y1 and the like, where the variable n is an integer
representing the largest number of carbon atoms in the alkyl radical.
The term "C8_nalkynyl" as used herein means straight and/or
branched chain, unsaturated alkyl groups containing from 8 to "n" carbon
atoms and one or more, suitably one to five, more suitably one to three triple
bonds, and includes (depending on the identity of n), 2-methylprop-1-ynyl, 1-
butynyl, 2-butynyl, 3-butynyl, 1,3-butadiynyl, 3-methylbut-1-ynyl, 4-methylbut-
ynyl, 4-methylbut-2-ynyl, 2-methylbut-1-ynyl, 1-pentynyl, 2-pentynyl, 3-
pentynyl, 4-pentynyl, 1,3-pentadiynyl, 1,4-pentadiynyl, 3-methylpent-1-ynyl, 4-
methylpent-2-yny14-methylpent-2-ynyl, 1-hexynyl and the like, where the
variable n is an integer representing the largest number of carbon atoms in
the alkyl radical.
The term "C8_nalkylenearyl" as used herein means a straight
and/or branched chain, saturated alkylene group containing from eight to "n"
carbon atoms bonded to an aryl group comprising a monocyclic or polycyclic
aromatic ring system containing from 6 to 14 carbon atoms and at least one
aromatic group, and wherein the alkylene group includes (depending on the
identity of n), n-butylene, s-butylene, isobutylene, 2,2-dimethylbutylene, n-
pentylene, 2-methylpentylene and the aryl group includes phenyl, naphthyl,
anthracenyl, 1,2-d ihyd ronaphthyl,
1,2,3,4-tetrahydronaphthyl, fluorenyl,
indanyl, indenyl, ferrocenyl and the like, where the variable n is an integer
representing the largest number of carbon atoms in the alkyl radical.
The term "aryl" as used herein means a monocyclic, bicyclic or
tricyclic aromatic ring system containing from 6 to 14 carbon atoms and
includes phenyl, naphthyl, anthracenyl, 1,2-dihydronaphthyl, 1,2,3,4-
tetrahydronaphthyl, fluorenyl, indanyl, indenyl and the like.
The term "carboxylic acid" or as used herein means a group of
the formula CO2H.
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The term "carboxylate" as used herein means a group of the
formula -CO2R (or -0O2), wherein R is Ci_malkyl, suitably Ci_salkyl, or where
a hydrophobic group is required, C8_20alkyl.
The term "amide" as used herein means a group of the formula
CONR'R", wherein R' and R" are independently selected from H and C1.
2oalkyl, suitably Ci.6alkyl, or where a hydrophobic group is required,
C8_20alkyl.
The term "alkyl sulfonate" as used herein means a group of the
formula SO2R", wherein R" is C1_20a1ky1, suitably Ci.6alkyl, or where a
hydrophobic group is required, C8_20alkyl.
The term "bitumen" as used herein refers to a mixture of organic
liquids that are highly viscous, black, sticky, and is composed primarily of
highly condensed polycyclic aromatic hydrocarbons but also contains other
elements such as nitrogen, sulfur, oxygen, metals and the like. Bitumen is the
residual (bottom) fraction obtained by fractional distillation of crude oil.
It is
the heaviest fraction and the one with the highest boiling point.
To "inhibit" or "suppress" or "reduce" a function or activity, such
bitumen sticking, is to reduce the function or activity when compared to
otherwise same conditions except for a condition or parameter of interest, or
alternatively, as compared to another conditions.
The term "hydrophobically associating polymer" as used herein
refers to a polymer composed of monomers, in which at least one monomer
contains hydrophobic moieties, which associate with each other as a result of
their hydrophobic nature. In one embodiment, a hydrophobically associating
polymer contains non-ionic monomers, anionic monomers, cationic
monomers, ampholytic monomers and hydrophobic monomers.
The term "effective amount" as used herein with respect to the
surfactant refers to an amount of the surfactant present in the drilling fluid
composition which is able to lower the friction coefficient of the drilling
fluid
compositions to a value between 0.01 and 0.15. The amount of the surfactant
needed to reduce the friction coefficient of the mixture will be dependent
upon
the type of surfactant, and may be determined by a person skilled in the art.
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The term "effective amount" with respect to hydrophobically associating
polymer as used herein refers to an amount of hydrophobically associating
polymer
which inhibits sticking and/or dispersion of bitumen during bitumen recovery
from oil
sands, suitably by encapsulating the bitumen. The amount of the
hydrophobically
associating polymer needed to encapsulate the bitumen will be dependent upon
the
type of polymer, and may be determined by a person skilled in the art.
The term "friction coefficient" as used herein refers to the friction between
the drilling string and wellbore or casing. A reduction in the friction
coefficient of steel
walls of drilling strings upon adsorption of the surfactants in drilling fluid
compositions on
ro the drilling strings surfaces results in the less drag and torque while
drilling operations.
The term "hydrophilic-lipophilic balance value" as used herein refers to the
degree of which a surfactant of the disclosure is hydrophilic or lipophilic.
The HLB value
of a non-ionic surfactant is calculated using the following formula, known as
the Griffin
formula:
HLB = 20 * Mh / M,
where Mh is the molecular mass of the hydrophilic portion of the Molecule, and
M is the
molecular mass of the whole molecule, giving a result on an arbitrary scale of
0 to 20.
For ionic surfactants, the HLB value is calculated using the Davies formula,
which is
calculated by summing the hydrophilic/hydrophobic contributions afforded by
the
structural components of the surfactant:
HLB = E(hydrophilic group contributions) - E(hydrophobic group contributions)
+7
In one embodiment, surfactants used in the drilling fluids of the present
disclosure have
HLB values less than 7.0, optionally less than about 6.5, or less than about
6.0, or less
than about 5Ø In another embodiment, the surfactants used in the present
disclosure
are hydrophobic (lipophilic), and adsorb on the bitumen surfaces to enhance
the
encapsulating ability of hydrophobic associating polymers and are also
lubricants to
greatly reduce the drag and torque while drilling operations.
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In understanding the scope of the present disclosure, the term
"comprising" and its derivatives, as used herein, are intended to be open
ended terms
that specify the presence of the stated features, elements, components,
groups,
integers, and/or steps, but do not exclude the presence of other unstated
features,
elements, components, groups, integers and/or steps. The foregoing also
applies to
words having similar meanings such as
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the terms, "including", "having" and their derivatives. Finally, terms of
degree
such as "substantially", "about" and "approximately" as used herein mean a
reasonable amount of deviation of the modified term such that the end result
is not significantly changed. These terms of degree should be construed as
including a deviation of at least - 5% of the modified term if this deviation
would not negate the meaning of the word it modifies.
DRILLING FLUID COMPOSITIONS
The present disclosure relates to drilling fluid compositions
which comprise surfactants having an HLB value of less than about 7Ø In
one embodiment, upon contact of the drilling fluid with metal walls of
drilling
strings, the surfactants of the present disclosure adsorb on the metal
surfaces
of drilling strings and reduce the friction coefficient between the metal
drilling
strings and wellbore or casing, resulting in lower drag and torque while
drilling
operations. In addition, hydrophobically associating polymers in the drilling
fluid inhibit bitumen from dispersing into drilling fluids and therefore
inhibit
sticking of the bitumen to drilling components during bitumen recovery
processes. In one embodiment, the hydrophobically associating polymers are
viscosifiers of the drilling fluid compositions, and in addition the polymers
are
also bitumen flocculents and bitumen sticking inhibitors for drilling fluids.
In
another embodiment, the surfactants with HLB values less than 7 enhance
the bitumen encapsulating ability of hydrophobically associating polymers.
Accordingly, the present disclosure includes a drilling fluid
composition comprising:
(a) one or more hydrophobically associating polymers;
(b) one or more surfactants having a hydrophilic-lipophilic
balance value of less than about 7.0;
(c) a water continuous phase comprising clay minerals; and
(d) optionally one or more conventional drilling fluid additives.
In another embodiment, the surfactants are present in an
amount effective to inhibit dispersion of bitumen during bitumen recovery from
oil sands. In another embodiment, the surfactants are present in an amount
effective to reduce the friction coefficient of the drilling fluids for
drilling strings.
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In another embodiment, the friction coefficient of the drilling fluids for the
standard steel walls is between 0.01 and 0.15, optionally between 0.02 and
0.10, or about 0.02 and 0.05. In another embodiment, the surfactants are
present in an amount effective to reduce the friction coefficient by at least
5
times, optionally 8 times, or about 10 times, as compared to a drilling fluid
composition which does not contain a surfactant having an HLB value of less
than about 7Ø
In another embodiment, the surfactants with HLB value less
than 7.0 enhance the encapsulating bitumen ability of hydrophobically
associating polymers.
In another embodiment of the disclosure, the surfactants are
nonionic, anionic, cationic or ampholytic surfactants with Hydrophile-
Lipophile
Balance (HLB) values less than 7.0, optionally less than about 6.5, or less
than about 6.0, or less than about 5Ø In another embodiment of the
disclosure, the surfactants are nonionic, anionic, cationic or ampholytic
surfactants with Hydrophile-Lipophile Balance (HLB) values between 1.0 and
7.0, optionally 1.0 and 5Ø In a further embodiment, the concentration of the
surfactant is in the range of about 0.1 to about 50 kilograms per cubic meter
of drilling fluid composition. In another embodiment, the concentration of the
surfactant is about 1 to about 5 kilograms per cubic meter of drilling fluid
composition.
In one embodiment, the surfactant is any compound that lowers
the surface tension of a liquid, allowing easier spreading, and lowering of
the
interfacial tension between two liquids, or between a liquid and a solid.
Surfactants may act as: detergents, wetting agents, emulsifiers, foaming
agents, de-foaming agents, dispersants, and lubricants, and examples of
surfactants include, but are not limited to, alkyl benzene sulfonates,
polyethylene oxides, polypropylene oxides, siloxane defoamers / lubricants,
carboxylates (fatty acids or salts). In another embodiment, the surfactant is
a
fatty acid, for example, long, branched or unbranched, aliphatic chain
carboxylic acids or carboxylates (CO2" or CO2H) containing between about 4
to about 28 carbon atoms. In another embodiment, the fatty acid is esterified.
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In another embodiment, the surfactant is a long chain fatty acid containing
between 8 and 24 carbon atoms (C8-C24-carboxylic acid), wherein long
aliphatic chain is either saturated or unsaturated.
In another embodiment of the disclosure, the hydrophobically
associating polymers are present in an amount effective to encapsulate the
bitumen. In an embodiment of the disclosure, the hydrophobically associating
polymers are water-soluble polymers. The hydrophobically associating
polymers may have an anionic charge, and, as such, these polymers not only
inhibit the dispersion of bitumen into the drilling fluids, keep the bitumen
water
wet and less sticky, thereby inhibiting bitumen from sticking to drilling
components, but they also have very little negative effects on the dispersing
stability of the anionic colloids of clay/polymers, as they do not reduce the
negative charge of the anionic colloids of clay/polymers or the anionic
polymers.
In another embodiment of the disclosure, the one or more
hydrophobically associating polymers include anionic and ampholytic
polymers.
In a further embodiment, the hydrophobically associating
polymer is selected from a homopolymer, copolymer, terpolymer, tetrapolymer
and mixtures thereof comprised of monomer units of the following groups I)-
iv):
i) vinyl monomers comprising at least one amide group;
ii) vinyl monomers comprising at least one carboxylic acid group
or carboxylate group;
iii) vinyl monomers comprising at least one of a quaternary
nitrogen atom, a quaternary nitrogen atom with an alkyl
sulfonate group, a quaternary nitrogen atom with a carboxylic
acid group or a quaternary nitrogen atom with a carboxylate
group; and
iv) vinyl monomers comprising a hydrophobic group, selected
from a C8_20alkyl group, a C8_20alkenyl group, a C8_20alkynyl
group, a C8_20alkylenearyl group and an aryl group, wherein the
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aryl group is substituted by at least one C4.20a1ky1 group, and,
optionally, a carboxylic acid group, a carboxylate group or an
amide group.
In another embodiment, the hydrophobically associating polymer
is a tetra-polymer comprising one unit selected from each of the monomer
groups i-iv) as described above.
In another embodiment, the vinyl monomer of group (i) is
acrylamide, and the vinyl monomer of group (ii) is acrylic acid or an
acrylate.
In another embodiment of the disclosure, the vinyl monomer of
group (iii) is 2-methacryloyloxyethyltri-methylammonium chloride (DMC) or
diallyl dimethylammonium chloride (DADMAC).
In another embodiment, the vinyl monomer of group (iv)
comprises a hydrophobic group selected from a Cs_isalkyl group, a C8-
i6alkenyl group, a Cs_isalkynyl group, a Cs_isalkylenearyl group and an aryl
group, wherein the aryl group is substituted by at least one C4_20alkyl group.
In a further embodiment, the vinyl monomer of group (iv) comprises a
hydrophobic group selected from C8_20a1ky1 methacrylate ester. In another
embodiment, the vinyl monomer of group (iv) is selected from C8_16alkyl
methacrylate ester.
In an embodiment, the hydrophobically associating polymer
comprises a copolymer, terpolymer or tetrapolymer comprising monomer units
selected from (i) acrylamide, (ii) acrylic acid or an acrylate, (iii) 2-
methacryloyloxyethyltri-methylammonium chloride (DMC) or diallyl dimethyl
ammonium chloride (DADMAC), and (iv) a C8_20alkyl methacrylate ester
In another embodiment, the hydrophobically associating polymer
comprises tetrapolymers comprising monomers selected from (i) acrylamide,
(ii) acrylic acid or an acrylate, (iii) and 2-methacryloyloxyethyltri-
methylannnnoniunn chloride (DMC) or diallyl dimethyl ammonium chloride
(DADMAC) and (iv) a C8_20a1ky1 methacrylate ester.
In another embodiment of the disclosure, the hydrophobically
associating polymers are selected from BT1211, BT1212, BT1213, BT1214,
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BT1215, BT1216, BT1217 and BT1218, supplied by the Chengdu Cationic
Chemistry company.
In another embodiment of the disclosure, the hydrophobically
associating polymers contain about 0.1 to about 10% of vinyl monomer units
comprising hydrophobic groups by weight. In another embodiment, the
hydrophobically associating polymers contain about 0.5 to about 5% vinyl
monomer units containing hydrophobic groups by weight.
In another embodiment, the hydrophobically associating
polymers are water soluble polymers.
In a further embodiment, the average molecular weight of the
hydrophobically associating polymers is from about 200 to about 20 million
grams per mole. In another embodiment, the average molecular weight of the
mixture of the hydrophobically associating polymers is from about 50,000 to
about 6 million grams per mole.
In another embodiment, the concentration of the polymers is
about 0.1 to about 20 kilograms per cubic meter of the drilling fluid
composition. In another embodiment of the disclosure, the concentration of
the polymers is about 2 to about 10 kilograms per cubic meter of the drilling
fluid composition. In another embodiment of the disclosure, the concentration
of the polymers is about 3 to about 5 kilograms per cubic meter of the
drilling
fluid composition.
In another embodiment, the composition comprises about 5 to
about 100 kilograms clay minerals per cubic meter of the drilling fluid
composition. In another embodiment, the drilling fluid composition comprises
about 5 to about 30 kilograms clay minerals per cubic meter of the drilling
fluid
composition. In another embodiment, the drilling fluid composition comprises
about 10 to about 30 kilograms clay minerals per cubic meter of the drilling
fluid composition.
In another embodiment, the clay mineral comprises bentonite.
In another embodiment, the clay mineral comprises dispersible shale clay
cuttings and shale formations which are located on the top of oil sands.
In another embodiment of the disclosure, the conventional
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drilling fluids additives are selected from one or more of viscosifiers,
filtrate
loss reducers, drilling fluid thinners, dispersants, shale inhibitors, clay
inhibitors, lubricants, defoaming agents, bridging agents, weighting agents,
pH adjusting agents and the circulation loss materials.
In another embodiment, the composition further comprises one
or more of clay inhibitors, drilling fluid lubricants, drilling fluid bridging
agents,
drilling fluid weighting agents and/or circulation loss materials. In another
embodiment, the clay inhibitors are selected from one or more of potassium
silicate, amine, glycol and inorganic salts.
In another embodiment of the disclosure, the conventional
drilling fluids additives are selected from one or more of viscosifiers,
filtrate
loss reducers, drilling fluid thinners, dispersants, shale inhibitors, clay
inhibitors, lubricants, defoaming agents, bridging agents, weighting agents,
pH adjusting agents and the circulation loss materials.
In another embodiment of the disclosure, the viscosifiers
comprise polymers selected from one or more of xanthan gum, polyanionic
cellulose (PAC), carboxyl methyl cellulose (CMC), guar gum, hydroxyl
propylene guar gum, hydroxyl ethylene cellulose (HEC), partial hydrolyzed
polyacrylamide (PHPA) and zwitterionic polymers. In another embodiment,
the concentration of the viscosifiers is about 0.1 to about 5 kilograms per
cubic meter of the drilling fluid composition. In another embodiment, the
concentration of the viscosifiers is about 1 to about 4 kilograms per cubic
meter of the drilling fluid composition. In another embodiment, the
concentration of the viscosifiers is about 1 to about 3 kilograms per cubic
meter of the drilling fluid composition.
In an embodiment of the disclosure, the filtrate loss reducers are
selected from one or more of polyanionic cellulose (PAC), carboxyl methyl
cellulose (CMC), starch, modified starch, lignite, lignosulfonates, modified
lignosulfonates and ampholytic polymers. In a further embodiment, the
concentration of the filtrate loss reducers is about 0.1 to about 20 kilograms
per cubic meter of the drilling fluid composition. In a further embodiment,
the
concentration of the filtrate loss reducers is about 1 to about 10 kilograms
per
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cubic meter of the drilling fluid composition. In a further embodiment, the
concentration of the filtrate loss reducers is about 3 to about 9 kilograms
per
cubic meter of the drilling fluid composition.
In another embodiment of the disclosure, the thinners or
dispersants are selected from one or more of lignite, lignosulfonates,
modified
lignosulfonates and ampholytic polymers. In a further embodiment, the
concentration of the thinners or dispersants is about 0.1 to about 5 kilograms
per cubic meter of the drilling fluid composition. In a further embodiment,
the
concentration of the thinners or dispersants is about 1 to about 3 kilograms
per cubic meter of the drilling fluid composition.
In a further embodiment of the disclosure, the defoamers are
selected from one or more of a silicone defoamer, an alcohol defoamer, an
aluminum stearate defoamer and a calcium oleate defoamer. In
an
embodiment, the concentration of the defoamers is about 0.1 to about 5
kilograms per cubic meter of the drilling fluid composition. In an embodiment,
the concentration of the defoamers is about 1 to about 3 kilograms per cubic
meter of the drilling fluid composition.
In another embodiment of the disclosure, the pH adjusting
agents are selected from one or more of NaOH, Na2CO3, NaHCO3, KOH,
K2CO3, KHCO3, citric acid and sulfamic acid. In another embodiment, the
concentration of the pH adjusting agent is about 0.1 to about 5 kilograms per
cubic meter of the drilling fluid composition. In another embodiment, the
concentration of the pH adjusting agent is about 0.1 to about 3 kilograms per
cubic meter of the drilling fluid composition. In another embodiment, the
concentration of the pH adjusting agent is about 0.5 kilograms per cubic meter
of the drilling fluid composition.
In another embodiment, the drilling fluid compositions of the
present disclosure further comprise one or more of clay inhibitors, drilling
fluid
lubricants, drilling fluid bridging agents, drilling fluid weighting agents
and/or
circulation loss materials.
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In another embodiment of the disclosure, the clay inhibitors are
selected from one or more of potassium silicate, amine, glycol and inorganic
salts.
The present disclosure also includes a method recovering
bitumen from oil sands comprising:
(a) contacting a drilling fluid composition as defined in any of the above
embodiments with the oil sands to obtain a mixture; and
(b) recovering the bitumen from the mixture. In one embodiment, the
one or more surfactants are present in an amount effective to reduce
the friction coefficient of the mixture and/or reduce the dispersion of
bitumen during bitumen recovery from oil sands.
In another embodiment of the disclosure, the contacting is done
under conditions to reduce the friction coefficient of the mixture, comprising
mixing the composition with the oil sands. In another embodiment, the
composition is contacted with the oil sands during a drilling operation, such
as
a steam assisted gravity drainage operation, using drilling components,
wherein the composition inhibits sticking of the bitumen to the drilling
components. In a further embodiment, the drilling operation produces oil sand
cuttings which are contacted with the composition, wherein the composition
encapsulates the bitumen in the oil sand cuttings, and also reduces the
friction coefficient of the mixture (cuttings and composition). It will be
understood by a person skilled in the art that the compositions of the present
disclosure are able to reduce the friction coefficient and encapsulate bitumen
in oil sands directly or from the cuttings of a drilling operation. When
drilling
components drill through the oil sands during a drilling operation, the
drilling
results in cuttings which contain bitumen, which are contacted with the
composition.
The present disclosure also includes a use of a drilling fluid
composition for the encapsulation of bitumen in oil sands and to reduce the
friction coefficient, wherein the drilling fluid is as defined in any of the
above
embodiments. In one embodiment, the surfactants are present in an amount
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effective to reduce the friction coefficient of the drilling fluid mixture
(oil sands
and drilling fluid).
Further included in the present disclosure is a method of
inhibiting the sticking and/or dispersion of bitumen during bitumen recovery
from oil sands comprising contacting the oil sands with one or more
hydrophobically associating polymers. Also included in the present disclosure
is a method of encapsulating bitumen during bitumen recovery from oil sands
comprising contacting the oil sands with one or more hydrophobically
associating polymers.
The following non-limiting examples are illustrative of the
present disclosure:
EXAMPLES
The xanthan gum (polyxan), bentonite (Gel), fatty acids, drilling starch
(Aquastar EX) were supplied by Diversity Technologies Corp. Polyanionic
Cellulose (PAC HV/LV) was provided by Luzhou North Qiaofeng Chemical
Company. The hydrophobically associating ampholytic polymer (BT 1217)
was provided by Chengdu Cationic Chemistry Company. The cationic polymer
(Ultimer 7753TM) was supplied by Nalco Global Equipment Solutions
Company. The polymer flocculant (Hyperfloc CE 2340TM) was supplied by
Hychem Inc. The oil sand sample was supplied by Nexen Inc. A Hamilton
Beach mixer was used to mix the drilling fluid compositions. An EP/Lubricity
Tester Model 212 Fann Instrument Company was used to test the coefficient
of friction of the prepared silicate drilling fluids. A Viscometer Model 35
from
Fann Instrument Company was used to test viscosity and an API Filter Press
from Fann Instrument Company was used to test the filtrate loss of drilling
fluids. A Brookfield Viscometer was supplied by Brookfield Engineering
Company.
Example 1: Preparation of a Polymer Drilling Fluid Compositions
To tap water was added 20 kg/m3 bentonite, 1 kg/m3 of polyanionic cellulose
regular (PAC HV), 1 kg/m3 of polyanionic cellulose regular (PAC LV), 1 kg/m3
of xanthan gum, and 4 kg/m3 of drilling grade starch. This mixture was then
mixed for 20 minutes using a Hamilton Beach mixer.
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Example 2: Bitumen Encapsulation Test of a Drilling Fluid Composition
To the polymer drilling fluid composition of Example 1 was respectively added
kg/m3 of BT 1217, 10 Um3 of Ultimer 7753TM 10 L/m3 of Hyperfloc CE
5 2340Tm. This mixture was then mixed for 15 minutes using a Hamilton Beach
mixer, at that point 100 kg/m3 of oil sands were added. The mixture was then
mixed for another 10 minutes using a Hamilton Beach mixer. After finishing
mixing, observed the drilling fluid composition's color and the floating oils
on
the top of the drilling fluid compositions.
Example 3: The Tests of Rheolgy and API Filtrate of Drilling Fluid
Compositions
The rheology of drilling fluid compositions were tested with Viscometer Model
35 from Fann Instrument Company and Brookfield Viscometer from Brookfield
Engineering, and the filtrate loss of this mud is tested with API Filter Press
form Fann Instrument Company. The coefficient of friction of this mixture was
then determined using a Fann EP/Lubricity Tester. Table 1 and Table 2 show
the testing results.
As illustrated in Table 1 andTable 2, the hydrophobically associating
ampholytic polymer (BT 1217) greatly increases Brookfield Viscosity and Yield
Point of the drilling fluid composition.
Example 4: Friction Coefficient Test of Drilling Fluid Compositions with
Surfactants
To the drilling fluid compositions as prepared in (Example 2) 5L/m3 of fatty
acids were added. The mixture was then mixed for 5 minutes using a
Hamilton Beach mixer. The coefficient of friction of this mixture was then
determined using a Fann EP/Lubricity Tester. The Tester is a standard
instrument designed for determining the coefficient of friction of drilling
fluids
and their additives. During the test, a hardened steel block and a ring are
placed in contact with each other in the presence of the drilling fluid to be
tested. A load of 150 inch pounds is placed upon a level arm which applies a
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pressure of between 5,000 and 10,000 pounds per square inch on the drilling
fluid to be tested which is between the block and the ring. The ring is
rotated
at 60 RPM. All the tested drilling fluids were run under these conditions,
and,
accordingly, the coefficients of the friction of values and torque reduction
values are directly comparable to each other. The testing results are shown in
Table 2.
As illustrated in Table 1 and Table 2, the fatty acids greatly reduce the
friction
coefficients of the drilling fluid compositions (from 0.26-0.30 to 0.03-0.06).
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Table 1: Drilling Fluid Compositions without Surfactants
Mud Formulations A B C D
Bentonite (kg/m3) 20 20 20 20
Xanthan Gum (Polyxan) (kg/m3) 1 , 1 1 1
PAC HV (kg/m3) 1 1 1 1
PAC LV (kg/m3) 1 1 1 1
Drilling Starch (kg/m3) 4 4 4 4
Surfactant (HLB: 1-5.5)
0 0 0
(Fatty Acids) (L/m3)
Hydrophobic Polymer
(BT1217 ) (kg/m3)
Cationic Polymer
(Ultimer7753 ) (L/m3)
Polymer Flocculant (i-lyperfloc
2340) (L/m4)
Nexen Oil Sand (kg/m3) 100 100 100
Mud Properties
600 rpm Reading 38 82 36 32
300 rpm Reading , 27 54 24 21
200 rpm Reading 22 43 19 17
100 rpm Reading 14 31 14 12
6 rpm Reading 4 9 4 3
3 rpm Reading 3 7 3 2.5
Gels (10s/10min, Pa) 1.5/2.5 3.5/5 1.5/2.5 1.25/2
PV (mPa-s) 11 28 12 11
YP (Pa) 8 , 13 6 5
API Filtration Loss (m1) 12 8.3 9.4 9
Mud Cake Thickness (mm) _ 1 1 1 1
pH Value 7 7 8.5 8
Brookfield Viscosity at 0.3 rpm
8,800 22,000 5,700 6,600
(mPa-s)
Brookfield Viscosity at 0.6 rpm
5,200 15,000 4,000 4,200
(mPa.$)
Friction Coefficient 0.34 0.26 0.3 0.27
Mud Appearance
Polymer Flocculation none some some ,
Sticking to Rheometer / Blender none some some
Floating Oil none some some
Mud Color Light grey Light brown Light
brown
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Table 2: Drilling Fluid Compositions with Surfactants
_
Mud Formulations A B C D
Bentonite (kg/m3) 20 20 20 20
Xanthan Gum (Polyxan) (kg/m3) 1 1 1 1
PAC HV (kg/m3) 1 1 1 1
PAC LV (kg/m3) 1 1 1 1
_
Drilling Starch (kg/m3) 4 4 4 4
Surfactant (HLB: 1-5.5)
5 5
(Fatty Acids) (Um3)
,
Hydrophobic Polymer 5
(BT1217 ) (kg/m3)
Cationic Polymer 10
(Ultimer7753 ) (L/m3) _
Polymer Flocculant (.1-lyperfloc 10
2340) (L/m) _
Nexen Oil Sand (kg/m3) 100 100 100
Mud Properties
600 rpm Reading 38 92 49 37
300 rpm Reading 27 67 32 24
200 rpm Reading 22 55 25 19
100 rpm Reading 14 38 18 13
6 rpm Reading 4 10 5 3
3 rpm Reading 3 8 4 2.5
Gels (10s/10min, Pa) 1.5/2.5 4/5 2/2.5 1.5/2
PV (mPa.$) 11 25 17 13
YP (Pa) 8 21 7.5 5.5
API Filtration Loss (ml) 12 8.2 9.2 8.8
Mud Cake Thickness (mm) 1 1 1 1
pH Value 7 7 8.5 8
Brookfield Viscosity at 0.3 rpm 8,800 24,800 6,000 6,800
(mPa.$)
Brookfield Viscosity at 0.6 rpm 5,200 15,600 4,200 4,400
(mPa-s)
Friction Coefficient 0.34 0.03 0.06 0.05
Mud Appearance
Polymer Flocculation none some some
Sticking to Rheometer / Blender none some some
Floating Oil none some some
Mud Color Light grey Light brown Light brown
