COMPOSITIONS AND METHODS RELATING TO THE STABILIZATION OF
HYDROPHOBICALLY MODIFIED HYDROPHILIC POLYMER TREATMENT
FLUIDS UNDER ALKALINE CONDITIONS
[0001] The present invention relates to methods and compositions for treating a
water- and hydrocarbon-producing subterranean formation with a relative permeability
modifier, and, more specifically, to improved treatment fluids, methods for preparing
treatment fluids, and methods for use thereof to reduce the water permeability of the
subterranean formation without substantially reducing the hydrocarbon permeability.
[0002] The production of water from hydrocarbon-producing wells constitutes a
significant technical problem and expense in oilfield operations. When a subterranean
formation contains a significant amount of water, the water's higher mobility often allows it
to flow to a hydrocarbon-producing zone of the formation by way of natural and manmade
fractures and high permeability streaks. If the ratio of recovered water to recovered
hydrocarbons becomes significantly large, the cost of separating the water from the
hydrocarbons and disposing of it becomes a significant economic barrier to production.
[0003] In order to reduce the production of undesired water from hydrocarbonproducing
subterranean formations, aqueous-soluble polymer solutions containing
crosslinking agents have been utilized in the art to enter water-containing zones of the
formation and block the flow of undesired water. Selective placement of these crosslinked
polymers in a subterranean formation and stability therein represent significant technical
challenges that have somewhat limited their use. A more recent strategy to reduce water
production from a subterranean formation has been to utilize agents known as relative
permeability modifiers. Such relative permeability modifiers are capable of reducing the
flow of water through a subterranean formation while having a minimal effect on the flow of
hydrocarbons. The use of relative permeability modifiers does not necessitate the use of
zonal isolation techniques that are often employed with crosslinked polymers.
[0004] Although a number of relative permeability modifiers have been successfully
employed in the field, some of them are unstable under certain conditions including, for
example, high or low pH, excessive salinity and/or extreme temperatures that are commonly
encountered downhole. For example, at temperatures greater than about 140 °F (60 °C), a
commonly encountered relative permeability modifier precipitates at a pH of greater than
about 8. Precipitation of the relative permeability modifier not only substantially terminates
its relative permeability-modifying properties but also can damage a subterranean formation
if the precipitation occurs downhole. Likewise, downhole precipitation can also occur in
high pH fracturing fluids for similar reasons.
[0005] The present invention relates to methods and compositions for treating a
water- and hydrocarbon-producing subterranean formation with a relative permeability
modifier, and, more specifically, to improved treatment fluids, methods for preparing
treatment fluids, and methods for use thereof to reduce the water permeability of the
subterranean formation without substantially reducing the hydrocarbon permeability.
[0006] The present invention provides a method comprising: providing a treatment
fluid comprising a relative permeability modifier, at least one surfactant, and an aqueous
phase base fluid; wherein the relative permeability modifier comprises a hydrophobically
modified hydrophilic polymer; and wherein the at least one surfactant is operable to maintain
the relative permeability modifier in a dissolved state in the treatment fluid above a pH of
about 8; and placing the treatment fluid in a subterranean formation. The at least one
surfactant may be an anionic curfactant.
[0007] The present invention also provides a method comprising: providing a
treatment fluid comprising a relative permeability modifier, at least one anionic surfactant,
and an aqueous phase base fluid; wherein the relative permeability modifier comprises a
hydrophobically modified hydrophilic polymer comprising at least one hydrophobically
modified hydrophilic monomer comprising a cetyldimethylammoniumethyl methacrylate
halide; wherein the at least one anionic surfactant is operable to maintain the relative
permeability modifier in a dissolved state in the treatment fluid above a pH of about 8 and
above a temperature of about 140 °F (60 °C); and wherein the at least one anionic surfactant
comprises at least one surfactant selected from the group consisting of a poly(ethylene oxide)
carboxylate and a poly(ethylene oxide) sulfonate; and placing the treatment fluid in a
subterranean formation.
[0008] Furthermore, the present invention provides a composition comprising: a
relative permeability modifier comprising a hydrophobically modified hydrophilic polymer
comprising at least one hydrophobically modified hydrophilic monomer comprising a
cetyldimethylammoniumethyl methacrylate halide; and at least one anionic surfactant;
wherein the at least one anionic surfactant is operable to maintain the relative permeability
modifier in a dissolved state in an aqueous phase base fluid above a pH of about 8 and above
a temperature of about 140 °F (60 °C); and wherein the at least one anionic surfactant
comprises at least one surfactant selected from the group consisting of a poly(ethylene oxide)
carboxylate and a poly(ethylene oxide) sulfonate.
[0009] The features and advantages of the present invention will be readily apparent
to those of ordinary skill in the art upon a reading of the description that follow.
[0010] The present invention relates to methods and compositions for treating a
water- and hydrocarbon-producing subterranean formation with a relative permeability
modifier, and, more specifically, to improved treatment fluids, methods for preparing
treatment fluids, and methods for use thereof to reduce the water permeability of the
subterranean formation without substantially reducing the hydrocarbon permeability.
[0011] There are many advantages of the present invention, only a few of which are
discussed or alluded to herein. The present invention provides compositions comprising a
relative permeability modifier that have improved stability under a variety of conditions
including, for example, elevated temperature and H, and methods related thereto. Due to
their increased stability, the present compositions are advantageous over those presently
known in the art, since they can be used under a wider array of downhole conditions. Such
improved relative permeability modifiers display substantial utility for more facile production
of hydrocarbons from subterranean formations. In addition, the present compositions and
methods can be extended for use in high pH fracturing fluids to combat downhole
precipitation that can occur during fracturing operations. Additional advantages will become
evident to those of ordinary skill in the art upon reading this disclosure.
[0012] The present invention provides methods and compositions that eliminate or
substantially minimize unwanted precipitation that can occur under certain conditions with
cetyl-modified poly(dimethylaminoethyl methacrylate) (poly C-DMEAMA) and other
relative permeability modifiers in a treatment fluid. The methods of the present invention
involve adding at least one surfactant to treatment fluids containing a relative permeability
modifier in an aqueous phase base fluid. It is believed that the surfactant advantageously
maintains the relative permeability modifier in a substantially dissolved state at pH values
greater than about 8 at temperatures up to 200 °F (93.3 °C) and greater. As defined herein, a
relative permeability modifier is in a substantially dissolved state when a treatment fluid
containing the relative permeability modifier remains clear, hazy, or slightly hazy upon visual
inspection following exposure to conditions (e.g., pH and temperature) that cause
precipitation of the relative permeability modifier in the absence of a surfactant. A preferred
condition indicating that the relative permeability modifier remains in a dissolved state is that
the treatment fluid remains clear following exposure to pH conditions that cause precipitation
of the relative permeability modifier in the absence of a surfactant. Although less preferred,
the relative permeability modifier can still remain in a substantially dissolved state if the
treatment fluid is only hazy or slightly hazy (i.e., turbid) following exposure to conditions
that cause precipitation of the relative permeability modifier in the absence of a surfactant. A
hazy or slightly hazy treatment fluid can indicate that the treatment fluid is on the verge of
precipitation, which may not be desirable in some applications. Inclusion of at least one
surfactant in the treatment fluid, as disclosed herein, can "improve" a hazy or slightly hazy
result into a clear result.
[0013] As defined herein, a "treatment fluid" is a fluid that is placed in a subterranean
formation in order to improve production from the subterranean formation. Treatment fluids
can include, without limitation, fracturing fluids, acidizing fluids, and damage control fluids.
Such treatment fluids can have an aqueous phase or hydrocarbon phase base fluid. An
aqueous phase base fluid can include fresh water, salt water, seawater, brine, or an aqueous
salt solution. Compositions of the present invention may be included in treatment fluids.
Compositions of the present invention may further comprise an aqueous phase base fluid in
which the relative permeability modifier and at least one surfactant are mixed. The relative
permeability modifier and at least one surfactant may be dissolved in the aqueous phase base
fluid. The aqueous phase base fluid may be an aqueous salt solution. Such aqueous salt
solutions can have a salt concentration ranging between about 0.1% and about 10% by
weight. The salt concentration may be between about 1% and about 10% by weight or
between about 2% and about 5% by weight.
[0014] Compositions comprising a relative permeability modifier and at least one
surfactant are described herein. The relative permeability modifier comprises a
hydrophobically modified hydrophilic polymer comprising at least one
cetyldimethylammoniumethyl methacrylate halide hydrophobically modified hydrophilic
monomer. Poly C-DMEAMA is commonly used at well bore temperatures up to about
325°C. Hence, the present invention significantly extends the working temperature range of
poly C-DMEAMA and like relative permeability modifiers under alkaline conditions.
Further, the present invention also advantageously circumvents the need to adjust the pH of
the treatment fluid upon incorporation of the relative permeability modifier therein, which is
an appreciable advantage.
[0015] In the present compositions, the relative permeability modifier has improved
solubility due to the presence of at least one surfactant as disclosed herein. Typically, the
relative permeability modifier is present at a concentration ranging between about 0.02% and
about 3% by weight. The relative permeability modifier may be present at a concentration
ranging between about 0.05% and about 1% by weight or from about 0.2% to about 1% by
weight. Typically, the surfactant is present at a concentration ranging between about 0.1%
and about 5% by weight. The surfactant may be present at a concentration ranging between
about 0.1% and about 2% by weight or between about 0.5% and about 1% by weight.
[0016] At least one anionic surfactant may be operable to maintain the relative
permeability modifier in a dissolved state in an aqueous phase base fluid above a pH of about
8 and above a temperature of about 140 °F (60 °C). The at least one anionic surfactant may
comprise at least one surfactant selected from a poly(ethylene oxide) carboxylate and a
poly(ethylene oxide) sulfonate.
[0017] Surfactants that are suitable for use in the present invention may include
anionic surfactants. Illustrative anionic surfactants that can be used in the present invention
include, for example, poly(ethylene oxide) sulfonates and poly(ethylene oxide) carboxylates.
Such anionic surfactants may have a structural formula of R -(0-CH -CH2)n-0-CH 2-X in
which X is C0 2 or S0 3 , n is an integer ranging from about 2 to about 20, and R1 is an alkyl,
alkenyl, alkynyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl,
heteroaryl, or heteroaralkyl group containing about 4 to about 22 carbon atoms. It will be
understood that any of the aforementioned groups not expressly containing heteroatom
functionality (e.g., containing O, N, S, F, CI, Br or I moieties) can further include at least one
heteroatom functionality either as part of the main carbon chain or as a side chain
functionality. Further, the aforementioned groups can be in either linear or branched chain
forms. It will be further understood that reference herein to poly(ethylene oxide) sulfonates
or poly(ethylene oxide) carboxylates will equivalently refer to their protonated carboxylic
acid or sulfonic acid forms, that is poly(ethylene oxide) sulfonic acids or poly(ethylene oxide)
carboxylic acids.
[0018] Suitable anionic surfactants can also include, for example, poly(propylene
oxide) sulfonates or poly(propylene oxide) carboxylates having a structural formula of R'-(0-
CH2-CH2-CH2)n-0 -CH2-X, where the variables are defined as above. Alternatively, suitable
anionic surfactants can include, for example, poly(ethylene oxide) sulfates having a structural
formula of R1-(0-CH 2-CH2)n-0-S0 3 or poly(propylene oxide) sulfates having a structural
formula of R1-(0-CH 2-CH2-CH2)n-0-S0 3 , where the variables are defined as above.
[0019] In their deprotonated forms, charge balance is maintained in the poly(ethylene
oxide) sulfonates and poly(ethylene oxide) carboxylates and other anionic surfactants by a
cation. The cation can include, without limitation, monovalent cations (e.g., alkali metal
cations and ammonium cations), divalent cations (e.g., alkaline earth cations) and tnvalent
cations. Illustrative monovalent cations include, for example, lithium, sodium, potassium,
rubidium, ammonium, alkylammonium, dialkylammonium, trialkylammonium, and
tetraalkylammonium (e.g., tetramethylammonium, tetraethylammonium,
tetrapropylammonium, and tetrabutylammonium) cations. Illustrative divalent cations
include, for example, beryllium, magnesium, calcium, strontium and barium cations. The
cation can be a transition metal or lanthanide metal cation. One of ordinary skill in the art
will recognize that the cation selection for a given surfactant can modify the solubility of the
surfactant itself or the solubility it conveys to a given hydrophobically modified hydrophilic
polymer in an aqueous phase base fluid. Selection of the cation for a given operation is a
matter of routine optimization and lies within the capabilities of one of ordinary skill in the
art. When the identity of the cation is not expressly set forth herein, it will be understood that
the cation's identity can vary without limitation.
[0020] The at least one anionic surfactant may be a poly(ethylene oxide) carboxylate
having a structural formul
where R2 is an alkyl, alkenyl, alkynyl or cycloalkyl group and y is an integer ranging from
about 2 to about 20. The at least one anionic surfactant may be a poly(ethylene oxide)
carboxylate having a structural formula of
where C9H19 is a straight chain alkyl group. Such an anionic surfactant is commercially
available under the trade name "EMCOL CNP 110" from Akzo Nobel Corporation.
[0021] The at least one anionic surfactant may be a poly(ethylene oxide) carboxylate
having a structural formula of 3-(0 -CH2-CH2)n-0-CH -C0 , where R3 comprises an alkyl,
aryl or alkenyl group comprising about 4 to about 22 carbon atoms and n is an integer
ranging from about 3 to about 15. Optionally, R3 is an oleyl group and n is 10. Alternatively,
R is a lauryl group and n is 13. A number of structurally related poly(ethylene oxide)
carboxylate surfactants are commercially available from Clariant Corporation under the trade
name "EMULSOGEN".
[0022] The compositions can further comprise at least one additional surfactant that is
not an anionic surfactant. Such additional surfactants can comprise at least one cationic
surfactant, at least one amphoteric surfactant or at least one nonionic surfactant. The at least
one additional surfactant may be an amphoteric surfactant. Inclusion of the additional
amphoteric surfactant can further improve the solubility conveyed by the at least one anionic
surfactant. A suitable amphoteric surfactant to be added with at least one anionic surfactant
is, for example, "HC-2," an amphoteric surfactant that is commercially available from
Halliburton Energy Services. Other examples of amphoteric surfactants are known to those
of ordinary skill in the art and include, for example, betaines (e.g., cocoamidopropyl betaine,
palmitamidopropyl betaine and lauryl betaine), glycinates and imidazolines. One of ordinary
skill in the art will recognize that a suitable additional amphoteric surfactant can be selected
through routine experimental optimization.
[0023] Amphoteric (zwitterionic) surfactants can be used in addition to or instead of
at least one anionic surfactant. Suitable amphoteric surfactants include, for example, fatty
acids having quaternized amine groups, betaines, glycinates and imidazolines.
[0024] The methods of the present invention may comprise providing a treatment
fluid comprising a relative permeability modifier, at least one surfactant, and an aqueous
phase base fluid; and placing the treatment fluid in a subterranean formation. The relative
permeability modifier comprises a hydrophobically modified hydrophilic polymer. The at
least one surfactant may be an anionic surfactant. The at least one surfactant may be operable
to maintain the relative permeability modifier in a dissolved state in the treatment fluid above
a pH of about 8. The at least one anionic surfactant may be further operable to maintain the
relative permeability modifier in a dissolved state in the treatment fluid at a temperature
above about 140 °F (60 °C).
[0025] Hydrophobically modified hydrophilic polymers of the present invention
comprise at least one hydrophobically modified hydrophilic monomer and, optionally, at least
one hydrophilic monomer. As such, the present hydrophobically modified hydrophilic
polymers can be considered as homopolymers, copolymers, terpolymers or higher order
polymer structures. Positioning of the hydrophilic monomer units and the hydrophobically
modified hydrophilic monomer units in copolymer and higher order polymer structures can
vary without limitation and can be, for example, alternating, random, block or a combination
thereof. Examples of suitable hydrophilic monomers include, for example, 2-acrylamido-2-
methyl propane sulfonic acid, N,N-dimethylacrylamide, vinyl pyrrolidone,
dimethylaminoethyl methacrylate, dimethylaminoethyl methacrylamide, acrylic acid,
methacrylic acid, dimethylaminopropyl methacrylate, dimethylaminopropyl methacrylamide,
trimethylammoniumethyl methacrylate halide (halide = chloride, bromide, iodide or a halide
equivalent such as, for example, a tosylate or methanesulfonate), methacrylamide, and
hydroxyethyl aerylate.
[0026] The hydrophobically modified hydrophilic polymer may be prepared by
polymerizing at least one hydrophobically modified hydrophilic monomer or a mixture of at
least one hydrophobically modified hydrophilic monomer and at least one hydrophilic
monomer. The hydrophobically modified hydrophilic polymer may be prepared by
functionalizing an existing hydrophilic polymer with a hydrophobic agent to form a
hydrophobically modified hydrophilic polymer containing at least one hydrophobically
modified hydrophilic monomer and, optionally, at least one hydrophilic monomer.
Illustrative hydrophobically modified hydrophilic monomers include, for example, alkyl
acrylates, alkyl methacrylates, alkyl acrylamides, alkyl methacrylamides,
alkyldimethylarnmoriiumethyl methacrylate bromide, alkyldimethylammoniumethyl
methacrylate chloride, alkyldimethylammoniumethyl methacrylate iodide,
alkyldimethylammoniumpropyl methacrylate bromide, alkyldimethylammoniumpropyl
methacrylate chloride, alkyldimethylammoniumpropyl methacrylate iodide, alkyl
dimethylammoniumethyl methacrylamide bromide, dimethylammoniumethyl
methacrylamide chloride, dimethylammoniumethyl methacrylamide iodide,
dimethylammoniumpropyl methacrylamide bromide, dimethylammoniumpropyl
methacrylamide chloride and dimethylammoniumpropyl methacrylamide iodide. In general,
alkyl groups of the hydrophobically modified hydrophilic monomers contain about 4 to about
22 carbon atoms.
[0027] The hydrophobically modified hydrophilic polymer may comprise at least one
alkyldimethylammoniumethyl methacrylate halide hydrophobically modified hydrophilic
monomer. In such embodiments, the alkyl group may comprise about 4 to about 22 carbon
atoms and the halide can be chloride, bromide, iodide, or halide equivalent (e.g.,
toluenesulfonate or methanesulfonate), for example. The alkyl group may be a cetyl group
containing 16 carbon atoms. That is, the hydrophobically modified hydrophilic polymer
comprises at least one cetyldimethylammoniumethyl methacrylate halide monomer unit. As
used herein, a hydrophobically modified hydrophilic polymer containing at least one
cetyldimethylammonium methacrylate halide monomer unit will be referred to as cetylmodified
poly(dimethylaminoethyl methacrylate) (poly C-DMEAMA). Poly C-DMEAMA
can be prepared by functionalization of an existing poly(dimethylaminoethyl methacrylate)
polymer or by co-polymerization of a mixture of cetyldimethylammoniumethyl methacrylate
halide and dimethylaminoethyl methacrylate (for example, see United States Patent
7,1 14,568, which is incorporated by reference herein in its entirety).
[0028] The at least one surfactant may comprise at least one anionic surfactant such
as, for example, a poly(ethylene oxide) sulfonate or a poly(ethylene oxide) carboxylate.
Other suitable anionic surfactants can include, without limitation, a poly(propylene oxide)
sulfonate, a poly(propylene oxide) carboxylate, a poly(ethylene oxide) sulfate, or a
polypropylene oxide) sulfate.
[0029] The at least one anionic surfactant may comprise a poly(ethylene oxide)
carboxylate having a structural formula of
where the variables are defined as above. The at least one anionic surfactant may comprise a
poly(ethylene oxide) carboxylate having a structural formula of
where C9H19 is a straight chain alkyl group.
[0030] The at least one anionic surfactant comprises a poly(ethylene oxide)
carboxylate having a structural formula of R -(0-CH -CH2)n-0-CH 2-C0 2 , where R3
comprises an alkyl, aryl or alkenyl group comprising about 4 to about 22 carbon atoms and n
is an integer ranging from about 3 to about 15. Optionally, R is an oleyl group and n is 10.
Such an anionic surfactant is commercially available from Clariant Corporation under the
trade name "EMULSOGEN COL 100". Alternatively, R3 is a lauryl group and n is 13. Such
an anionic surfactant is commercially available from Clariant Corporation under the trade
name "EMULSOGEN LS 24N".
[0031] The treatment fluid may further comprise at least one additional surfactant that
is not an anionic surfactant. The at least one additional surfactant may comprises at least one
cationic surfactant, at least one nonionic surfactant, and at least one amphoteric surfactant.
The at least one additional surfactant may be an amphoteric surfactant. The at least one
additional surfactant may be "HC-2".
[0032] The present methods may further comprise mixing the relative permeability
modifier and the at least one anionic surfactant with the aqueous phase base fluid. The at
least one anionic surfactant may be mixed with the relative permeability modifier before
being mixed with the aqueous phase base solution. The present methods can be conducted by
mixing a mixture of the relative permeability modifier and the at least one anionic surfactant
with an aqueous phase base fluid of a treatment fluid. Alternatively, the relative permeability
modifier can be mixed with an aqueous phase base fluid of a treatment fluid, with the at least
one anionic surfactant being added thereafter.
[0033] The present methods may comprise providing a treatment fluid comprising a
relative permeability modifier, at least one anionic surfactant, and an aqueous phase base
fluid; and placing the treatment fluid in a subterranean formation. The relative permeability
modifier may comprise a hydrophobically modified hydrophilic polymer comprising at least
one cetyldimethylammoniumethyl methacrylate halide hydrophobically modified hydrophilic
monomer. The at least one anionic surfactant may be operable to maintain the relative
permeability modifier in a dissolved state in the treatment fluid above a pH of about 8 and
above a temperature of about 140 °F (60 °C). The at least one anionic surfactant may
comprise at least one surfactant selected from a poly(ethylene oxide) carboxylate or a
poly(ethylene oxide) sulfonate.
[0034] The present compositions and methods can reduce the permeability of a
subterranean formation to aqueous based fluids without substantially changing the
permeability of the subterranean formation to hydrocarbons. After placement downhole in a
subterranean formation containing water-producing zones and hydrocarbon-producing zones,
the relative permeability modifier alters the permeability of the water-producing zones
without substantially affecting the production of hydrocarbons from the hydrocarbonproducing
zones. Without being bound by theory or mechanism, Applicants believe that
during normal "leak-off of the aqueous phase base fluid, the relative permeability modifier
is adsorbed into the subterranean formation, thereby leading to a significant reduction in
water permeability. It will be appreciated by those of ordinary skill in the art that the present
compositions and methods are advantageous, at a minimum, because they allow zonal
isolation between the water-producing zones and the hydrocarbon-producing zones of a
formation at the time of completion, thereby eliminating or postponing the need for water
shutoff during the production phase of the well. Further, the present compositions and
methods can advantageously extend the life of a well.
[0035] Treatment fluids of the present invention can be used in both newly drilled
subterranean formations and in formations needing re-stimulation. Further, the present
treatment fluids can optionally comprise any number of additional components including, for
example, other relative permeability modifiers, clays, scale inhibitors, corrosion inhibitors,
gelling agents, crosslinking agents, foaming agents, proppants, salts, acids, fluid loss control
additives, gas, catalysts, clay control agents, dispersants, flocculants, scavengers (e.g., H2S
scavengers, C0 2 scavengers or 0 2 scavengers), lubricants, breakers, friction reducers,
antifoam agents, bridging agents, viscosifiers, weighting agents, and the like.
[0036] To facilitate a better understanding of the present invention, the following
examples are given. In no way should the following examples be read to limit, or to define,
the scope of the invention.
Examples
[0037] Example 1: Surfactant Stabilization of Cetyl-Modified
Poly(dimethylaminoethyI methacrylate). The ability of a particular surfactant to stabilize a
poly C-DMEAMA solution was evaluated based upon the surfactant's ability to maintain a
clear or hazy solution under conditions at which poly C-DMEAMA ordinarily precipitates.
Test results are summarized in Table 1 below. For the testing, poly C-DMEAMA was
dissolved at a concentration of 2000 pp in a 2% wt/vol. potassium chloride solution.
Thereafter, a surfactant, surfactant combination or non-surfactant additive was added to the
poly C-DMEAMA solution at the concentrations (gal/Mgal, ml/1) indicated in Table 1. After
mixing, the combined solution was placed in a 190 °F (87.7 °C) bath. Under these
conditions, the poly C-DMEAMA solution without added surfactant produced a pH of -8.5,
and a precipitate formed upon heating. A "precipitate" result in the solution was taken to
indicate a negative or neutral role for a given surfactant or like additive, whereas a "hazy",
"slightly hazy" or "clear" result in the solution was taken to indicate a positive role for the
given surfactant by maintaining the poly C-DMEAMA in solution, with a "clear" solution
being an especially positive result.
Table 1
Surfactant
Polymer Surfactant Added Concentration pH Results
(gal/Mgal, ml/1)
poly DMAEMA — ~ 8.5 Precipitate
poly DMAEMA -- — 9.0 Precipitate
poly C-DMEAMA -- — 9.2 Precipitate
poly C-DMEAMA ~ — 9.4 Precipitate
poly C-DMEAMA — — 9.6 Hazy
poly C-DMEAMA — — 9.8 Hazy
poly C-DMEAMA — 10.0 Hazy
Anionic Surfactants
poly C-DMEAMA EMCOLCNP1 10 0.5 8.9 Hazy
poly C-DMEAMA EMCOLCNP1 0 0.5 9.5 Hazy
poly C-DMEAMA EMCOLCNP1 10 0.5 9.7 Hazy
poly C-DMEAMA EMCOLCNP1 10 1 10.0 Clear
Surfactant
Polymer Surfactant Added Concentration pH Results
(gal/Mgal, ml/1)
poly C-DMEAMA EMCOLCNP1 10 1 11.0 SI. Haze
poly C-DMEAMA EMCOLCNP1 0 2 10.0 Clear
poly C-DMEAMA EMCOLCNP110 2 11.0 SI. Haze
poly C-DMEAMA EMCOLCNP1 10/HC-2b 1/1 9.0 Clear
poly C-DMEAMA EMCOLCNPl lO/HC-2 1/1 9.2 Clear
poly C-DMEAMA EMCOLCNPl lO/HC-2 1/1 9.4 Clear
poly C-DMEAMA EMCOLCNPl lO/HC-2 0.5/0.5 8.7 Hazy
poly C-DMEAMA EMCOLCNPl lO/HC-2 0.5/0.5 9.0 Hazy
poly C-DMEAMA EMCOLCNPl lO/HC-2 0.5/0.5 9.2 Hazy
poly C-DMEAMA STEPWET DOS70 2 ~ Surfactant soln.
hazy in 2% KC1
poly C-DMEAMA AQF-2d 2 9.0 Precipitate
poly C-DMEAMA EMULSOGEN DTC ACID 2 8.4 Hazy
poly C-DMEAMA EMULSOGEN COL 050A 1 6.8 Hazy
poly C-DMEAMA EMULSOGEN COL 050 1 9.2 Hazy
poly C-DMEAMA EMULSOGEN COL 050A 1 9.4 Hazy
poly C-DMEAMA EMULSOGEN COL 050A 1 9.5 Hazy
poly C-DMEAMA EMULSOGEN COL 050A 2 8.9 Hazy
poly C-DMEAMA EMULSOGEN COL 050A 2 9.1 Hazy
poly C-DMEAMA EMULSOGEN COL 050A 2 9.4 Hazy
poly C-DMEAMA EMULSOGEN LS 24N8 0.5 8.9 Hazy
poly C-DMEAMA EMULSOGEN LS 24N 0.5 9.1 Hazy
poly C-DMEAMA EMULSOGEN LS 24N 0.5 9.3 Hazy
Surfactant
Polymer Surfactant Added Concentration pH Results
(gal/Mgal, ml/1)
poly C-DMEAMA EMULSOGEN LS 24N 1 8.7 Clear
poly C-DMEAMA EMULSOGEN LS 24N 1 9.0 Hazy
poly C-DMEAMA EMULSOGEN LS 24N 1 9.3 Ha
poly C-DMEAMA EMULSOGEN LS 24N 2 8.8 Clear
poly C-DMEAMA EMULSOGEN LS 24N 2 9.0 Clear
poly C-DMEAMA EMULSOGEN LS 24N 2 9.2 Clear
poly C-DMEAMA EMULSOGEN LS 24N 2 9.6 SI. Haze
poly C-DMEAMA EMULSOGEN COL 00 2 9.0 Clear
poly C-DMEAMA EMULSOGEN COL 100 2 9.2 Clear
poly C-DMEAMA EMULSOGEN COL 100 1 8.8 Clear
poly C-DMEAMA EMULSOGEN COL 100 1 9.0 Clear
poly C-DMEAMA EMULSOGEN COL 100 1 9.3 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.5 8.9 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.5 9.1 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.5 9.3 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.5 10.0 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.5 11.0 SI. Haze
poly C-DMEAMA EMULSOGEN COL 100 0.45 8.7 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.45 9.4 V. SI. Haze
poly C-DMEAMA EMULSOGEN COL 100 0.45 10.0 Hazy
poly C-DMEAMA EMULSOGEN COL 100 0.45 11.0 Hazy
poly C-DMEAMA EMULSOGEN COL 100 0.4 4.6 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.4 5.3 Clear
Surfactant
Polymer Surfactant Added Concentration pH Results
(gal/Mgal, ml/1)
poly C-DMEAMA EMULSOGEN COL 100 0.4 8.8 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.4 9.0 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.4 9.2 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.4 9.4 SI. Haze
poly C-DMEAMA EMULSOGEN COL 100 0.4 9.6 V. SI. Haze
poly C-DMEAMA EMULSOGEN COL 100 0.4 9.8 V. SI. Haze
poly C-DMEAMA EMULSOGEN COL 100 0.4 10.3 V. SI. Haze
poly C-DMEAMA EMULSOGEN COL 100 0.3 8.8 Clear
poly C-DMEAMA EMULSOGEN COL 100 0.3 9.0 Hazy
poly C-DMEAMA EMULSOGEN COL 100 0.3 9.3 Hazy
poly C-DMEAMA EMULSOGEN COL 100 / 0.2/0.2 8.8 Clear
EMULSOGEN COL 050A
poly C-DMEAMA EMULSOGEN COL 100 / 0.2/0.2 9.1 Clear
EMULSOGEN COL 050A
poly C-DMEAMA EMULSOGEN COL 100 / 0.2/0.2 9.4 Clear
EMULSOGEN COL 050A
poly C-DMEAMA EMULSOGEN COL 100 / 0.2/0.2 9.7 Clear
EMULSOGEN COL 050A
poly C-DMEAMA EMULSOGEN COL 100 / 0.2/0.2 10.0 Clear
EMULSOGEN COL 050A
poly C-DMEAMA EMULSOGEN COL 100 / 0.2/0.2 10.6 Clear
EMULSOGEN COL 050A
poly C-DMEAMA STABILIZER 434C' 1 9.0 Precipitate
poly C-DMEAMA STABILIZER 434C 1.5 8.8 Precipitate
Surfactant
Polymer Surfactant Added Concentration pH Results
(gal/Mgal, ml/1)
poly C-DMEAMA STABILIZER 434C 2 8.9 Clear
poly C-DMEAMA STABILIZER 434C 2 9.0 Clear
poly C-DMEAMA STABILIZER 434C 2 9.5 Clear
poly C-DMEAMA STABILIZER 434C 11.2 SI. Hazy
poly C-DMEAMA STABILIZER 434D 2 9.0 Precipitate
poly C-DMEAMA DDBSA k 50# 9.2 Precipitate
poly C-DMEAMA STRATALOCK F1 0.5 9.0 Hazy
poly C-DMEAMA STRATALOCK F 1 10.2 Clear
poly C-DMEAMA STRATALOCK F 1 11.0 Hazy
poly C-DMEAMA STRATALOCK F 1 12.0 Hazy
poly C-DMEAMA STRATALOCK F 2 10.2 Clear
poly C-DMEAMA STRATALOCK F 2 10.1 Hazy
poly C-DMEAMA STRATALOCK F 4 9.0 Clear
poly C-DMEAMA STRATALOCK F 4 10.2 Clear
poly C-DMEAMA STRATALOCK F 4 11.0 V. SI. Hazy
poly C-DMEAMA SEM-7 m 2 9.0 Precipitate
poly C-DMEAMA POLYSTEP B430S" 2 9.0 Precipitate
Cationic Surfactants
poly C-DMEAMA DMCB-80 0 4 9.0 Hazy
poly C-DMEAMA AROMOX DMCP 4 10.1 Hazy
Nonionic Surfactants
poly C-DMEAMA DUAL SPACER B 4 9.0 Hazy
poly C-DMEAMA DUAL SPACER B 2 8.8 Precipitate
Surfactant
Polymer Surfactant Added Concentration pH Results
(gal/Mgal, ml/1)
poly C-DMEAMA DUAL SPACER B 2 9.2 Precipitate
poly C-DMEAMA MUSOL A 2 9.0 Precipitate
poly C-DMEAMA GASPERM 1000s 2 9.0 Precipitate
poly C-DMEAMA PEN 88M 2 9.0 V. Hazy
poly C-DMEAMA ETHOMEEN C/25 2 8.9 Hazy
poly C-DMEAMA ETHOMEEN C/25 2 9.1 Hazy
poly C-DMEAMA ETHOMEEN C/25 2 9.3 Hazy
poly C-DMEAMA TWEEN 40 2 8.8 Hazy
Amphoteric Surfactants
poly C-DMEAMA AMPHOSOL CGW 1 8.5 Hazy
poly C-DMEAMA AMPHOSOL CG 1.5 9.2 Precipitate
poly C-DMEAMA AMPHOSOL CG 1.5 9.4 Precipitate
poly C-DMEAMA AMPHOSOL CG 1.5 9.6 Precipitate
poly C-DMEAMA AMPHOSOL CG 2 8.5 Clear
poly C-DMEAMA AMPHOSOL CG 4 10.1 Clear
poly C-DMEAMA AMPHOSOL CG 4 11.2 Hazy/Precipitate
poly C-DMEAMA MIRATAINE CAB-A X 2 10.2 Hazy
poly C-DMEAMA MIRATAINE CAB-A 4 10.1 Clear
poly C-DMEAMA MIRATAINE CAB-A 4 11.1 Hazy
poly C-DMEAMA MIRATAINE BET0-30 y 4 — Surfactant was
insol. in 2% C1
poly C-DMEAMA HC-2 1 8.8 Precipitate
poly C-DMEAMA HC-2 1 9.5 Hazy
Surfactant
Polymer Surfactant Added Concentration
PH Results
(gal/Mgal, ml/1)
poly C-DMEAMA HC-2 1.5 8.5 Clear
poly C-DMEAMA HC-2 1.5 9.0 Hazy
poly C-DMEAMA HC-2 1.5 9.5 Precipitate
poly C-DMEAMA HC-2 1.5 10.0 Hazy
poly C-DMEAMA HC-2 1.5 11.0 Hazy
poly C-DMEAMA HC-2 2 10.0 Hazy
poly C-DMEAMA HC-2 4 10.0 Hazy
poly C-DMEAMA HC-2 2 11.4 Hazy
poly C-DMEAMA HC-2 3 11.4 Hazy
poly C-DMEAMA HC-2 4 11.4 SI. Hazy
poly C-DMEAMA HC-2 5 11.4 SI. Hazy
poly C-DMEAMA HC-2 10 11.4 SI. Hazy
poly C-DMEAMA SCHERCOTAINE PABZ 2 9.0 Clear
poly C-DMEAMA SCHERCOTAINE PAB 2 10.0 Precipitate
poly C-DMEAMA CHROMABOND S-100aa 2 8.9 Hazy
poly C-DMEAMA CHROMABOND S-100 2 9.3 Hazy
poly C-DMEAMA CHROMABOND S-403E 2 8.7 Hazy
poly C-DMEAMA CHROMABOND S-403E 2 9.2 Hazy
Non-SurfactantAdditives
poly C-DMEAMA 60% sodium lactate 2 9.0 V. Hazy
poly C-DMEAMA Tartaric acid 50# 9.4 Hazy
poly C-DMEAMA Sodium Citrate 50# 8.8 Precipitate
poly C-DMEAMA Sodium Citrate 50 9.0 Hazy
Surfactant
Polymer Surfactant Added Concentration P Results
(gal/Mgal, ml/1)
poly C-DMEAMA Sodium Citrate 50# 9.2 Hazy
poly C-DMEAMA Sodium Citrate 50# 9.4 Hazy
poly C-DMEAMA Propionic Acid 2 9.0 V. Hazy
poly C-DMEAMA Benzoic Acid 50# 9.0 Precipitate
poly C-DMEAMA Benzoic Acid 50# 9.5 Hazy
poly C-DMEAMA Caprylic Acid 5 9.1 Precipitate
poly C-DMEAMA Sodium Xylene Sulfonate 2 9.0 Precipitate
poly C-DMEAMA Sodium Xylene Sulfonate 10 9.0 Precipitate
v. = very, si. = slight
a EMCOL CNP 110 is an aralkyl ethoxylated carboxylate surfactant that is
commercially available from Akzo Nobel Corporation.
b HC-2 is a cocoamine betaine surfactant that is commercially available from
Halliburton Energy Services.
STEPWET DOS70 is sodium dioctyl sulfosuccinate surfactant that is commercially
available from Stepan Company.
d AQF-2 is an alcohol sulfonate surfactant that is commercially available from
Halliburton Energy Services.
EMULSOGEN DTC ACID is trideceth-7 carboxylate surfactant that is commercially
available from Clariant Corporation.
EMULSOGEN COL 050A is an alkyl ether carboxylate surfactant having a formula
R-(0-CH CH2)5-0-CH -C0 2H (R = C alkyl) that is commercially available from
Clariant Corporation.
EMULSOGEN LS 24N is sodium laureth-13 carboxylate surfactant that is
commercially available from Clariant Corporation.
h EMULSOGEN COL 100 is an alkyl ether carboxylate surfactant having a formula
R-(0-CH 2CH )io-0-CH2-C0 2H (R = oleyl) that is commercially available from Clariant
Corporation.
STABILIZER 434C is an oxyalkylated sulfonate surfactant that is commercially
available from Halliburton Energy Services.
J STABILIZER 434D is an ethoxylated isododecyl alcohol sulfonate surfactant that is
commercially available from Halliburton Energy Services.
DDBSA is dodecylbenzene sulfonic acid.
STRATALOCK F is an alkylaryl polyoxycarboxylate that is commercially available
from Halliburton Energy Services.
m SEM-7 is an ethoxylated alcohol sulfate that is commercially available from
Halliburton Energy Services.
POLYSTEP B430S is an ethoxylated alcohol sulfate that is commercially available
from Stepan.
DMCB-80 is benzyl cocoalkyl dimethyl quaternary ammonium chloride surfactant
that is commercially available from Akzo Nobel Corporation.
p AROMOX DMC is a mixture of coco dimethylamine N-oxide and coco
dimethylamine surfactant that is commercially available from Akzo Nobel Corporation.
DUAL SPACER B is nonylphenol polyethylene glycol ether surfactant that is
commercially available from Halliburton Energy Services.
r MUSOL A is an ether alcohol that is commercially available from Halliburton
Energy Services.
s GASPERM 1000 is a non-ionic surfactant mixture that is available from Halliburton
Energy Services.
PEN 88M is an ethoxylated alcohol that is commercially available from Halliburton
Energy Services.
ETHOMEEN C/25 is a coco alkyl ethoxylated amine surfactant that is commercially
available from Akzo Nobel Corporation.
TWEEN 40 is polyoxyethylene sorbitan monopalmitate surfactant that is
commercially available from Sigma-Aldrich Corporation.
AMPHOSOL CG is cocoamidopropyl betaine that is commercially available from
Stepan.
x MIRATAINE CAB-A is a cocoamidopropyl betaine that is commercially available
from Rhodia.
y MIRATAINE BETO-30 is an oleyldimethylarnidopropyl betaine that is
commercially available from Rhodia.
SCHERCOTAINE PAB is palmitamidopropyl betaine surfactant that is
commercially available from Scher Chemicals.
CHROMABOND S-100 is poly(N-carboxymethyl-4-vinylpyridinium) chloride
surfactant that is commercially available from ISP Chemical Corporation.
CHROMABOND S-403E is 4-ethenyl pyridine homopolymer N-oxide surfactant
that is commercially available from ISP Chemical Corporation.
[0038] Example 2: Permeability Reduction in a Sandstone Core Using
Surfactant-Stabilized Cetyl-Modified Poly(dimethylaminoethyl methacrylate). A
sandstone core was treated with a 2000 ppm poly C-DMEAMA solution at 175 °F (79.4 °C),
and the reduction in core permeability was measured according to standard methods
described in United States Patent 6,476,169, which is incorporated herein by reference in its
entirety. The sequence of addition for the permeability measurements was 1) water, 2) oil, 3)
water, 4) poly C-DMEAMA treatment fluid, and 5) water. Surfactant-stabilized poly CDMEAMA
solutions were prepared in two ways. First, a poly C-DMEAMA treatment
solution was prepared, and the surfactant was then added to the treatment fluid at the
indicated concentration. Second, the surfactant was added to bulk poly C-DMEAMA, and
the treatment fluid was prepared thereafter by dissolving the bulk poly C-DMEAMA at the
indicated concentration. Permeability reduction results are summarized in Table 2.
Table 2
Surfactant Surfactant (gal/MCgaoln, cmenl/t1r)ation pH %RPeerdmucetaiobnility
6.0 98
Addition of Surfactant to
poly C-DMEAMA
Solution
Emulsogen COL 100 0.5 8.7 98
Emulsogen COL 100 0.5 9.5 98
Emulsogen COL 100 / 0.15/0.45 8.8 98
Emulsogen LS 24N
Addition of Surfactant to
Bulk poly C-DMEAMA
Emulsogen COL 100 0.4 8.7 98
Emulsogen COL 0.4 10.0 97
[0039] As shown in Table 2, incorporation of a stabilizing surfactant in a poly CDMEAMA
treatment fluid did not degrade the permeability reduction. Without the added
surfactant, the poly C-DMEAMA treatment fluid was less effective at pH values greater than
8 due to precipitation.
[0040] Therefore, the present invention is well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein. The particular embodiments
disclosed above are illustrative only, as the present invention may be modified and practiced
in different but equivalent manners apparent to those skilled in the art having the benefit of
the teachings herein. Furthermore, no limitations are intended to the details of construction
or design herein shown, other than as described in the claims below. It is therefore evident
that the particular illustrative embodiments disclosed above may be altered, combined, or
modified and all such variations are considered within the scope of the present invention.
While compositions and methods are described in terms of "comprising," "containing," or
"including" various components or steps, the compositions and methods can also "consist
essentially of or "consist of the various components and steps. All numbers and ranges
disclosed above may vary by some amount. Whenever a numerical range with a lower limit
and an upper limit is disclosed, any number and any included range falling within the range is
specifically disclosed. In particular, every range of values (of the form, "from about a to
about b," or, equivalently, "from approximately a to b," or, equivalently, "from
approximately a-b") disclosed herein is to be understood to set forth every number and range
encompassed within the broader range of values. Also, the terms in the claims have their
plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.
Moreover, the indefinite articles "a" or "an," as used in the claims, are defined herein to mean
one or more than one of the element that it introduces. If there is any conflict in the usages of
a word or term in this specification and one or more patent or other documents that may be
incorporated herein by reference, the definitions that are consistent with this specification
should be adopted.

CLAIMS:
1. A method comprising:
providing a treatment fluid comprising a relative permeability modifier, at
least one surfactant, and an aqueous phase base fluid;
wherein the relative permeability modifier comprises a
hydrophobically modified hydrophilic polymer; and
wherein the at least one surfactant is operable to maintain the relative
permeability modifier in a dissolved state in the treatment fluid above a pH of about
8; and
placing the treatment fluid in a subterranean formation.
2. The method of claim 1, wherein the at least one surfactant is an anionic surfactant.
3. The method of claim 2, wherein the at least one anionic surfactant is further operable
to maintain the relative permeability modifier in a dissolved state in the treatment
fluid at a temperature above about 140 °F (60 °C).
4. The method of claim 1, 2 or 3, wherein the hydrophobically modified hydrophilic
polymer comprises at least one hydrophobically modified hydrophilic monomer.
5. The method of claim 4, wherein the hydrophobically modified hydrophilic monomer
comprises an alkyldimethylammoniumethyl methacrylate halide;
wherein the alkyl group comprises about 4 to about 22 carbon atoms.
6. The method of claim 5, wherein the alkyl group is a cetyl group.
7. The method of any one of claims 2 to 6, wherein the at least one anionic surfactant
comprises at least one surfactant selected from the group consisting of a poly(ethylene
oxide) sulfonate and a poly(ethylene oxide) carboxylate.
8. The method of any preceding claim, wherein the treatment fluid further comprises at
least one additional surfactant that is not an anionic surfactant.
9. The method of any one of claims 2 to 8, wherein the at least one anionic surfactant
comprises a poly(ethylene oxide) carboxylate having a structural formula of
10. The method of any one of claims 2 to 9, wherein the at least one anionic surfactant
comprises a poly(ethylene oxide) carboxylate having a structural formula of
R3-(0 -CH2-CH2) n-0-CH2-C02 ;
wherein R comprises an alkyl, aryl or alkenyl group comprising about 4 to
about 22 carbon atoms and n is an integer ranging from about 3 to about 15.
11. The method of claim 10, wherein R3 is an oleyl group and n is 10.
12. The method of claim 10, wherein R3 is a lauryl group and n is 13.
13. The method of any one of claims 2 to 12, further comprising:
mixing the relative permeability modifier and the at least one anionic
surfactant in the aqueous phase base fluid.
14. The method of claim 13, wherein the at least one anionic surfactant is mixed with the
relative permeability modifier before being mixed in the aqueous phase base fluid.
15. The method of claim 1:
providing a treatment fluid comprising a relative permeability modifier, at
least one anionic surfactant, and an aqueous phase base fluid;
wherein the relative permeability modifier comprises a
hydrophobically modified hydrophilic polymer comprising at least one
hydrophobically modified hydrophilic monomer comprising a
cetyldimethylammoniumethyl methacrylate halide;
wherein the at least one anionic surfactant is operable to maintain the
relative permeability modifier in a dissolved state in the treatment fluid above a pH of
about 8 and above a temperature of about 140°F; and
wherein the at least one anionic surfactant comprises at least one
surfactant selected from the group consisting of a poly(ethylene oxide) carboxylate
and a poly(ethylene oxide) sulfonate; and
placing the treatment fluid in a subterranean formation.
16. The method of claiml 5, wherein the at least one anionic surfactant comprises a
poly(ethylene oxide) carboxylate having a structural formula of
R3-(0-CH 2-CH2)n-0 -CH2-C0 -;
wherein R3 comprises an alkyl, aryl or alkenyl group comprising about 4 to
about 22 carbon atoms and n is an integer ranging from about 3 to about 15.
17. The method of claiml 6, wherein R is an oleyl group and n is 10.
18. The method of claiml 6, wherein R is a lauryl group and n is 13.
19. The method of any one of claims 15 to , wherein the treatment fluid further
comprises at least one additional surfactant that is not an anionic surfactant.
20. The method of any one of claims 15 to 19, further comprising:
mixing the relative permeability modifier and the at least one anionic
surfactant in the aqueous phase base fluid.
21. The method of claim20, wherein the at least one anionic surfactant is mixed with the
relative permeability modifier before being mixed in the aqueous phase base fluid.
22. A composition comprising:
a relative permeability modifier comprising a hydrophobically modified
hydrophilic polymer comprising at least one hydrophobically modified hydrophilic
monomer comprising a cetyldimethylammoniumethyl methacrylate halide; and
at least one anionic surfactant;
wherein the at least one anionic surfactant is operable to maintain the
relative permeability modifier in a dissolved state in an aqueous phase base fluid
above a pH of about 8 and above a temperature of about 140 °F (60 °C); and
wherein the at least one surfactant comprises at least one surfactant
selected from the group consisting of a poly(ethylene oxide) carboxylate and a
poly(ethylene oxide) sulfonate.
23. The composition of claim 22, wherein the at least one anionic surfactant is further
operable to maintain the relative permeability modifier in a dissolved state in the
treatment fluid at a temperature above about 140 °F (60 °C).further comprising one or
more additional features according to dependent claims 3 to 14.
24. The composition of claim 22 or 23, wherein the hydrophobically modified
hydrophilic polymer comprises at least one hydrophobically modified hydrophilic
monomer.
25. The composition of claim 24, wherein the hydrophobically modified hydrpphilic
monomer comprises an alkyldimethylammoniumethyl methacrylate halide;
wherein the alkyl group comprises about 4 to about 22 carbon atoms.
26. The composition of claim 25, wherein the alkyl group is a cetyl group.
27. The composition of any one of claims 22 to 26, wherein the treatment fluid further
comprises at least one additional surfactant that is not an anionic surfactant.
28. The composition of any one of claims 22 to 27, wherein the at least one anionic
surfactant comprises a poly(ethylene oxide) carboxylate having a structural formula
of
29. The composition of any one of claims 22 to 28, wherein the at least one anionic
surfactant comprises a poly(ethylene oxide) carboxylate having a structural formula
of
R -(0-CH 2-CH2)n-0 -CH2-C0 2 ;
wherein R comprises an alkyl, aryl or alkenyl group comprising about 4 to
about 22 carbon atoms and n is an integer ranging from about 3 to about 1 .
30. The composition of claim 29, wherein R3 is an oleyl group and n is 10.
31. The composition of claim 29, wherein R3 is a lauryl group and n is 13.
32. The composition of any one of claims 22 to 31, further comprising:
mixing the relative permeability modifier and the at least one anionic
surfactant in the aqueous phase base fluid.
33. The composition of claim 32, wherein the at least one anionic surfactant is mixed
with the relative permeability modifier before being mixed in the aqueous phase base
fluid
34. The composition of any one of claims 22 to 33, further comprising one or more
additional components selected from other relative permeability modifiers, clays,
scale inhibitors, corrosion inhibitors, gelling agents, crosslinking agents, foaming
agents, proppants, salts, acids, fluid loss control additives, gas, catalysts, clay control
agents, dispersants, flocculants, scavengers (e.g., H2S scavengers, C0 2 scavengers or
0 2 scavengers), lubricants, breakers, friction reducers, antifoam agents, bridging
agents, viscosifiers, weighting agents, and the like.