Inverting surfactants for inverse emulsions

Abstract

A water-in-oil emulsion is provided, the water-in-oil emulsion comprising an alkylpropylenediamine and an ethoxylated alcohol as an invert surfactant, the invert surfactant being present in an amount less than 5 weight percent of the water-in-oil emulsion.

Description

Technical Field

[0001] The present disclosure relates to invert surfactants for use in water-in-oil emulsions. Background Art

[0002] Aqueous treatment fluids can be used for various underground treatments. Such treatments include, but are not limited to, drilling operations, production stimulation operations, and completion operations. As used herein, the term "treatment" refers to any underground operation in which a fluid is used in conjunction with a desired function and / or for a desired purpose. The term "treatment" does not imply any specific effect of the fluid.

[0003] Water-soluble polymers can be used as friction reducers in well treatment fluids to modify the rheological properties of the fluid to minimize turbulence and thereby prevent the consequent energy loss in the fluid as it is pumped through a pipe. In some cases, the water-soluble friction reducing polymer is suspended in a water-in-oil emulsion, where upon addition to the aqueous treatment fluid, the emulsion must be inverted to release the friction reducing polymer into the fluid. Performance in the field depends on the ability of the emulsion to quickly invert or rupture.

[0004] Inverting surfactants tend to be very hydrophilic. Typical inverting surfactants include ethoxylated alcohols, which can quickly invert emulsions. A key challenge in using ethoxylated alcohols as inverting surfactants is their effect on emulsion stability. Excessive amounts of ethoxylated alcohols can improve hydration but can significantly destabilize the emulsion. Summary of the invention

[0005] The present disclosure provides a friction-reducing treatment solution, which comprises: a water-in-oil emulsion, the water-in-oil emulsion comprising an oil phase and an aqueous phase, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present in the oil phase as dispersed different particles and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion; and an invert surfactant, which is present in an amount less than 5 weight percent of the water-in-oil emulsion and comprises an alkylpropylenediamine and an ethoxylated alcohol.

[0006] Also provided is a method for treating a portion of a subterranean formation, the method comprising the steps of: inverting a water-in-oil emulsion having an oil phase and an aqueous phase to provide a treatment fluid, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion, and an inversion surfactant is present in an amount less than 5 weight percent of the water-in-oil emulsion and comprises an alkylpropylenediamine and an ethoxylated alcohol; and introducing the treatment fluid into the portion of the subterranean formation.

[0007] Another embodiment includes a method of improving the friction reducing properties of an aqueous treatment fluid, the method comprising the steps of providing a water-in-oil emulsion comprising: an oil phase and an aqueous phase, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion; and an inverting surfactant, the inverting surfactant being present in an amount less than 5 weight percent of the water-in-oil emulsion and comprising an alkylpropylenediamine and an ethoxylated alcohol; and inverting the emulsion in an aqueous treatment fluid, wherein the resulting aqueous treatment fluid is improved in friction reduction when compared to a similar aqueous treatment fluid in which the inverted emulsion does not comprise the alkylpropylenediamine.

[0008] In one aspect, the alkylpropylenediamine comprises an alkyl group containing from 10 to 20 carbon atoms. In another aspect, the alkylpropylenediamine is selected from oleylpropylenediamine and cocoylpropylenediamine.

[0009] In one aspect, the water soluble polymer comprises a nonionic monomer and an anionic monomer.

[0010] In another aspect, the water soluble polymer comprises a nonionic monomer and a cationic monomer. DETAILED DESCRIPTION

[0011] In general, the composition according to the present disclosure comprises: a water-in-oil emulsion comprising an oil phase and an aqueous phase, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion; and an inverting surfactant present in an amount less than 5 weight percent of the water-in-oil emulsion and comprising an alkylpropylenediamine and an ethoxylated alcohol. Surprisingly, the emulsion exhibits a rapid hydration rate and is stable under a variety of conditions. The resulting aqueous treatment fluid has an improvement in friction reduction when compared to a similar aqueous treatment fluid in which the inverted emulsion does not comprise an alkylpropylenediamine.

[0012] The term "friction reducing polymer" refers to a polymer that reduces the losses caused by friction between an aqueous fluid in turbulent flow and tubulars (e.g., pipes, coiled tubing, etc.) and / or formations. It is added to the slick water treatment at a concentration of 0.1 to 5 pounds per 1000 gallons of stimulation fluid. In other embodiments, the friction reducing polymer is added at a concentration of 0.25 to about 2.5 pounds per 1000 gallons of stimulation fluid.

[0013] The water-in-oil emulsion or oil-external phase emulsion used in the present disclosure is an emulsion in which the water-soluble (eg, friction-reducing) polymer of the present embodiments is suspended in a water-in-oil emulsion, which may include an inverting surfactant, water, a water-soluble polymer, an inert hydrophobic liquid, and an emulsifier.

[0014] As used herein, the term "inversion" refers to exposing a water-in-oil emulsion to conditions that cause the aqueous phase to become the continuous phase. The inversion surfactant should be present in an amount sufficient to provide the desired emulsion inversion upon contact with water in the aqueous treatment fluid. U.S. Pat. No. 3,624,019 discloses a method for inverting a water-in-oil emulsion containing a water-soluble polymer as a non-limiting example, the contents of which are incorporated herein by reference.

[0015] In an exemplary embodiment, the invert surfactant is present in an amount less than 5 weight percent of the emulsion.When a material is referred to herein as being "present in an amount less than," it is understood to be present in an amount greater than zero.

[0016] Suitable inverse surfactants include combinations of alkylpropylenediamines and ethoxylated alcohols. Examples of ethoxylated alcohols include ethoxylated C12-C16 alcohols. In one embodiment, the alkyl group of the alkylpropylenediamine contains 10 to 20 carbon atoms. In another embodiment, the alkyl group contains 12 to 18 carbon atoms. Examples of alkylpropylenediamines include oleylpropylenediamine (DAO) and coconut oil propylenediamine (DACO). Prior to this disclosure, alkylpropylenediamines were not considered inverse surfactants. Without the benefit of this disclosure, those skilled in the art would have no reason to expect that alkylpropylenediamines could be successfully used in this manner. For example, alkylpropylenediamines are more lipophilic than hydrophilic and are even insoluble in water.

[0017] The water phase of the present disclosure is the dispersed phase of different particles in the oil phase, and comprises water and water-soluble polymers. The water present in the emulsion generally includes fresh water, brackish water, salt water (e.g., water comprising one or more salts dissolved therein), brine (e.g., produced from underground strata), seawater, mine water, pond water, etc. or a combination thereof. Typically, the fresh water contains less than 1000 ppm of total dissolved solids; the brackish water contains 1,000 ppm to less than 10,000 ppm of total dissolved solids; the salt water contains 10,000 ppm to 30,000 ppm of total dissolved solids; and the brine contains the total dissolved solids at a level exceeding 30,000 ppm. In general, the water used can come from any source, as long as the water does not contain excess compounds that may adversely affect other components in the emulsion.

[0018] In the present disclosure, water-soluble polymers exist at a level of at least about 5 weight percents, at least 10 weight percents in some instances, at least about 15 weight percents, at least about 20 weight percents in other instances based on the weight of the water-in-oil emulsion, and can exist at an amount of up to about 33 weight percents, up to about 35 weight percents in some instances, up to about 37 weight percents in other instances and up to about 40 weight percents based on the weight of the water-in-oil emulsion. When the amount of water-soluble polymers was too low, it may be uneconomical to use the water-in-oil emulsion. When the amount of water-soluble polymers was too high, the performance of water-soluble polymers may not reach the best. The amount of water-soluble polymers in the aqueous phase of the water-in-oil emulsion can be any value between any values ​​listed above or can be in the scope between any values ​​listed above.

[0019] As used herein, the term "polymer" and similar terms are used with the ordinary meaning understood by those skilled in the art, and therefore can be used herein to refer to or describe a macromolecule (or a group of such molecules) comprising a repeating unit. Polymers can be formed in various ways, including by polymerizing monomers and / or by chemically modifying one or more repeating units of a precursor polymer. Polymers can be "homopolymers", which contain substantially identical repeating units formed, for example, by polymerizing a particular monomer. Polymers can also be "copolymers", which contain two or more different repeating units formed, for example, by copolymerizing two or more different monomers and / or by chemically modifying one or more repeating units of a precursor polymer. The term "terpolymer" can be used herein to refer to a polymer comprising three or more different repeating units.

[0020] Typically, the composition of the water-soluble polymer will be the same or about the same as the composition of the monomer mixture used to prepare the water-soluble polymer.

[0021] The water-soluble polymer in the water-in-oil emulsion is prepared by polymerizing a monomer solution comprising nonionic monomers, cationic monomers and / or anionic monomers contained at levels that provide a desired amount of water-soluble polymer. In one embodiment, the water-soluble polymer is a nonionic polymer. In one embodiment, the water-soluble polymer is an anionic polymer. In a specific embodiment, the anionic polymer has a charge of about 10% to about 50%, a charge of about 15% to about 45%, a charge of about 20% to about 40%, or a charge of about 25% to about 35%. In one embodiment, the water-soluble polymer is a cationic polymer. In a specific embodiment, the cationic polymer has a charge of about 10% to about 50%.

[0022] The water-soluble polymers usually comprise (meth)acrylamide as nonionic monomer.

[0023] The water-soluble polymer may contain one or more nonionic monomers to provide the desired properties to the polymer. Non-limiting examples of other suitable nonionic monomers that may be included in the monomer mixture and ultimately in the resulting water-soluble polymer include N,N-dimethyl(meth)acrylamide (DMF), N-vinylacetamide, N-vinylformamide, acrylonitrile (including hydrolysis products of acrylonitrile residues), acrylonitrile-dimethylamine reaction products and / or corresponding salts (non-limiting examples are sodium, potassium and / or ammonium salts and mixtures thereof).

[0024] The amount of nonionic monomer in the monomer mixture for preparing water-soluble polymer can be at least about 40 weight percents based on the weight of the monomer mixture, at least about 50 weight percents in some cases and at least about 60 weight percents in other cases. When the amount of nonionic monomer is too low, the molecular weight of the water-soluble polymer obtained may be lower than the desired value. In addition, the amount of nonionic monomer in the monomer mixture can be up to about 100 weight percents based on the weight of the monomer mixture, up to about 90 weight percents in some cases and up to about 80 weight percents in other cases. The amount of nonionic monomer in the monomer mixture can be any value or scope between any values ​​listed above.

[0025] In certain embodiments, water-soluble polymers include one or more anionic monomers. The term "anionic monomer" refers to a monomer with a negative charge. Representative anionic monomers include (meth) acrylic acid, sodium acrylate, ammonium acrylate, 2-acrylamide-2-methylpropanesulfonic acid (AMPS), vinyl sulfonic acid, styrene sulfonic acid, maleic acid, sulfopropyl acrylate or sulfopropyl methacrylate, or other water-soluble forms of these or other polymerizable carboxylic acids or sulfonic acids, sulfomethylated acrylamide, allyl sulfonate, itaconic acid, acrylamide methylbutyric acid, fumaric acid, vinylphosphonic acid, allylphosphonic acid, phosphonomethylated acrylamide, etc., and salts of these substances. Exemplary salts of these anionic monomers include, but are not limited to, sodium salts and ammonium salts.

[0026] In some embodiments, the water soluble polymer does not include (meth)acrylic acid.

[0027] The amount of anionic monomer in the monomer mixture for preparing water-soluble polymer can be at least about 0.5 weight percent, at least about 1 weight percent in some cases, at least about 2 weight percent in other cases and at least about 5 weight percent in other cases based on the weight of the monomer mixture. In addition, the amount of anionic monomer in the monomer mixture can be up to about 35 weight percent, up to about 20 weight percent in some cases and up to about 15 weight percent in other cases based on the weight of the monomer mixture. When the amount of anionic monomer is too high, the water-soluble polymer may have undesirable flocculation characteristics. The amount of anionic monomer in the monomer mixture can be any value or range between any values ​​listed above.

[0028] In some embodiments, the water-soluble polymer includes one or more cationic monomers. The term "cationic monomer" refers to a monomer having a positive charge. Representative examples of cationic monomers include: dialkylaminoalkyl esters of acrylic acid and methacrylic acid and their quaternary salts or acid salts, including but not limited to dimethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate methyl sulfate quaternary salt, dimethylaminoethyl acrylate benzyl chloride quaternary salt, dimethylaminoethyl acrylate sulfate, dimethylaminoethyl acrylate hydrochloride, diethylaminoethyl acrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl methacrylate methyl sulfate quaternary salt, dimethylaminoethyl methacrylate benzyl chloride quaternary salt, dimethylaminoethyl methacrylate sulfate, dimethylaminoethyl methacrylate hydrochloride, dimethylaminoethyl Methacryloyl hydrochloride; dialkylaminoalkyl acrylamide or dialkylaminoalkyl methacrylamide and its quaternary salt or acid salt, such as acrylamidopropyl trimethyl ammonium chloride, dimethylaminopropyl acrylamide methyl sulfate quaternary salt, dimethylaminopropyl acrylamide sulfate, dimethylaminopropyl acrylamide hydrochloride, methacrylamidopropyl trimethyl ammonium chloride, dimethylaminopropyl methacrylamide methyl sulfate quaternary salt, dimethylaminopropyl methacrylamide sulfate, dimethylaminopropyl methacrylamide hydrochloride; diethylaminoethyl acrylate, diethylaminoethyl methacrylate and diallyl dialkyl ammonium halides, such as diallyl diethyl ammonium chloride and diallyl dimethyl ammonium chloride.

[0029] The amount of cationic monomer in the monomer mixture for preparing the water-soluble polymer can be at least about 5 weight percent, in some cases at least about 15 weight percent, and in other cases at least about 20 weight percent based on the weight of the monomer mixture. In addition, the amount of cationic monomer in the monomer mixture can be up to about 60 weight percent, in some cases up to about 50 weight percent, in other cases up to about 40 weight percent, in some cases up to about 30 weight percent, and in other cases up to about 25 weight percent based on the weight of the monomer mixture. When the amount of cationic monomer is too high, the water-soluble polymer may have undesirable flocculation characteristics when used in the method of the present invention. The amount of cationic monomer in the monomer mixture can be any value or range between any of the values ​​listed above.

[0030] Water-soluble polymers suitable for embodiments of the present invention can be prepared according to any of a variety of polymerization methods. Suitable methods for realizing such polymerization are disclosed, for example, in U.S. Patents 3,284,393, 4,024,097, 4,059,552, 4,419,344, 4,713,431, 4,772,659, 4,672,090, 5,292,800 and 6,825,301, and their related disclosures are incorporated herein by reference. In one embodiment, suitable water-soluble polymers can be prepared using emulsion polymerization. In the case of benefiting from the present disclosure, those skilled in the art will recognize the suitable polymerization method for synthesizing suitable water-soluble polymers. Embodiments of the present invention are not polymerization methods for synthesizing water-soluble polymers of embodiments of the present invention, as long as they produce desired water-soluble polymers.

[0031] The water-soluble polymers of the disclosed subject matter generally have a molecular weight sufficient to provide a desired level of activity. Generally speaking, the friction-reducing polymer has a higher molecular weight in order to provide a satisfactory level of friction reduction. As a non-limiting example, the weight average molecular weight of the water-soluble copolymer can be in the range of about 2,000,000 to about 20,000,000, in some cases up to about 30,000,000, as determined using intrinsic viscosity. Those skilled in the art will recognize that water-soluble polymers with molecular weights outside the listed ranges may still provide a certain degree of friction reduction in aqueous treatment fluids.

[0032] As used herein, intrinsic viscosity is determined using an Ubbelohde capillary viscometer and a water-soluble polymer solution in 1M NaCl solution at 30°C and pH 7 at 0.05 wt%, 0.025 wt%, and 0.01 wt%, and the measured values ​​are extrapolated to zero concentration to determine the intrinsic viscosity. The molecular weight of the water-soluble polymer is then determined using the Mark-Houwink equation known in the art.

[0033] Alternatively, the reduced viscosity of the water-soluble polymer at a concentration of 0.05 wt% is used to measure the molecular size. Thus, the water-soluble polymer has a reduced viscosity of about 10 dl / g to about 40 dl / g, in some cases 15 dl / g to about 35 dl / g, and in other cases 15 dl / g to about 30 dl / g, as determined in an Ubbelohde capillary viscometer at 30°C, pH 7 in 1 M NaCl solution at a polymer concentration of 0.05 wt%.

[0034] Suitable water-soluble polymers of the present disclosure can be in acid form or salt form. Various salts can be prepared by neutralizing anionic monomers with alkali (e.g., sodium hydroxide, potassium hydroxide, ammonium hydroxide). As used herein, the term "water-soluble polymer" is intended to include water-soluble polymers in acid form and various salts thereof.

[0035] In the water-in-oil emulsion of the present invention, the oil phase exists in the form of a continuous phase and includes an inert hydrophobic liquid. As a non-limiting example, the inert hydrophobic liquid may include paraffins, cycloalkanes, aromatic hydrocarbons, benzene, xylene, toluene, mineral oil, kerosene, naphtha, petrolatum, branched isoparaffin solvents, branched hydrocarbons, saturated, straight-chain and / or branched paraffins and combinations thereof. Specific non-limiting examples include natural, modified or synthetic oils, mineral oils and vegetable oils (e.g., canola oil, coconut oil, rapeseed oil, etc.).

[0036] The inert hydrophobic liquid is present in the water-in-oil emulsion in an amount sufficient to form a stable emulsion. In some embodiments, the inert hydrophobic liquid may be present in the water-in-oil emulsion in an amount of about 10 weight percent to about 80 weight percent.

[0037] In embodiments of the present disclosure, the inert hydrophobic liquid is present at a level of at least about 15 weight percent, in some cases at least about 17.5 weight percent, in other cases at least about 20 weight percent, and in some cases at least about 22.5 weight percent based on the weight of the water-in-oil emulsion, and can be present in an amount up to about 40 weight percent, in some cases up to about 35 weight percent, in other cases up to about 32.5 weight percent, and in some cases up to about 30 weight percent based on the weight of the water-in-oil emulsion. The total amount of the inert hydrophobic liquid in the water-in-oil emulsion can be any value between any of the values ​​recited above or can be within a range between any of the values ​​recited above.

[0038] In some embodiments, the emulsion may further comprise an emulsifier. Any suitable water-in-oil emulsifier may be used as one or more surfactants for preparing the water-in-oil emulsions comprising water-soluble polymers of the present invention. In embodiments of the present disclosure, surfactants include those having an HLB (hydrophile-lipophile balance) value between 2 and 10, between 3 and 9 in some cases, and between 3 and 7 in other cases.

[0039] As used herein, HLB is calculated using a method known in the art to calculate values ​​based on the chemical groups of a molecule. The method uses the following formula:

[0040] HLB=7+m*Hh+n*Hl

[0041] Where m represents the number of hydrophilic groups in the molecule, Hh represents the value of the hydrophilic group, n represents the number of lipophilic groups in the molecule, and Hl represents the value of the lipophilic group.

[0042] Surfactant can be by at least about 0.1 weight percent of water-in-oil emulsion, at least about 0.25 weight percent in some cases, at least about 0.5 weight percent in other cases, at least about 0.75 weight percent in some cases and at least about 1 weight percent level in other cases exist.When the amount of surfactant is too low, water may not be fully dispersed in the oil phase, and / or water-in-oil emulsion may tend to separate into oil phase and water.In addition, the amount of surfactant can be up to about 7 weight percents of water-in-oil emulsion, up to about 5 weight percents in some cases and up to about 2.5 weight percents in other cases.In water-in-oil emulsion, the amount of surfactant can be any value between any value listed above or can be in the scope between any value listed above.

[0043] In some embodiments, the emulsion may further include an inhibitor. Wherein, an inhibitor may be included to prevent premature polymerization of the monomers before initiating the emulsion polymerization reaction. As will be appreciated by those skilled in the art, with the benefit of the present disclosure, polymers may be synthesized using emulsion polymerization techniques, wherein an inhibitor is used to prevent premature polymerization. Examples of suitable inhibitors include, but are not limited to, quinones. Examples of suitable inhibitors include 4-methoxyphenol (MEHQ). The inhibitor should be present in an amount sufficient to provide the desired prevention of premature polymerization. In some embodiments, the inhibitor may be present in an amount ranging from about 0.001% to about 0.1% by weight of the emulsion.

[0044] In some embodiments, emulsion polymerization can be used to prepare suitable emulsions containing water-soluble polymers of embodiments of the present invention. Suitable emulsion polymerization techniques can have various initiation temperatures, depending, inter alia, on the amount and type of initiator used, the amount and type of monomer used, the amount and type of inhibitor used, and many other factors known to those skilled in the art. In one embodiment, suitable emulsion polymerization techniques can have an initiation temperature of about 25°C. Due to the exothermic nature of the polymerization reaction, during the conduction of the polymerization reaction, the mixture may be maintained at a temperature higher than the initiation temperature, for example, in the range of about 30°C to about 70°C or about 40°C to about 60°C.

[0045] Various mixtures can be used to prepare the emulsions used in the embodiments of the present invention. Suitable mixtures may include acrylamide and / or anionic and / or cationic monomers, water, a water-immiscible liquid, an initiator, and an emulsifier. Optionally, the mixture may also include an inhibitor, a base (e.g., sodium hydroxide) for neutralizing the salt form of acrylic acid to form a friction-reducing polymer, a complexing agent that allows the gradual release of the monomers during the polymerization reaction, an activator that initiates the polymerization at a lower temperature, and a reversing agent. With the benefit of this disclosure, those skilled in the art will know the amount and type of components to include in the mixture based on various factors, including the desired molecular weight and composition of the water-soluble polymer and the desired initiation temperature.

[0046] In some embodiments of the disclosed subject matter, a batch process can be used to break a water-in-oil emulsion. In this embodiment, the water-in-oil emulsion and water are transported to a common mixing tank. Once in the tank, the solution is stirred or mixed for a specific length of time in order to impart energy to it. After mixing, the resulting solution must be aged to allow sufficient time for the molecules to unzip.

[0047] In some embodiments, a continuous in-line mixer and an in-line static mixer may be used to mix a water-in-oil emulsion containing a water-soluble polymer with water. Non-limiting examples of suitable mixers for mixing and feeding are disclosed in U.S. Patents 4,522,502, 4,642,222, 4,747,691 and 5,470,150, which are incorporated herein by reference. Non-limiting examples of suitable static mixers can be found in U.S. Patents 4,051,065 and 3,067,987, which are incorporated herein by reference.

[0048] Once the water-in-oil emulsion is broken into the water, any other additives are added to the solution to form a treatment fluid, which is then introduced into a portion of a subterranean formation.

[0049] The water present in the treatment fluid generally includes fresh water, brackish water, salt water (e.g., water containing one or more salts dissolved therein), brine (e.g., produced from underground formations), seawater, mine water, pond water, etc., or a combination thereof. Generally, fresh water contains less than 1000 ppm of total dissolved solids; brackish water contains total dissolved solids at a level of 1,000 ppm to less than 10,000 ppm; salt water contains total dissolved solids at a level of 10,000 ppm to 30,000 ppm; and brine contains total dissolved solids at a level of more than 30,000 ppm. In general, the water used can be from any source, as long as the water does not contain excess compounds that may adversely affect other components in the treatment fluid.

[0050] In general, water-soluble polymers may be included in any aqueous treatment fluid used for subsurface treatments to reduce friction. Such subsurface treatments include, but are not limited to, drilling operations, stimulation treatments (e.g., fracturing treatments, acidizing treatments, fracturing acidizing treatments), and completion operations. With the benefit of this disclosure, those skilled in the art will be able to recognize suitable subsurface treatments where friction reduction may be desired.

[0051] In these applications, the fracturing fluid (i.e., well treatment fluid) can be configured as a gelled fluid, a foamed gel fluid, an acidic fluid, water and potassium chloride treatment fluid, etc. The fluid is injected under a pressure that effectively produces one or more cracks in the underground stratum. Depending on the type of well treatment fluid used, various additives can also be added to the fracturing fluid to change the physical properties of the fluid or provide some beneficial function. In one embodiment, the fluid does not contain a water-soluble polymer in an amount sufficient to form a gel. Optionally, a proppant (e.g., sand or other hard materials) is added, which is used to keep the cracks open after the fracturing operation. In addition, a fluid loss reducer can be added to partially close the portion with a higher porosity in the stratum, thereby fracturing in the stratum with a lower porosity. Other oilfield additives that can also be added to the fracturing fluid include demulsifiers, defoamers, scale inhibitors, H2S and / or O2 scavengers, biocides, crosslinking agents, surface tension reducers, gel breakers, buffers, surfactants and non-emulsifiers, fluorocarbon surfactants, clay stabilizers, fluid loss reducers, foaming agents, friction reducers, temperature stabilizers, diverters, shale and clay stabilizers, paraffin / asphaltene inhibitors, corrosion inhibitors and acids. For example, in aqueous treatment fluids, especially acids can be included for matrix or fracture acidizing. In the fracturing embodiment, proppants can be included in the aqueous treatment fluid to prevent crack closure when hydraulic pressure is released. In a specific embodiment, the treatment fluid also includes a biocide.

[0052] The water-soluble polymers of the present disclosure should be included in the aqueous treatment fluid of the present disclosure in an amount sufficient to provide the desired friction reduction. In some embodiments, the water-soluble polymers of the present disclosure may be present in an amount of at least about 0.0025%, in some cases at least about 0.003%, in other cases at least about 0.0035%, in some cases at least about 0.05%, by weight of the aqueous treatment fluid, and may be present in an amount of up to about 4%, in some cases up to about 3%, in other cases up to about 2%, in some cases up to about 1%, in other cases up to about 0.02%, in some cases up to about 0.1%, in other cases up to about 0.09%, and in certain cases up to about 0.08%, by weight of the aqueous treatment fluid. The amount of the water-soluble polymer included in the aqueous treatment fluid may be any value between any of the values ​​listed above or within a range between any of the values ​​listed above.

[0053] In some embodiments, the water-soluble polymer may be present in the aqueous treatment fluid in an amount ranging from about 0.0025% to about 0.025%, in some cases ranging from about 0.0025% to less than about 0.01%, in other cases ranging from about 0.0025% to about 0.009%, and in some cases ranging from about 0.0025% to about 0.008% by weight of the aqueous treatment fluid.

[0054] In some embodiments, when using the water-in-oil emulsions of the present invention, the amount of water-soluble polymer in the aqueous treatment fluid can be at least about 5%, in some cases at least about 7.5%, in other cases at least about 10%, in some cases at least about 12.5%, in other cases at least about 15%, in some cases at least about 20%, and in other cases at least about 25% less than when using a water-in-oil emulsion containing a polymer of the same composition at a concentration of 30 weight percent or more in the aqueous treatment fluid.

[0055] Also provided is a method for treating a portion of a subterranean formation, the method comprising the steps of: inverting a water-in-oil emulsion having an oil phase and an aqueous phase to provide a treatment fluid, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion, and an inversion surfactant is present in an amount less than 5 weight percent of the water-in-oil emulsion and comprises an alkylpropylenediamine and an ethoxylated alcohol; and introducing the treatment fluid into the portion of the subterranean formation.

[0056] In other embodiments, the present disclosure provides a method for improving the friction reduction properties of an aqueous treatment fluid, the method comprising the steps of: providing a water-in-oil emulsion, the water-in-oil emulsion comprising: an oil phase and an aqueous phase, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion; and an inverting surfactant, the inverting surfactant being present in an amount less than 5 weight percent of the water-in-oil emulsion and comprising an alkylpropylenediamine and an ethoxylated alcohol; and inverting the emulsion in an aqueous treatment fluid, wherein the resulting aqueous treatment fluid is improved in friction reduction when compared to a similar aqueous treatment fluid in which the inverted emulsion does not comprise the alkylpropylenediamine.

[0057] The aqueous treatment fluids of the embodiments of the present invention can be used in any underground treatment where friction reduction is desired. Such underground treatments include, but are not limited to, drilling operations, production stimulation treatments, and completion operations. With the benefit of this disclosure, those skilled in the art will be able to recognize suitable underground treatments where friction reduction may be desired.

[0058] Although specific embodiments have been discussed, the description is illustrative only and not restrictive. Many variations of the present disclosure will become apparent to those skilled in the art after reading this description.

[0059] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this specification belongs.

[0060] As used in the specification and claims, the singular form "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0061] As used herein, unless otherwise indicated, the term "about" or "approximately" refers to an acceptable error for a particular value determined by one of skill in the art, which depends in part on how the value is measured or determined. In certain embodiments, the term "about" or "approximately" refers to within 1, 2, 3, or 4 standard deviations. In certain embodiments, the term "about" or "approximately" refers to within 50%, 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, or 0.05% of a given value or range.

[0062] In addition, it should be understood that any numerical range indicated herein is intended to include all subranges contained therein. For example, the range "1-10" is intended to include all subranges between and including the indicated minimum value 1 and the indicated maximum value 10 (that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10). Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless otherwise expressly stated, the various numerical ranges specified in this application are approximate values.

[0063] The present disclosure will be further described by reference to the following examples. The following examples are illustrative only and are not intended to be limiting. Unless otherwise indicated, all percentages are by weight of the total composition.

[0064] Example 1

[0065] The ingredients of the final inverse emulsion are shown in Table A. In all cases, the base emulsion was a 30% active acrylamide-acrylic acid copolymer inverse emulsion. The inverse surfactant was slowly added to the base emulsion and mixed for 30 minutes to obtain the final emulsion. C12 linear alcohol, 9 moles EO (LA-9) or 12 moles EO (LA-12) and oleyl propylene diamine (DAO) were tested as inverse surfactants.

[0066] Table A

[0067]

[0068] Flow loop testing

[0069] The oil and gas industry uses a flow loop test to evaluate the performance of polyacrylamide inverse emulsions as friction reducers. After the polymer is injected into the water, a higher percentage of friction reduction and rapid reversal represent favorable performance. The friction flow loop is constructed of 5 / 16" ID stainless steel tubing with a total length of approximately 30 feet. The test solution is pumped from the bottom of a tapered 5-gallon reservoir. The solution flows through the tubing and returns to the reservoir.

[0070] Flow was achieved using a plunger pump equipped with a variable speed drive. Pressure was measured by two in-line pressure gauges, the last of which was located approximately 2 feet from the discharge port of the return reservoir. Four gallons of synthetic brine with 100K ppm total dissolved solids (TDS) was prepared in the sample reservoir, the pump was started, and the delivery flow rate was set to 5 gal / min. The brine was recirculated until the temperature equilibrated to 25°C and a stable pressure differential was achieved. This pressure was recorded as the "initial pressure" of the 2% KCl solution.

[0071] The pure water-in-oil emulsion polymer of the test amount was quickly injected into the sample reservoir containing 100K TDS water with a syringe, and a timer was started. The dosage was recorded as gallons of water-in-oil emulsion per thousand gallons of 100K TDS (gpt). The pressure was reported at 30 seconds, 1 minute, 3 minutes and 5 minutes respectively. The initial differential pressure reading with the 100K TDS solution was compared to calculate the pressure drop at each time interval. The friction reduction percentage was determined as described in the 36th row of the 9th column to the 43rd row of the 10th column of U.S. Patent No. 7,004,254. The results are shown in Table B, where the dosage is the amount of the water-in-oil emulsion used, expressed in gallons / thousand gallons, and the active dose is the amount of the polymer used, expressed in weight percentage of the 100K TDS treatment fluid. In this test, the highest friction reduction that can be achieved is about 65%.

[0072] Table B

[0073]

[0074] The data show several trends. First, with the same proportion of reversing surfactant, the inventive compositions A (0.2% DAO), B (0.5% DAO), and C (1.0% DAO) all show higher friction reduction than the control A, which has only LA-9 as the reversing surfactant. These examples show that even a small percentage of DAO can significantly improve friction reduction performance.

[0075] Furthermore, the friction reduction of the inventive compositions B and C is superior to that of the control B (which has a higher LA-9 loading). Also surprisingly, the inventive composition A exhibits good stability at both high temperatures (up to 80°C) and low temperatures (down to -40°C). In contrast, the control B becomes a mushy substance after storage at -30°C and then thawing at room temperature.

[0076] Example 2

[0077] Composition D of the present invention includes DAO with C12 linear alcohol, 12 moles of EO (LA-12) as the inverse surfactant of the polyacrylamide inverse emulsion. 0.5 wt% of DAO and 1.0 wt% of LA-12 were added and mixed with the base inverse emulsion for 30 min. The final emulsion was stable at high temperature 50°C and low temperature -30°C. Even in a higher concentration of brine (150K ppm TDS), it showed amazing friction reduction performance.

[0078] Example 3

[0079] The inverse emulsion samples were hydrated for 1 minute using a Waring stirrer at 1200 rpm. Viscosity was measured using a Fann Model 35 or similar viscometer. Composition D exhibited significantly higher viscosity than control C in water with varying amounts of TDS. The viscosity increase of polyacrylamide inverse emulsions in combination with water is an important property for oilfield use. In oilfield applications, it is desirable for the emulsion to develop high viscosity within seconds or minutes of mixing with water.

[0080] Table C

[0081]

[0082] The disclosed subject matter has been described with reference to specific details of particular embodiments thereof. Such details are not intended to be considered as limitations on the scope of the disclosed subject matter unless they are included in the appended claims.

[0083] Therefore, the exemplary embodiments described herein are well adapted to achieve the objects and advantages mentioned, as well as those inherent therein. The specific embodiments disclosed above are illustrative only, as the exemplary embodiments described herein may be modified and practiced in different but equivalent ways, which are obvious to those skilled in the art having the benefit of the teachings herein. In addition, it is not intended to limit the details of construction or design shown herein except as described in the claims below. It is therefore obvious that the specific illustrative embodiments disclosed above may be changed, combined or modified, and all such variations are considered to be within the scope and spirit of the exemplary embodiments described herein. The exemplary embodiments described herein illustratively disclosed herein may be appropriately practiced in the absence of any elements not specifically disclosed herein and / or any optional elements disclosed herein. Although compositions and methods are described in terms of "comprising", "containing" or "including" various components or steps, compositions and methods may also be "substantially composed of" or "composed of" the various components, substances and steps. As used herein, the term "substantially composed of" should be interpreted as meaning to include the listed components, substances or steps and such additional components, substances or steps that do not substantially affect the basic and novel characteristics of the composition or method. In some embodiments, a composition "consisting essentially of the recited components or substances" according to embodiments of the present disclosure does not include any additional components or substances that alter the basic and novel characteristics of the composition. If there is any conflict in the usage of a word or term in this specification and one or more patents or other documents that may be incorporated herein by reference, the definition consistent with this specification shall be adopted.

Claims

1. A friction reducing treatment solution comprising: A water-in-oil emulsion comprising an oil phase and an aqueous phase, in, The oil phase is a continuous phase comprising an inert hydrophobic liquid; wherein the water phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion; and An invert surfactant present in an amount less than 5 weight percent of the water-in-oil emulsion and comprising alkylpropylenediamine, oleylpropylenediamine and / or cocopropylenediamine, and an ethoxylated alcohol.

2. The treatment solution according to claim 1, wherein The alkylpropylenediamine includes an alkyl group having 10 to 20 carbon atoms.

3. The treatment solution according to claim 1, wherein The water-soluble polymer comprises a nonionic monomer and an anionic monomer.

4. The treatment solution according to claim 3, wherein The nonionic monomer is acrylamide.

5. The treatment solution according to claim 3, wherein The anionic monomer is selected from the group consisting of (meth)acrylic acid, sodium acrylate, ammonium acrylate, 2-acrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, maleic acid, sulfopropyl acrylate, sulfopropyl methacrylate, sulfomethylated acrylamide, allyl sulfonate, itaconic acid, acrylamidomethylbutyric acid, fumaric acid, vinylphosphonic acid, allylphosphonic acid, phosphonomethylated acrylamide and salts thereof.

6. The treatment solution according to claim 1, wherein The water-soluble polymer comprises a nonionic monomer and a cationic monomer.

7. A method of treating a portion of a subterranean formation, comprising: a. inverting a water-in-oil emulsion having an oil phase and an aqueous phase to provide a treatment fluid, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid, wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion, and an inverting surfactant is present in an amount less than 5 weight percent of the water-in-oil emulsion and comprises alkylpropylenediamine, oleylpropylenediamine and / or cocoylpropylenediamine, and an ethoxylated alcohol; and b. Introducing the treatment fluid into the portion of the subterranean formation.

8. The method according to claim 7, wherein: The water-soluble polymer comprises a nonionic monomer and an anionic monomer.

9. The method according to claim 8, wherein: The nonionic monomer is acrylamide.

10. The method according to claim 7, wherein: The water-soluble polymer comprises a nonionic monomer and a cationic monomer.

11. A method of improving the friction reducing properties of an aqueous process fluid, comprising: a. Providing a water-in-oil emulsion, the water-in-oil emulsion comprising: i. an oil phase and an aqueous phase, wherein the oil phase is a continuous phase comprising an inert hydrophobic liquid; ii. wherein the aqueous phase is present as dispersed distinct particles in the oil phase and comprises water and a water-soluble polymer, wherein the water-soluble polymer comprises 5 to 40 weight percent of the water-in-oil emulsion; and iii. an inverting surfactant present in an amount less than 5 weight percent of the water-in-oil emulsion and comprising alkylpropylenediamine, oleylpropylenediamine and / or cocopropylenediamine, and an ethoxylated alcohol; and b. inverting the emulsion in an aqueous treatment fluid; wherein the resulting aqueous treatment fluid has an improvement in friction reduction when compared to a similar aqueous treatment fluid wherein the inverted emulsion does not contain the alkylpropylenediamine.

12. The method according to claim 11, wherein: The water-soluble polymer comprises a nonionic monomer and an anionic monomer.

13. The method according to claim 12, wherein: The nonionic monomer is acrylamide.

14. The method according to claim 11, wherein: The water-soluble polymer comprises a nonionic monomer and a cationic monomer.

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