OA17447A - Use of organic acids or a salt thereof in surfactant-based enhanced oil recovery formulations and techniques. - Google Patents

Abstract

The present disclosure provides a surfactant formulation for use in treating and recovering fossil fluid from a subterranean formation. The surfactant formulation includes a nonionic surfactant, organic acid selected from citric acid, diglycolic acid, glycolic acid and a salt thereof and injection water. The surfactant formulation may be injected into one or more injection wells located within the subterranean formation and fossil fluids can then be subsequently recovered from one or more producing wells.

Description

Use Of Organic Acids Or A Sait Thereof Tu Surfactant-Hascd

Enhanced Oil Recovery Formulations And Techniques

Field of the invention

Tiie présent disclosure is directed to surfactant formulation containîng a nonionic surfactant, an organic acid selected from citric acid, diglycolîc acid, glycolic acid and a sait thereof and injection water and to a process for rccovering fossil fluids from subterranean réservoirs employing such surfactant formulations.

Background Information

Fossil fluids are generally recovered from underground formations by penetrating the formation with one or more welis and pumping or permitting the fossil fluid to flow to the surface through 15 the well. In primary recovery, a naturel driving energy such as an underlyiiig active water drive or a gas under some minimum pressure may possess sufficient pressure to drive the fluid to the well and then to the surface. In many instances, the naturel driving energy is insufficient or becomes insufficient to cause the fluid to flow to the well. Thus, a substantiel portion of the fossil fluid to be recovered can remain in the formation after dcplctïon of the naturel driving 20 energy. In such cases, varions secondaiy or tertiaiy recovety techniques must be applied to recover the remaining fluid.

One such technique involves the injection of water through one or more injection wells to drive the residual fluid towards a producing well. When the injection of water no longer results in 25 acceptable rates of production, the producing well must either be abandoned or subjected to other processes to further increase extraction. A variety of processes are known încluding steam fiooding, polymer flooding, alkali floodîng, miscible flooding with carbon dioxide, and floodîng with aqueous surfactant solutions. With respect to flooding with an aqueous surfactant solution, a surfactant package is added to the injection water and injectcd into the well for the purpose of 30 decreasing the interfacial tension between the injection water and fossil fluid phases thus leading to an increase in fossil fluid extraction. The challenge one skilled in the art faces when impleinenting such a process is determining an effective combination of components which make up the surfactant package, Many combinations must generally be tried before a suitable surfactant package can be foijnulated having good tolérance towards the multivalent cations found in tlie brine of many formations as well as having low adsorptîon onto rock of the formation. Forexample:

US Pat. No. 3,811,504 discloses the use of a three surfactant system containing an alkyl sulfate, an alkyl polycthoxylatcd sulfate, and a polyethoxylated alkylphenol;

US Pat. No. 3,890,239 discioses a surfactant composition useful in recovering oil from a formation that includes an organic sulfonate, a sulfated or sulfonated oxyalkylated alcohol and a poiyalkylene glycol alcohol etlier;

US Pat. No. 4,463,806 discloses a surfactant package containing a water-soluble etherlinked sulfonate, an alcohol and a petroleum sulfonate or alkylbenzene sulfonate;

US Pat. No. 7,629,299 discloses the use of alcohol ether su! fanâtes derived from unsaturaled alcohol ethers;

US Pat. Publ. No. 2005/01999395 discloses the use of an alkali and an alkylaryl sulfonate surfactant derived from alpha-olefîns for recovering oil from a formation;

US Pat. Publ. No. 2006/0185845 discloses a composition that includes an alipliatic anionîc surfactant and an alipliatic nonionic additive for use in treating a formation;

US Pat. Publ. No. 2007/0191633 discloses a blend for recovering oils that contains water or brine, an alcohol or alcohol etlier and a bifunctional anionic surfactant;

US Pat. Publ. No. 2009/0270281 discloses a surfactant mixture including a hydrocarbon radical having 12-30 carbons and a branched hydrocarbon having 6 to 11 carbon atoms for use in teitiary oil extraction;

US Pat. Publ. No. 2011/0046024 discloses the use of an alkylated hydroxyaromatic sulfonate, a solvent, a passivator and a polymer for recovering oil from a formation;

US Pat. Publ. No. 2011/0048721 discloses the use of high molecular weight sulfated internai olclfîn sulfonate sulfates and high molecular weight dialkylphcnol alkoxylate sulfonate sulfates for use in oîl recovery;

US Pat. Publ. No. 2011/0190174 discloses tristyrylphenol alkoxylate sulfates and their use as a surfactant in oil recovery applications;

U.S. Pat. Publ. No. 2011/0281779 discloses the lise of an anionic ether surfactant comprising a branched hydrophobe group derived from a Guerbet alcohol; and

U.S. Pat. Publ. No. 2013/0068312 which discloses a nonionic surfactant and a métal sait.

Despite the state of the art, there is a continuing need for new surfactant packages and formulations useful in the recovery of fossil fluids, especially under high salinity and high

température conditions. Provided herein are surfactant packages and surfactant formulations addressing the needs in the art and methods of using such formulations.

Su m mary of the Invention

The présent disclosure relates to a surfactant formulation for treating a fossil fluid-bearing subterranean formation comprising a nonionic surfactant, an organic acid selected from citric acid, diglycolic acid, glycolic acid and a sali thereof and injection water.

In a further embodiment, the présent disclosure provides a process for preparing a surfactant formulation for use in treating a fossil fluid-bearing subterranean formation by combining a nonionic surfactant with an organic acid selected froin citric acid, diglycolic acid, glycolic acid and a sait thereof and injection water.

In a still further embodiment, the présent disclosure provides a process for the recovei-y of fossil fluids from a subterranean formation by injecting a surfactant formulation containing a nonionic surfactant, an organic acid selected from citric acid, diglycolic acid, glycolic acid and a sait thereof and injection water into one or more injection wells located within the subtenanean formation and recovering the fossil fluids from one or more producing wells. The injection well 20 and the producing well may be the same well or different wells.

In yet another embodiment, the présent disclosure relates to a surfactant package for use in treating a fossil fluid-bearing subtenanean formation comprising a nonionic surfactant and an organic acid selected from citric acid, diglycolic acid, glycolic acid and a sait thereof.

Detailed Description

If appearing herein, the term comprising and dérivatives thereof are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed 30 herein. In order to avoid any doubt, ail formulations claimed herein through use of the tenn comprising may include any additional additive, adjuvant, or compound, unless stated to the contrary. hi contrast, the term, consîsting essentially of' if appearing herein, cxcludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability and the term consîsting ofif used, excludes any component, step or procedure not specifically dclineated or listed. The terni or, unless stated otlierwise, refers to the listed members individually as well as in any combination.

The articles a and an are used herein to refer to one or to more than one (i.e. to at least one) of 5 the grammatical object of the article. By way of example, a nonionic surfactant means one nonionic surfactant or more than one nonionic surfactant,

The phrases in one embodiment, according to one embodiment, and the like generally mean the particuiar feature, structure, or characteristic following the phrase is included in at least one 10 embodiment of the présent invention, and may be included in more than one embodiment of the présent invention. Importantly, such phrases do not necessarily refer to the saine embodiment.

If the spécification states a component or feature may, can, could, or înîght be inchided or bave a characteristic, that particuiar component or feature is not required to be included or hâve 15 tiie characteristic.

For methods of treating a fossil fluid-bcaiîng subterranean formation, the term “treating” includes placing a chemical within the subterranean formation using any suitable manner known in the ai t, for example, pumping, injecting, pouring, releasing, displacing, squeezing, spotting, or circulating 20 the chemical into a well, well bore or stibiei-ranean formation.

The term “fossil fluids” include oleaginous materials such as those found in oil field deposits, oil shales, tar sands, heavy oil deposits, and the like. The fossil fluids are generally a mixture of naturally occurring hydrocarbons that can be refined into diesel, gasoline, heating oil, jet oil, 25 kerosene and other products called petrochemicals. Fossil fluids derived from subterranean formations may include, but are not limited to, kerogen, bitumen, pyrobitumen, asphalteiies, oils or combinations thereof.

The term “alkyl” is inclusive of both straight chain and branched chain groups and of cyclic 30 groups. Straight chain and branched chain groups may hâve up to 30 carbon atoms unless otherwise specified. Cyclic groups can be monocyclic or polycyclic, and in some embodiments, can hâve from 3 to 10 carbon atoms. The term “alkylene” is the divalent form of the alkyl groups defined above.

The term “aryl” includes carbocyclîc aromatic rings or ring Systems, for exaniple, having l, 2 or 3 rings and optionally containing at least one heteroatoin (e.g, O, S or N) in the ring. Examples of aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, furyl, thienyl, pyridyl, quionlinyl, isoquinlinyl, indoyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl, and tliiazolyl,

The term “alkylaryl” refers to an aryl moiety to which au alkyl group is attached.

The term “alkylphenol” refers to a phénol moiety to which an alkyl group is attached.

The term “alkali métal” refers to lithium, sodium or potassium.

The term “alkalîne earth métal” refers to calcium, barium, magnésium or strontium.

The term “lower carbon chain alcohols” refers to alcohols having no more than 10 carbon atoms.

As used herein, a “surfactant” refers to a chemical compound that lowers the interfacial tension between two liquids.

The term “iionionic surfactant” refers to a surfactant where the molécules forming the surfactant are uncharged.

As used herein, tlie terni “substantially free” means, when used with reference to the substantial absence of a material in a formulation, that such a material is présent, if at ail, as an incidental impurity or by-product. In other words, the material does not affect the properties of the formulation.

The phase “subterranean formation” encompasses both areas below exposed earth and areas below earth covered by water, such as an océan or fresh water. Températures in a subterranean formation may range from about 25T to about 300°F. In soine embodiments, the température of the formation îs at least about 100°F, in other embodiments tlie température of the formation is at least about 125°F, while in other embodiments, température of the fonnation is at least about 150°F.

The présent disclosure generally provides a surfactant formulation for treating and recovering fossil fluids from a subterranean formation, and especially for treating and recovering fossil fluids from a subterranean formation under high salinity and/or high température conditions. According to one embodiment, the surfactant formulation includes a nonionic surfactant, organic acid 5 selected from citric acid, dîglycolic acid, glycolic acid and a sait thereof and injection water. It has been surprisingly found that the addition of minor amounts of lhe organic acid or sait thereof to the surfactant formulation adds salinity and hardness tolérance to the formulation, especially at high salinity conditions as well as phase stability at high température conditions. When the surfactant formulation is mixed with oil, ultra-low interfacial tensions are also observed.

Moreover, additional components usually found in surfactant formulations, such as carboxylated surfactants, that are generally included to improve stability of the surfactant formulation, can be substantially reduced or eliminated thereby speeding up the process of developing ail effective formulation as well as decreasing the cost of the formulation. In one particular embodiment, the surfactant formulation is substantially free of carboxylated surfactants.

As noted above, the surfactant formulation includes a nonionic surfactant. The nonionic surfactant can be any compound having a hydrophobie head, a hydrophilic tail and possible intermediate groups. In one embodiment, the nonionic surfactant comprises a compound having a hydrophobie head that is a natural or synthetically-based alkyl group or an alkylatyl group and a 20 hydrophilic tail that is an alkoxylate group. The surfactant formulation can comprise one nonionic surfactant or a mixture of nonionic surfactants.

According to one embodiment, the nonionic surfactant is an alkoxylated alkylphenol or an alkoxyiated alcohol. The alkoxylated alkylphenol or alkoxylated alcohol comprise onc or more 25 repeating C| to C4 alkylene oxide groups, preferably one or more ethoxylate groups, propoxylate groups or a mixture thereof. hi some embodiments, the alkoxylated alkylphenol or alkoxylated alcohol can comprise 2 to 50 alkylene oxide units. According to other embodiments, the alkoxylated alkylphenol or alkoxylated alcohol eau comprise 5 to 45 alkylene oxide units, while in still other embodiments, the alkoxylated alkylphenol or alkoxylated alcohol can comprise 10 to 30 30 alkylene oxide units.

In another embodiment, the alkylphenol is phénol having one or more lînear or branched Ci to C₂₅ alkyl groups attached, while in other embodiments, the alkylphenol is phénol having onc or more lînear or branched C_; to C₂o alkyl groups attached, while in still further embodiments, the

alkylphenol is phénol having one or more linear or branched C& to Ch alkyl groups attached. According to one particular embodiment, the alkylphenol is phénol having one or more p-octyl or p-nonyl groups attached.

According to another embodiment, the alcohol is a linear or branched saturated aliphatic alcohol compound comprising 5 to 30 carbon atoms. In stîll other embodiments, tlie alcohol is a linear or branched saturated aliphatic alcohol compound comprising 7 to 25 carbon atoms, while in still another embodiment, the alcohol is a saturated aliphatic alcohol compound comprising 10 to 20 carbon atoms.

The alkoxylated alkylphenol or alkoxylated alcohols described above can be produced using one of a number of different catalytic processes. Of these processes, one of the most commoii includes the use of an alkaline catalyst such as sodium alkoxide, a quatcrnary ammonium base or sodium hydroxide. At the end of the reaction, an acid (e.g., acetic acid, propionic acid, sulfuric 15 acid, mixtures thereof) is used to neutralize the alkaline catalyst, thereby producing a meta! sait.

Métal sait can be suspended in the nonionic surfactant produced in tlieses processes in concentrations that range from about 500 to about 10000 parts-per-million (ppm), where a value of about 1500 ppm is typical. An example of such a process can be found, among other places, in U.S. Pat. No. 2,677,700, which is incorporated herein by reference in ils entirety,

Other catalytic processes for producing the alkoxylated alkylphenol or alkoxylated alcohol include those that use a Lewis Acid catalysis process. An example of this process eau be found in U.S. Pat. No, 4,483,941, which is incorporated herein by reference in its entirety, and which describes the alkoxylation of organic materials in the presence of at least one catalyst comprising 25 BFj and métal alkyls or métal alkoxidcs, S1F4 and métal alkyls or métal alkoxides, and mixtures thereof. Other catalytic processes include the use of titanium catalysis, such as titanium isopropoxide and/or other titanium trialkoxide. These Lewis Acid catalysis processes, however, also must be neutralized with a base, thereby producing métal salts in concentrations from about 500 to about 2500 parts-per-million (ppm). Also acid catalyzed alkoxylations lead to harmful 30 side products that must be removed prier to use.

A11 additional catalytic process for preparing the alkoxylated alkylphenol or alkoxylated alcohol can include tlie use of double métal cyanide (DMC) catalysts. DMC catalysts are known for epoxide polymerizatîon, i.e. for polymerizing alkylene oxides such as propylene oxide and ethylene oxide to yield poly(alkylene oxide) polymère, also referred to as polyctlicr polyols. The catalysts are highly active, and give polyether polyols that bave low unsaturation compared with similar polyols made using strong basic catalysts like potassium hydroxide. In addition to the préparation of polyether polyols, the catalysts can be used to make a variety of polymer products, 5 including polyester polyols and polyetherester polyols. The polyols can be used to préparé polyuréthanes by reacting them with polyisocyanates under appropriate conditions.

As appreciated, OMC catalysts are not acidic or alkaline catalysts, but rather are transition métal catalysts which do not need to be neutralized as is the case with the acidic or alkaline catalysts.

The DMC catalysts aie typically used at a concentration that is lower than the métal concentrations discussed herein foi· the acidic or alkaline catalysts process, but are still présent at a concentration of at least 80 ppm. Because the DMC catalysts are not detrimental to the subséquent préparation of polyuréthanes they are allowed to remain with the polyether polyol. Altematively, removal of the DMC catalyst can be accomplished with an alkali métal hydroxide 15 to form an insoluble sait that is then filtered.

According to another embodiment, the alkoxylated alcohol is an alkoxylatcd Guerbet alcohol of formula (1)

R^!-O-BO_rPO„-EO_w-H (I) wherein R² corresponds to an aliphatic, branched hydrocarbon group derived from a

Guerbet alcohol where n corresponds to the number of carbon atoms and may range from 12 to

50; BO corresponds to a butoxy group; t corresponds to the number of butoxy groups présent and 25 may range from 0 to 50; PO corresponds to a propoxy group; u corresponds to the number of propoxy groups présent and may range from 0 to 50; EO corresponds to an ethoxy group; and w corresponds to the number of ethoxy groups présent and may range from 0 to 50 with the proviso that t+u+w>I.

Guerbet alcohols and methods of making them are well known to those skilled in the ait. In the course of a Guerbet reaction, primary alcohols are dimerized at high températures in the presence of a catalyst to primary alcohol products branched at the 2-position. The réaction proceeds by the following sequential steps: (i) oxidation of the primary alcohol to an aldéhyde; (ii) aldol condensation of the aldéhyde; (iii) déhydration of tlie aldol product; and (iv) hydrogénation and réduction ofthe allylic aldéhyde.

The Guerbet reaction may be carried out at a température range of about between !75°C - 275°C.

Catalysts which may be used include NaOH, KOH, nickel, lead salts, oxides of copper, lead, zinc, chromîum, molybdenum, tungsten and manganèse, palladium compounds and sïlver compounds.

The Guerbet alcohol R²-OH is then alkoxylated in the next process step. The procedure for alkoxylation is known in principle to those skilled in the art. It is lîkcwise known to those skilled 10 in the art that the reaction conditions can influence the molecular weight distribution of the alkoxylates.

In one embodiment, the alkoxylated Guerbet alcohol of formula (I) is prepared by base-catalyzed alkoxylation. The Guerbet alcohol is first admixed in a pressure reactor with alkali métal 15 hydroxides, such as potassium hydroxide, or with alkali métal alkoxides, such as sodium niethoxide. By means of reduced pressure, foi· example < 100 mbar, and/or an increase in the température, for example from 30°C to 150°C, it is possible to draw off water still présent in the mixture. The alcohol is then présent as the corresponding alkoxide. This is followed by inertization with inert gas and addition of the alkylenc oxide at températures between 60°C 20 I8O°C and up to a pressure of max. 10 bar. At the end of the reaction, tlie catalyst can be neutralized by adding acid, such as acetic or phosphoric acid, and can be filtered off if required.

In another embodîment, the alkoxylated Guerbet alcohol of formula (I) may be prepared by techniques known to those skilled in the art which leads to narrower molecular weight 25 distributions than in the case of base-catalyzed synthesis. To this end, the catalysts which may be used are, for example, double hydroxide clays, double métal cyanidc catalysts, or Zn-Co type catalysts. To perform the réaction, the Guerbet alcohol is admixed with the catalyst and the mixture dewatered as described above and reacted with the alkylene oxides as described above. Generally, not more than 250 ppm of catalyst based on the total weight of the mixture is used. 3 0 The catalyst can remain in the final product due to this small amount.

In yet another embodiment, the alkoxylated Guerbet alcohol of formula (1) inay be prepared using a DMC catalyst or by acid-catalyzed alkoxylation. The acids may bc Bronstcd or Lewis acids. To perform the reaction, the Guerbet alcohol is admixed with the catalyst, and the mixture

ΙΟ dcwatered as described above and rcactcd with alkylene oxides as described above. At the end of the réaction, the acid can be neutralized by adding a base, such as KOH or NaOH, and filtered off if required.

The block structure indicated in formula (I) inay be obtained by subsequently adding butlylcnc oxide, propylene oxide, and ethylene oxide in their respective amounts in any order to the Guerbet alcohol. Thus, in one embodiment, the Guerbet alcohol is first butoxylated with t butlylene oxide units to form a butyloxated Guerbet alcohol, and then propoxylated with u propylene oxide units and then ethoxylated with w nuits of ethylene oxide units. In some 10 embodiments, different catalysts inay used during alkoxylation, for example, a DMC catalyst may be used during propoxylation while an alkali métal hydroxide may be used during cthoxylation. In other embodiments, the butylène oxide units, propylene oxide units and ethylene oxide units are added to the Guerbet alcohol in random order. The properties of the résultant alkoxylated Guerbet alcohol can be tailored to enhanced oil recovery needs by the skilled artisan by selccting 15 the number of BO, PO and EO units. The alkoxylated Guerbet alcohol of formula (I) will comprise a terminal OH- group.

In one embodiment, the surfactant formulation comprises from about 0.005 to about 10 weight percent of the nonionic surfactant, based on the total weight of the surfactant formulation. In 20 another embodiment, the surfactant formulation comprises from about 0.01 to about 5 weight percent of the nonionic surfactant, based on the total weight of the surfactant formulation. In still another embodiment, the surfactant formulation comprises from about 0.5 to about 3 weight percent of the nonionic surfactant, based on the total weight of the surfactant formulation.

The surfactant formulation further includes an organic acid selected from citric acid, diglycolic acid, glycolic acid and a sait thereof. It has been surprisîngly round that the surfactant formulation performs unexpectedly well in very fresh water to very hard, brtney water (where TDS can range from 1000 ppm to >200,000 ppm and hardness can range from 0 ppm divalents to 30,000 ppm) when the organic acid or preferably a sait thereof is included in the surfactant 30 formulation.

In some embodiments, the organic acid is selected from diglycolic acid, glycolic acid and a sait thereof. In yct another embodiment, the organic acid is diglycolic acid or a diglycolic acid sait. In still another embodiment, the organic acid is glycolic acid or a glycolic acid sait.

In one particular embodiment, the organic acid is provided as a powder in pure fonn which is then preferably used in an aqueous solution. In still another embodiment, glycolic acid or glycolic acid sait may be produced from sodium chloroacctatc or ehloroacetie acid under strong alkaline conditions. In still another embodiment, the organic acid is provided in the fonn of a sait that can be illustrated by the alkali métal or alkaline earth métal salts, such as sodium, calcium, lithium, magnésium, zinc and potassium, as well as the ammonium and alkanolamine salts such as monoethanolainine and tiiethanolamine (which it is bclîcved form alkaiiolaiiimonium salts) salts, and the like and mixtures thereof. In one particular embodiment, the organic acid is a glycolic acid sait, for example, the sodium sait (i.e. sodium glycolate and/or disodium glycolate).

The organic acid or sait thereof can be used in amounts sufficient to effect surfactant formulation stabilization. These can be illustrated by surfactant formulations containing ratios rangîng between about 0.05 parts by weight organic acid or a sali thereof to about 15 parts by weight nonionic surfactant to about 2 parts by weight organic acid or a sait thereof to about 10 parts by weight nonionic surfactant, while in other embodiments, the ratios may range between about 0.5 parts by weight organic acid or a sait thereof to about 12 parts by weight nonionic surfactant to about J .25 parts by weight organic acid or a sait thereof to about 9 parts by weight nonionic surfactant.

The suifactant formulation also includes injection water. In one embodiment, the injection water may be seawater, brine, fresh water from an aquifer, river or lake, or a mixture thereof. Thus, according to many embodiments, the injection water contains minerais, for example, barium, calcium, magnésium, and/or minerai salts, for example, sodium chloride, potassium chloride, magnésium chloride.

It’s well known water salinity and/or water hardness may affect recovery of fossil fluids in a formation. As used herein, “salinity” refers to the amount of dissolved solids in the injection water. Thus, in one embodiment, the injection water has a salinity of at least about 20,000 ppm. Jn another embodiment, the injection water has a salinity of at least about 30,000 ppm. In still another embodiment, the injection water has a salinity of at least about 50,000 ppm. Jn still a further embodiment, the injection water has a salinity of at least about 100,000 ppm. In a further embodiment, the injection water has a salinity of at least about 200,000 ppm.

According to another embodiment, tbe surfactant formulation may optionally comprise a cosurfactant. In one embodiment, tlie co-surfactant is an alkylaryl sulfonate represented by the formula (II):

R

ASO(ID where R^a is hydrogen or an alkyi group containing from l to 3 carbon atoms, R^b is hydrogen or an alkyi group containing from l to 3 carbon atoms, R° is an aïkyl group having from 8 to 40 carbon atoms and A is a monovalent cation. In one embodiment, A is an alkali métal ion, an ammonium ion or substituted ammonium ion. Exemples of substituted ammonium ions include ammonium independently substituted with from I to 4 aliphatic or aromatic hydrocarbyl groups having from l to 15 carbon atoms.

The compound of formula (Π) may be obtained by the alkylation of an aromatic compound. In one embodiment, the aromatic compound is benzene, toluene, xylene or a mixture thereof. Foi' embodiments where tlie aromatic compound includes xylene, the xylene compound may be orthoxylene, meta-xylene, para-xylene, or a mixture thereof.

The aromatic compound may be alkylated with a mixture of normal alpha olefins containing from C_s to C₄₀, carbons and in sonie embodiment, C_l4 to C₃₀ carbons to yield an aromatic alkylate. The aromatic alkylate is then sulfonated to form an alkylaromatic sulfonic acid which is then neutralized with a source of alkali or alkaline earth métal or anunonia thereby producîng an alkylaryl sulfonate compound, lu one embodiment, the source is an alkali métal hydroxidc, such as, but not limited to, sodium hydroxidc or potassium hydroxide.

Other co-surfactants which may optionally bc included in the surfactant formulation are the type derived from alkyi dipheny! oxide sulfonic acids and their salts, Examples include the monoalkyl diphenyl oxide disulfonates, the monoalkyl diphenyl oxide monosulfonates, the dialkyl dipheny! oxide monosulfonates, and the dialkyl diphenyl oxide disulfonates, and their mixtures.

For cxample, the surfactant formulation may optionally include a co-surfactant of the formula

(ΙΠ) wherein R³ and R⁴ are, independently at each occurrence, hydrogen, linear or branched CrC₁₆ alkyl, or aryl; and X is independently hydrogen, sodium or potassium.

Co-surfactants of formula (III) contain a pair of sulfonate groups on a diphenyl oxide backbone. The two sulfonates provide double charge density to the molécule. The double charge provides a more powerful, more durable, and more versatile surfactant molécule when compared to single charge anionics. This higher local charge density results in greater potentiel for solvating and coupîing action. In addition, the flexible ether Itnkage of the molécule allows variable distance between the sulfonates, allowing interactions with a broad variety of other materials in solution as well as excellent coupîing with other surfactants and ingrédients.

In one embodiment, one or both of R₃and Rjare preferably independently linear or branched CjCj6 alkyl, preferably Q-Cjgalkyl.

In one embodiment, X at each occurrence is preferably sodium.

Further preferred alkyl diphenyl oxide sulfonic acid based co-surfactants include: disodium hexadecyldiphenyloxidc disulfonate; disodium dihexadecyldîphenyloxide disulfonate; sodium dipropyldiphenyleneoxide sulfonate, disodium didecyldiphenylene oxide disulfonate, and disodium mono- and di-sec-hexyldiplienylene oxide disulfonate, as well as their mixtures. Such materials can be readily prepared by a person of ordinary skill in the ail, using well known techniques. Suitable procedures are described in U.S. Pat. No. 6,743,764, and references cited therein, which is incorporated herein by reference. Several of the foregoing materials are also commercially available under the DOWFAX™ brand (from The Dow Chemical Company).

In another embodiment, the co-surfactant is an internai olefîn sulfonate. An internai olefin is an olefïn whose double bond is located anywhere along the carbon chain except at a terminal carbon atom. A linear internai olefin does not hâve any alkyl, aryl, or alîcyclic branching on any of the double bond carbon atoms or on any carbon atoms adjacent to tlie double bond carbon atoms, Typical commercial products produced by isomerîzation of alpha olefïns are predoininantly linear and contain a low average number of branches per molécule.

Exemples of commercially available internai olefîn sulfonates, include, for instance, Petrostcp™ S2, a C15-C18 IOS, is available from Stepan Company and Enordet™ internai olefin sulfonates available from Shell Chemicals and other suppliers.

Internai olefin sulfonates may also bc prepared by sulfonation of a Cû-Cjo internai olefin or mixture of internai olefins according to well-known methods. In one suitable approach, sulfonation is performed in a continuons thin-film reactor maintained at 10°C to 50°C. The internai olefin or mixture is placed in the reactor along with sulfur trioxide diluted with air. The molar ratio of internai olefïn to sulfur trioxide is maintained at a suitable ratio, e.g., from about 0,7:1 to about 1,1:1, The sulfonated dérivative of internai olefîn or mixture may be neutralized with alkali, e.g., sodium hydroxide, to form the corresponding sali. The réaction is exothermic and the viscosity of tlie reaction product may dépend on the amount of water présent, General conditions and processes for sulfonation of olefins are disclosed in U.S. Pat. No. 4,252,192, the teachings of which are incorporated herein by reference. The internai olefïn used as a source for the Cû-Cîo internai olefin sulfonate can be di-, tri-, or tetrasubstituted with linear or branched alkyl groups. Internai olefin sources can be obtained from a variety of processes, including olefin (e.g., ethyleue, propylene, butylène) oligomérization, a-olefin metathesis, Fischcr-Tropsch processes, catalytic dchydrogenation of long-chain paraffins, thermal crackîng of hydrocarbon waxes, and dimerized vinyl olefin processes. A well-known ethylene oligomérization process is the Shell higher olefin process (SI1OP), which combines ethylene oligomérization to form aolefins, isomerîzation of the a-olcfins to form internai olefins, and metathesis of these internai olefins with butènes or ethylene to form a-olefins of different chain lengths. Commercially available internai olefins made by SHOP typîcally contai» about six mole percent or higher of trisubstîtuted internai olefins. Internai olefin sulfonates and their préparation are described in many référencés, including U.S. Pat. Nos. 4,532,053, 4,555,351 , 4,597,879, and 4,765,408, and U.S. Pat. Appl. Publ, No. 2010/0282467, the teachings of which are incorporated by reference.

In one aspect, the internai olefin used to make the internai olefin sulfonate is produced by metathesis of an α-olefin and lias a higlt proportion of disubstitution and a correspondingly low proportion of trisubstitution. Such internai olefin sulfonates, which are disclosed in U.S. Pat, Appl. Publ. No. 2010/0282467, provide advantages for enhanced oil recovery, including lower optimal salinities.

According to one embodiment, the co-surfactant is added to the surfactant formulation at a ratio of between about 1:20 parts by weight of co-surfactant to nonionic surfactant to about 1:1 parts by weight of co-surfactant to nonionic surfactant. In another embodiment, the co-surfactant is added to the surfactant formulation at a ratio of about 1:15 parts by weight of co-surfactant to nonionic surfactant to about 1:5 parts by weight of co-surfactant to nonionic surfactant. In still another embodiment, the co-surfactant is added to the surfactant formulation at a ratio of about 1:12.5 parts by weight of co-surfactant to nonionic surfactant to about 1:7.5 parts by weight of cosurfactant to nonionic surfactant.

The surfactant formulation may further optionally include a dialkyl sulfosuccinate represented by the formula (IV):

r⁶ooc ch₂ hcso₃m

R’OOC ^(IV) where R⁶ and R⁷ are each independently an alkyl group containing 5 to 13 carbon atoms and M is an alkali métal ion, an alkalînc earth tnetal ion, an ammonium ion or a substituted ammonium ion. Examples of substituted ammonium ions include ammonium independently substituted with from 1 to 4 aliphatic or aroinatic hydrocarbyl groups having from I to 15 carbon atoms.

According to one embodiment, R⁶ and R^T are independently a C₅ alkyl, a C₆ alkyl, a C₈ alkyl or a Cb alkyl. These groups may be derived, for example, from respectively, amyl alcohol, methyl amyl alcohol ( 1,4-diinetliyl butyl alcohol), 2-ethyl hexanol, and mixed isoincrs ofalcohols.

lu another embodiment, M is an alkali métal ion or alkaline earth inetal ion. In a further embodiment, M is sodium.

According to one embodiment, the dialkyl sulfosuccinate is added to the surfactant formulation at a ratio of between about 1:15 parts by weight of dialkyl sulfosuccinate to nonïonic surfactant to about 1:10 parts by weight of dialkyl sulfosuccinate to nonïonic surfactant. In still another embodiment, the dialkyl sulfosuccinate is added to the surfactant formulation at a ratio of between about 1:7.5 parts by weight of dialkyl sulfosuccinate to nonïonic surfactant to about 1:5 parts by weight of dialkyl sulfosuccinate to nonïonic surfactant. In a further embodiment, the 10 dialkyl sulfosuccinate is added to the surfactant formulation at a ratio of between about 1:2.5 parts by weight of dialkyl sulfosuccinate to nonïonic surfactant to about 1:1 parts by weight of dialkyl sulfosuccinate to nonïonic surfactant.

In another embodiment, the surfactant formulation may optionally include a solvent. Examples 15 of solvents include, but are not limited to, alcohols, such as lower carbon chain alcohols, for example, isopropyl alcohol, éthanol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, n-amyl alcohol, sec-amyl alcohol, n-hexyl alcohol, and sec-hexyl alcohol; lower carbon chain alcohols that hâve been alkoxylated with ethylene oxide (EO), propylene oxide (PO) or butylène oxide (BO), for example, n-butanol + 1EO, n-butanol + 2EO, n-butanol + 3EO, n-hexanol + 6EO, 220 ethylhexanol+ 2EO and iso-butanol + 3EO, alcohol ethers, polyalkylenc alcohol ethers, such as ethylene glycol monobutyl ether, polyalkylenc glycols, sucli as ethylene glycol and propylene glycol, poly(oxyalkylenc) glycols, such as diethylene glycol, poly(oxyalkylene) glycol ethers, or any mixtures thereof.

In one embodiment, the solvent is added to the surfactant formulation at a ratio of between about 20:1 parts by weight of solvent to nonïonic surfactant to about 1:1 parts by weight of solvent to nonïonic surfactant. In another embodiment, the solvent is added to the surfactant formulation at a ratio of between about 15:1 parts by weight of solvent to nonïonic surfactant to about 2.5:1 parts by weight of solvent to nonïonic surfactant. In still another embodiment, the solvent is added to 30 the surfactant formulation at a ratio of between about 10:1 parts by weight of solvent to nonïonic surfactant to about 5:1 parts by weight of solvent to nonïonic surfactant.

In yet another embodiment, the surfactant formulation may optionally include a chelant, or a polymer.

Examples of chélants which may be used include, but are not limited to, EDTA, EDTA salts, EDDS, EDDS salts, phosphate compounds, ascorbic acid, tetiasodîum iminodîsuccinate, citric acid, dicarboxymethylglutamic acid, maleic acid, dicthylenetriaminepentacetic acid, cyclohexan trans-l,2-diaminetetraacetic acid, ethanoldiglycinc, diethanolglycine, hydroxyelhyl-ethylenc5 diaminctriacetic acid, ethylene bis [2-(o-hydroxyphenyl)-glycine], nîtrilotriacetic acid (NTA), a nonpolar amino acid, méthionine, oxalic acid, a polar amino acid, arginine, asparagine, aspartic acid, glutainic acid, glutamine, lysine, ornithine, a siderophore, desferrioxamine B, hydrolysed wool, succinic acid, sodium metaborate, sodium silicate, sodium ortbosilicate, and any mixture thereof.

ln one particular embodiment, the surfactant formulation is substantially free of EDTA, EDTA salts and phosphate compounds.

According to another embodiment, the surfactant formulation comprises from about 0 to about 10 15 weight percent of chelant, based on the total weight of the surfactant formulation. In another embodiment, the surfactant formulation comprises from about 0.01 to about 5 weight percent of chelant, based on the total weight of the surfactant formulation. In yet another embodiment, the surfactant formulation comprises from about 0.1 to about 3 weight percent of chelant, based on the total weight of the surfactant formulation.

Examples of polymers include, but are not limited to, polyacryiamidcs, partially liydrolyzed polyacrylamide, polyacrylates, ethylenic copolymers, biopolytners, carboxymetliylccllulose, polyvinyl alcohols, polystyrène sulfonates, polyvinylpyrrolidone, AMP S (2-acryIamide-2-methyl propane sulfonates), modîfied starches and mixtures thereof. Examples of ethylenic copolymers 25 include copolymers of acrylic acid and acrylamidc, acrylic acid and lauryl acetylate, lauryl acrylate and acrylamide. Exampies of biopolymers include xanlhan gum and guar gum.

In one embodiment, the surfactant formulation comprises from about 0 to about 2 weight percent of polymer, based on the total weight of the surfactant formulation. In another embodiment, the 30 surfactant formulation comprises from about 0.01 to about 1 weight percent of polymer, based on the total weight of the surfactant formulation. In still another embodiment, the surfactant formulation comprises from about 0.2 to about 0.5 weight percent of polymer, based on the total weight of the surfactant formulation.

Γη still another embodiment, tlie surfactant formulation may optionally include an alkali métal hydroxide, carbonate or chloride. The addition of such materials can: altcr lhe surface properties of the formation so that surfactant rétention is reduced; provide stability to ether sulfates from hydrolysis; activate surfactants in the crude oil; and raise the salinity of the injection water so a 5 salinity gradient is achieved as the formulation propagates through tlie fonnatîon. In one embodiment, the alkali métal hydroxide, carbonate or chloride is added (o the surfactant formulation prior to being pumped into the fossil fluid-bearing subterranean formation. In another embodiment, the surfactant formulation contains from about 0.01 weight percent to about 2 weight percent, for e.g., from about 0.05 weight percent to about 1.5 weight percent or from 10 about 0.01 weight percent to about 1 weight percent, of alkali métal hydroxide, carbonate or chloride based on lhe total weight of the surfactant formulation.

The surfactant formulation may be prepared by a process of mixing the nonionic surfactant with an organic acid selected from citric acid, diglycolic acid, glycolic acid, and a sait thereof and 15 injection water. The components may be mixed together in any order using customary devices, such as, but not limited to, a stirred vessel or static mixer.

In another embodiment, tliere îs provided a method for designing a surfactant formulation for use in recovering fossil fluids from a subterranean formation. The method includes measuring the 20 température of the subterranean formation, measuring the înterfacial tension in tlie injection water and fossil fluid, adding a nonionic surfactant to the injection water to decrease the înterfacial tension in tlie injection water and fossil fluid to less tlian 1 x 10'¹ dynes/cm, and adding an organic acid selected from citric aeîd, diglycolic acid, glycolic acid and a sait thereof to the mixture of injection water and nonionic surfactant in an amount necessary to inake tlie mixture 25 phase stable at tlie température of the subterranean formation. In one embodiment, the injection water has a salinity of at least about 20,000 ppm and the subterranean formation is at a température in the range between about 80^DF to about 300°F, while in other embodiments the formation is at a température in the range between about 125°F to about 300°F.

In another embodiment, there is provided a surfactant package for treating a fossil fluid-bearing subterranean formation comprising a nonionic surfactant, an organic acid selected from citric acid, diglycolic acid, glycolic acid and a sait thereof and injection water. In a further embodiment, tlie surfactant package comprises an alkoxylated alkylphenol, alkoxylated alcohol or alkoxylated Guerbet alcohol of formula (I) described above and glycolic acid or a sait thereof. In some embodiments. the surfactant package can be further combined with injection water and optional components described above to form a surfactant formulation.

Tlie surfactant formulation described herein may be injected into one or more injection wells located within the subterranean formation such that fossil fluîd is subsequently produced from one or more producing wells. In one embodiment, the injection well and producing well are the same well. In another embodiment, the injection well and producing well are adjacent to one another. In one embodiment, the subterranean formation température conditions are between about 80°F and about 300°F, preferably between about 125°F and about 300°F.

Considération must be given to the fact that although this disclosure lias been described and disclosed in relation to certain preferred embodiments, obvious équivalent modifications and alterations thereof will become apparent to one of ordinary skill in this art upon reading and iindeistanding (Tris spécification and the claims appended hereto. The présent disclosure includes the subject matter defîned by any combination of any one of the various claims appended lierelo with any one or more of the remaining claims, including the incorporation of the features and/or limitations of any dépendent claim, singly or in combination with features and/or limitations of any one or more of the other dépendent claims, with features and/or limitations of any one or more of the independent claims, with the remaining dépendent claims in their original text being read and applied to any independent claim so modified. This also includes combination of the features and/or limitations of one or more of the independent claims with the features and/or limitations of another independent claim to arrive at a modified independent claim, with the remaining dépendent claims in their original text being read and applied to any independent claim so modified. Accordingly, the presently disclosed invention is intended to cover ail such modifications and alterations, and is limited only by the scope of the claims which follow, in view of the foregoing and other contents of this spécification.

Claims (16)

1. Wliat is claimed is:

   1. Λ surfactant formulation for treating a fossil fluid-bearing subterranean formation comprising a nonionic surfactant, organic acid selected from citric acid, diglycolic acid, glycolîc acid and a sait thereof, and injection water.
2. 2. The surfactant formulation according to claim 1, wherein the nonionic surfactant comprises a compound having a hydrophobie head that is a natural or synthetically-based alkyi group or an alkylaryl group and a hydrophilic tail that is an alkoxylate group.
3. 3. The surfactant formulation according to claim 1, wherein the nonionic surfactant is an alkoxylated alkylphenol or an alkoxylated alcohol comprising one or more repeating Ci to C₄ alkylcnc oxide groups.
4. 4. The surfactant formulation according to claim 1, wherein the nonionic surfactant is an alkoxylated alkylphenol having one or more linear or branched Cj to C₂; alkyi groups attachèd.
5. 5. The surfactant formulation according to claim 1, wherein the nonionic surfactant is an alkoxylated linear or branched saturated aliphatic alcohol compound comprising 5 to 30 carbon atoms.
6. 6. The surfactant formulation according to claim 1, wherein the nonionic surfactant is a an alkoxylated Guerbet alcohol of formula (I)

   Κ²-0-ΒΟγΡΟ,γΕΟ^Η

   CD wherein R² corresponds to an aliphatic, branched hydrocarbon group C_nH_2li+i derived from a Guerbet alcohol where n corresponds to the number of carbon atoms and may range from 12 to 36; BO corresponds to a butoxy group; t corresponds to the number of butoxy groups présent and may range from 0 to 50; PO corresponds lo a propoxy group; u corresponds to the number of propoxy groups présent and may range from 0 to 50; EO corresponds to an ethoxy group; and w corresponds to the number of ethoxy groups présent and may range from 0 to 50 with the proviso that t+u+w>l.
7. 7. The surfactant formulation according to claim 1, wherein the organic acid is glycolic acid or a glycolic acid sait.
8. 8. The surfactant formulation according to claim 7, wherein the glycolic acid sait is sodium 5 glycolate and/or disodium glycolate.
9. 9. The surfactant formulation according to claim 1, wherein the injection water is seawater, brine, fresh water from an aquifer, river or lake, or a mixture thereof.
10. 10 10. A method of prcparing a surfactant formulation for treating a fossil fluid-bearing subterranean formation comprising mixing a nonionic surfactant with an organic acid selected from citric acid, diglycolic acid, glycolic acid and a sait thereof and injection water.
11. 11. A process for recovering fossil fluids from a fossil fluid-bearing subterranean formation

    15 comprising injecting the surfactant formulation of daim 1 into one or more injection wells such that oil is subsequently produced from one or more producing wells.
12. 12. Λ surfactant package for treating a fossil fluid-bearing subterranean formation comprising a nonionic surfactant and an organic acid selected from citric acid, diglycolic acid,

    20 glycolic acid and a sait thereof.
13. 13. The surfactant package according to claim 12, wherein the nonionic surfactant is an alkoxylated alkylphenol having one or more lînear or branched C| to alkyl groups attached.

    25
14. 14. The surfactant formulation according to claim 12, wherein the nonionic surfactant is ail alkoxylated lînear or branched saturated aliphatic alcohol compound comprising 5 to 30 carbon atoms.
15. 15. The surfactant formulation according to claim 12, wherein the nonionic surfactant is a an

    3 0 alkoxylated Guerbet alcohol of formula (I)

    R²-O-BO_rPO_tl-EO_lv-H (I) wherein R² corresponds to an aliphatic, branched hydrocarbon group C_nH2,₁₊] derived from a Gucrbet alcohol where n corresponds to the number of carbon atoms and may range from 12 to 36; BO corresponds to a butoxy group; t corresponds to the number of butoxy groups présent and may range froin 0 to 50; PO corresponds to a ptOpoxy group; u corresponds to tlie number of propoxy groups présent and may range from 0 to 50; EO corresponds to an ctlioxy group; and w corresponds to the number of ethoxy groups présent and may range from 0 to 50 with the proviso that t+u+w>L
16. 16. The surfactant formulation according to claim 12, wherein the organic acid is glycolic acid or a glycolic acid sait.