Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: A method for enhancing oil recovery includes the step of providing a subsurface reservoir containing hydrocarbons therewithin. A wellbore is provided in fluid communication with the subsurface reservoir. A surfactant-polymer solution is formed for injection into the reservoir. The surfactant-polymer solution is formed by mixing a composition with at least one surfactant, at least one polymer, and at least one co-solvent or co-surfactant such that the surfactant-polymer solution is clear and aqueous stable. The surfactant-polymer solution is injected through the wellbore into the reservoir. A chaser solution is formed for injection into the reservoir. The chaser solution has an additional predetermined quantity of the co-solvent or co-surfactant. The chaser solution is injected through the injection wellbore into the reservoir to increase the production of hydrocarbons from the reservoir while maintaining the clear and aqueous stability of the surfactant-polymer solution.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: The present invention includes compositions and methods for treating a hydrocarbon-bearing formation having brine and at least one temperature, wherein the brine has at least one first composition by obtaining first compatibility information for a first model brine and a first treatment composition at a model temperature, wherein the first model brine has a composition selected at least partially based on the first brine composition, wherein the model temperature is selected at least partially based on the formation temperature, and wherein the first treatment composition comprises at least one first surfactant and at least one first solvent; based at least partially on the first compatibility information, selecting a treatment method for the hydrocarbon-bearing formation, and treating the hydrocarbon-bearing formation with the selected treatment method.

Abstract: The present invention is directed to the use of electromagnetic radiation, acoustic energy, and surfactant injection to recover hydrocarbon-containing materials from a hydrocarbon-bearing formation.

Abstract: A composition and method for improving the fluid efficiency of many oilfield treatments is given. The composition is a solid additive, in a viscosified fluid, in a size range small enough that it enters formation pores; it optionally bridges there to form an internal filter cake, and then decomposes to provide a breaker for the viscosifying system for the fluid. Examples of suitable additives include waxes, polyesters, polycarbonates, polyacetals, polymelamines, polyvinyl chlorides, and polyvinyl acetates. Degradation of the additive may be accelerated or delayed.

Abstract: A method is given for treating a wellbore to increase the production of hydrocarbons from a subterranean formation penetrated by a wellbore, involving a period of injecting into the formation an aqueous injection fluid having a different chemical potential than the aqueous fluid in the formation. If there is water blocking, an osmotic gradient is deliberately created to cause flow of water into the injected fluid; hydrocarbon is then produced by imbibition. If the pore pressure in the water-containing pores in the formation is too low, an osmotic gradient is deliberately created so that water flows from the injected fluid into the water-containing pores, increasing the pore pressure and facilitating hydrocarbon production by imbibition. The method may be repeated cyclically. A semipermeable membrane may be created to enhance the osmosis. Wetting agents may be used to influence imbibition.

Abstract: Recovery of hydrocarbon fluid from low permeability sources is enhanced by introduction of a treating fluid. The treating fluid may include one or more constituent ingredients designed to cause displacement of hydrocarbon via imbibition. The constituent ingredients may be determined based on estimates of formation wettability. Further, contact angle may be used to determine wettability. Types and concentrations of constituent ingredients such as surfactants may be determined for achieving the enhanced recovery of hydrocarbons.

Abstract: Disclosed are methods for improving the production of heavy/viscous crude oil from subterranean formations comprising secondary production through use of a displacement fluid (typically a waterflood) wherein the subterranean formation is subjected to cyclic periods of overinjection of the displacement fluid followed by underinjection of the displacement fluid, but keeping the overall cumulative voidage replacement ratio (VRR) within a defined range, typically targeted to be about 1. In some aspects, the initial production of such heavy/viscous crude oil is limited, if possible, followed this cyclic secondary production methodology. By keeping the initial production, VRR, and cumulative VRR in defined ranges, the expected ultimate recovery (EUR) can be optimized, and overall production increased for example by as much as 100% or more relative to conventional production methods.

Abstract: Fluids viscosified with viscoelastic surfactants (VESs) may have their viscosities reduced (gels broken) by the direct or indirect action of a synergistic internal breaker composition that contains at least one first internal breaker that may be a mineral oil and a second breaker that may be an unsaturated fatty acid. The internal breakers may initially be dispersed oil droplets in an internal, discontinuous phase of the fluid. This combination of different types of internal breakers break the VES-gelled aqueous fluid faster than if one of the breaker types is used alone in an equivalent total amount.

Abstract: The present invention provides a method for recovering oil from a subterranean reservoir using waterflooding, wherein the flooding fluid used in the waterflooding process comprises water and one or more ionic polyvinyl alcohol copolymers. The use of one or more ionic polyvinyl alcohol copolymers is expected to increase the recovery of oil by improving both the oil/water mobility ratio and the sweep efficiency in reservoirs with a high degree of heterogeneity.

Abstract: The invention relates to a chemical composition and a process for using the chemical composition to remove and recover petroleum hydrocarbons from a contaminated substrate including an ammonia compound; a nitrogen-containing compound; and an aqueous carrier solution.

Abstract: A method of gravel packing a wellbore penetrating a subterranean formation is provided. The wellbore has a cased section and an uncased section and contains synthetic or oil-based drilling fluids containing drilled solids. To carry out the method, fresh synthetic or oil-based displacement fluid that is free of drilled solids is introduced into the wellbore to displace the synthetic or oil-based drilling fluids from the uncased section of the wellbore. A water-based displacement fluid is introduced into the wellbore to displace fluids within the cased section of the wellbore. A sand control screen assembly is run to a selected depth within the uncased section of the wellbore. A gravel pack slurry containing gravel and a water-based carrier fluid is then introduced into the wellbore.

Abstract: Methods and aqueous acid solutions for acidizing wells containing sludging and emulsifying oil are disclosed. An aqueous acid solution of the invention comprises water, hydrochloric acid, a cationic hydrochloric acid corrosion inhibitor and a conjugate ion pair of a cationic amine oxide surfactant and an anionic surfactant that does not react with the cationic hydrochloric acid corrosion inhibitor.

Abstract: A composition of a microemulsion including a mixture of a combination of surfactants and co-surfactants, an oil phase and an aqueous phase is described. In addition, a method for the advanced recovery of heavy oils is described which includes the steps of injecting a bank containing a microemulsion composition, injecting a bank of a polymer solution, and injecting water. The microemulsion composition can be applied in arenitic and carbonatic reservoirs, containing oils with API below 22.3° API, in both onshore and offshore fields.

Abstract: A method of treating a hydrocarbon containing formation is described. The method may include providing a hydrocarbon recovery composition to the hydrocarbon containing formation. Hydrocarbons in the hydrocarbon containing formation may interact with the hydrocarbon recovery composition. The hydrocarbon recovery composition may include an aliphatic anionic surfactant and an aliphatic nonionic additive. In some embodiments, an aliphatic anionic surfactant may be branched. In other embodiments, an aliphatic nonionic additive may be branched.

Abstract: An aqueous fluid useful for the recovery of crude oil from a subterranean formation, including water and one or more organophosphorus materials and methods for using same.

Abstract: The invention provides a method for treating a subterranean formation penetrated by a wellbore, the method comprising the steps of formulating a treatment fluid and introducing the treatment fluid through the wellbore. The treatment fluid comprises water; diutan; and a sufficient amount of salt to increase the density of the treatment fluid to at least 8.5 lb/gal, wherein at least 50% by weight of the salt is selected from the group consisting of: bromide salts, non-bromide salts having a higher salting-in effect than bromide according to the Hofmeister series as measured by the salt's effect on the cloud point of poly(ethylene oxide) that has a molecular weight of 4×106, and any combination in any proportion thereof. The invention also provides a treatment fluid for use in a subterranean formation penetrated by a wellbore, the treatment fluid comprising: water; diutan; and a sufficient amount of salt to increase the density of the treatment fluid to at least 8.

Abstract: A method for enhancing the production of liquid hydrocarbons from oil-wet, fractured reservoirs comprising injecting a surfactant solution into the reservoir, pressurizing the reservoir, maintaining the pressure, and recovering liquid hydrocarbons. In an embodiment, the method comprises closing production wells for a period to maintain reservoir pressure and surfactant exposure within the matrix.

Abstract: A microemulsion system is disclosed which comprises a solvent subsystem, a co-solvent subsystem and a surfactant subsystem comprises at least one monoalkyl branched propoxy sulfate anionic surfactant, where the microemulsion system are useful in drilling, producing, remediation, and fracturing application to reduce water blocks and water blocking in formation of a producing formation.

Abstract: An optimum salinity profile in surfactant/polymer flooding from formation water to post-flush drive that leads to the highest oil recovery factor is shown. The optimum salinity determined from core-flooding experiments is preferably used in the surfactant slug. The surfactant slug is protected from deterioration by the injection of cushion slugs immediately before and after the injection of the surfactant slug in a reservoir wherein the cushion slugs have the same salinity or about the same salinity as the surfactant slug. According to embodiments, a salinity lower than the lowest salinity of Type III, Csel, is used in the post-flush drive, while formation water could be of any salinity.

Abstract: A system for producing oil and/or gas from an underground formation comprising a first array of wells dispersed above the formation; a second array of wells dispersed above the formation; wherein the first array of wells comprises a mechanism to inject a miscible enhanced oil recovery formulation into the formation while the second array of wells comprises a mechanism to produce oil and/or gas from the formation for a first time period; and wherein the second array of wells comprises a mechanism to inject a remediation agent into the formation while the first array of wells comprises a mechanism to produce the miscible enhanced oil recovery formulation from the formation for a second time period.

Abstract: A method of oil production is provided. The method includes forming an injection well and a production well. The method also includes pumping a mixture of oxygen and carbon dioxide (CO2) into the injection well. In addition, the method also includes minimizing gravity segregation by providing a relatively high level of CO2 in the mixture.

Abstract: An oil recovery method employing amphoteric surfactants with the steps of: a) Injecting into one or more injection wells an aqueous solution containing a mixture of amphoteric surfactants containing mixture of amphoteric surfactants having a hydrocarbyl chain length between 8 and 26 and certain degree of unsaturation, and b) recovering the oil from one or more producing wells. The aqueous injection fluid may also contain one or more of the following: a thickening agent, an alkali, a co-solvent.

Abstract: A method for enhancing oil recovery includes the step of providing a subsurface reservoir containing hydrocarbons therewithin. A wellbore is provided in fluid communication with the subsurface reservoir. A surfactant-polymer solution is formed for injection into the reservoir. The surfactant-polymer solution is formed by mixing a composition with at least one surfactant, at least one polymer, and at least one co-solvent or co-surfactant such that the surfactant-polymer solution is clear and aqueous stable. The surfactant-polymer solution is injected through the wellbore into the reservoir. A chaser solution is formed for injection into the reservoir. The chaser solution has an additional predetermined quantity of the co-solvent or co-surfactant. The chaser solution is injected through the injection wellbore into the reservoir to increase the production of hydrocarbons from the reservoir while maintaining the clear and aqueous stability of the surfactant-polymer solution.

Abstract: This invention provides a fine bubble generating apparatus which can efficiently generate fine bubbles on the nanometer level. This apparatus comprises a cylindrical member (40) having a cylindrical inner peripheral surface, a first end wall member (42) configured to close one end of the cylindrical member, and a second end wall member (44) configured to close the other end of the cylindrical member. The cylindrical member (40) and the first and second end wall members (42) and (44) define a fluid swirling chamber (46). The cylindrical member has a fluid inlet hole (48) at a position close to the second end wall member (44) to supply a gas-liquid mixed fluid in the tangential direction of the peripheral surface of the fluid swirling chamber (46). The second end wall member has a fluid outlet hole (50) extending therethrough along the center axis of the inner peripheral surface of the fluid swirling chamber.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: A method of treating a subterranean formation penetrated by a well bore including: (a) preparing a fracturing fluid containing a mixture resulting from: (I) providing a water-in-oil emulsion composition that includes: (i) 5% to 99% by weight of a water-in-oil emulsion polymer comprising a polymer or copolymer containing repeat units from an acrylamide monomer; (ii) 0.5% to 90% by weight of a carrier solvent; and (iii) 0 to 90% by weight of a fluidizing agent; and adding (iv) 0.1% to 10% by weight of one or more inorganic microparticles, where the total of all components is 100% by weight; and (II) adding the water-in-oil emulsion composition to water; and (b) contacting the subterranean formation with the fracturing fluid.

Abstract: Single phase microemulsions (SPMEs) and in situ-formed microemulsions may be used to clean up and remove non-polar materials from reservoir production zones of oil and gas wells. This clean up occurs by solubilization of the non-polar material into the microemulsion when the treatment fluid contacts the non-polar material. An in situ microemulsion may be formed when one or more surfactant and a polar phase (e.g. water or brine), and eventually some small amount of organic phase, contacts the reservoir formation and solubilizes the non-polar material encountered in the porous media. The microemulsions are effective for removing the formation damage caused by non-polar materials which include, but are not necessarily limited to oil-based mud, synthetic-based mud, paraffins, asphaltenes, emulsions, slugs, and combinations thereof.

Abstract: This invention involves a process for recovering oil from a subterranean reservoir where an injection fluid containing one or more primary surfactants of the structure below along with one or more co-surfactants, solvent and optionally a viscosifier and one or more alkalis injected into one or more injection wells and the oil is recovered from one or more producing wells. where: Ar=any aromatic moiety, M=H, Na, K, Ca, Mg, NH4, or an amine, m+n=10 to 28, R, R?, R?=separately and independently H, CH3, branched alkyl having 2-30 carbons, linear alkyl having 2-30 carbons, CH3(CH2)mCH(CH2)nSO3M, O(CH2CH2O)xH, O(CHCH3CH2O)xH, or O(CH2CH2O)aO(CHCH3CH2O)bH, x=1 to 30, y=1 to 30, a+b=1 to 30. The primary surfactant may be prepared in the acid form at one location and shipped as a neat product to be formulated into the final injection brine at or near the point of injection.

Abstract: There is a method for enhancing the recovery of oil from a reservoir. The method has the step of a) introducing a flooding fluid into the reservoir and b) extracting the oil through a wellbore at a location different than the point of introduction of the flooding fluid into the reservoir. The flooding fluid has water and an amount of one or more non-polymeric viscoelastic surfactants sufficient to provide an interfacial surface tension of about 1 mNm or less and a viscosity of about 10 cps or more. The one or more surfactants is selected from the group of one or more cationic surfactants, one or more zwitterionic surfactants, one or more amphoteric surfactants, one or more anionic surfactants, and combinations thereof.

Abstract: A method for treating a portion of a subterranean formation or a proppant pack is provided. In general, the method comprises the steps of: (A) forming or providing a treatment fluid comprising: (i) water; (ii) a chelating agent capable of forming a heterocyclic ring that contains a metal ion attached to at least two nonmetal ions; and (iii) a viscosity-increasing agent; and (B) introducing the treatment fluid into the wellbore under sufficient pressure to force the treatment fluid into the matrix of the formation or the proppant pack.

Abstract: A method of treating a hydrocarbon-containing formation including injecting a scale inhibiting well treating fluid into a well, wherein the well treating fluid includes a self-diverting acid that includes about 1% to 20% by volume of at least one viscoelastic surfactant selected from a family of compounds described by where R3 contains at least 10 carbon atoms, p=1-6, R2 contains 1-6 carbon atoms and R1 contains 1-6 carbon atoms; and up to about 20% by weight scale inhibitor.

Abstract: Mixtures of at least one nonionic surfactants and at least one ionic surfactant together with a gas create foams to aid the removal of produced hydrocarbon fluids from gas wells and pipelines. The foam-forming composition has superior performance in unloading liquids.

Abstract: A process for the recovery of oil from subterranean reservoirs by injecting an aqueous fluid containing from about 0.05 to about 2.0% by weight of a bi-functional surfactant or a mixture of surfactants containing one or more of the following structures; Optionally the aqueous fluid may contain mixtures of individual surfactants having carboxylic, and sulfonate or sulfate functionalities. The remainder of the composition includes water or brine, a cosolvent and optionally a viscosity control agent, and optionally an alkali.

Abstract: A process for recovering oil by injecting into a subterranean oil-bearing reservoir through one or more injection wells, an aqueous solution containing one or more amphoteric alkyl amido betaine surfactants that form a viscoelastic gel reducing interfacial tension and increasing the viscosity of the injection fluid simultaneously, displacing the solution into the reservoir, and recovering the oil from one or more production wells. These viscoelastic gels are tolerant to electrolytes and multivalent cations. They are shear reversible and adsorbed little onto the reservoir. Their viscosity is reduced when contacting certain hydrocarbons but remains high when contacting water or brine. This allows the fluid to preferentially penetrate the oil-bearing portions of the formation and resulting additional oil recovery.

Abstract: The present invention is directed to the use of electromagnetic radiation, acoustic energy, and surfactant injection to recover hydrocarbon-containing materials from a hydrocarbon-bearing formation.

Abstract: Methods of steam flooding for stimulating hydrocarbon production are provided. In general, the methods comprise the steps of: (A) injecting a mutual solvent preflush fluid capable of dissolving oil into the near-wellbore region of at least a portion of a wellbore; (B) injecting an aqueous preflush fluid further comprising a surfactant capable of oil-wetting silica; (C) injecting a treatment fluid into the near-wellbore region, wherein the treatment fluid comprises a curable resin, and wherein: (i) when injected, the curable resin is in an uncured state; and (ii) after being cured, the curable resin is stable up to at least 350° F. (177° C.); and (D) driving steam to break through the near-wellbore region.

Abstract: A method for increasing the foam stability of foams made with cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of an amphiphilic polymeric foam stabilizer containing at least one portion that is a partially hydrolyzed polyvinyl ester or partially hydrolyzed polyacrylate. The foam stabilizer allows foams to be used at temperatures at which the unfoamed fluids would not have stable viscosity, and allows use of lower viscoelastic surfactant concentrations in the liquid phase. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: An oil-in-water-in-oil emulsion (O/W/O) comprising a first oil-in-water emulsion dispersed in a second oil, and a method of preparing the same. The O/W/O emulsion can be used as a drive fluid in an enhanced oil recovery process. The O/W/O emulsion of this invention may also be used as a lubricant, and has the beneficial property of being resistant to shear forces.

Abstract: An oil recovery method employing amphoteric surfactants with the steps of: a) Injecting into one or more injection wells an aqueous solution containing a mixture of amphoteric surfactants containing mixture of amphoteric surfactants having a hydrocarbyl chain length between 8 and 26 and certain degree of unsaturation, and b) recovering the oil from one or more producing wells. The aqueous injection fluid may also contain one or more of the following: a thickening agent, an alkali, a co-solvent.

Abstract: An apparatus and method for injecting surfactant into a well for coal bed methane (CBM) recovery, tight sand gas extraction, and other gas extraction techniques provides for the mixing of surfactant and water near the downhole end of the well, maximizing water removal for gas recovery. The apparatus may include a check valve that feeds a nozzle to atomize the spray of surfactant into the well production tube. Surfactant is not sprayed directly into the formation, thereby protecting the formation from damage and recovering surfactant even in the case where water is not present. The capillary tube feeding surfactant to the check valve may be placed externally to the production tube to facilitate ease of cleaning and clearing of the production tube.

Abstract: Methods of steam flooding for stimulating hydrocarbon production are provided. In general, the methods comprise the steps of: (A) injecting a mutual solvent preflush fluid capable of dissolving oil into the near-wellbore region of at least a portion of a wellbore; (B) injecting an aqueous preflush fluid further comprising a surfactant capable of oil-wetting silica; (C) injecting a treatment fluid into the near-wellbore region, wherein the treatment fluid comprises a curable resin, and wherein: (i) when injected, the curable resin is in an uncured state; and (ii) after being cured, the curable resin is stable up to at least 350° F. (177° C.); and (D) driving steam to break through the near-wellbore region.

Abstract: An aqueous viscoelastic surfactant (VES) fluid foamed or energized with carbon dioxide, in which the VES is more compatible with the carbon dioxide, is made by the addition of one or more than one synergistic co-surfactant. The synergist co-surfactant includes quaternary amines and ethoxylated carboxylates having a hydrophobic chain shorter than the hydrophobic chain of the VES. Improved compatibility is evidenced for a given surfactant concentration either by formation and maintenance of a foam under conditions at which the foam could not otherwise have been formed or maintained, or by either higher viscosity of the foamed fluid at a given temperature or longer foam life at a given temperature or a higher temperature at which useful fluid viscosity can be generated or maintained for a useful time. The aqueous carbon dioxide foamed fluids may be used in acidizing, acid fracturing, gravel packing, diversion, and well cleanout.

Abstract: A method for selectively blocking water inflow from a water-producing formation of a hydrocarbon well provides for injecting into the well a controlled-gelation aqueous solution containing a hydrophobically-aggregating gelling agent and an effective amount of an inhibitor which suppresses hydrophobic aggregation of the gelling agent. The gelling agent is a water soluble-copolymer comprising hydrophilic and hydrophobic monomer units. The inhibitor is soluble in water so that when the controlled-gelation aqueous solution contacts aqueous media the inhibitor disperses so that gelation occurs and the formation is blocked. However, the inhibitor is substantially insoluble in hydrocarbons so that when the controlled-gelation aqueous solution contacts hydrocarbon media the inhibitor continues to suppress said hydrophobic aggregation and gelation is suppressed. The solution may be used to control the flow of water into oil wells, making it possible to reduce the water cut.

Abstract: Compositions containing surfactant compounds according to formula (I) ROCH2CH(OH)CR1R2ZCR1R2CH(OH)CH2OR,??(I) wherein Z is S, SO, or SO2, can have a range of equilibrium and/or dynamic surface tensions and a range of foaming performance attributes, depending upon the particular values of Z, R, R1, and R2. The compounds of formula (I) may be prepared by a process that includes reaction of a sulfide source such as a metal sulfide or bisulfide with an alkyl glycidyl ether. The compounds may be useful in any of a broad range of applications requiring the use of a surfactant.