Abstract: A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid comprising at least one polymerizable monomer and at least one antistatic agent to control build up of static charge. The second fluid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

Abstract: Methods of improving shear recovery time of viscoelastic surfactant fluid systems are described, one method involving providing a viscoelastic surfactant fluid system comprising a major portion of a surfactant and a rheology enhancer in a concentration sufficient to shorten shear recovery time of the fluid system compared to shear recovery time of the fluid system absent the rheology enhancer, the rheology enhancer selected from aromatic sulfonates having a molecular weight of at least 500; and injecting the fluid system down a well. The rheology enhancer may be a lignosulfonate derived from wood pulping. Viscoelastic surfactant systems including the rheology enhancer are also described.

Abstract: A method of modifying the rheological properties of a fluid include adding to the fluid at least one polymer that is the reaction product of at least one water soluble, allyic monomer and at least one structure inducing agent. The polymer is adapted to increase the viscosity of the fluid and to impart non-Newtonian characteristic to the fluid. Non-Newtonian characteristics are, for example, evidenced by the fluid exhibiting an n value of less than 1 upon addition of the polymer as determined by the equation ?=K?n, wherein ? is shear stress, ? is and shear rate and K is a flow consistency index.

Abstract: A method of forming a subterranean well and a method of reducing the swelling of shale clay during the drilling of the subterranean well. The method features the use of a water based drilling fluid, wherein the drilling fluid is formulated to include: an aqueous based continuous phase; a weight material; an optional shale hydration inhibition agent and a shale encapsulator. The shale encapsulator has the formula: in which x and y have a value so that the molecular weight of the cation is in the range of about 10,000 to about 200,000 AMU; A is selected from C1-C6 alkyl, C2-C6 ether or C2-C6 amide; R, R?and R?are independently selectable C1-C3 alkyl; and B?is a charge balancing anion to the quaternary amine. The shale hydration inhibition agent and the shale encapsulator may be present in sufficient concentrations to reduce the swelling of the subterranean formation in the presence of water.

Abstract: The present invention relates to novel aqueous wellbore treatment fluids containing a gas component, a heteropolysaccharide, an electrolyte, and a surfactant, wherein the fluids may further include an organoamino compound. The fluids exhibit good rheological properties at elevated temperatures. Methods of use of fluids comprising at least an aqueous medium, a gas component, a heteropolysaccharide and a surfactant for hydraulically fracturing, well cleanup and gravel packing operations, are also disclosed.

Abstract: An ionic liquid may be used to inhibit the swelling and/or disintegration of clay in a subterranean formation. A subterranean clay-containing formation may be treated with the ionic liquid by contacting the formation with a well treatment composition containing the ionic liquid dispersed or dissolved in a carrier fluid. Damage to the formation caused by contact with the well treating composition is reduced or substantially eliminated.

Abstract: The invention concerns an aqueous viscoelastic fracturing fluid for use in the recovery of hydrocarbons. According to the invention, the fluid comprises a cleavable viscoelastic surfactant and a hydrophobically-modified polymer, wherein the cleavable surfactant comprises a head group and a hydrophobic tail of at least 18 carbon atoms connected through a degradable acetal, amide, ether or ester bond and wherein the concentration of the hydrophobically-modified polymer is comprised between its overlap concentration c* and its entanglement concentration ce.

Abstract: A sterically hindered quaternary ammonium composition is prepared by contacting a solvent having hydroxyl functionality, a halohydrin, and a sterically hindered tertiary amine, under reaction conditions sufficient to produce a sterically hindered quaternary ammonium compound. The reaction proceeds with excellent yield. The resulting compounds are particularly useful for inhibiting formation of hydrates in hydrocarbon reservoirs and pipelines. Novel compositions of matter include sterically hindered quaternary ammonium compounds conforming to the formulas C27H58XNO2 and C29H63XNO2, wherein X is a halogen.

Abstract: Viscoelastic compositions are disclosed herein containing an effective amount of one or more random or structurally defined polycationic quaternary ammonium compounds for controlling the viscoelasticity of the composition. In one aspect, the present technology provides polycationic quaternary ammonium compounds that comprise bis-quaternary compound. The bis-quaternary compounds of the present technology can be symmetric or dissymmetric. In another aspect, the present technology provides viscoelastic well bore treatment fluids comprising water, and at least one polycationic quaternary ammonium compound that comprises a bis-quaternary compound. In another aspect, the present technology provides polycationic carboxylates. Preferred viscoelastic compositions of the present technology maintain viscoelasticity at a temperature greater than about 80° C., preferably greater than about 100° C. or 110° C.

Abstract: A method of reducing the viscosity of oil-based drilling fluids and well service fluids at low temperatures and a thinner compound for use in such drilling fluids and well service fluids is disclosed. The method comprises adding to said drilling fluids or well service fluids a thinner having the formula: R—(C2H4O)n(C3H6O)m(C4H8O)k-H where R is a saturated or unsaturated, linear or branched alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging form about 0 to about 10, and k is a number ranging from about 0 to about 10.

Abstract: Corrosion and gas hydrate inhibitors having improved water solubility and increased biodegradability The invention thus provides the use of compounds of the formula (1) where R1, R2 are each independently C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, R3 is C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, —CHR5—COO? or —O?, R4 is M, hydrogen or an organic radical which optionally contains heteroatoms and has from 1 to 100 carbon atoms, B is an optionally substituted C1- to C10-alkylene group, D is an ethylene group substituted by an organic radical having from 1 to 600 carbon atoms, X, Y are each independently O or NR6, R5, R6 are each independently hydrogen, C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, and M is a cation as corrosion and gas hydrate inhibitors, and also the compounds of formula 1.

Abstract: Viscoelastic compositions are disclosed herein containing an effective amount of one or more random or structurally defined polycationic quaternary ammonium compounds for controlling the viscoelasticity of the composition. In at least one aspect, the present technology provides polycationic quaternary ammonium compounds comprising dissymmetric bis-quaternary compounds. In another aspect, the present technology provides viscoelastic compositions comprising polycationic quaternary ammonium compounds that comprise dissymmetric bis-quaternary compounds. In yet another aspect, the present technology provides polycationic quaternary ammonium compounds comprising a carboxylate functional polycationic quaternary ammonium compound. Preferred viscoelastic compositions of the present technology maintain viscoelasticity at a temperature greater than about 80° C., preferably greater than about 100° C. or about 110° C.

Abstract: Viscoelastic compositions are disclosed herein containing an effective amount of one or more random or structurally defined polycationic quaternary ammonium compounds for controlling the viscoelasticity of the composition. In at least one aspect, the present technology provides polycationic quaternary ammonium compounds comprising bis-quaternary compounds. In another aspect, the present technology provides viscoelastic compositions that comprise polycationic quaternary ammonium compounds comprising bis-quaternary compounds. Preferred viscoelastic compositions of the present technology maintain viscoelasticity at a temperature greater than about 80° C., preferably greater than about 100° C. or about 110° C. when the amount of the one or polycationic quaternary compounds is less than about 10% by weight based on the total weight of the composition.

Abstract: A surfactant blend for servicing wells includes a first non-ionic surfactant having a hydrophilic-lipophilic balance of between about 10 and about 15; a second non-ionic surfactant having a hydrophilic-lipophilic balance of between about 2 and about 6; and an anionic surfactant.

Abstract: The invention concerns an aqueous viscoelastic fracturing fluid for use in the recovery of hydrocarbons. According to the invention, the fluid comprises a viscoelastic surfactant and a hydrophobically-modified polymer wherein the concentration of the hydrophobically-modified polymer is comprised between its overlap concentration c* and its entanglement concentration ce.

Abstract: Methods are provided including methods of treating a well bore with drilling fluids comprising organophilic clays treated with quaternary ammonium surfactants having at least two amide linkages. In some embodiments, the methods comprise: providing a drilling fluid comprising a nonaqueous phase and an organophilic clay treated with a quaternary ammonium surfactant having at least two amide linkages; and placing at least a portion of the drilling fluid into the well bore. In other embodiments, the methods comprise combining an organophilic clay with a quaternary ammonium surfactant having at least one amide linkage to form a mixture, and combining the mixture with a fluid comprising a nonaqueous phase to form a drilling fluid. Additional methods are also provided.

Abstract: Viscoelastic surfactant based aqueous fluid systems useful as thickening agents in various applications, e.g. to suspend particles produced during the excavation of geologic formations. The surfactants are zwitterionic/amphoteric surfactants such as dihydroxyl alkyl glycinate, alkyl ampho acetate or propionate, alkyl betaine, alkyl amidopropyl betaine and alkylimino mono- or di-propionates derived from certain waxes, fats and oils. The thickening agent is used in conjunction with an inorganic water-soluble salt or organic additive such as phthalic acid, salicylic acid or their salts.

Abstract: Foamed treatment fluids comprising water, a gas, and a foaming and foam stabilizing surfactant mixture comprising an alkali salt of an alkyl ether sulfate, wherein the alkali salt of the alkyl ether sulfate comprises an alkali salt of a C6-10 alkyl ether sulfate, and an alkali salt of a C4 alkyl ether sulfate, an alkyl amidopropyl amphoteric surfactant selected from the group consisting of an alkyl amidopropyl hydroxysultaine, an alkyl amidopropyl betaine, and combinations thereof, and an alkyl amidopropyl dimethylamine oxide. Methods comprising providing the foamed treatment fluid and introducing the foamed treatment fluid into a subterranean formation.

Abstract: A method for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a rheology enhancer selected from partially hydrolyzed polyvinyl ester and partially hydrolyzed polyacrylates. The rheology enhancer also increases fluid viscosity and very low rheology enhancer concentration is needed. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: A wellbore servicing composition comprising a metal oxide, a soluble salt and a viscosifier wherein the viscosifier comprises a quaternary amide, a quaternary amide ester, or combinations thereof. A wellbore servicing composition comprising magnesium oxide, a chloride or phosphate salt and a quaternary material. A wellbore servicing composition comprising magnesium oxide, magnesium chloride, and a quaternary material wherein the quaternary material comprises a quaternary amide, a quaternary amide ester or combinations thereof and wherein the quaternary material is present in an amount of from about 0.05 wt. % to about 5 wt. % and a plot of the composition's plastic viscosity as a function of the amount of quaternary material is about linear.

Abstract: An improved method and fracturing fluid for hydraulic fracturing of a subterranean formation, the fracturing fluid including a surfactant, a water soluble or dispersible anionic organic salt, an acid and a low molecular weight organic solvent.

Abstract: Among many things, in some embodiments, dual-function additives that enhance fluid loss control and the stability of viscoelastic surfactant fluids, and their associated methods of use in subterranean formations, are provided. In one embodiment, the methods comprise: providing a viscoelastic surfactant fluid that comprises an aqueous base fluid, a viscoelastic surfactant, and a dual-function additive that comprises a soap component; and introducing the viscoelastic surfactant fluid into at least a portion of a subterranean formation.

Abstract: An acidic viscoelastic surfactant fluid composition is formulated with an acid, for example hydrochloric acid, a cationic surfactant, for example a quaternary amine, and a break-enabling salt, for example NH4Cl. The fluid composition has low viscosity as formulated, undergoes an increase in viscosity as the acid is consumed when it reacts with an acid-reactive material, and returns to approximately the initial viscosity as the last of the acid is consumed. The fluid composition is used as a diverting fluid or as the main treatment fluid in oilfield treatments such as matrix acidizing and acid fracturing.

Abstract: A corrosion inhibitor composition comprising one or more organic solvents, one or more corrosion inhibitor intermediates and about 0.1 to about 20 weight percent of one or more iodide salts dissolved in said composition and methods of using the corrosion inhibitor composition in acid fracturing and matrix acid stimulation of subterranean formations.

Abstract: A method for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of an amphiphilic polymeric rheology enhancer containing at least one portion that is a partially hydrolyzed polyvinyl ester or partially hydrolyzed polyacrylate. The rheology enhancer also increases fluid viscosity and very low rheology enhancer concentration is needed. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: A method and an amide composition used therein for inhibiting, retarding, mitigating, reducing, controlling and/or delaying formation of hydrocarbon hydrates or agglomerates of hydrates. The method may be applied to prevent or reduce or mitigate plugging of conduits, pipes, transfer lines, valves, and other places or equipment where hydrocarbon hydrate solids may form under the conditions. At least one amide compound is added into the process stream, where the compound may be mixed with another compound selected from amino alcohols, esters, quaternary ammonium, phosphonium or sulphonium salts, betaines, amine oxides, other amides, simple amine salts, and combinations thereof.

Abstract: A method for increasing the rate of shear rehealing of fluids made with cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a rheology enhancer package containing, for example a polyethylene glycol-polypropylene glycol block copolymer and a polynaphthalene sulfonate. The rheology enhancer package allows viscoelastic surfactant fluids to be used at lower viscoelastic surfactant concentrations in certain applications, for example certain oilfield treatments, for example fracturing and gravel packing. Preferred surfactants are betaines and quaternary amines.

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: This invention relates to the use of alkyl amido quaternary ammonium salts, and formulations thereof, as thickening agents in aqueous based fluids, especially those used in oil field applications. The quaternary ammonium salts of the present invention exhibit improved gelling characteristics.

Abstract: An aqueous drilling fluid which contains a diquaternary ammonium cation functionalized clay which provides a substantially constant rheological profile, with respect to salinity, when incorporated into well drilling fluids. A further aspect of the invention is a well drilling process which employs a drilling fluid containing the diquaternary ammonium cation functionalized clay described hereafter. A clay/organic chemical composition that comprises: (a) montmorillonite clay and (b) one or more diquaternary ammonium compounds.

Abstract: A scale dissolver fluid for dissolving scale in a subterranean hydrocarbon-bearing formation comprises an effective amount of a scale dissolver formulation and an effective amount of a surfactant for controlling the viscosity of the fluid. In use, formation hydrocarbons act on the surfactant to reduce the viscosity of the fluid so that the fluid selectively invades a hydrocarbon-bearing zone of the formation.

Abstract: An acidic viscoelastic surfactant fluid composition is formulated with an acid, for example hydrochloric acid, a cationic surfactant, for example a quaternary amine, and a break-enabling salt, for example NH4Cl. The fluid composition has low viscosity as formulated, undergoes an increase in viscosity as the acid is consumed when it reacts with an acid-reactive material, and returns to approximately the initial viscosity as the last of the acid is consumed. The fluid composition is used as a diverting fluid or as the main treatment fluid in oilfield treatments such as matrix acidizing and acid fracturing.

Abstract: A well service fluid comprising one or more anionic viscoelastic surfactants and one or more polymers is described. The fluids can contain an aqueous or non-aqueous fluid and/or a buffer for adjusting the pH of the fracturing fluid. The well service fluid can be used as a fracturing fluid in order to control water production from a well, while simultaneously increasing the oil production from the well.

Abstract: The invention provides the use of compounds of the formula (1) where R1, R2 are each independently C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, R3 is C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, —CHR6COO? or —O?, A is a C2- to C4-alkylene group, B is a C1- to C10-alkylene group, X is O or NR7 R6, R7 are each independently hydrogen, C1- to C22-alkyl, C2- to C22-alkenyl, C6- to C30-aryl or C7- to C30-alkylaryl, R4 is a C1- to C50-alkyl, C2- to C50-alkenyl radical, C6- to C50-aryl or C7- to C50-alkylaryl, R5 is hydrogen, —OH or a C1- to C4-alkyl radical, n, m are each independently a number from 0 to 30, x is a number from 1 to 6, as corrosion and gas hydrate inhibitors, and also the compounds of formula 1.

Abstract: Composition and method for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a co-gelling agent selected from triblock oligomeric compounds having hydrophilic (for example polyether) and hydrophobic (for example alkyl) portions. The co-gelling agent also increases fluid viscosity and very low co-gelling agent concentration is needed. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

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 sterically hindered quaternary ammonium composition is prepared by contacting a solvent having hydroxyl functionality, a halohydrin, and a sterically hindered tertiary amine, under reaction conditions sufficient to produce a sterically hindered quaternary ammonium compound. The reaction proceeds with excellent yield. The resulting compounds are particularly useful for inhibiting formation of hydrates in hydrocarbon reservoirs and pipelines. Novel compositions of matter include sterically hindered quaternary ammonium compounds conforming to the formulas C27H58XNO2 and C29H63XNO2, wherein X is a halogen.

Abstract: A thermoviscoelastic system (TVE) fluid useful in a well treatment method can include a hydrophobically-modified polymer and a viscoelastic surfactant (VES) in an aqueous medium, wherein the polymer has a lower critical solution temperature (LCST). The polymer can have water solubility for preparation below the LCST, and the TVE has a low viscosity for pumping down a well bore in communication with a subterranean formation. When the TVE is heated above the LCST, interaction between the hydrophobic groups of the polymer and the VES form a cross-linked network to increase the viscosity to transport proppant into a fracture. The thickened TVE can have a low leak-off rate, optionally including colloidal particles or other fluid loss control agent, and can be broken by contact with hydrocarbons as during flowback from the reservoir.

Abstract: This Invention relates to methods of treating a subterranean hydrocarbons reservoir comprising contacting the formation with a treating fluid comprising an aqueous solution, an acid, a surfactant acting as gelling agent essentially consisting of erucylamidopropyl betaine (or a protonated/deprotonated homolog or salt thereof). The treating fluid may further comprise a lower n-alcohol for improved temperature stability.

Abstract: The present invention relates to viscoelastic fluids that contain nanotube structures that may be used advantageously as oilfield stimulation fluids in many different applications, most particularly as a fracturing fluid. Viscoelastic fluid compositions of the present invention include an aqueous medium, a viscoelastic surfactant, an organic or inorganic acids, or salt thereof, organic acid salts, inorganic salts, and a nanotube component. The invention is also called to a methods of treating a subterranean well bores in which the viscoelastic fluid is injected into the wellbore to perform operations such as fracturing, drilling, acid fracturing, gravel placement, removing scale, matrix acidizing, and removing mud cake. Further, a method of preparing a nanotube viscoelastic fluid comprising the steps of effectively mixing a carbon nanotube component into a viscoelastic fluid, and sonicating the mixture in order to incorporate the carbon nanotube component is claimed.

Abstract: Viscoelastic surfactant based aqueous fluid systems useful as thickening agents in various applications, e.g. to suspend particles produced during the excavation of geologic formations. The surfactants are zwitterionic/amphoteric surfactants such as dihydroxyl alkyl glycinate, alkyl ampho acetate or propionate, alkyl betaine, alkyl amidopropyl betaine and alkylimino mono- or di-propionates derived from certain waxes, fats and oils. The thickening agent is used in conjunction with an inorganic water-soluble salt or organic additive such as phthalic acid, salicylic acid or their salts.

Abstract: A packer fluid is provided for use with a wellbore fluid in an annulus or casing bore, having an aqueous portion which contains additives for preventing corrosion, microbiological activity, salt and scale deposition, and an environmentally-acceptable capping fluid which resides at a top of the wellbore to act as freeze protection and as thermal insulation in a the frost penetration layer. The additives in the packer fluid are particularly selected to exist in the aqueous additive fluid and in the wellbore fluid and to be substantially immiscible with the capping fluid and thereby prevent significant migration of the additives into the capping fluid which would compromise its environmental acceptability.

Abstract: A fluid-loss pill that includes a brine solution and an effective amount of a viscoelastic surfactant is disclosed. The viscoelastic surfactant preferably includes at least one compound selected from the family of compounds described by where R1, R2, R3, R4 and R5 are carbon atom or carbon chains, saturated or unsaturated, single or multiple unsaturation, straight chain, branched chain or cyclic including aromatic or alicyclic groups, and R1 contains 16–26 carbon atoms, R2 contains 2–10 carbon atoms, R3, R4 and R5 contains 1–6 carbon atoms. Methods of treating a well that include injecting fluid-loss pill into a well to control lost-circulation or to kill a well.

Abstract: A water based drilling fluid for use in drilling a subterranean well through a subterranean formation that swells in the presence of water, the drilling fluid is formulated to include: an aqueous based continuous phase; a weigh material; a shale encapsulator and an optional shale hydration inhibition agent. The shale encapsulator has the formula: which x and y have a value so that the molecular weight of the cation is in the range of about 10,000 to about 200,000 AMU; A is selected from C1–C6 alkyl, C2–C6 ether or amide; R, R? and R? are independently selectable C1–C3 alkyl; and B? is a charge balancing anion to the quaternary amine. The shale encapsulator and the optional shale hydration inhibition agent may be present in sufficient concentrations to reduce the swelling of the subterranean formation in the presence of water.

Abstract: The present invention relates to an additive, and its use for inhibiting nucleation, growth and agglomeration of gas hydrates by adding an effective amount of an inhibitor to a multiphasic mixture which tends to hydrate formation and consists of water, gas and optionally condensate, or to a drilling fluid which tends to form gas hydrates. Said inhibitor comprising dialkoxylated quaternary ammonium compounds of the formula 1 where R1, R2 are each independently radicals of the formulae—(B)—(O—A)n—O—CO—R5 or —(A—O)n—(C)—CO—O—R5, R3 is C1- to C30-alkyl or C2- to C30-alkenyl, R4 is an organic radical which optionally contains heteroatoms and has from 1 to 100 carbon atoms, R5 is an alkyl or an alkenyl, n is a number from 1 to 20, A is an alkylene group, B is an alkylene group, C is a C1- to C6-alkylene group and X is an anion, are used as gas hydrate inhibitors.

Abstract: The present invention relates to acidic treatment fluids that comprise an acid fluid and an ester-containing quaternary ammonium compound (“esterquat”) and methods of their use. One embodiment of the present invention provides a method of inhibiting metal corrosion during a subterranean treatment operation comprising using an acidic treatment fluid comprising an acidic fluid and an esterquat. Another embodiment of the present invention provides a method of reducing sludge formation during a subterranean treatment operation formation comprising the step of using an acidic treatment fluid comprising an acidic fluid and an esterquat. Another embodiment of the present invention provides a method of inhibiting the formation of emulsions during a subterranean treatment operation comprising using an acidic treatment fluid comprising an acidic fluid and an esterquat. Another embodiment of the present invention provides an acidic subterranean treatment fluid comprising an acidic fluid and an esterquat.

Abstract: An oil-based demulsifying formulation which can be used in the treatment of drains bored in oil-based mud, non ecotoxic and optimally compatible with formation fluids, comprises at least one wetting agent chosen from anionic surfacetants and at least one demulsifier (or “emulsion breaker”) chosen from copolymers of ethylene oxide and propylene oxide, alcohol or phenol derivatives with alkoxylated or polyalkoxylated chain formations, polyalkyleneglycols, polyamines, alkoxylated or polyalkoxylated derivatives of amines, quaternary ammonium salts, quaternized alkanolamine esters, alkyl esters of fatty acids or natural oils, possible alkoxylated or polyalkoxylated, and silicated derivatives such as polysiloxanes.

Abstract: A scale dissolver fluid for dissolving scale in a subterranean hydrocarbon-bearing formation comprises an effective amount of a scale dissolver formulation and an effective amount of a surfactant for controlling the viscosity of the fluid. In use, formation hydrocarbons act on the surfactant to reduce the viscosity of the fluid so that the fluid selectively invades a hydrocarbon-bearing zone of the formation.

Abstract: A viscous aqueous high density well treatment fluid composition stable at high temperature containing a surfactant and inorganic salts is described. Methods of preparing the fluid and increasing the stability and viscosity of the fluid are given. The fluid is useful for wellbore cleanout, hydraulic fracturing, gravel packing, completion, acid diversion, lost circulation reduction, well killing, cementing, selective water shutoff, and fracture fluid diversion.

Abstract: Viscoelastic surfactants are described for use in aqueous systems to generate thickened fluids. The surfactants are alkyl amidoamine salts of inorganic acids and/or organic acids. The fluids may also contain inorganic salts, organic salts or mixtures thereof. Additionally, the fluids may contain a co-surfactant. These fluids are particularly useful in oilfield applications such as hydraulic fracturing, gravel packing, drilling, completion, etc. Viscoelastic fluids of the invention are also useful in industrial and consumer product fluid applications as rheology control agents.