Abstract: A composition and method for removing a filter cake from a horizontal wellbore in a subterranean formation using a composition containing a inorganic or organic acidic material, a cationic fluorocarbon surfactant, an alkyl alcohol, water optionally containing ammonium chloride and at least one of an alkyl polyglycoside and a betaine surfactant to produce a stable foam used to remove filter cake from a horizontal wellbore.

Abstract: A composition and method for removing a filter cake from a horizontal wellbore in a subterranean formation using a composition containing a inorganic or organic acidic material, a cationic fluorocarbon surfactant, an alkyl alcohol, water optionally containing ammonium chloride and at least one of an alkyl polyglycoside and a betaine surfactant to produce a stable foam used to remove filter cake from a horizontal wellbore.

Abstract: In one embodiment, the present invention provides a drilling fluid composition that comprises a surfactant-free emulsion comprising an oleaginous fluid, a fluid that is at least partially immiscible with the oleaginous fluid, and emulsion facilitating particles. In another embodiment, the present invention provides a method of treating a subterranean formation comprising providing a treatment fluid that comprises a surfactant-free emulsion, the surfactant-free emulsion comprising an oleaginous fluid, a fluid that is at least partially immiscible with the oleaginous fluid, and emulsion facilitating particles; and treating the subterranean formation.

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: N,N-Dialkylpolyhydroxyalkylamines may be made by the reductive alkylation of an N-alkylpolyhydroxyalkylamine with an aldehyde or ketone, or with an equivalent compound, in the presence of a transition metal catalyst and hydrogen. The reaction is performed in a reaction solvent that contains at least 30 wt % of an organic solvent. The use of a sufficiently high proportion of an appropriate organic solvent in the reaction mixture reduces the amount of water present in the reaction mixture, and provides rapid reaction rates and high yields of the desired product. The N,N-dialkylpolyhydroxyalkylamines may be used in a wide variety of applications.

Abstract: Corrosive effects arising during oilfield treatment applications are inhibited and/or prevented by introducing into an oil or gas well at least one compound of formula I: wherein: R1 is independently H, —[—CnH2nO—]a—H, or an alkyl group having from 1 to about 24 carbon atoms; R2 is independently H or —[—CnH2nO—]b—H, R3 is independently —[—CH2]c—, or —Cd2d—[—OCnH2n—]e—, R4 is independently H or —[—CnH2nO—]f—H, R5 is independently H or —[—CnH2nO—]g—H, a is from about 1 to about 8; b+f+g is between 0 to about 30; c is from about 1 to 6; d is from about 1 to 6; e is from about 1 to about 8; and n is 2 or 3. Such corrosive effects are especially inhibited in the treatment of sour wells where H2S corrosion is a potential problem as well as conduits used during the treatment of subterranean formations.

Abstract: A wellbore fluid comprising a base fluid and a particulate bridging agent comprised of a sparingly water-soluble material selected from the group consisting of melamine(2,4,5-triamino-1,3,5-triazine), lithium carbonate, lithium phosphate (Li3PO4), and magnesium sulfite.

Abstract: Compositions and process for recovering of oil from subterranean oil-bearing reservoirs consisting of green non-toxic biodegradable strong alkali metal salt of polymerized weak acids, one or more surfactants, an aqueous fluid, a optionally one or more mobility control agents and optionally one or more co-solvents are disclosed. Such compositions are injected into the reservoir through one or more injection wells and assist in recovering trapped oil through one or more producing wells. A preferred green non-toxic biodegradable strong alkali metal salt of polymerized weak acids is the sodium salt of polyaspartic acid shown below where n is 10 to 50. The compositions and the process of the present invention offer the advantage of improved compatibility with unsoftened waters, surfactants, and various mobility control agents. The green non-toxic, biodegradable properties of the alkali makes it particularly suitable for environmentally sensitive applications such as offshore and inland lakes.

Abstract: Disclosed are compositions and methods for treating subterranean formations, in particular, oilfield stimulation compositions and methods using polymer viscosified fluid crosslinked with metal complexes with amino and/or phosphonic acids to provide an increased crosslinking temperature and a low pH sensitivity. The metal complexes can be used with borate crosslinkers to provide continuous viscosification as the temperature is increased.

Abstract: A process for recovering heavy oil with the steps of: a) injecting into one or more injection wells an aqueous injection fluid containing one or more surfactants designed to form a pseudo-emulsion between the injection fluid and the heavy oil, and, b) recovering the oil from one or more producing wells. The process does not require the addition of outside mechanical or thermal energy or solvents to recover the heavy oil and does not form emulsions between the injection fluid and the heavy oil that may be difficult to break when brought to the surface or may cause increased viscosity and injectivity problems within the reservoir.

Abstract: A low toxicity composition and method of reducing the swelling of clay in well comprising circulating in the well a water-based fluid comprising a functionally effective concentration of the additive formed from the following reaction of a tertiary amine of the following general formula: wherein R1 and R2 are alkyl or hydroxyalkyl groups with one to three carbon atoms or combinations thereof, and R3 is a hydroxyalkyl group with one to three carbon atoms, with an alkylating agent of the following general formula: R-A wherein R is an alkyl radical with one to three carbon atoms, and A is an organic or inorganic anion selected from the group consisting of sulfate, phosphate, carbonate, and combinations thereof.

Abstract: A method of modifying the permeability to water of a subterranean formation comprising injecting into the subterranean formation an aqueous composition comprising from about 0.005 percent to about 2 percent, by weight, of a water-soluble alkylene oxide branched polyhydroxyetheramine or a salt thereof, wherein the alkylene oxide branched polyhydroxyetheramine is prepared by reacting a diepoxide with one or more alkylene oxide functionalized amines and one or more amines having two reactive hydrogen atoms and optionally reacting the resulting polyhydroxyetheramine with an acid or alkylating agent to form the salt.

Abstract: A method of cleaning a wellbore prior to the production of oil or gas is disclosed, wherein the wellbore has been drilled with an invert emulsion drilling mud that forms an invert emulsion filter cake. The method may include the steps of circulating a breaker fluid into the wellbore, where the breaker fluid includes an aqueous fluid, and imino diacetic acid or salt thereof. Optionally an acid buffering agent, and a weighting age are also included. The breaker fluid is formulated such that after a predetermined period of time and the filter cake present in the wellbore or on the wellbore face is substantially degraded. Other methods may also include drilling the wellbore with a water-based drilling mud that forms a water-based filter cake, wherein the method may include the steps of circulating a breaker fluid into the wellbore, where the breaker fluid may include an aqueous fluid, and an iminodiacetic acid or a salt thereof.

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: 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: A formulation containing a copolymer derived from a cationic monomer effectively inhibits and controls the formation of inorganic scales. Suitable copolymers include those comprising an acrylamide unit and a quaternary ammonium salt group, and optionally an acrylate and/or nitrogen heterocyclic monomer including those wherein the quaternary ammonium salt is a unit of the formula: wherein R is methyl or hydrogen; R4 is a C1 to C6 alkyl group, optionally substituted with halogen, hydroxyl and alkoxy groups, X is halogen; and R1, R2 and R3 are independently selected from the group consisting of alkyl and alkoxy groups. Suitable nitrogen heterocyclic compounds include N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, N-vinylcaprolactam, N-vinylimidazole and N-vinylpyridine.

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: A process for preparing a stable zirconium triethanolamine cross-linking agent comprises contacting a solution of a zirconium triethanolamine complex with water at a temperature of 50° C. to 90° C. at a mole ratio of triethanolamine:zirconium in the range of 3.5:5.5 and at a mole ratio of water:zirconium in the range of 20:1 to 1:1. The stable zirconium triethanolamine complex can be used in a cross-linking composition. Further disclosed are methods to use the composition in oil field applications for hydraulic fracturing and plugging of permeable zones and leaks in subterranean formations.

Abstract: A clear, stable, salt-free solution of a 1:1 molar complex of zirconium and N,N,N?,N?-tetrakis-(2-hydroxypropyl)ethylene diamine. The solution can be used in a cross-linking composition comprising a cross-linkable organic polymer for oil field applications such as fluid fracturing and plugging permeable zones in 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 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: Nanoemulsion, macroemulsions, miniemulsions, microemulsion systems with excess oil or water or both (Winsor I, II or III phase behavior) or single phase microemulsions (Winsor IV) improve the removal of filter cakes formed during hydrocarbon reservoir wellbore drilling with OBM. The macroemulsion, nanoemulsion, miniemulsion, microemulsion systems with excess oil or water or both or single phase microemulsion removes oil and solids from the deposited filter cake. In one non-limiting embodiment, the emulsion system (e.g. single phase microemulsion, nanoemulsion, or other emulsions) may be formed in situ (downhole) rather than produced or prepared in advance and pumped downhole. Skin damage removal from internal and external filter cake deposition can be reduced.

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: Pumpable multiple phase vesicle compositions carry agents and components downhole or through a conduit, and controllably releasing them at a different place and time by breaking the compositions. In one non-limiting embodiment the pumpable multiple phase vesicles have a third phase containing a first phase which bears the agent to be controllably released. The first and third phases of the vesicles are separated by a surface active material bilayer that forms the second phase. The pumpable multiple phase vesicles may have internal and external phases that are both oil miscible, both aqueous miscible, or both alcohol miscible. The surface active material bilayer may be composed of compounds such as phospholipids, alkyl polyglycosides, gemini surfactants, sorbitan monooleate, sorbitan trioleate, and many others. The agent may be released by one or more of a variety of mechanisms.

Abstract: Of the many methods provided, in one aspect, the present invention provides a method comprising: providing a treatment fluid comprising: an aqueous base fluid, a first surfactant, and a surfactant-based fluid loss control agent capable of forming a viscoelastic fluid; and introducing the treatment fluid into a well bore that penetrates the subterranean formation.

Abstract: Compositions and methods are given for delayed breaking of viscoelastic surfactant gels inside formation pores, particularly for use in hydraulic fracturing. Breaking inside formation pores is accomplished without mechanical intervention or use of a second fluid. Acidic internal breakers such as sulfuric acid and nitric acid are used. The break may be accelerated, for example with a free radical propagating species, or retarded, for example with an oxygen scavenger.

Abstract: The invention is of oil-based drilling fluids including invert emulsion fluids that are able to maintain a relatively consistent rheological profile over a wide temperature range. The invention also includes new additives that enable the preparation of drilling fluids with viscosities that are less affected by temperature over a temperature range from less than about 40° F. to more than about 250° F. compared to conventional fluids. These additives are based on reaction products of polyamines and carboxylic acids with two or more carboxylic moieties combined with alkoxylated amines and fatty acid amides. In addition, this invention permits the use of reduced amounts of organoclay rheological additives in drilling fluids.

Abstract: An oilfield treatment method is given that uses fluids that contain surfactants used as foamers and/or viscosifiers such that the fluids pass the Alberta Energy and Utilities Board Directive 27 requirements for low toxicity to certain bioluminescent bacteria. Such fluids may be used in oilfield treatments, for example drilling and stimulation, near fresh water aquifers. The surfactants are certain non-ionic surfactants that are not aromatic, or certain amphoteric surfactants (that can be neutral), or certain zwitterionic surfactants, (in which both positive and negative charges are present in a single molecule so that the whole molecule is neutral).

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: A method for stimulating thick or multilayered heterogeneous or homogeneous formations in a single trip without packers involves perforating with tubing conveyed perforation, then injecting a self-diverting acid, then moving the tubing string and perforating at a new location, and then injecting additional self-diverting acid. The sequence may be repeated. The acid is preferably a viscoelastic diverting acid. The self-diverting acid may be alternated with conventional treatment fluid. The job is designed to treat the least permeable zone(s) first and maximizes acid efficiency.

Abstract: A method and composition are described for improving recovery of oil from an oil reservoir. The method includes adding an effective amount of a fatty acid alkyl ester oil recovery composition to an oil reservoir and recovering oil from the reservoir. The composition may include in predominant proportion a fatty acid alkyl ester as well as effective concentrations of a surfactant, a colloid, and an acid. One exemplary composition includes 96% soy methyl ester, 3% surfactant, and 1% vinegar.

Abstract: The invention provides a fluid for use in a subterranean formation penetrated by a wellbore, the fluid comprising: (a) water; (b) delayed release acid; (c) a surfactant comprising a tertiary alkyl amine etboxylate generally represented by the following formula: wherein R is an alkyl group or groups, X is about 2 to about 15, and Y is about 2 to about 15; and (e) a gelling agent. The invention also provides a method of fracturing a subterranean formation, comprising the step of forming a foamed fracturing fluid comprising water; a surfactant comprising a tertiary alkyl amine ethoxylate generally represented by the formula above; a gelling agent; and a gas. The method also provides the step of introducing the foamed fracturing fluid into a subterranean formation at a pressure sufficient to create a fracture in the subterranean formation. The method also provides the step of introducing an acid into the subterranean formation.

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: A method for minimizing the amount of metal crosslinked viscosifier necessary for treating a wellbore with proppant or gravel is given. The method includes using fibers to aid in transporting, suspending and placing proppant or gravel in viscous carrier fluids otherwise having insufficient viscosity to prevent particulate settling. Fibers are given that have properties optimized for proppant transport but degrade after the treatment into degradation products that do not precipitate in the presence of ions in the water such as calcium and magnesium. Crosslinked polymer carrier fluids are identified that are not damaged by contaminants present in the fibers or by degradation products released by premature degradation of the fibers.

Abstract: An under-balanced drilling fluid additive is disclosed which reduces reactive shale and/or clay swelling during under-balanced drilling operations, where the additive includes an effective amount of a choline salt. A method for under-balanced drilling is also disclosed including the step of circulating a drilling fluid including an effective amount of a choline salt to reduce reactive shale and/or clay swelling during under-balanced drilling operations.

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 method for using an invert emulsion fluid in a well bore, comprising placing an invert emulsion fluid in a well bore, wherein the invert emulsion fluid comprises an oleaginous fluid, a non-oleaginous fluid and an emulsifier comprising one or more amines generally represented by the formula: wherein R is a radical selected from the group consisting of abietyl, hydroabietyl, dihydroabietyl, tetrahydroabietyl, and dehydroabietyl, each R? may be the same or different and is an alkyl having from about 1 to about 3 carbons, each A may be the same or different and is NH or O, and the sum of x and y ranges from about 1 to about 20, and contacting the invert emulsion fluid with an acid solution to reversibly convert the invert emulsion to an oil-in-water emulsion.

Abstract: An organic based emulsion-breaking formulation for use in treating well bores drilled in oil-bearing mud that is not eco-toxic and is optimally compatible with formation fluids comprises: as the emulsion-breaking agent, at least one constituent selected from non-ionic amphiphilic compositions obtained by reacting at least one polymerized vegetable oil with at least one aminoalcohol and alkyl esters (for example C1 to C8) of fatty acids derived from natural, vegetable or animal oils; optionally, at least one wetting agent selected from anionic surfactants; and optionally at least one solvent; the assembly being as a mixture in an organic base. Such a formulation can be weighted by mineral fillers.

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: The present invention relates to subterranean treatment fluids. In particular, the present invention relates to subterranean treatment fluid compositions that comprise polyoxazoline compositions and methods for using such compositions in subterranean applications. In one embodiment, the present invention provides a method of controlling shale swelling in a subterranean formation comprising introducing a treatment fluid into the subterranean formation, wherein the treatment fluid comprises a base fluid and a polyoxazoline composition. In another embodiment, the present invention provides a method of treating a portion of a subterranean formation comprising the steps of: introducing a treatment fluid that comprises a base fluid and a polyoxazoline composition; and treating a portion of the subterranean formation. Other embodiments are provided.

Abstract: Invert emulsion compositions including an oleaginous, a non-oleaginous and an amine surfactant that are useful in the oil and gas well drilling art are disclosed. The amine surfactant is selected so that the invert emulsion can be converted form a water-in-oil type emulsion to a oil-in-water type emulsion upon the protonation of the amine surfactant. Deprotonation of the amine surfactant reverses the conversion. This solution also permits the conversion of oil-wet solids in the fluid into water-wet solids.

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: The present invention relates to methods of chemically generating gas in aqueous fluids utilized in the drilling and completion of wells such as drilling fluids, spacer fluids, and aqueous acid solutions. In one embodiment, the invention provides a method of preventing the formation of fractures in a subterranean formation during a drilling operation. In other embodiments, the present invention provides methods of separating a first fluid and a second fluid in a subterranean formation; methods of forming lightweight well treatment fluids; methods of enhancing the permeability of a subterranean zone; lightweight drilling fluids; lightweight spacer fluids; foamed aqueous acidic well treatment fluids; and methods of making foamed aqueous and aqueous acidic well treatment fluids.

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: A process for enhancing the productivity of a formation consists of introducing into the formation a viscoelastic fluid which contains at least one surfactant, at least one quaternary amine polyelectrolyte, water, and a non-aqueous solvent. The surfactant forms aggregation structures or vesicles. The fluid, which significantly enhances fluid viscosity and thermal stability, is particularly effective as a diverting fluid to divert an acid treatment package from a high permeability or undamaged portion of a formation to a low permeability or damaged portion of a formation as well as a fracturing fluid. In addition, the fluid is useful for sand control completion.

Abstract: A new class of sulfur scavenging or converting compositions is disclosed comprising diamine terminated, amine-aldehyde adducts, where the adducts are substantially bimolecular amine-aldehyde adducts and the composition is substantially free of trimer and/or triazines. Methods for making and using the new class of sulfur scavenging or converting composition are also disclosed.