Abstract: A thermal insulating packer fluid contains water and/or brine, a crosslinkable viscosifying polymer, a crosslinking agent and an optional set retarder. The composition is capable of inhibiting unwanted heat loss from production tubing or uncontrolled heat transfer to outer annuli. The viscosity of the composition is such as to reduce the convection flow velocity within the annulus.

Abstract: The present invention includes composition having a nonionic, fluorinated polymeric surfactant, water and solvent. Embodiments of compositions according to the present invention are useful, for example, for recovering hydrocarbons from subterranean clastic formations.

Abstract: Disclosed are methods comprising providing an aqueous polymer dispersion comprising water, an anionic salt, a water-based friction reducing polymer, a polyol, an anionic surfactant, and a nonionic surfactant; mixing the aqueous polymer dispersion with additional water to form an aqueous treatment fluid; and introducing the aqueous treatment fluid into a subterranean formation. Also disclosed are methods comprising providing an aqueous treatment fluid comprising water, an anionic salt, a water-based friction reducing polymer in an amount sufficient to provide friction reduction without forming a gel, a polyol, an anionic surfactant, and a nonionic surfactant; and introducing the aqueous treatment fluid into a subterranean formation.

Abstract: Methods for controlling particulate segregation comprising providing a mixture of an aqueous tackifying composition with a treatment fluid; slurrying the mixture with a first type of solid particulates and a second type of solid particulates and wherein the first type of solid particulates have a tendency to segregate from the second type of solid particulates when slurried into a liquid; and, placing the slurry into a portion of a subterranean formation. Methods for controlling particulate segregation comprising providing a treatment fluid; at least partially coating with an aqueous tackifying composition: a first type of solid particulates and a second type of solid particulates and wherein the first type of solid particulates have a tendency to segregate from the second type of solid particulates when slurried into a liquid; slurrying the two types of particulates into the treatment fluid; and, placing the slurry into a portion of a subterranean formation.

Abstract: A method of stimulating and stabilizing an area of a subterranean formation comprising placing an acid fluid into an area of a subterranean formation and allowing the acid to at least partially dissolve a portion of the area of the subterranean formation; placing a consolidation fluid into the area of the subterranean formation; and, placing an afterflush fluid into the area of the subterranean formation. A method of stimulating and stabilizing an area of a subterranean formation comprising placing an acid fluid into an area of a subterranean formation and allowing the acid to at least partially dissolve a portion of the area of the subterranean formation; placing a consolidation fluid into the area of the subterranean formation; and, placing a fracturing fluid into the area of the subterranean formation at a pressure sufficient to create or extend at least one fracture therein.

Abstract: The present invention relates to spacer fluids used in subterranean operations and, more particularly, to spacer fluids that comprise water-soluble relative permeability modifiers and methods of using the spacer fluids in subterranean operations. In one embodiment, the present invention provides a method of displacing a first fluid from a well bore that comprises introducing the first fluid into the well bore; and displacing the first fluid with a spacer fluid, the spacer fluid comprising water, and a water-soluble relative permeability modifier comprising a hydrophobically modified polymer or a hydrophilically modified polymer. In another embodiment, the present invention provides a spacer fluid that comprises water, and a water-soluble relative permeability modifier comprising a hydrophobically modified polymer or a hydrophilically modified polymer.

Abstract: Method of treating a portion of a subterranean formation comprising: placing a pre-pad fluid into a portion of a subterranean formation wherein the pre-pad fluid comprises a low-viscosity aqueous tackifying composition that comprises an aqueous tackifier compound and an aqueous fluid; placing a fracturing fluid into the portion of the subterranean formation at a pressure sufficient to create or extend at least one fracture therein; and, activating the aqueous tackifier compound with an activator so as to consolidate the unconsolidated particulates.

Abstract: Methods of reducing the fluid loss from a wellbore servicing fluid include combining a terpolymer with the wellbore servicing fluid to reduce the fluid loss from the fluid, followed by displacing the fluid into a wellbore. In an embodiment, the following monomers are used to make the terpolymer: from about 75 wt. % to about 95 wt. % of 2-acrylamido-2-methylpropanesulfonic acid or an alkali salt thereof; from about 3 wt. % to about 15 wt. % of acrylamide; and from about 3 wt. % to about 15 wt. % of N-vinyl-2-pyrrolidone, all weight percentages being based on a total weight of the monomers. The wellbore servicing fluid may comprise water or an aqueous salt solution such as a formate solution. The wellbore servicing fluid may also comprise clay such as montmorillonite and attapulgite clay.

Abstract: The present invention provides compositions and methods for enhancing subterranean well productivity by enhancing fracture conductivity. A method of increasing the conductivity of a fracture in a portion of a subterranean formation comprising providing a slurry comprising a fracturing fluid, a degradable material, and proppant particulates coated with a tackifying agent; allowing the degradable material to become at least temporarily attached to the tackifying agent coated onto the proppant particulates so as to avoid substantial segregation of the degradable material from the proppant particulates within the slurry; introducing the slurry to the fracture and allowing the proppant particulates and degradable material to form a substantially uniform particulate pack; and, allowing the degradable material to degrade and produce a particulate pack having voids therein.

Abstract: Methods of temporarily reducing the permeability of one or more selected sections of a subterranean formation penetrated by a horizontal well bore and the flow of water or water and hydrocarbons or hydrocarbons therefrom are provided. The methods comprise the steps of preparing or providing an aqueous treating fluid comprising water and a water-soluble formation permeability reducing agent, introducing the aqueous treating fluid into one or more selected sections and when required, contacting the one or more selected sections with an aqueous treating fluid comprising water and a formation permeability restoring chemical.

Abstract: A method for reducing or completely eliminating water influx in an oil or natural gas borehole includes introducing in the borehole an aqueous solution of a copolymer comprising: A) 40–98 wt. % of structural units of formula (I), wherein: R1 is hydrogen or methyl; R2 represents C2–C10 alkylene; and Me+ represents an ammonium metal ion and an alkali metal ion; B) 0.1 to 58 wt. % of structural units of formula (II); C) 0.1 to 10 wt. % of structural units of formula (III), wherein: R3 and R4 independently of each other represent hydrogen, methyl or ethyl, or R3 and R4 represent together a propylene group, which, with inclusion of a radical (A), form a pyrrolidon radical or, with inclusion of a pentamethylene group, forms a caprolactam radical; D) 0.10 to 10 wt % of structural units of formula (IV). The method also includes introducing in the ground or deposit, simultaneously with the copolymer or subsequently, an agent for crosslinking the copolymer.

Abstract: The present invention provides a method and treatment fluid for blocking the permeability of an elevated-temperature zone in a reservoir of a subterranean formation penetrated by a wellbore, the method comprising the steps of: a) selecting the zone to be treated, wherein the upper limit of the temperature range of the zone is equal to or greater than 190° F. (88° C.); b) forming a well treatment fluid comprising: water; a water-soluble polymer comprising polymerized vinyl amine units; and an organic compound capable of crosslinking with the vinyl amine units of the water-soluble polymer; c) selecting the water-soluble polymer and the organic compound of the well treatment fluid such that the gel time of the well treatment fluid is at least 2 hours when measured at the upper limit of the temperature range of the zone; and d) injecting the well treatment fluid through the wellbore and into the zone.

Abstract: Reduced friction fluids comprising an aqueous liquid, carbon dioxide, and a polymer comprising acrylamide and an acrylamide copolymer derivative. And methods of treating a subterranean formation comprising the steps of providing a reduced friction fluid comprising an aqueous liquid, carbon dioxide, and a polymer comprising acrylamide and an acrylamide copolymer derivative; and, introducing the reduced friction fluid to a subterranean formation.

Abstract: A method and composition is provided for a relative permeability modifier for use with aqueous well treatment fluids that comprises a hydrophobically modified water soluble polymer or a hydrophilically modified water soluble polymer.

Abstract: New polymers, and their applications in water-based wellbore service fluids, such as, for example, drilling fluids, yield desirable filtration control and rheological properties to such fluids even after exposure to HTHP aging. Typical temperatures encountered during such aging are around 350–400° F. and the duration of the exposure is some significant time such as 16 hours or longer. Preferably, the polymers are random terpolymers of N-vinylcaprolactam, vinyl sulfonate monomer 2-acrylamido-2-methyl-1-propanesulfonic acid, and monomer acrylamide, most preferably in a molar ratio of 15:20:65 respectively. The polymers reduce HTHP filtration volumes in fresh water, sea water, potassium chloride, and lime mud systems. The polymers may also be used to inhibit or reduce shale erosion.

Abstract: The present invention provides compositions of treating subterranean zones penetrated by well bores in primary well cementing operations, well completion operations, production stimulation treatments and the like. The invention includes aqueous well treating fluids comprised of water and a water soluble polymer complex fluid loss control additive. Preferred polymer complexes comprise water-soluble polymers made in the presence of hydroxyethylcellulose.

Abstract: Cement compositions comprising an improved fluid loss control additive, and methods for cementing using such cement compositions, are provided herein. Exemplary embodiments of the cement compositions comprise a hydraulic cement, water, and a fluid loss control additive comprising an acrylamide copolymer derivative, a dispersant, and a hydratable polymer. Optionally, other additives suitable for inclusion in cement compositions may be added.

Abstract: A cement slurry comprising a base for reducing the impact of an alkaline solution may be displaced into a wellbore and allowed to set. The base may comprise a metal carbonate that is soluble in water such as potassium carbonate. The cement slurry may further include cement, water, and a salt that is soluble in the water such as potassium chloride. The alkaline solution may be present in a formate-based drilling fluid displaced into the wellbore ahead of the cement slurry. Despite being contacted by such an alkaline solution, the thickening time of the cement slurry is long enough and the set time is short enough to provide for the formation of an impermeable mass in the annulus of the wellbore. The thickening times may range from about 4 hours to about 16 hours, and the set times may be less than about 24 hours.

Abstract: Water soluble associative polymers and compositions comprising them together with alkali metal salts of carboxylic acid are disclosed. Methods comprise introducing into a wellbore a fluid comprising such associative polymers and alkali metal salts of carboxylic acid, e.g., cesium formate. Disclosed water soluble associative polymers have functionality including at least sulfonate groups, carboxylate groups and hydrophobes associative with one another in a saturated aqueous solution of an alkali metal salt of a carboxylic acid.

Abstract: Aqueous treatment fluids that comprise water, and a friction reducing copolymer that comprises acrylamide in an amount in the range of from about 60% to about 90% by weight and acrylic acid in an amount in the range of from about 10% to about 20% by weight. Methods of treating portions of subterranean formation using the aqueous treatment fluid that comprise providing an aqueous treatment fluid comprising water, and a friction reducing copolymer that comprises acrylamide in an amount in the range of from about 60% to about 90% by weight and acrylic acid in an amount in the range of from about 10% to about 20% by weight; and introducing the aqueous treatment fluid into the portion of the subterranean formation.

Abstract: Barium sulfate and/or calcium carbonate scale inhibitor composition composed of a water-soluble polymer having incorporated phosphate functionality, the polymer being formed from at least one ethylenically unsaturated carboxylic acid monomer, at least one ethylenically unsaturated vinyl sulfonate monomer, or a mixture thereof. The scale inhibitor composition can be used as a means of detecting inhibitor composition in downhole and topside oilfield treatments by means that are faster and more accurate than turbidometric measurement.

Abstract: The present invention provides improved methods of fracturing subterranean zones penetrated by well bores and improved fracturing fluids. The fracturing fluids are basically comprised of water, a terpolymer of 2-acrylamido-2-methylpropane sulfonic acid, acrylamide and acrylic acid, or its salts, a cross-linking agent for the terpolymer and a delayed viscosity breaker for effecting a controlled reduction in the viscosity of the fracturing fluid.

Abstract: Methods of cementing in a subterranean formation include passing a swelling agent to a permeable zone in a subterranean formation. The swelling agent is combined with a carrier fluid before being passed to the permeable zone. Upon contacting an aqueous fluid, the swelling agent swells in the permeable zone. The aqueous fluid may already be present in the subterranean formation, or alternatively, it may be introduced to the subterranean formation after passing the swelling agent into the subterranean formation. The swelling agent substantially inhibits a cement slurry subsequently pumped into the subterranean formation from passing through the permeable zone. The cement slurry therefore continues flowing down through the casing and up through the annulus where it sets and forms a strong cement column.

Abstract: The present invention provides methods of reducing the production of both water and particulates from subterranean formations; the methods are particularly useful in conjunction with subterranean formations surrounding wellbores and fractures. The methods comprise the steps of applying to a subterranean formation a pre-flush fluid, applying aqueous surfactant fluid, applying a low-viscosity consolidating fluid, and applying an after-flush fluid.

Abstract: The present invention relates to cementing operations, and more particularly, to cement compositions comprising set retarder compositions and methods of using the cement compositions in surface and subterranean applications. In some embodiments, the present invention provides cement compositions that comprise a hydraulic cement comprising an API cement, water, and a set retarder composition, the set retarder composition comprising an acrylamide polymer derivative; and an iron compound. In other embodiments, the present invention provides cement compositions, set retarder compositions, methods of cementing, methods of retarding the set time of a cement composition, and methods of preparing a cement composition.

Abstract: A method of reducing friction resulting from turbulent flow in an aqueous fracturing fluid in an oil field fracturing process comprising adding to the aqueous fracturing fluid an effective friction-reducing amount of one or more dispersion polymers, wherein the dispersion polymer is composed of from about 5 to about 95 mole percent of one or more nonionic monomers and from about 95 to about 5 mole percent of one or more cationic or anionic monomers and has a molecular weight of at least 100,000.

Abstract: Methods of cementing subterranean zones penetrated by well bores and well cement compositions are disclosed. A well cement composition of the invention basically comprises a hydraulic cement, water in an amount sufficient to form a pumpable slurry and a fluid loss control polymer additive comprising 77.9 weight % of the calcium salt of 2-acrylamido-2-methyl propane sulfonic acid, 8 weight % of the calcium salt of maleic acid, 11 weight % of N-vinyl caprolactam, 3 weight % of 4-hydroxybutyl vinyl ether and 0.1 weight % of methylene bisacrylamide.

Abstract: A high temperature viscosifying and fluid loss controlling additive for use in well cements, well cement compositions including the additive and methods of using the compositions are provided. The well cement compositions of this invention are comprised of a hydraulic cement, water and a viscosifying and fluid loss controlling additive comprising a mixture of a polymer comprised of at least one monomer which is calcium tolerant, anionic and disperses basic cement slurries, at least one monomer which hydrolyzes in basic cement slurries to generate anionic carboxylate groups that bind with calcium and viscosify the slurries and at least one monomer which generates non-ionic pendant groups on the polymer upon hydrolyzing in basic cement slurries to prevent polymer precipitation and a homopolymer of a monomer which hydrolyzes in basic cement slurries to generate anionic carboxylate groups that bind with calcium, viscosify the slurries and prevent settling in the slurries.

Abstract: A well fracturing 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 buffer for adjusting the pH of the fracturing fluid. The well service fluid can 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 present invention provides methods of treating subterranean zones penetrated by well bores in primary well cementing operations, well completion operations, production stimulation treatments and the like. The methods are basically comprised of introducing into the subterranean zone an aqueous well treating fluid comprised of water and a water soluble polymer complex fluid loss control additive.

Abstract: The present invention provides a well treatment fluid that contains water, an oxidized chitosan-based compound, and a water-soluble compound having carbonyl groups, wherein the oxidized chitosan-based compound has the property of being soluble in water up to about 2 wt % while maintaining a viscosity of less than about 1000 cp. The water used for the well treatment fluid is selected from the group consisting of fresh water, seawater, natural brine, formulated brine, 2% KCl solution, and any mixtures in any proportion thereof. The present invention also provides a method of treating a subterranean formation penetrated by a wellbore comprising the steps of: (a) forming the well treatment fluid, and (b) contacting the subterranean formation with the fluid.

Abstract: This invention is directed to a composition comprising expandable cross linked polymeric microparticles having an unexpanded volume average particle size diameter of from about 0.05 to about 10 microns and a cross linking agent content of about 1,000 to less than about 9,000 ppm of labile cross linkers and from 0 to about 300 ppm of non-labile cross linkers and to the use of the composition for modifying the permeability of subterranean formations and increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.

Abstract: Compositions and methods are provided for reducing the permeability of subterranean zones. More particularly, water-soluble polymeric compositions which form cross-linked gels in the zones. In general, the composition comprises (a) at least one water-soluble polymer; (b) at least one organic gelling agent capable of cross-linking the water-soluble polymer; and (c) at least one water-soluble formate. More preferably, the water-soluble polymer is a copolymer of (i) at least one non-acidic ethylenically unsaturated polar monomer, and (ii) at least one copolymerisable ethylenically unsaturated ester. The gelling agent is preferably selected from the group consisting of a polyalkyleneimine, polyfunctional aliphatic amine, an aralkylamine, and a heteroaralkylamine. The preferred water-soluble formate is selected from the group consisting of ammonium formate, lithium formate, sodium formate, potassium formate, rubidium formate, cesium formate, and francium formate.

Abstract: Methods of cementing subterranean zones penetrated by well bores and well cement compositions are provided. A well cement composition of the invention is basically comprised of a hydraulic cement, water in an amount sufficient to form a pumpable slurry and a fluid loss control polymer additive comprised of 69 weight % of the calcium salt of 2-acrylamido-2-methyl propane sulfonic acid, 14 weight % of the calcium salt of maleic acid, 14 weight % of N-vinyl caprolactam and 3 weight % of 4-hydroxybutyl vinyl ether.

Abstract: The present invention provides methods of treating subterranean zones penetrated by well bores wherein the static temperatures of the zones are as high as 400° F. and greater. The aqueous treating fluids are basically comprised of an aqueous liquid containing one or more inorganic monovalent salts, multivalent salts or both in an amount no greater than about 5% by weight of said aqueous liquid and one or more synthetic hectorite clay gelling and thixotropy imparting agents selected from the group of a synthetic hectorite clay having the composition by weight on a dry basis of 59.5% SiO2, 27.5% MgO, 0.8% Li2O and 2.8% Na2O, a synthetic hectorite clay having the composition by weight on a dry basis of 54.5% SiO2, 26.0% MgO, 0.8% Li2O, 5.6% Na2O and 4.1% P2O5 and a synthetic hectorite clay having the composition by weight on a dry basis of 54.5% SiO2, 26.0% MgO, 0.8% LiO2, 5.6% Na2O, 4.1% P2O5 and also containing inorganic polyphosphate peptizers.

Abstract: This invention is directed to a composition comprising expandable cross linked polymeric microparticles having an unexpanded volume average particle size diameter of from about 0.05 to about 10 microns and a cross linking agent content of about 1,000 to less than about 9,000 ppm of labile cross linkers and from 0 to about 300 ppm of non-labile cross linkers and to the use of the composition for modifying the permeability of subterranean formations and increasing the mobilization and/or recovery rate of hydrocarbon fluids present in the formations.

Abstract: The present invention provides methods of preventing the flow of water or gas or both through a subterranean zone having a high temperature and a depth such that a long pumping time is required to place a sealing composition therein. The methods basically comprise the steps of preparing a polymeric sealing composition comprised of water, a cross-linking agent and a selected water-soluble polymer which reacts with the cross-linking agent and forms a sealing gel which is stable for a desired period of time at the temperature of the zone and has a pumping time before gelation in the presence of the cross-linking agent whereby the composition can be pumped to the depth of the zone and placed therein. Thereafter, the sealing composition is pumped into the zone and allowed to form a sealing gel therein.

Abstract: The present invention provides a water-based fluid, in particular for drilling, completion or for any other intervention in a well such as a hydrocarbon well, in which the viscosity is controlled by a system constituted by precipitated silica nanoparticles (A) associated with a water-soluble copolymer (B) comprising one or more water-soluble co-monomers (I) having little or no affinity for silica and one or more co-monomers (II) which absorb onto the silica. The invention is of particular application to the secondary recovery of hydrocarbons.

Abstract: A well fracturing 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: What is disclosed is the preparation and use of synthetic water soluble copolymers useful in modifying the water permeability characteristics of subterranean hydrocarbon producing formations. The copolymers are in the form of dilute, pumpable, homogeneous, aqueous solutions and comprise a crosslinked synthetic copolymerizate with intramolecular and intermolecular crosslinking in a non-gelled state and a molecular size/shape corresponding to a K-value of 220-450.

Abstract: A well treatment fluid composition comprises a solvent (such as water), a polymer soluble or hydratable in the solvent, a crosslinking agent, an inorganic breaking agent, and an ester compound. Preferably, the hydratable polymer is a polysaccharide, such as galactomannan, cellulose, or derivatives thereof. The crosslinking agent is preferably a borate, titanate, or zirconium-containing compound. The inorganic breaking agent is preferably a metal-based oxidizing agent, such as an alkaline earth metal or transition metal-based oxidizing agent. The ester compound is preferably an ester of polycarboxylic acid, such as an ester of oxalate, citrate, or ethylenediamine tetraacetate. One example of a suitable ester compound is acetyl triethyl citrate.

Abstract: A process wherein an aqueous solution of amidoalkane sulfonic acid monomer, described hereafter, the homopolymer of such monomer, the co-polymer or the salt of said monomer or homopolymer, or polyacrylamide polymer, is admixed with the fluids or solids to be cleaned. Thus, solids and fatty acids are flocculated in the completion and workover fluids, hydrocarbon fluids, halogenated hydrocarbon fluids, amines, solvents, glycols, potassium carbonate and other gas processing fluids. The oil free particulate solids as well as the produced waters are thereby rendered environmentally acceptable for discharge to the environment. Hydrocarbon fluids are rendered suitable for storage while the other fluids such as completion and workover fluids are rendered suitable for reuse.

Abstract: A composition containing a chelating agent and an amino carboxylic acid and a method for breaking a gel formed by a crosslinkable polymer and a crosslinking agent. The composition may also be used for selectively removing crosslinked polymer gels from an oil-bearing zone in a subterranean formation in the presence of a water formation plugged by a crosslinkable polymer and a crosslinking agent. Aqueous solutions of phosphonates and sulfonates are also useful in the method.

Abstract: The invention concerns a water-based additive for well fluid, comprising an acrylamide and branched styrene sulphonate copolymer. It also concerns a water-based fluid comprising an acrylamide and branched styrene sulphonate copolymer. The additive is useful for controlling the filtering of a well fluid through the wall. The invention is advantageously applicable to drilling and/or completion of oil wells having a temperature higher than 120° C.

Abstract: Compositions and methods for modifying the permeability of subterranean formations for the purpose of selectively reducing excessive production of aqueous fluids. The compositions include copolymers which may be added to an aqueous fluid to form a water control treatment fluid. The copolymers may include copolymers having a hydrophillic monomeric unit, a first anchoring monomeric unit and a filler monomeric unit, with the first anchoring monomeric unit being based on N-vinylformamide. Additional anchoring monomeric units may also optionally be present. The copolymers may be employed in well treatment fluids introduced into production wells or injection wells. The copolymers may also be utilized in conjunction with stimulation treatments and with introduction of other well treatment fluids.

Abstract: Methods and compositions for reducing the permeabilities of subterranean zones are provided. The methods of the invention are basically comprised of introducing an aqueous composition comprised of a chelated organic gelling agent and a copolymer of an ethylenically unsaturated polar monomer and an ethylenically unsaturated ester or a terpolymer or tetrapolymer of an ethylenically unsaturated polar monomer, an ethylenically unsaturated ester and a monomer selected from AMPS® and/or N-vinylpyrrolidone into the zone and then allowing the aqueous composition to form a cross-linked gel in the zone.

Abstract: The invention concerns a water based foaming composition and the method of making it. The composition is optimized in that it contains a surfactant specifically selected according to the polymer also present in the composition. The surfactant and the polymer are selected so that they are oppositely charged. The invention is very useful in drilling or treating wells.

Abstract: A method and a drilling fluid/cement slurry composition for cementing a wellbore. The drilling fluid/cement slurry composition comprises A cement slurry composition comprising:a) a cementitious material;b) a drilling fluid; andc) a dispersant selected from the group consisting of water soluble polymers comprising allyloxybenzene sulfonate or allyloxybenzene phosphonate polymerized with at least one of acrylic acid, acrylamides, alkyl acrylamides, maleic anhydride, itaconic acid, sulfonated or phosphonated styrene sulfonated or phosphonated vinyl toluene, sulfonated or phosphonated isobutylene, acrylamidopropane sulfonate, acrylamidopropanephosphonate, vinyl alcohol, sulfonated or phosphonated propene and alkali, alkaline earth and ammonium salts thereof.

Abstract: Spacer fluids comprising a dispersant selected from the group consisting of water soluble polymers comprising allyloxybenzene sulfonate or allyloxybenzene phosphonate polymerized with at least one of acrylic acid, acrylamides, alkyl acrylamides, maleic anhydride, itaconic acid, sulfonated or phosphonated styrene, sulfonated or phosphonated vinyl toluene, sulfonated or phosphonated isobutylene, acrylamidopropane sulfonate or acrylamidopropanephosphonate, vinyl alcohol, sulfonated or phosphonated propene and alkali metal, alkaline earth metal and ammonium salts thereof and water with optional additional components such as surfactants, viscosifiers and wetting materials to form a rheologically compatible spacer fluid for use between a drilling fluid and a cement slurry and a method for using such spacer fluids to displace drilling fluids from a wellbore space with a cement slurry.

Abstract: A well completion spacer fluid is provided which is particularly suitable for separating a cement slurry from drilling fluid in primary cementing operations. The well completion spacer fluid is also useful for separating other potentially incompatible fluids in the wellbore, such as, separating drilling fluid from a completion brine. The spacer fluid basically comprises water, a hydrous magnesium silicate clay, silica and organic polymer(s).