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: 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: An excavation fluid composition useful for enlarging a cavity in the earth includes a synthetic polymer and sodium silicate. The excavation fluid composition is formulated so as to enable the fluid in contact with unstable or sandy soils in the selected areas of the excavation to react and form silicate-based derivatives with lesser solubility, and movement and thus improve soil stability at the excavation wall.

Abstract: An aqueous drilling fluid used in drilling wells through subterranean formations having a pH of between about 7 and about 12 and a viscosity of from about 20 to about 80 sec (Marsch cone) which is prepared by admixing fresh water, brine or seawater with about 0.02 lb to about 2.5 lb per barrel, based on polymer actives, of one or more anionic dispersion polymers, wherein the anionic dispersion polymers are composed of about 2 to about 98 mole percent of one or more anionic monomers and from about 98 to about 2 mole percent of one or more nonionic monomers and wherein the anionic dispersion polymers have a RSV of from about 10 to about 50 dL/g, a method of drilling a well bore through a subterranean formation and a method of viscosifying an aqueous drilling fluid.

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 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: An aqueous drilling fluid used in drilling wells through subterranean formations having a pH of between about 7 and about 12 and a viscosity of from about 20 to about 80 sec (Marsch cone) which is prepared by admixing fresh water, brine or seawater with about 0.02 lb to about 2.5 lb per barrel, based on polymer actives, of one or more anionic dispersion polymers, wherein the anionic dispersion polymers are composed of about 2 to about 98 mole percent of one or more anionic monomers and from about 98 to about 2 mole percent of one or more nonionic monomers and wherein the anionic dispersion polymers have a RSV of from about 10 to about 50 dL/g, a method of drilling a well bore through a subterranean formation and a method of viscosifying an aqueous drilling fluid.

Abstract: Water soluble nonionic friction reducers and added to coacervate gels having excellent shear viscosities and other properties. A preferred gel comprises poly diallyl dimethyl ammonium chloride, a lesser amount of sodium lauryl sulfonate, and lauryl alcohol. Excellent friction reducing properties are manifested; a particularly practical use for the compositions is in subterranean formation fracturing.

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: Coacervate gels having excellent shear viscosities and other properties are made with anionic or cationic polymers, a smaller amount of a surfactant having a charge opposite that of the polymer, and a hydrophobic alcohol. The Zeta Potential of the gel is maintained at an absolute value of at least 20. Optional gel promoting additives include betaines and amine oxides. A preferred gel comprises poly diallyl dimethyl ammonium chloride, a lesser amount of sodium lauryl sulfonate, and lauryl alcohol. The gels are particularly useful in well drilling fluids and well fracturing fluids.

Abstract: Novel branched or crosslinked polymers containing (meth)acrylamidopropyltrimethyl ammonium halide; (meth)acrylic acid or 2-(meth)acrylamido-2-methylpropane sulfonic acid; methylene bis-acryamide and the like; and a C4-C22 alkyl (meth) acrylate and the use thereof in papermaking, subterranean well drilling and well cementing operations is disclosed.

Abstract: The invention relates to a rheology stabilizer or thinner for high-temperature high-pressure high-mineralized degree drilling fluids, methods of their preparation and use. The rheology stabilizer is a copolymer synthesized by an olefinic acid, ester of an olefinic acid, a sulfonic acid containing unsaturated linkage(s), an amide or imide containing unsaturated linkage(s), a quaternary compound containing olefinic linkage(s) reacting chemically with phosphorous acid or hypophosphorous acid, more particularly, copolymer of acrylic acid, 2-hydroxypropyl acrylate, N-(4-sulfophenyl)-maleimide, allyltrimethylammonium chloride and phosphorous acid. The copolymers have very high resistance to high-temperature high-pressure high-valence ions, can high-effectively adjust the rheology and thixotropy of drilling fluids, and can be used as the rheology stabilizer, thinner, clay and shale stabilizer of drilling fluids.

Abstract: The invention provides water-soluble copolymers without crosslinking, consisting of the following components: A 5-95% by weight of bivalent structural units derived from acrylamidopropenylmethylenesulfonic acid or its salts, B 1-45% by weight of bivalent structural units derived from open-chain N-vinylamides, C 1-45% by weight of bivalent structural units derived from cyclic N-vinyl-substituted amides, and if desired D 0-50% by weight of a further comonomer selected from the group consisting of acrylamide, acrylic acid and acrylonitrile, the components A to C and, if present, D adding up to 100% by weight.

Abstract: Water based drilling fluid compositions which contain at least one viscosity builder and at least one rheological control agent wherein the rheological control agent is an amphoteric polymer, the cationic groups of the amphoteric polymer being quaternary ammonium groups.

Abstract: Compositions and methods useful in creating boreholes, tunnels and other excavations in unstable soils and earth formations, especially those composed partially or wholly of sand, gravel or other granular or permeable material are disclosed. The fluids include a polymer, and a soluble silicate ion source. The fluids of the invention, when used according to the methods of the invention, have unique dual functionality as excavating fluids and as earth-grouting or soil-hardening compositions.

Abstract: A drilling fluid having a brine base fluid, aluminum chlorohydrate as a viscosifying agent, an alkoxylated surfactant, and an amphoteric polymer encapsulant has been found to have excellent viscoelasticity and suspension characteristics. Surprisingly, it has been discovered that a synergistic effect is present between the aluminum chlorohydrate and the surfactant such that less of each component is required when both are used together to suspend the same amount of solids, than if one or the other is used separately.

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 drilling fluid comprising a blend of brine and additives for maintaining rheological properties in a neutral or slightly acidic brine and a method for using the drilling fluid to drill into a producing formation are disclosed. The drilling fluid comprises viscosifying polymer and fluid loss polymer that function in the brine without substantially adversely affecting their properties. The brine is substantially free of insoluble solids. The viscosifying polymer and/or the fluid loss control polymer can be acid soluble. Zinc salts in the form of zinc bromide alone or in a mixture of zinc bromide and calcium bromide are added to increase the density of the brine solution. The viscosifying polymer has pendant amide and sulfonic acid or sulfonate groups. Alternatively or additionally, the viscosifying polymer comprises a polysaccharide. The fluid loss control polymer can comprise a cross-linked, cationic or amphoteric starch. Soluble solids are dispersed in the brine.

Abstract: This invention provides a composition for and a method of using the composition to reduce the loss of liquid from aqueous compositions employed while rotary drilling. The composition of this invention comprises a polymeric material selected from homopolymers, random copolymers and random terpolymers, each of which includes a vinylamide morpholine derivative in the recipe for making the polymeric material.

Abstract: The soluble polymers comprising an N-vinyl amide such as an N-vinyl lactam are found to be useful in processes wherein the polymer is introduced into a subterranean wellbore. Polymers useful in the recovery of natural resources are prepared by polymerizing an N-vinyl lactam by free radical initiation with polymerization conducted in an aqueous solution polymerization medium preferably containing a mixture of dissolved electrolytes, or in a polymerization medium consisting essentially of a tertiary alkanol. Copolymers of such N-vinyl lactams with unsaturated amides, and terpolymers prepared by polymerizing an N-vinyl lactam and an unsaturated amide with a selected termonomer compound are also useful when prepared by these methods. The invention also broadly encompasses utilizing a water-soluble polymer comprising at least one of a hydrophilic vinyl-containing sulfonate, phosphonate or ester and/or a hydrophilic N-vinyl lactam for applications under hostile conditions.

Abstract: A foamable drilling fluid for use in well operations such as deep water offshore drilling where risers are not employed in returning the fluid to the surface mud pit. A preferred foamable drilling fluid comprises a prehydrated clay such as bentonite, sea water, a surfactant selected from the group consisting of .alpha.-olefinsulfonates, alkylpolyglycosides, alcohol sulfates, salts of ethoxylated alcohol sulfates, and a stabilizing surfactant consisting of cocoamine betaine. The stabilized foam drilling fluid resists foam breakdown upon drilling cessation, prevents fluid loss to reduce filter cake buildup and increases the carrying capacity of cuttings and other solids. In addition, a foamable drilling fluid is provided including an hydraulic material selected from the group consisting of Portland cement, siliceous material like fumed silica, blast furnace slag and pozzolans such as fly ash.

Abstract: A composition and a process for treating a subterranean formation are disclosed. The process comprises injecting into the subterranean formation a composition which comprises a polymer, a crosslinking agent, a liquid, optionally a clay, and further optionally a weighting agent wherein the polymer forms a gel in the formation, in the presence of the crosslinking agent.

Abstract: This invention relates to an improved water based drilling fluid containing a controlled cross-linked polymeric fluid loss control agent. The novel polymeric fluid loss control agent of this invention exhibits improved thermal stability and other enhanced drilling fluid additive properties. The controlled cross-linking of the polymer of this invention results from the addition of specific amounts and types of cross-linking agents.

Abstract: A method for inhibiting barium sulfate precipitation in low pH aqueous fluids of underground petroleum-bearing formations by adding to such systems an effective amount of low molecular weight water-soluble polymer containing 5-35 weight percent sulfonic acid monomer units and 65-95 weight percent carboxylic acid monomer units, is provided. Polymer compositions based on 10-15 weight percent 2-acrylamido-2-methyl-1-propanesulfonic acid, 15-65 weight percent acrylic acid and 25-70 weight percent maleic acid are particularly preferred for use at very low pH conditions, e.g., 5.5 or less in the presence of high sulfate ion and barium ion concentrations.

Abstract: A foamable drilling fluid for use in well operations such as deep water offshore drilling where risers are not employed in returning the fluid to the surface mud pit. A preferred foamable drilling fluid comprises a prehydrated clay such as bentonite, sea water, a surfactant selected from the group consisting of .alpha.-olefinsulfonates, alkylpolyglycosides, alcohol sulfates, salts of ethoxylated alcohol sulfates, and a stabilizing surfactant consisting of cocoamine betaine. The stabilized foam drilling fluid resists foam breakdown upon drilling cessation, prevents fluid loss to reduce filter cake buildup and increases the carrying capacity of cuttings and other solids. In addition, a foamable drilling fluid is provided including an hydraulic material selected from the group consisting of Portland cement, siliceous material like fumed silica, blast furnace slag and pozzolans such as fly ash.

Abstract: The invention concerns the use of mixed hydroxydes of bivalent and trivalent metals with a three-dimensional spaced-lattice structure of the garnet type to control the thixotropic thickening of aqueous preparations, using swellable clays and/or other swellable layer-silicate compounds of natural and/or synthetic origin as visosity-increasing agents. The preferred garnet-type mixed hydroxydes are catoites of the basic structure Ca.sub.3 Al.sub.2 (OH).sub.12 a minor proportion of whose OH units can be exchanged for acid groups, in particular silicate groups.

Abstract: This invention relates to an earth stabilization fluid and to a method for using such an earth stabilization fluid. This invention uses a continuous phase that has been added to a borehole and a polymer material that forms gel masses having desired functional properties when added to the continuous phase.

Abstract: A method and use for a dry composition comprising a mixture of water-soluble polymer and an aluminum citrate preparation is disclosed. The polymer is capable of cross-linking in the presence of water and aluminum ions. Any water-soluble polymer known to the art is suitable. Cross-linked polymer forms a gel in highly permeable, watered-out regions of oil-containing rock, allowing for increased oil recovery and decreased water use and recycling.

Abstract: For controlling the dispersion of solids, e.g., cuttings, in water-based fluid used during operations such as drilling, completion or workover operations in a well crossing at least one permeable geologic formation, there is added to the fluid an optimized amount of a water soluble polymer HM PAM based on acrylamide and hydrophobic units. In a variant, a useful amount of hydrophobically modified cellulose derivative, e.g., modified hydroxyethylcellulose, HMHEC, is also added, thus forming a fluid containing HM PAM and HM HEC. The process has particular application to slim-hole and/or strongly deviated drilling.

Abstract: Swelling and migration of subterranean clay is inhibited during drilling for and stimulation of the production of hydrocarbon fluids, and preparation therefor, by treating said formations with a copolymer of about 5% to about 50% of an anionic monomer such as acrylic acid, methacrylic acid, or 2-acrylamido-2-methyl propane sulfonic acid and the balance a cationic monomer selected from dimethyl diallyl ammonium chloride, or acryloxy or methacryloxy ethyl, propyl or 3-methyl butyl trimethyl ammonium chlorides or methosulfates. Permeability damage to the formation is reduced in the presence of the copolymer; it is particularly effective in spite of the presence of a foaming agent.

Abstract: This invention relates to a method for preparing and earth stabilization fluid, a method for using such an earth stabilization fluid and to the earth stabilization fluid itself. This invention uses a continuous phase that has been added to a borehole and a polymer material that forms gel masses having desired functional properties when added to the continuous phase.

Abstract: A water-based drilling fluid comprising a water soluble tetrapolymer in combination with clayey materials.

Abstract: A water based drilling fluid composition and an additive for water based drilling fluid compositions having as components poly(N-vinyl-2-pyrrolidone/sodium 2-acrylamido-2-methylpropane sulfonate) and ferrous sulfate useful in controlling high temperature water loss in drilling a well to recover oil and gas from a subterranean formation in a hostile environment and their methods of use.

Abstract: Cement compositions which have improved properties such as increased stability, reduced settling tendencies, enhanced fluid loss properties and the like and methods of using such cement compositions are provided. The cement compositions are comprised of water, hydraulic cement and an aqueous colloidal silicic acid suspension wherein the colloidal silicic acid particles have a specific surface area in the range of from about 50 m.sup.2 /g to about 1000 m.sup.2 /g.

Abstract: A water-based drilling fluid comprising a water soluble tetrapolymer in combination with clayey materials.

Abstract: This invention relates to an improved aqueous based drilling fluid and specifically to a water soluble polymer that imparts desirable performance characteristics to the final drilling fluid. The invention also relates to the method for preparation of the polymer and drilling fluid. The water soluble polymer is especially useful in that it exhibits superior tolerance to divalent cations, salts, solids and elevated temperatures when added to aqueous drilling fluids. The polymer additive is characterized by increased viscosity at low shear rates and improved fluid loss control thereby exhibiting superior rheological and thixotropic properties. The polymer consists of reaction products of sulfonated monomers and monomers added to enhance the functional characteristics of the polymer.

Abstract: A method of thickening, stabilizing, controlling mobility, or enhancing water retention in aqueous media and electrolyte-containing aqueous media employs neutrally-charged polyamphoteric graft copolymers of polysaccharides with zwitterionic monomers or cationic/anionic monomer pairs. These polyampholytes are characterized by their unique resistance to loss of intrinsic viscosity in the presence of electrolytes. These polyampholytes may be prepared by an inverse emulsion method of graft copolymerization. One such electrolyte-tolerant polyampholyte is a novel composition prepared by graft copolymerization of guar gum.

Abstract: A fluid loss control additive for use in well cementing operations wherein the downhole temperature ranges from about 200.degree. to about 500.degree. F. The additive is a polymer comprised of 2-acrylamido-2-methyl propane-3-sulphonic acid, N-vinyl,-N-methylacetamide, in the presence or absence of arcylamide. This additive is also effective in saltwater cement slurries.

Abstract: A non-polluting dispersing agent for drilling fluids based on soft water or salt water.A dispersing agent for aqueous drilling fluids, optionally saline, belonging to the group of polymers and/or copolymers containing acid functions which is characterized in that, to ensure that these fluids retain their rheological characteristics, even under the extreme temperature and pressure conditions prevailing in deep bore holes, said dispersing agent is a salt of said polymers and/or copolymers of which the salifying cation corresponds to a metal having a Pauling electronegativity at least equal to 0.95 and preferably greater than 1.

Abstract: A method of improving high temperature fluid loss and rheology stabilization of high calcium brine clay-containing oil well drilling fluids which comprises adding thereto a stabilizing amount of a water-soluble terpolymer composition comprising:______________________________________ Ingredients % by weight ______________________________________ NaAMPS 72-3.8 N,N-dimethylacrylamide 13.5-0.7 Acrylonitrile 9.5-0.5 ______________________________________said composition containing lignin, modified lignin, brown coal or modified brown coal in an amount ranging between 5-95% with the lignin, modified lignin, brown coal or modified brown coal having been present during the polymerization of the water-soluble polymer.

Abstract: A method of improving high temperature fluid loss and rheology stabilization of high calcium brine clay-containing oil well drilling fluids which comprises adding thereto a stabilizing amount of a water-soluble terpolymer composition comprising:______________________________________ Ingredients % by weight ______________________________________ NaAMPS 72-3.8 N,N-dimethylacrylamide 13.5-0.7 Acrylonitrile 9.5-0.5 ______________________________________said composition containing lignin, modified lignin, brown coal or modified brown coal in an amount ranging between 5-95% with the lignin, modified lignin, brown cell or modified brown coal having been present during the polymerization of the water-soluble polymer.