Abstract: Aqueous wellbore treatment fluids having improved thermal stability are provided. The wellbore treatment fluids comprise at least one polysaccharide and an effective amount of at least one polyacrylamide to maintain its stability at a temperature greater than about 250° F. A formate compound is not required to achieve high-temperature stability in the fluid. Thus, the fluid is less expensive than conventional polymer-containing aqueous wellbore treatment fluids. The aqueous fluid may serve as, for example, a drilling fluid in the wellbore and thus may be circulated through the wellbore without being concerned that it could become unstable due to exposure to relatively high downhole temperatures.

Abstract: An improved composition and method is provided for preventing or alleviating lost circulation during the drilling of wellbores in subterranean formations, and particularly during the drilling of oil and gas wells. The method is suited for horizontal and directional wells as well as more vertical wells. The composition of the invention comprises a synergistic blend of resilient, angular, carbon-based material and a water-swellable, crystalline synthetic polymer. The method employs the composition of the invention in preventing lost circulation.

Abstract: Methods of improving the thermal stability of an aqueous wellbore treatment fluid are provided. The wellbore treatment fluid comprises at least one polysaccharide and an effective amount of at least one polyacrylamide to maintain its stability at a temperature greater than about 250° F. A formate compound is not required to achieve high-temperature stability in the fluid. Thus, the fluid is less expensive than conventional polymer-containing aqueous wellbore treatment fluids. The aqueous fluid may serve as, for example, a drilling fluid in the wellbore. It may be circulated through the wellbore without being concerned that it could become unstable due to exposure to relatively high downhole temperatures.

Abstract: A drilling fluid system comprising a brine and a quantity of cationic copolymers comprising a ratio of acrylamide monomers to cationic derivatives of acrylamide monomers, wherein the quantity and the ratio are effective to maintain effective rheology and fluid loss control in said drilling fluid system at temperatures of at least about 250° C. for at least about 16 hours.

Abstract: An inhibitive water-based polymer mud system and method for using the system in drilling and in stabilizing wellbores is disclosed for use in water sensitive formations as an alternative to oil-based muds. The system comprises a non-ionic low molecular weight polyacrylamide in combination with a non-ionic high molecular weight polyacrylamide, preferably long chain alcohol and poly anionic cellulose.

Abstract: A wellbore fluid including a peroxide degradable polymer and an encapsulated peroxide source. The peroxide degradable polymer may be a polysaccharide. The peroxide source may include an inorganic peroxide, including zinc and alkaline earth metal peroxides, such as magnesium peroxide. The encapsulating material may be a polymer, including enteric polymers. The release of peroxide, from peroxide sources generally, can be controlled by means of pH such that peroxide source can be activated, and peroxide released, by a change in pH. In a wellbore, this pH change can be effected by using produced fluids to lower the pH of a more basic wellbore fluid.

Abstract: A water-based drilling fluid composition includes water and at least one rheology modifier and/or fluid loss control agent, and at least one other ingredient of polymeric additive, inorganic salts, dispersants, shale stabilizers, weighting agents, or finely divided clay particles, depending upon the desired attributes, wherein the rheology modifier and/or the fluid loss control agent comprises carboxymethylated raw cotton linters (CM-RCL) made from the baled raw cotton linters or comminuted raw cotton linters with increased bulk density.

Abstract: A drilling fluid or mud additive having several components, including leonardite (humic acid); potassium acetate; partially hydrolyzed polyacrylamide (PHPA); polyanionic cellulose polymer (PAC); sulfonated asphalt; sulfoalkylated tannin; polystyrene maleic anhydride copolymer; micronized cellulose fiber; and calcium carbonate. These components are preferably premixed in a dry formulation as a powder or as pellets, and shipped to the site in bags or bulk tanks. This offers substantial advantages over the prior art in that the drilling mud of the present invention may be formed simply by adding the dry mix to a predetermined amount of water, and is thus much easier to make than the prior art wet mix drilling fluids, which typically require precise ratios of several different powders and liquids to be mixed together. Hydration buffers help keep the powder or pellets dry and flowable.

Abstract: An electropositive and water-based production well treating fluid system exhibits electropositivity by using a cationic viscosifier meanwhile matched with a cationic fluid loss additive and, optionally, contains a mud-building agent, an electrical stabilizing agent, a colloid-stabilizing agent, lubricant, an oil layer protective agent and/or a weighting agent. The electropositive production well treating fluid can beffer solve the contradiction of technical requirements between “treating fluid stability” and “bore hole stability”, and features a strong ability to inhibit the dispersion of clay, a good effect of protecting oil-gas reservoirs, fast drilling speeds, regular shape of bore holes and good resistance to salt.

Abstract: The invention concerns modified hydrophobic polyelectrolytes by amide formation of a hydrophilic skeleton by n-alkylamines whereof the alkyl chain comprises 6 to 22 carbon atoms. Preferably, the amide formation is obtained by di-n-dodecylamine. The hydrophilic skeleton is preferably a sodium polyacrylate or polyacrylic acid corresponding to a statistical acrylate-AMPS copolymer. Said polymers can be used for stabilizing direct or invert emulsions likely to be destabilized or inverted by a modification in the degree of salinity of the aqueous phase or a pH modification. The invention is particularly useful for stabilizing oil drilling fluids or the like in particular drilling, fracturation, acidification or completion fluids.

Abstract: The present invention concerns a water-based drilling mud for utilization in the drilling of oil wells comprising an aqueous phase wherein the aqueous phase contains an oil soluble polymer in the form of a gel as a fluid loss reducer. The subject invention further reveals a method of lubricating a drilling bit during the drilling of a well which comprises circulating a water-based drilling mud in the vicinity of the drilling bit wherein the water-based drilling mud is comprised of an aqueous phase, and wherein the aqueous phase contains an oil soluble polymer in the form of a gel as a fluid loss reducer.

Abstract: Provided 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 provided 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: Settable drilling fluids comprising an aqueous-based drilling fluid and cement kiln dust. Methods of cementing in a subterranean formation comprising: providing a settable drilling fluid comprising an aqueous-based drilling fluid and cement kiln dust, introducing the settable drilling fluid into a subterranean formation, and allowing the settable drilling fluid to set in the subterranean formation. Methods of converting an aqueous-based drilling fluid to a settable drilling fluid comprising: providing the aqueous-based drilling fluid, and adding cement kiln dust to the aqueous-based drilling fluid to form the settable drilling fluid. Methods of drilling a well bore and cementing a well bore comprising: drilling a well bore, circulating an aqueous-based drilling fluid in the well bore during the step of drilling the well bore, adding cement kiln dust to the aqueous-based drilling fluid to form a settable drilling fluid, and allowing the settable drilling fluid to set in the well bore.

Abstract: Fluids comprising an aqueous acid, synthetic polymer, metal crosslinking agent and lactic acid or a salt thereof have particular applicability in fracturing subterranean formations of an oil or gas well. The lactic acid acts as a delaying agent. As a result, crosslinking of the synthetic polymer and metal crosslinking agent typically occurs at a temperature of 100° F. or higher.

Abstract: Self-generating foamed fluids for circulation through a well during drilling operations and methods for circulating such self-generating foamed drilling fluids are provided for. The drilling fluid comprises an aqueous solvent, a polymer, a surfactant, a first foam generating agent, and a second foam generating agent. The first and second foam generating agents react to generate a gas within the drilling fluid and thereby to foam the drilling fluid. Preferably, the foam generating agents are selected such that they react to generate carbon dioxide. Preferably a base fluid comprising excess amounts of only one of the foam generating agents is pumped into the drill string using a hydraulic pump. The other foam generating agent then is injected in a controlled manner downstream of the circulation pump such that the drilling fluid is foamed after being pumped for circulation through the well. The novel drilling fluids preferably have a density of from about 5.8 lb/gal to about 0.

Abstract: Water based drilling, drill-in, and completion fluids comprising surfactant-polymer blends that are effective to generate effective rheology comprising low shear rate viscosity and effective fluid loss control properties. The water based fluids preferably are substantially solid free.

Abstract: The present invention concerns a water-based drilling mud for utilization in the drilling of oil wells comprising an aqueous phase wherein the aqueous phase contains an oil soluble polymer in the form of a gel as fluid loss reducer. The subject invention further reveals a process for preparing an oil soluble polymer fluid loss control agent comprising the steps of dissolving at least one polymer in a hydrocarbon oil to form a clear solution or a gel, adding an emulsifier to the solution or the gel, and keeping the mixture under conditions of agitation until a clear creamy mixture is obtained.

Abstract: A composition of matter for use in stablizing shale formations in earth boreholes comprising polymeric products, e.g., polymers of a dialkyl aminoalkyl methacrylate, which can optionally be quaternized with an alkyl halide to produce drilling fluid additives which stablize borehole formations containing reactive clays in the presence of an aqueous medium.

Abstract: Invert emulsion drilling system fluids comprising an oleaginous continuous phase and a non-oleaginous dispersed phase, the dispersed phase comprising organofunctional compound(s) effective to provide shale inhibition. The organofunctional compound(s) may be used either as a supplement to or as a substitute for metallic salts.

Abstract: A drilling fluid additive system is provided wherein the system comprises: a drilling fluid additive comprising talc, graphite and at least one carrier such as a glycol; and hydrophilic clay, a pH controller, a fluid loss controller, and at least one dispersant.

Abstract: Clay is stabilized in the drilling of wells and other formation treatment for hydrocarbon production by the addition to the drilling or other fluid fluid of potassium formate together with a cationic formation control additive.

Abstract: An annular fluid or packer fluid, and methods of making the same, that includes a water-miscible solvent, a viscosifying additive, a crosslinking agent, a crosslinking inhibitor having the facility to inhibit crosslinking between the viscosifying additive and the crosslinking agent, and an initiating agent having the facility to overcome an action of the crosslinking inhibitor and to initiate crosslinking between the viscosifying additive and the crosslinking agent, is shown and described. The fluid has a thermal conductivity of no more than about 0.25 btu/(hr·ft·° F.) and a potential to substantially increase its viscosity upon sitting for a selected period of time.

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: A drilling system fluid and method of using same. The drilling system fluid comprises water as a continuous phase, an amount of a multivalent metal, and a quantity of a water soluble polyacrylamide copolymer having a charge density of at least about 1%. In a preferred embodiment, the fluid also comprises a second amount of a monovalent salt effective to increase gas hydrate suppression and decrease density when compared to a fluid consisting essentially of only a divalent salt in the absence of the monovalent salt.

Abstract: Methods of forming chemical casings include drilling a well bore with a drilling fluid having a pH in the range of from about 6 to 10 and comprising water, a water soluble or water dispersible polymer which is capable of being cross-linked by a thermoset resin and causing the resin to be hard and tough when cured, a particulate curable solid thermoset resin, a water soluble or dispersible thermoset resin, and a delayed dispersible acid-catalyst for curing the solid thermoset resin and the water soluble thermoset resin, whereby the drilling fluid forms a filter cake on the walls of the wellbore that cures into a hard and tough cross-linked chemical casing thereon.

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: A drilling fluid or mud having several components, including leonardite (humic acid); potassium acetate; partially hydrolyzed polyacrylamide (PHPA); polyanionic cellulose polymer (PAC); sulfonated asphalt; sulfoalkylated tannin; polystyrene maleic anhydride copolymer; micronized cellulose fiber; calcium carbonate; and calcium carbonate. These components are preferably premixed in a dry formulation as a powder or as pellets, and shipped to the site in bags or bulk barrels. This offers substantial advantages over the prior art in that the drilling mud of the present invention may be formed simply by adding the dry mix to a predetermined amount of water, and is thus much easier to make than the prior art wet mix drilling fluids, which typically require precise ratios of several different powders and liquids to be mixed together. The humic acid serves as hydration buffer to help keep the powder or pellets dry and flowable.

Abstract: A method is disclosed for drilling a wellbore employing a drilling fluid providing the advantages of easy pumpability of a low viscosity fluid with the drill cuttings suspension capability of a highly viscous fluid. The viscosity of the fluid is also easily and quickly adjustable so that the fluid rheology may be adapted during drilling as the subterranean conditions change. These advantages are obtained by including in said fluid a reversibly crosslinkable polymer and an encapsulated crosslink activator. The crosslink activator causes crosslinking after the fluid is in the wellbore. The crosslinking is reversed at the well surface to reduce the viscosity of the fluid to enable the drill cuttings to be easily removed. Crosslink activator is added back to the fluid and the fluid is returned to the borehole. The amount of crosslink activator and/or crosslinkable polymer may be adjusted in the fluid to change the fluid rheology to conform the fluid to changes in the well conditions as monitored real time.

Abstract: A method of treating a well including injecting a thermally stable, substantially water-free well-treating fluid into the well, wherein the well-treating fluid comprises a polymer, a glycol compound, and a salt is disclosed. In another embodiment, a thermally stable, substantially water-free well fluid including a polymer, a diol compound, and a salt is disclosed.

Abstract: The present invention relates to methods, aqueous treating fluids and friction pressure reducers for the treating fluids. A treating fluid of the invention comprises water and a non-toxic environmentally acceptable friction pressure reducer comprising a mixture of a copolymer of acrylamide and dimethylaminoethyl acrylate quaternized with benzyl chloride and a stabilizing and dispersing homopolymer of ethanaminium,N,N,N-trimethyl-2-[(1,oxo-2-prbpenyl)oxy]-chloride.

Abstract: A composition for sealing porous subterranean formations comprises a mixture of a water-swellable clay and a water insoluble, water absorbent, water-swellable polymer, wherein the mixture is coated with a material that is resistant to penetration by water. The water penetration resistant material helps the delay the onset of swelling of the clay and polymer until it reaches the formations intended for sealing. Mixing the clay with the water-swellable polymer prior to coating assists in coating of the water-swellable polymer with the water penetration resistant material. The coated mixture can be suspended in an aqueous liquid, and then pumped into a subterranean cavity to seal porous formations therein.

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: The use of polymer latices is described for fluid loss control in water-based drilling fluids. The latices used are water insoluble. The latices are essentially non-swelling in an aqueous solution. The latices are selected from known latices such that they are absorbed within a filter cake building up at the interface between the wellbore and porous formations in essentially the same state as they are in the aqueous drilling fluid during circulation.

Abstract: The present invention relates to a cement slurry set in a wellbore. The slurry comprises cement, at least one mineral filler, water and a determined amount of at least one hydrophobically modified acrylamide or acrylate derivative. The present invention also relates to an additive specific to a cement slurry and acting as a filtrate reducer and as a rheological control agent, the additive comprising mainly a hydrophobically modified acrylamide or acrylate derivative.

Abstract: A water-based drilling fluid having a polymer latex capable of providing a deformable latex film on at least a portion of a subterranean formation has been discovered to provide reduced drilling fluid pressure invasion when used to drill in shale formations for hydrocarbon recovery operations. A precipitating agent such as a silicate or an aluminum complex (e.g. sodium aluminate) is preferably used in conjunction with the polymer. Typically, the water present contains a salt to form a brine, often to saturation, although the invention may be practiced with fresh water. If a salt is employed, it is often helpful to additionally employ a surfactant, such as a betaine, for example.

Abstract: Methods of consolidating formations or forming chemical casing or both while drilling are provided. One method of the invention comprises drilling a well bore with a drilling fluid comprised of water, a polymeric cationic catalyst which is adsorbed on weak zones or formations formed of unconsolidated clays, shale, sand stone and the like, a water soluble or dispersible polymer which is cross-linked by a thermoset resin and causes the resin to be hard and tough when cured, a particulate curable solid thermoset resin, a water soluble thermoset resin, and a delayed dispersible acid catalyst for curing the solid and water soluble resins. The drilling fluid forms a filter cake on the walls of the well bore that cures and consolidates the unconsolidated weak zones and formations penetrated by the well bore so that sloughing is prevented and forms a hard and tough cross-linked chemical casing on the walls of the well bore.

Abstract: Methods of consolidating formations or forming chemical casing or both while drilling are provided. One method of the invention comprises drilling a well bore with a drilling fluid comprised of water, a polymeric cationic catalyst which is adsorbed on weak zones or formations formed of unconsolidated clays, shale, sand stone and the like, a water soluble or dispersible polymer which is cross-linked by a thermoset resin and causes the resin to be hard and tough when cured, a particulate curable solid thermoset resin, a water soluble thermoset resin, and a delayed dispersible acid catalyst for curing the solid and water soluble resins. The drilling fluid forms a filter cake on the walls of the well bore that cures and consolidates the unconsolidated weak zones and formations penetrated by the well bore so that sloughing is prevented and forms a hard and tough cross-linked chemical casing on the walls of the well bore.

Abstract: This invention provides a water-free oil based fluid polymer suspension composition for use as a rheology modifier and fluid loss reducer in oil or gas well servicing fluids. It has been found that by using white medicinal oil as a carrier, high solids content and environmental friendly anhydrous fluidized polymer suspensions of xanthan gum, cellulose ethers, guar gum and derivatives thereof can be prepared. More specifically, in one aspect, an oil-based fluid polymer suspension (FPS) composition for use in oil or gas well servicing fluids is preferred containing: a) a hydrophilic polymer, b) an organophilic clay, c) a stabilizer, and d) a white medicinal oil having selected properties.

Abstract: An improved composition and method is provided for preventing or alleviating lost circulation during the drilling of wellbores in subterranean formations, and particularly during the drilling of oil and gas wells. The method is suited for horizontal and directional wells as well as more vertical wells. The composition of the invention comprises a synergistic blend of resilient, angular, carbon-based material and a water-swellable, crystalline synthetic polymer. The method employs the composition of the invention in preventing lost circulation.

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: This invention discloses methods for reducing lost circulation in wellbores. The invention utilizes certain selected water swellable polymers that swell at a rate slow enough to reach the lost circulation zone of a well before those polymers have swollen to an extent that disrupts the drilling process. These selected polymers may be used alone or in conjunction with other lost circulation materials which do not swell or also swell slowly enough to reach the lost circulation zone without interfering with the drilling operation. Mixtures of such materials are also disclosed.

Abstract: The present invention relates to a method for preparing microgels of controlled size. According to the method, a gelling composition comprising a polymer and a crosslinking additive intended for the polymer is injected into a porous and permeable medium, and a monodisperse solution of microgels of substantially constant size is recovered at the outlet. The invention also relates to an application of the method for reducing the permeability of porous and permeable formations of reservoir rock type.

Abstract: A drilling system fluid and method of using same. The drilling system fluid comprises water as a continuous phase, an amount of a multivalent metal, and a quantity of a water soluble polyacrylamide copolymer having a charge density of at least about 1%. In a preferred embodiment, the fluid also comprises a second amount of a monovalent salt effective to increase gas hydrate suppression and decrease density when compared to a fluid consisting essentially of only a divalent salt in the absence of the monovalent salt.

Abstract: Clay is stabilized in the drilling of wells and other formation treatment for hydrocarbon production by the addition to the drilling or other fluid fluid of potassium formate together with a cationic formation control additive.

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 provides a method of taking a crustal core sample, wherein the crustal core sample is obtained in a state coated with antimicrobial polymeric gel obtained by polymerizing an antimicrobial monomer. It is preferred that antimicrobial monomer is a quaternary ammonium salt compound, and the polymer contains a component derived from the antimicrobial monomer in a proportion of 1 to 10 mol %.

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: A drilling fluid system comprising a brine and a quantity of cationic copolymers comprising a ratio of acrylamide monomers to cationic derivatives of acrylamide monomers, wherein the quantity and the ratio are effective to maintain effective rheology and fluid loss control in said drilling fluid system at temperatures of at least about 250° C. for at least about 16 hours.

Abstract: A drilling fluid and method of using same. The drilling fluid comprises water as a continuous phase, an amount of calcium chloride, and a quantity of a polyacrylamide copolymer. The amount of calcium chloride and the quantity of polyacrylamide copolymer in the drilling fluid are sufficient to produce a rate of penetration approaching that achieved using a synthetic oil-based drilling fluid while preventing substantial screen blinding. In a preferred embodiment, the continuous phase also comprises a second amount of a monovalent salt effective to increase gas hydrate suppression and decrease density when compared to a fluid consisting essentially of only a divalent salt in the absence of the monovalent salt.

Abstract: The present invention comprises a stable hydrocolloid composition in which preferably welan gum is uniformly dispersed in a superplasticizer solution such as sulfonated naphthalene, sulfonated melamine, modified lignosulfate, their derivatives and mixtures thereof. The solution is wet milled to form an extremely fine particle size distribution of the gum. The composition is rapidly hydratable and useful as a stabilizing additive in many cement and drilling fluid applications.