Abstract: The device comprises a body provided with bypass ports embodied therein and an insert with a jet pump and sealing elements. The insert comprises a pass channel, a channel for supplying an active medium to the pump nozzle, a channel which is used for supplying a pumped-out medium to the pump and which communicates with the pass channel and an output channel connected to an annular space. A mounting seat for a sealing unit is embodied in the pass channel above the channel for supplying the pumped-out medium. Said mounting seat is provided with an axial channel for passing a cable, which is used for moving instruments along the well bore, therethrough and through the pass channel. An axially movable spring-loaded steady bush provided with bypass holes in the wall thereof is arranged in the body. The insert provided with the pump is placed on the mounting seat embodied in the bush. An annular recess limiting the bush displacement is embodied in the body.

Abstract: Of the many methods provided, in one embodiment, a method is provided that comprises: providing an acid-generating fluid that comprises an acid-generating compound, a base fluid, and a salt; placing the acid-generating fluid in a well bore penetrating a subterranean formation; allowing the salt to affect the hydrolysis of the acid-generating compound; and allowing the acid-generating compound to produce an acid that then acidizes at least a portion of the formation or damage contained therein.

Abstract: The present disclosure relates to a system and method for producing a well-fracturing gel using a gel concentrate such that the method and system are capable of timely adjusting the properties of the gel on the fly just prior to introducing the gel into the well. Further, the present disclosure provides for producing a gel with an overall shorter production time as well as adjusting the properties of the gel just prior to injecting the gel into the well.

Abstract: Delayed breakers are given that break viscoelastic surfactant fluids inside the pores of formations into which the fluids have been injected. The breakers comprise proteins, proteins that contain breakers, or cells that contain breakers. Proteins become breakers, and proteins and cells release breakers, due to a triggering mechanism that may be, for example, a change in temperature, pH, or salinity.

Abstract: A method is for treating a subterranean formation penetrated by a wellbore is given which comprises injecting into the subterranean formation a well treatment fluid having a high pH.

Abstract: Methods and compositions useful for subterranean formation treatments, such as hydraulic fracturing treatments and sand control that include porous materials. Such porous materials may be selectively configured porous material particles manufactured and/or treated with selected glazing materials, coating materials and/or penetrating materials to have desired strength and/or apparent density to fit particular downhole conditions for well treating such as hydraulic fracturing treatments and sand control treatments. Porous materials may also be employed in selected combinations to optimize fracture or sand control performance, and/or may be employed as relatively lightweight materials in liquid carbon dioxide-based well treatment systems.

Abstract: A method and apparatus for fracturing a formation containing a wellbore comprising the steps of (a) injecting a gel into the wellbore; (b) permitting for the gel to increase viscosity and (c) fracturing the formation in the vicinity of the gel.

Abstract: A method of using an organic peroxide containing composition as a gel breaker and a method of transporting the composition is disclosed, wherein the composition has a freeze point less than or equal to ?10° C. and a diluent which contains water and an organic solvent selected from ethylene glycol, methanol, ethanol and 1-propanol. During shipment, the amount of available oxygen in the composition is less than or equal to 1 weight percent.

Abstract: A method is provided for in-situ production of oil shale wherein a network of fractures is formed by injecting liquified gases into at least one substantially horizontally disposed fracturing borehole. Heat is thereafter applied to liquify the kerogen so that oil shale oil and/or gases can be recovered from the fractured formations.

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: A low viscosity fluid for reducing fluid loss in a relatively low permeability formation has a viscosity of less that 10 CP and contains a low molecular weight viscosifying agent The aqueous medium may be fresh water, salt water, brine or slickwater. The invention has particular applicability when an ultra lightweight (ULW) proppant or sand control particulate is employed. The fluid may be used in reservoirs having a relative permeability less than 10 mD.

Abstract: The invention concerns an aqueous viscoelastic fluid for use in the recovery of hydrocarbons. According to the invention, the aqueous viscoelastic fluid comprises a monomer, a dimer or an oligomer of a viscoelastic surfactant able to form a viscoelastic gel under downhole conditions, said surfactant comprising a hydrophobic tail and a hydrophilic head, and being of the following formulae: R—X—Y-Z where R is the hydrophobic tail of the surfactant, Z is the hydrophilic head of the surfactant, said hydrophilic head being charged, X is a stabilising group and Y chain is a linear, saturated or unsaturated, hydrocarbon chain of 1, 2 or 3 carbon atoms or a branched, saturated or unsaturated hydrocarbon chain wherein the main chain is of 1, 2 or 3 carbon atoms, possibly incorporating an aromatic ring.

Abstract: Methods that include a method comprising providing a hydrocarbon-acid emulsion composition that comprises an acid phase, a hydrocarbon blend phase, and an emulsifying agent; and placing the hydrocarbon-acid emulsion composition in a subterranean formation. In some embodiments, the hydrocarbon blend phase comprises at least about 65% hydrocarbons having from six carbons (C6) through eleven carbons (C11). In other embodiments, the hydrocarbon blend phase has a flash point greater than about 100° F. Additional methods are also provided.

Abstract: Exemplary embodiments provide methods of treating a subterranean formation to improve gas production therefrom. Exemplary embodiments of the methods comprise introducing a cationic polyorganosiloxane into the subterranean formation, wherein the cationic polyorganosiloxane comprises at least two quaternary ammonium groups.

Abstract: A composition for treating a portion of a wellbore or a portion of a subterranean formation is provided, the composition comprising: (a) water; (b) a source of hydrogen peroxide, and (c) an activator for the source of hydrogen peroxide; wherein the pH of the composition is adjusted to be within an appropriate range for the type of activator. A method for treating a portion of a wellbore or a portion of a subterranean formation, the method comprising the steps of: forming or providing a composition comprising: (a) water; (b) a source of hydrogen peroxide, and (c) an activator for the source of hydrogen peroxide; wherein the pH of the composition is adjusted within an appropriate range for the type of activator; and introducing the composition through a wellbore to treat a portion of a wellbore or a portion of a subterranean formation. The activator can be a water-soluble alkanoyl-donor compound or a chelated transition metal. Preferably, the composition further comprises an iron chelating agent.

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: Well treatment is disclosed that includes injecting a well treatment fluid with insoluble polyol polymer such as polyvinyl alcohol (PVOH) dispersed therein, depositing the insoluble polymer in the wellbore or an adjacent formation, and thereafter dissolving the polymer by reducing salinity and/or increasing temperature conditions in the environment of the polymer deposit. The method is disclosed for filter cake formation, fluid loss control, drilling, hydraulic fracturing and fiber assisted transport, where removal of the polyol at the end of treatment or after treatment is desired. The method is also disclosed for providing dissolved polyol as a delayed breaker in crosslinked polymer viscosified systems and viscoelastic surfactant systems. Also disclosed are well treatment fluids containing insoluble amorphous or at least partially crystalline polyol, and a PVOH fiber composition wherein the fibers are stabilized from dissolution by salinity.

Abstract: A method to clean a wellbore and the near wellbore area adjacent to the wellbore of a hydrocarbon bearing and/or coal bed methane formation adjacent to the production zone of the wellbore is provided. Specifically, a method for removing liquids such as water and/or oil from the near wellbore formation is provided. Furthermore, A method to clean a casing inserted into a wellbore is also disclosed. A method for cleaning a wellbore of fracturing fluid, with or without proppant is also disclosed. Each of the methods includes the steps of injecting either liquid carbon dioxide or a treatment medium comprising liquid carbon dioxide into a wellbore through tubing such that the location at which the treatment medium is administered may be controlled. In some embodiments, pressure within the wellbore is regulated in order to either maintain the treatment medium in the liquid state, or allow at least a portion of the treatment medium to vaporize upon introduction into the wellbore.

Abstract: A method to clean a wellbore and the near wellbore area adjacent to the wellbore of a hydrocarbon bearing formation adjacent to the production zone of the wellbore is provided. A method to clean a casing inserted into a wellbore is also disclosed. A method for cleaning a wellbore of fracturing fluid, with or without proppant is also disclosed. Each of the methods includes the steps of injecting either liquid carbon dioxide or a treatment medium comprising liquid carbon dioxide into a wellbore through tubing such that the location at which the treatment medium is administered may be controlled. In some embodiments, pressure within the wellbore is regulated in order to either maintain the treatment medium in the liquid state, or allow at least a portion of the treatment medium to vaporize upon introduction into the wellbore. Once the treatment medium has at least partially vaporized it will loosen and/or entrain undesirable materials from within the wellbore or casing.

Abstract: A method for increasing the rate of shear rehealing of fluids made with cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a polymeric rheology enhancer selected from polypropylene glycols and block copolymers of polypropylene glycol and polyethylene glycol. For applications in which rapid shear rehealing is required, the rheology enhancer allows fluids to be made and used at lower viscoelastic surfactant concentrations. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: A monovalent cation containing well fluid composed of an aqueous brine containing at least 0.6 equivalents per liter of a water soluble monovalent cation salt, is substantially free of divalent cations, and an amount of a starch derivative selected such that the well fluid has the following characteristics: (a) a low shear rate viscosity greater than about 5,000 centipoise; (b) a high shear rate viscosity at 511 sec?1 in the range from about 15 to about 70 centipoise measured at 120° F. is described. The fluid may be formulated to be substantially free of xanthan gums and preferably has less than 0.25 lb/bbl of xanthan gum.

Abstract: A fluid loss control system for use in a well penetrating a subterranean formation includes a microgel for forming a monolayer on rock surfaces in fractures in the subterranean formation. A method for fluid loss control in a subterranean formation includes placing a fluid loss control solution in a wellbore penetrating the subterranean formation, wherein the fluid loss control solution comprises a microgel for forming a monolayer on rock surfaces in fractures in the subterranean formation.

Abstract: A method for well treatment by forming a temporary plug in a fracture, a perforation, a wellbore, or more than one of these locations, in a well penetrating a subterranean formation is provided, in which the method of well treatment includes: injecting a slurry comprising a degradable material, allowing the degradable material to form a plug in a perforation, a fracture, or a wellbore in a well penetrating a formation; performing a downhole operation; and allowing the degradable material to degrade after a selected time such that the plug disappears.

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

Abstract: 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: The present invention relates to methods, systems, and apparatus for inducing fractures in a subterranean formation and more particularly to methods and apparatus to place a first fracture with a first orientation in a formation followed by a second fracture with a second angular orientation in the formation. The first and second fractures are initiated at about a fracturing location. The initiation of the first fracture is characterized by a first orientation line. The first fracture temporarily alters a stress field in the subterranean formation. The initiation of the second fracture is characterized by a second orientation line. The first orientation line and the second orientation line have an angular disposition to each other.

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: Methods for treating a formation penetrated by a wellbore which improves fluid loss control during treatment. In some aspects, the treatments include preparing an aqueous fluid including one or more water inert polymers and an optional viscosifier, injecting the aqueous fluid into the wellbore at a pressure equal to or greater than the formation's fracture initiation pressure, and thereafter injecting into the wellbore a proppant laden fluid at a pressure equal to or greater than the formation's fracture initiation pressure. The water inert polymer may be a polymer such as an emulsion polymer or a latex polymer. Some methods of the invention use a fluid which may have a normalized leak off coefficient (Cw/sqrt(K)) equal to or less than about 0.0022, 0.0014, or 0.0010. A conventional fluid loss additive may or may not be used in conjunction with the treatment fluid and/or the proppant laden fluid. The water inert polymer may or may not substantially enter formation pores.

Abstract: One embodiment of the present invention provides methods of treating a subterranean formation with a viscosified treatment fluid comprising combining water, a carbonyl-containing first compound, and an amine-containing second compound; wherein the carbonyl-containing first compound comprises at least one carbonyl moiety and is either a gelling agent or a derivatizing agent, and wherein the amine-containing second compound comprises at least one amine moiety and is a gelling agent when the carbonyl-containing first compound is a derivatizing agent and is a derivatizing agent when the carbonyl-containing first compound is a gelling agent; allowing at least one carbonyl moiety from the first compound and at least one amine moiety from the second compound to form a derivatizing linkage and create a derivatized gelling agent; and, placing the viscosified treatment fluid into a portion of a subterranean formation.

Abstract: An aqueous, viscoelastic fluid gelled with a viscoelastic surfactant (VES) is stabilized and improved with an effective amount of an alkali earth metal oxide and/or alkali earth metal hydroxide. These fluids are more stable and have reduced or no tendency to precipitate, particularly at elevated temperatures. The additives may also increase viscosity to the point where less VES is required to maintain a given viscosity. These stabilized, enhanced, aqueous viscoelastic fluids may be used as treatment fluids for subterranean hydrocarbon formations, such as in hydraulic fracturing.

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

Abstract: A method for shortening the shear recovery time of zwitterionic viscoelastic surfactant fluids by adding a rheology enhancer having the structure: R-(EO)x(PO)y—R?—OH in which R is an alkyl group that is straight chained or branched, saturated or unsaturated, and contains from 3 to about 18 carbon atoms, x is from 0 to about 14, y is from 0 to about 7, R? is an alkyl group that contains from 0 to about 14 carbon atoms and is straight chained, branched if having more than 3 carbon atoms, saturated, unsaturated if having more than one carbon atom, the total number of carbon atoms in R plus R? is from 3 to about 21, and the EO and PO groups, if present, may be in any order. The rheology enhancer also increases fluid viscosity and thermal stability. Preferred surfactants are betaines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: Methods of treating a subterranean formation comprising providing a viscosified treatment fluid that comprises a base fluid and a gelling agent, providing a breaker composition that comprises an oxidizing breaker and a breaker activator that comprises a metal and a protein, allowing the viscosified treatment fluid to interact with the breaker composition, treating the subterranean formation with the viscosified treatment fluid, and allowing a viscosity of the viscosified treatment fluid to be reduced. Further, methods of reducing the viscosity of a viscosified treatment fluids and methods of activating oxidizing breakers are also provided.

Abstract: The handling, transport and delivery of particulate materials, particularly fine particles, may be difficult. Alkaline earth metal oxide particles such as magnesium oxide (MgO) may be suspended in glycerin and/or alkylene glycols such as propylene glycol up to loadings of 51 wt %. Such suspensions or slurries make it easier to deliver MgO and similar agents into fluids, such as aqueous fluids gelled with viscoelastic surfactants (VES). The MgO serves as stabilizers and/or fluid loss control agents for VES-gelled fluids used to treat subterranean formations, e.g. for well completion or stimulation in hydrocarbon recovery operations. The particle size of the magnesium oxide or other agent may be between 1 nanometer to 0.4 millimeter.

Abstract: Methods of treating a portion of a subterranean formation, comprising: providing an aqueous treatment fluid comprising water, and a friction reducing copolymer that comprises acrylamide and an acrylic acid ester; and introducing the aqueous treatment fluid into the portion of the subterranean formation. Methods of fracturing a subterranean formation comprising: providing an aqueous treatment fluid comprising water, and a friction reducing copolymer that comprises acrylamide and an acrylic acid ester; and introducing the aqueous treatment fluid into the subterranean formation at or above a pressure sufficient to create one or more fractures in the subterranean formation. Aqueous treatment fluids comprising: an aqueous fluid and a friction reducing copolymer that comprises acrylamide and an acrylic acid ester.

Abstract: Methods are provided including a method comprising: providing a treatment fluid comprising particulates at least partially coated with a polymer, wherein the polymer is deposited on the particulates by at least partially coating the particulates with a polymer solution comprising the polymer and a solvent and then exposing the particulates to an aqueous medium such that the solvent substantially dissociates from the polymer solution and such that the polymer substantially remains on the particulates; introducing the treatment fluid into a portion of a subterranean formation; and, depositing at least a portion of the particulates in the portion of the subterranean formation.

Abstract: A well treating fluid useful in slickwater fracturing processes contains polyacrylamide friction reducer and a viscosity breaker capable of reducing the viscosity of the well treating fluid to about the viscosity of water at ambient temperatures of typical underground formations. The viscosity breaker is selected from the group consisting of hydrogen peroxide, calcium peroxide, magnesium peroxide, and zinc peroxide and is present in an amount above about 0.002% by weight.

Abstract: Disclosed are acid fracturing methods for subterranean siliceous formations employing a viscous dissolving fluid to create a permeable conduit that bypasses the near wellbore damage. The viscous dissolving fluids used according to the invention are acid-fracturing treatment fluids containing a dissolving agent viscosified with a material such as a viscoelastic surfactant, and the fluid is injected into a sandstone formation at a pressure sufficient to create a hydraulic fracture. Also, the viscous dissolving fluid leaks off into the faces of the fracture thus “stimulating” the formation. Hence when the hydraulic fracture has closed there is a part of the formation that has been effectively stimulated, creating a pathway for fluids to preferentially flow to the wellbore. The formation may then be flowed back to produce a substantial volume of the treatment fluid.

Abstract: A method of acidizing a subterranean formation with a diverting agent composed of a gelled or thickened viscoelastic foam or fluid generated from (i.) an amidoamine oxide gelling agent and (ii.) an acid or foam, water and/or brine. The gelled or thickened foam or fluid may be generated in-situ or introduced directly into the formation by mixing of the amidoamine oxide gelling agent and acid or foam, water and/or brine. As the acid spends, the acidizing fluid thickens. When the acid is further spent, the fluid viscosity declines eventually returning to a low viscosity state, allowing for easy cleanup. The process allows for selective acidizing of less permeable zones of the formation and more uniform stimulation of the hydrocarbon bearing formation.

Abstract: Propped fractures in formations from which fluids are produced are described that have wormholes extending out into the formations from the faces of the fractures at locations distant from boreholes. Methods are given for creating such propped fractures having wormholes in which either a closed propped fracture is formed and then the wormholes are formed, or the entire fracture and channel system is formed before the closure occurs.

Abstract: The invention provides a fluid for use in a subterranean formation penetrated by a wellbore, the fluid comprising: (a) water; (b) an orthoester; and (c) a surfactant comprising a tertiary alkyl amine ethoxylate generally represented by the following formula: wherein R is an alkyl group or aryl group, and wherein X and Y are each independently at least one. The invention also provides a method of fracturing a subterranean formation, comprising the step of forming a foamed fracturing fluid comprising water; an orthoester; a surfactant comprising a tertiary alkyl amine ethoxylate generally represented by the formula above; 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.

Abstract: Many methods are provided including methods of stabilizing a portion of a subterranean formation or reducing the production of particulates from a portion of a subterranean formation comprising contacting the portion of the subterranean formation with a pre-flush fluid; contacting the portion of the subterranean formation with a consolidation fluid comprising a resin and an aqueous dissolvable solvent; and, contacting the portion of the subterranean formation with an after-flush fluid. Also provided are methods of fracturing a portion of a subterranean formation while controlling particulates comprising contacting the portion of the subterranean formation with a pre-flush fluid; contacting the portion of the subterranean formation with a consolidation fluid comprising a resin and an aqueous dissolvable solvent; and, contacting the portion of the subterranean formation with a fracturing fluid at a pressure sufficient to create or enhance a fracture in the subterranean formation.

Abstract: The present invention relates to the field of additives to enhance hydraulic fracturing used in the production of oil and gas. The additive is an inorganic nitrogen and phosphorus-containing composition that can be added to, or used in conjunction with aqueous or non-aqueous hydraulic fracturing fluids or fracturing fluid adjunctives.

Abstract: Delayed breakers are given that break viscoelastic surfactant fluids inside the pores of formations into which the fluids have been injected. The breakers comprise proteins, proteins that contain breakers, or cells that contain breakers. Proteins become breakers, and proteins and cells release breakers, due to a triggering mechanism that may be, for example, a change in temperature, pH, or salinity.

Abstract: The present invention relates to high porosity propped fractures and methods of creating high porosity propped fractures in portions of subterranean formations. Another embodiment of the present invention provides a method of forming a high porosity propped fracture in a subterranean formation, comprising providing a slurry comprising a fracturing fluid and proppant particulates coated with an adhesive substance; introducing the slurry into a portion of a fracture within the subterranean formation; and, depositing the proppant particulates into the portion of the fracture within the subterranean formation so as to form a high porosity propped fracture. Another embodiment of the present invention provides a high porosity propped fracture comprising proppant particulates substantially coated with an adhesive substance wherein the propped fracture has a porosity of at least about 50%.

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: A formulation containing a copolymer derived from a cationic monomer effectively inhibits and controls the formation of inorganic scales. The formulation has particular application in the removal of zinc sulfide and iron sulfide scales formed when zinc bromide brines are used as completion fluids. The copolymer exhibit high solubility in high-density brines, such as zinc bromide brines. The polymers may be introduced into an oil or gas well as a portion of a carrier fluid or with brine. The preferred copolymer for use in the invention contains an acrylamide unit and a diallyldimethylammonium salt and, optionally, an acrylic acid or a salt thereof. The weight average molecular weight of such inhibitor copolymers is generally between from about 500,000 to about 5,000,000.

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.