Abstract: Methods are provided for increasing the production of hydrocarbons from shaly formations that contain adsorbed condensed hydrocarbon gases by treating such formations with dewatering compositions comprising surfactants that cause the surfaces of the formation to be or to remain oil-wet. The methods may be used in stimulation (acidizing or acid fracturing or hydraulic fracturing), remediation or workover, and in enhancing flow from natural fractures or from unstimulated formations.

Abstract: Improved methods of generating gas in and foaming aqueous well fluids introduced into a subterranean zone are provided. A method of the invention includes the steps of combining with an alkaline aqueous well fluid one or more gas generating chemicals and a mixture of foaming and foaming stabilizing surfactants so that the gas generating chemical or chemicals react with the alkaline aqueous well fluid and gas and foam are formed in the well fluid while it is being pumped, and then pumping the well fluid into the subterranean zone.

Abstract: The effect of various chemical or biological agents in well treatment fluids can be delayed by sequestering the agents in the discontinuous phase of an emulsion for a period of time, before the emulsion is destabilized by exposure to at least one of: (1) a change in temperature, (2) a change in pH, (3) a change in salinity, (4) a change in alcohol concentration, (5) a change in stabilizing surfactant concentration, (6) a change in organic ion concentration, (7) a change in destabilizing surfactant concentration, (8) a change in surfactant adsorbent material concentration, (9) an ultrasonic pulse, and (10) an electrical field. Upon exposure to the emulsion destabilizing condition, the agent sequestered in the discontinuous phase of the emulsion is released into the continuous phase of the fluid composition, where it can have its intended effect.

Abstract: A water-base fluid for use in drilling wells and other drilling operation includes a shale which swells in the presence of water. The fluid preferably includes: an aqueous based continuous phase, and a shale hydration inhibition agent having the formula: H2N—R—{OR′}x—Y in which R and R′ are alkylene groups having 1 to 6 carbon atoms and x is a value from about 1 to about 25. The Y group should be an amine or alkoxy group, preferably a primary amine or a methoxy group. The shale hydration inhibition agent should be present in sufficient concentration to reduce the swelling of the shale. The fluid may be used for formulating drilling fluids such as invert emulsion drilling muds or clear brine drilling fluids. The fluid may also be used in the slurrification and disposal of drill cuttings that contain water swellable clays or shales.

Abstract: Non-aqueous base wellbore fluids characterized by enhanced electrical conductivity due to formulation with specified ionic liquids are disclosed. Drilling, completion, and workover methods utilizing the wellbore fluids are also disclosed.

Abstract: Disclosed is a method of increasing the low shear rate viscosity and the shear thinning index of aqueous fluids containing a divalent cation salt, a crosslinked amylopectin starch which functions as both a viscosifier/suspending agent and as a fluid loss control additive, and a bridging agent, the fluids resulting from the method, and the use of the fluids in drilling a well, wherein the bridging agent is a sized particulate magnesium carbonate or a mixture of sized magnesium carbonate and sized calcium carbonate. The median (D50) particle size of the magnesium carbonate is from about 2 &mgr;m to about 10 &mgr;m. The weight ratio of calcium carbonate to magnesium carbonate is from about 70/30 to about 0/100.

Abstract: A drilling fluid comprising a pyruvate-free xanthan, which may be an acetate-free pyruvate-free xanthan, and a high density calcium-based brine. Preferably the pyruvate-free xanthan is a genetically prepared pyruvate-free xanthan. A process for recovering crude oil from an oil-bearing subterranean formation by drilling the formation and using a drilling fluid comprising a pyruvate-free gum and a high density calcium-based brine.

Abstract: The Invention relates to novel fluids and techniques to optimize/enhance the production of hydrocarbon from subterranean formations (e.g., “completion fluids”), in particular, fluids and techniques are disclosed and claimed which remove wellbore damage and near-wellbore damage in the form of coating formed from drilling and production-related operations (“filtercake”); the techniques can be applied either by themselves or in conjunction with other completion operations, such as gravel packing; preferred embodiments are chelating agent and enzyme systems in a viscoelastic surfactant (VES) matrix.

Abstract: A well service fluid and method using same for brine-sensitive formations is disclosed. The fluid is an invert oil emulsion comprising heavy, solids-free brine, an oil or synthetic, and sufficient emulsifier to create the emulsion. The fluid has particular applicability in gravel packing a horizontal well.

Abstract: Disclosed is a composition for and method of reducing the loss of fluid from well drilling, completion, or workover fluids during well drilling, completion, or workover operations, particularly for reducing or overcoming the lost circulation of drilling fluids. The composition comprises an aqueous liquid containing partially hydrated chitosan particles wherein the chitosan particles have been partially hydrated at a pH less than about 4.5, and wherein the aqueous liquid has a pH of at least about 6.5 such that any further solublizing of the chitosan is prevented. The aqueous liquid, preferably when mixed with a drilling, completion, or workover fluid, is effective in decreasing the loss of such fluids after introducing the partially hydrated chitosan-containing liquid or fluid into the flow passages in a well to which such fluids are being lost.

Abstract: A method for controlling the rheology of aqueous systems, particularly for those intended for underground use, includes injecting an aqueous viscoelastic fluid containing a surfactant gelling agent into the system. The viscoelastic surfactant composition of the invention comprises, as a gelling agent, at least one fatty aliphatic amidoamine oxide in a glycol solvent. The composition also maintains the levels of free fatty acid and free amine within critical parameters in order to achieve superior performance. The additives may be incorporated in the viscoelastic fluid to tailor its use in stimulation fluids, drilling muds, fracture fluids, and in applications such as permeability modification, gravel packing, cementing, and the like.

Abstract: Novel polymer compositions are disclosed, along with their use as well service fluids, for example as completion fluids, work-over fluids or drilling fluids, comprising water soluable copolymers having sulfonate groups and carboxylate groups, along with alkali metal salts of carboxylic acid. Exemplary copolymer has 5 to 95 wt. % structural units derived from 2-acrylamido-2-methylpropanesulfonic acid or salt thereof, and 5 to 95 wt. % structural units derived from acrylic acid or salt thereof. A salt of the polymer may be used, such as the sodium, potassium, ammonium and calcium salts. Exemplary alkali metal salts of the polymer composition include sodium, potassium and cesium salts of formic acid and/or acetic acid in amounts suitable to develop high temperature viscosity suitable for such well servicing fluids. The polymer composition is hydrateble/soluble in a brine of sodium and/or potassium and/or cesium salts of formic and/or acetic acid.

Abstract: The invention provides clay-free, preferably biopolymer free, well drilling and servicing fluids comprising an aqueous divalent cation-containig water soluble salt, a bridging agent, and a pre-gelatinized crosslinked amylopectin starch suspending agent and fluid loss control additive. The concentration of the starch derivative is sufficient to provide the fluid with the following charactristics: (a) a low shear rate viscosity less than about 10,000 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.; (c) a fluid loss less than about 10 milliliters as measured at 185° F. and 250 psi differential pressure across a 5 micron disk for 30 minutes; and (d) anti-settling characteristics as exhibited upon static aging the fluid for 16 hours at 185° F.

Abstract: The invention provides clay-free, preferably biopolymer free, well drilling and servicing fluids comprising an aqueous divalent cation-containing water soluble salt, a bridging agent, and a pre-gelatinized crosslinked amylopectin starch suspending agent and fluid loss control additive. The concentration of the starch derivative is sufficient to provide the fluid with the following charactersitics: (a) a low shear rate viscosity less than about 10,000 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.; (c) a fluid loss less than about 10 milliliters as measured at 185° F. and 250 psi differential pressure across a 5 micron disk for 30 minutes; and (d) anti-settling characteristics as exhibited upon static aging the fluid for 16 hours at 185° F.

Abstract: A process for circulating an aqueous foam in a wellbore includes the steps of forming a foam from an aqueous composition having a determined pH value, injecting the foam into a well so that it circulates from the surface to the well bottom and then back from the well bottom to the surface, and then changing the pH value of the foam when it returns to the surface. The aqueous composition from which the foam is made includes at least one ionic surfactant whose charge does not practically depend on the pH value and a polyampholytic polymer whose global charge depends on the pH value. This composition gives the foam the property that when the pH of the foam is varied at the surface of the well, the charge of the polyampholytic polymer is modified and the foam becomes destabilized and breaks more readily.

Abstract: Pumpable multiple phase compositions for carrying agents and components downhole and controllably releasing them by breaking the suspensions are described. The multiple phase composition may have an external or third phase, which in turn has a first pumpable emulsion internally. The first pumpable emulsion has a second phase containing a first phase which bears the agent to be controllably released. The entire pumpable multiple phase composition may thus be an oil phase-in-aqueous phase-in-oil phase emulsion, or an aqueous phase-in-oil phase-in-aqueous phase emulsion. For example, a water-soluble shale stabilizer could be delivered downhole in an aqueous phase-in-oil phase-in-aqueous phase multiple phase emulsion by injecting the multiple phase composition into a water-based drilling fluid, and then the suspension broken by rotary bit nozzles under high shear stress to release the shale stabilizer at the drilling zone.

Abstract: A wellbore service fluid comprising viscoelastic surfactants in combination with means for controlling the concentration of at least partially charged sites within the fluid is described.

Abstract: A drilling, drill-in, or completion fluid comprising water as a continuous phase, said continuous phase comprising a gas hydrate inhibiting amount of a blend comprising an ethylene glycol derivative and a propylene glycol derivative. The propylene glycol derivative is present in an amount effective to inhibit hydration of shale by the water base. The density of the fluid may be reduced by substituting the blend for salt, and by increasing the amount of propylene glycol derivative in the blend. The blend preferably should comprise at least about 10 vol % of the fluid, and a preferred ratio in the blend is about 35 vol % tripropylene glycol bottoms to about 65 vol % ethylene glycol.

Abstract: The materials include non-polyampholite crosslinked polymers and gels based on a polymer which in uncrosslinked form is substantially soluble in ionic fluids and substantially insoluble in water. The materials change their state of hydration in response to an environmental trigger. The disclosed materials are useful as drilling, completion or workover fluids in wells such as hydrocarbon producing wells. According to the disclosed method, crosslinked polymers or gels are introduced into a stratum, blocking or bridging the pores of the stratum. Thereafter, an environmental condition is changed to cause the hydrated material to become less hydrated to unblock the pores allowing production from the well.

Abstract: The materials include non-polyampholite crosslinked polymers and gels based on a polymer which in uncrosslinked form is substantially soluble in ionic fluids and substantially insoluble in water. The materials change their state of hydration in response to an environmental trigger. The disclosed materials are useful as drilling, completion or workover fluids in wells such as hydrocarbon producing wells. According to the disclosed method, crosslinked polymers or gels are introduced into a stratum, blocking or bridging the pores of the stratum. Thereafter, an environmental condition is changed to cause the hydrated material to become less hydrated to unblock the pores allowing production from the well.

Abstract: A drilling fluid contains caustic, a natural wax, a natural thinner, glycerol, phosphoric acid and/or boric acid, and optionally a gel. The drilling fluid can be prepared in modules. Each module contains additional compounds to improve or change the action of the drilling fluid depending on the condition found in the field. The drilling fluid adjusts the properties of conventional drilling muds including increasing lubrication, thins the drilling mud, decreases bit balling, decreases rock resistance and controls phase separation of the drilling muds.

Abstract: A fluid selected form the group consisting of a drilling, a drill-in, and a completion fluid, said fluid comprising a substantially linear heteropolyglycol in an amount effective to perform a function selected from the group consisting of polymer stabilization, shale stabilization, and a combination thereof. The fluid preferably comprises water as a continuous phase, and the heteropolyglycol preferably consists essentially of monomers selected from the group consisting of ethylene oxide and linear alpha-omega alkylene diols.

Abstract: Simplified drilling fluids (and other well bore fluids) contain a non-aqueous-base fluid and a viscosifying/fluid loss agent that meets certain performance criteria.

Abstract: The present invention is directed to an oil-free, water-soluble, liquid, polymer dispersion for use in thickening aqueous mediums, particularly completion and workover fluids used in the oil and gas drilling business. The dispersions of the present invention are comprised of hydroxyethyl cellulose and propylene glycol derivatives, preferably both propylene glycol polyether polyols and an aliphatic propylene glycol ether. Optionally these dispersions include water. Because of their low toxicity, these dispersions are particularly useful for drilling in offshore environments. These compositions rapidly disperse in and viscosity a variety of brines, including sea water and other light brines, with minimum shear and without fisheye formation.

Abstract: A drilling fluid additive for controlling solids comprising a carrageenan material, such as iota or kappa carrageenan. The drilling fluid additive may be used with other additives, such as a polyacrylate dispersant. Among other things, the drilling fluid additive may be used to drill deviated or horizontal wells, or wells having large diameter boreholes.

Abstract: Wellbore fluids are disclosed which comprise liquid dispersions of particulate mixed divalent metal carbonates having a generally platy crystal form. Mixed alkaline earth metal carbonates are preferred. The invention further relates to a method of well construction, well remediation, or stimulation utilizing such wellbore fluids.

Abstract: A plugging liquid for plugging of a zone of a subterranean formation around a drill hole, consisting of an emulsion comprising (a) a continuous phase containing a hydrophobic liquid, an emulsifier and a crosslinking agent for a polysaccharide, and (b) a discontinuous phase containing water and a polysaccharide. A variant of the plugging composition contains in addition a weighting material in the discontinuous phase. Also described is a method for preparing the plugging liquid and a method for plugging a zone of a subterranean formation penetrated by a drill hole in fluid communication with the zone, according to which method the new plugging liquid is injected into the zone via the drill hole and is subjected to high shear forces in the drill hole, whereby the polysaccharide and the crosslinking agent are brought into contact with one another with resulting initiation of a crosslinking of the polysaccharide and the crosslinking agent and a setting of the plugging liquid.

Abstract: The disclosed invention is a solids-stabilized emulsion and method for making same for use in recovering hydrocarbons from a subterranean formation. More specifically, the emulsion comprises oil and water and is stabilized using undissolved solid particles, which are preferably at least partially oleophilic. Carbon dioxide or another gas is added to the emulsion to adjust the emulsion's viscosity to the desired level. The solids-stabilized emulsion may be used either as a drive fluid for displacing hydrocarbons from the formation or to produce a barrier for diverting flow of fluids in the formation. Such solid particles may be either formation solid particles (i.e., indigenous to the formation) or nonformation solid particles (i.e., obtained from outside the formation). Nonformation solid particles may either be naturally occurring or synthetic. Some preferred solids include clays, quartz, feldspar, gypsum, coal dust, asphaltenes, and polymers.

Abstract: The materials include non-polyampholite crosslinked polymers and gels based on a polymer which in uncrosslinked form is substantially soluble in ionic fluids and substantially insoluble in water. The materials change their state of hydration in response to an environmental trigger. The disclosed materials are useful as drilling, completion or workover fluids in wells such as hydrocarbon producing wells. According to the disclosed method, crosslinked polymers or gels are introduced into a stratum, blocking or bridging the pores of the stratum. Thereafter, an environmental condition is changed to cause the hydrated material to become less hydrated to unblock the pores allowing production from the well.

Abstract: A process for the treatment of oil wells having a high content of "acid gases", comprises circulating through or pumping into the well a slurry comprising a water-soluble, solid salt and a saline solution, which slurry does not react with the "acid gases" and which has a density of more than 13 and preferably of at least 14 lb/gal.

Abstract: The invention provides brine based well drilling and servicing fluids which exhibit relatively thermally stable rheological and filtration characteristics. The fluids comprise a brine, an amorphous silica viscosifier, a biopolymer viscosifier, a fluid loss control additive, and a bridging agent. By utilizing both a silica viscosifier and a biopolymer viscosifier to provide the desired rheological characteristics, the fluids have enhanced thermal stability thus maintaining their suspension and hole cleaning properties over an extended temperature range.

Abstract: Elastic solids having reversible stress-induced fluidity are prepared, e.g., by combining liquid formulations with a crystalline mixed metal hydroxide conforming substantially to the formulaLi.sub.m D.sub.d T(OH).sub.(m+2d+3+n.multidot.a) (A.sup.n).sub.a .multidot.xH.sub.2 Owhere m is amount of Li, d is amount of divalent metal D, T is a trivalent metal, A represents at least one anion or negative-valence radical of valence n and a is the amount of A, and xH.sub.2 O represents excess waters of hydration, if any. These make useful coatings.The instantly reversible fluidization of these unique elastic solids may be expressed as:.sigma.=k.sub..alpha. .epsilon. when .epsilon.<F, for the solid phase; and.sigma.=f(d.epsilon.'/dt) when .epsilon.'>F, (this equation represents a generalized form for the usual theological equations); for a cycle of .epsilon., -xF <.epsilon.<xF, and when .epsilon.' equals 0 the liquid phase changes back to the solid phase, andwhere the symbol .sigma. represents stress; k.

Abstract: Solids-free, essentially all-oil and invert emulsion wellbore fluids are employed in well drilling, completion, and workover operations. Techniques for remediating dense aromatic solvents wellbore fluids entail removal and/or dissolution of particulate matter.

Abstract: The invention involves biopolymer/oil suspension compositions for the oil service industry, most particularly drilling and completion fluids, which provide such fluids a variety of desirable properties. Biopolymers include water soluble polymers and water swellable polymers. Such biopolymer/oil suspension compositions are essentially mixtures of biopolymers such as cellulosics in an oil medium with a specific anti-settling additive. The invention is particularly directed to providing enhanced anti-settling properties to such biopolymer/oil compositions; that is, the ability of the biopolymer/oil composition to retain the biopolymers in suspension prior to the composition being introduced into drilling and completion fluids. The invention in one embodiment is described as a liquid biopolymer-in-oil additive compositions for use in aqueous-based completion fluids, containing an agent comprising: a) one or more polyamides, and b) hydrogenated caster oils including castorwax.

Abstract: The invention provides for either (a) increasing the yield point or gel strength of an aqueous based drilling fluid; (b) decreasing the fluid loss of an aqueous based drilling fluid; (c) decreasing the coefficient of friction of an aqueous based drilling fluid; or (d) decreasing the aqueous activity of an aqueous based fluid drilling fluid thus decreasing the swelling of shales contacted by an aqueous based fluid, the methods comprises adding to the drilling fluid an amount of an alkyl glycoside, preferably methyl glucoside, sufficient to effect such increase or decrease. The invention also provide for aqueous based completion fluids, workover fluids, and well working fluids containing an alkyl glucoside solubilized in the aqueous phase of said fluids.

Abstract: Polymer enhanced foam fluid is utilized for completion, workover, and kill operations in wells penetrating subterranean formations. The foam is formed by appropriately adding a gas to an aqueous solution of a substantially noncrosslinked water soluble polymer and a surfactant. The solution and the foam are substantially free of crosslinking agents. The foam may be generated at the surface or in a wellbore.

Abstract: A thixotropic thermal insulating fluid includes a heavy hydrocarbon, water and oleophilic clay, wherein said heavy hydrocarbon is present in an amount of between about 75% to about 92% by volume of the fluid, said water is present in an amount of between about 5% to about 15% by volume of the fluid, and said oleophilic clay is present in an amount of between about 3% to about 10% by volume of the fluid. The fluid may be prepared by mixing water in an amount of between about 5% to about 15% by total volume of the fluid with oleophilic clay in an amount of between about 3% to about 10% by total volume of the fluid so as to provide a substantially homogeneous first gel product; and mixing said first gel product with a heavy hydrocarbon in an amount of between about 75% to about 92% by total volume of the fluid under agitation for a time sufficient to provide a second thixotropic gel product.

Abstract: The present invention relates to a process used in a well for controlling the filtration of a drilling, a completion or a workover fluid set in a well. The process comprises adding a predetermined amount of at least one hydrophobically modified cellulose derivative. In a variant of the invention, the cellulose derivative is a hydrophobically modified hydroxyethylcellulose. The invention further relates to a drilling, a completion or a workover fluid including at least one hydrophobically modified cellulose derivative, for example hydrophobically modified hydroxyethylcellulose and notably viscosifiers such as polymers or reactive clay.

Abstract: A water-based well completion and workover fluid is disclosed which has improved rheological and filtration control properties at temperatures up to about 450.degree. F. The composition comprises a saturated brine solution, a sized-salt that is insoluble in the saturated brine solution, and a water-soluble filtration additive comprising a polymer produced from at least two monomers selected from the group consisting of 2-acrylamido-2-methylpropanesulfonate, acrylamide, and 2-vinylpyrrolidone.

Abstract: This invention relates to a composition comprising a mixture of a brine and a liquid oil, and (A) an emulsifying amount of (i) at least one reaction product of a hydrocarbyl-substituted succinic acylating agent, and at least one of (a) ammonia, (b) an alcohol, or (c) an amine, or at least one salt of the reaction product; or (ii) at least one reaction product of a hydroxyaromatic compound, an aldehyde, and an amine, and (B) at least one surfactant selected from the group consisting of a polyoxyalkylene amine, a polyoxyalkylene amide, a polyoxyalkylene alcohol, a polyoxyalkylene phenol, a polyoxyalkylene ester, a fatty acid salt, an amine or an alkaline earth or transition metal sulfonate, or a reaction product of a hydroxyamine or a polyalkylenepolyamine with an acylating agent selected from the group consisting of a fatty monocarboxylic acylating agents, a dicarboxylic acylating agent other than a succinic acylating agent, and a tricarboxylic acylating agent.

Abstract: A method of making a well fluid for use in a well which includes the steps of determining uphole and downhole operating temperatures in the well, and then contacting a well lubricant with a lubricating additive, wherein the lubricating additive has a cloud point temperature greater than the uphole operating temperature and less than the downhole operating temperature. A method of lubricating drilling equipment during opeation of a subterranean well, includes the steps of determining uphole and downhole operating temperatures in the well, and then contacting the drilling equipment with a treating fluid comprising a well lubricant and a lubricating additive, with the lubricating additive having a cloud point temperature greater than the uphole operating temperature and less than the downhole operating temperature.

Abstract: A composition, especially suitable for use as a mud sweep and a spacer. The composition includes a petroleum-based hydrocarbon, a biopolymer, a thickening agent, a surfactant and potassium chloride. Other optional ingredients in embodiments of the present invention include a lower alkanol, sodium salts and aluminum stearate.

Abstract: High temperature blocking gel is shown for temporary workover operations. The blocking gel is prepared by blending a guar or derivatized guar polymer with an aqueous fluid. The mixing method employed mixes and pumps the guar polymer essentially unhydrated. The resulting lower viscosity minimizes friction pressure during placement.

Abstract: A blended additive composition, which is useful for thinning aqueous drilling fluids, is disclosed. The composition includes a first component selected from the group including: a modified tannin, a modified lignite and sodium lignosulfonate; a second component being a polymer prepared from acrylic acid; and a third component being a metal compound selected from the group of metals including iron, tin, chromium, manganese, titanium, aluminum and zinc.

Abstract: Water-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.