Abstract: A method of making a rheology modified aqueous composition, particularly useful for drilling, milling and mining applications, is disclosed. The method includes admixing, with a clay and water, a material or materials whose constituents substantially conform to the proportions of the empirical formula M′mM″n(OH)(2m+3n+qa+br)(Aq)a(Br)b.

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 sweep material is disclosed comprising barium sulfate that has been ground and sieved, preferably in the range of about −95% 30 mesh to about +95% 100 mesh. The sweep material is added to and circulated with the drilling fluid during drilling of a deviated, directional or horizontal well to remove cuttings beds accumulated on the lower side of the well. After the drill cuttings are dislodged, the drilling fluid is sieved or screened to remove the barium sulfate to avoid a change in density of the fluid. The drilling operation does not have to be stopped during the sweep or cleaning treatment.

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 thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.

Abstract: A silicate drilling fluid having effective rheology and filtration control properties comprising water as a continuous phase wherein hematite is used as a weighting agent and manganese oxide is used as a bridging agent. The drilling fluids uses a minimal number of components, which includes a salt, preferably sodium chloride, water-soluble polymers for viscosification and filtration control, and a glycol for shale stabilization and filtration control.

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 water-base drilling fluid for use in drilling wells through a formation containing a shale which swells in the presence of water. The drilling fluid preferably includes: an aqueous based continuous phase, a weight material, and a shale hydration inhibition agent having the formula: H2N—CH(CH3)CH2{—OCH2CH(CH3)—}x—NH2 in which x is a value less than 15. The shale hydration inhibition agent should be present in sufficient concentration to reduce the swelling of the shale. Preferably x has an average number between about 1 and about 5 and more preferably x has an average number of about 2.6. Also inclusive of the present invention is a method of reducing the swelling of shale clay encountered during the drilling of a subterranean well, the method comprising circulating in the well a water-base drilling fluid formulated in accordance with the present invention.

Abstract: New compositions have been discovered which are useful as slurry concentrates to carry solid particles along in a fluid. A non-limiting example would be to carry proppants in a concentrate to a completion fluid being pumped downhole in a hydrocarbon recovery operation. The composition employs both a trivalent salt, such as aluminum chlorohydrate, as a viscosifying agent, and a surfactant. Surprisingly, it has been discovered that a synergistic effect is present between the aluminum chlorohydrate and the surfactant in 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. The viscoelasticity of the concentrate may be easily broken by dilution; other mechanisms are also anticipated.

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: A pourable aqueous composition for use as, or for dilution to form, a drilling mud comprises a least 2% by weight of a water soluble polyvalent metal salt of an alkyl polyoxyalkylene sulphuric or carboxylic acid, and at least 1% by weight of a corresponding salt of an alkyl benzene sulphuric acid, preferably in the presence of a water soluble inorganic salt or base of said polyvalent metal.

Abstract: An improved drilling fluid with enhanced anti-settling properties useful for oil well drilling systems is described. The invention includes a process for providing anti-settling properties to oil invert (i.e., water in oil emulsion) based fluids. The drilling fluid/drilling mud invention contains at least one copolymer reaction product of which the reactants comprise at least one ethylenically unsaturated carboxylic compound and at least one alpha-olefin. As an alternative embodiment one or more rheologically-active clays including organoclays and smectite clays in combination with such copolymer reaction product are also added to the drilling fluid. The invention also includes an anti-settling additive comprising a rheologically active clay and the above described copolymer.

Abstract: Disclosed are oil-in-water emulsions containing an aqueous continuous phase, an emulsified oleaginous liquid, and an oligosaccharide mixture composed of sugar units selected from the group consisting of arabinose, mannose, galactose, glucose, xylose, and mixtures thereof, and which consists primarily of pentosans, hexosans, and mixtures thereof, containing from one to ten sugar units. The emulsions preferably also contain an alkaline earth metal oxide or hydroxide, preferably lime. The emulsions may also contain aphrons.

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: The invention provides water base well drilling and servicing fluids containing a biopolymer viscosifier and a water soluble polyalkylene glycol shale stabilizing additive therein having enhanced thermal stability, as indicated by the low shear rate viscosity at 0.06 sec.sup.-1, the enhanced thermal stability being provided by an amorphous silica viscosifier therein.A method of enhancing the thermal stability of aqueous base well drilling and servicing fluids containing a biopolymer viscosifier and a water soluble polyalkylene glycol shale stabilizing additive therein is disclosed which comprises adding to the fluid an amorphous silica viscosifier.

Abstract: A solids composition based on clay minerals and consisting of a) 40-99.8 wt. % of a clay mineral with a reduced moisture content of .ltoreq.7 wt. %, b) 0.01-30 wt. % of a mixed metal hydroxide and c) 0.01-30 wt. % of a solid base, and if necessary other additives, is described. The solids composition of the invention is an easy-to-use thickening agent for water-based drilling fluids, and has a long-term stability of at least three months.

Abstract: New drilling fluids have been invented which are invert emulsion fluids comprising an oleaginous liquid, a non-oleaginous liquid, and a protonated amine. Such fluids are acidic and thus useful in drilling wells in which acidic gases such as CO.sub.2 or H.sub.2 S are likely to be encountered and break, i.e. de-emulsify, the drilling fluid.

Abstract: A chemical system and method to stop or minimize fluid loss during completion of wells penetrating hydrocarbon formations are provided. The inventions relates to formulating a highly stable crosslinked hydroxyethyl cellulose (HEC), control released viscosity reduction additives, and user friendly packaging. The chemical system contains a linear HEC polymer solution, a low solubility compound which slowly raises the fluid pH, a chelating agent which further increases the pH level beyond the equilibrium achievable by the low solubility compound, a metal crosslinker which crosslinks HEC at elevated pH, a crosslink delaying agent which allows fluid viscosity to remain low until the fluid reaches the subterranean formation, and optionally an internal breaker. The chemical additives are packaged as an integrated pallet and transported to a field location which allows operators to conveniently mix them before pumping.

Abstract: Disclosed are oil-in-water emulsions containing an aqueous polysaccharide-containing continuous phase, an emulsified oleaginous liquid, and an oligosaccharide mixture composed of sugar units selected from the group consisting of arabinose, mannose, galactose, glucose, xylose, and mixtures thereof, and which consists primarily of pentosans and hexosans containing from one to ten sugar units. The emulsions preferably also contain an alkaline earth metal oxide or hydroxide, preferably lime. The emulsions may also contain aphrons. Also disclosed is a method of increasing the low shear rate viscosity of aqueous polysaccharide-containing fluids which comprise incorporating into the fluids an oligosaccharide mixture, an oleaginous liquid, and optionally, an alkaline earth metal oxide or hydroxide.

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 water-based drilling fluid for use in shale formations having a given average pore size has solutes dissolved therein sized so as to allow the pores of the shale formations to at least partially restrict the solutes. For purposes of enhancing the restriction of the solutes by the shale pores, the dissolved solutes may have different radii. Additional solutes, preferably lower molecular weight salts, are dissolved in the drilling fluid to lower the activity of the water in the water-based drilling fluid.The same combination of additives, a first additive of dissolved molecular solutes sized to at least partially block a shale pore space and a second additive of dissolved molecular solutes selected to lower the water activity, are combined in a water-based carrier fluid and used in earth boreholes surrounded by shale formations as either a spotting fluid, or as a lubricant, or as a shale formation strengthener or as a completion fluid.

Abstract: The present invention provides a method of preparing a fluid for use in drilling and completion operations comprising mixing a fluid comprising a salt of an alkaline earth metal with a nonionic colloid-forming material in an amount and under conditions sufficient to convert a majority of said nonionic colloid-forming material into water insoluble hydrated colloidal complexes comprising hydrated ions of said alkaline earth metal complexed with said nonionic colloid-forming material, said complexes being effective to improve a property of said fluid selected from the group consisting of rheology, fluid loss control, and a combination thereof.

Abstract: Disclosed is a method of increasing the thermal stability or decreasing the fluid loss of aqueous polysaccharide-containing fluids which comprises incorporating into the fluids an oligosaccharide mixture composed of arabinose, mannose, galactose, glucose, and xylose sugar units, the oligosaccharide mixture consisting of the water soluble portion of thermally hydrolyzed lignocellulose and consisting primarily of pentosans and hexosans containing from one to four combined sugar units.Preferred fluids contain a biopolymer which increases the low shear rate viscosity of the fluids. Fluids which contain polysaccharides which impart other desirable characteristics to the fluids, such as increased viscosity at higher shear rates, fluid loss control, and the like, also exhibit increased thermal stability upon incorporating the oligosaccharide mixture therein.

Abstract: A thermally stable drilling fluid system includes drilling fluid and an additive wherein the additive includes styrene-butadiene copolymers having an average molecular weight greater than about 500,000 g/mol, wherein the drilling fluid system exhibits fluid loss control at high temperature and high pressure conditions.

Abstract: The invention relates to a gel made of apolar medium including:an apolar medium,a "multichain" liquid surface-active agent in acidic form, soluble or dispersible in the said apolar medium,an agent for neutralizing the said "multichain" surface-active agent,from 0.2 to 5 molecules of water per molecule of "multichain" surface-active agent,optionally at least one emulsifying agent and/or a solid filler which is soluble or insoluble in the apolar medium.This gel may be employed for the formulation of water-based drilling fluids.

Abstract: An oil in water dispersion composition is disclosed that comprises a mixture of water and(A) an overbased non-Newtonian colloidal disperse system comprising(1) solid metal-containing colloidal particles predispersed in(2) a disperse medium of at least one inert organic liquid and(3) at least one member selected from the class consisting of organic compounds which are substantially soluble in the disperse medium, where the molecules of said organic compound have polar substituents and hydrophobic portions;(B) a water soluble associative thickener comprising a base-neutralized copolymer having copolymerized therein about 90 to about 99 mole percent of a carboxyl-containing, ethylenically unsaturated hydrocarbon and about 1 to about 10 mole percent of a nonionic surfactant acrylate having the formula: ##STR1## wherein R.sup.1 is hydrogen or methyl, R.sup.

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: 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: A drilling fluid system that combines a carbon black/asphaltite/lignite mixture with a fish oil/glycol mixture; and a method for manufacturing a drilling fluid system that could be utilized with pre-existing water based muds during drilling and excavating applications.

Abstract: A method of increasing the penetration rate of a drill string within a deviated well bore is disclosed. The method includes providing a drill string with a drilling bottom hole assembly, and rotating the bit in order to create the deviated well bore as well as a filter cake on the walls of the well bore. A pill comprising a spherical bead is prepared and pumped down into the well bore. The pill is allowed to migrated to the low side of the bore hole so that tortuosity is reduced. A method of slide drilling, batch drilling, and running a liner in a well is also disclosed utilizing the spherical beads. In the novel methods disclosed, the spherical beads are allowed to migrate to the low side of the bore hole and are allowed to penetrate through the bore hole's filter cake.

Abstract: A method of preventing or controlling the loss of well drilling fluid into the pores and fractures of subterranean rock formations by the addition of resilient graphitic carbon particles to the drilling fluid in sufficient amounts to plug the pores and fractures. The graphitic carbon material reduces loss of circulation, lowers torque and drag, prevents casing wear while drilling, and provides a new method for the controlled release of graphite at extreme pressure. The material is non-toxic and imparts the well-known lubricating properties of graphite without contributing to surface sheen development under US EPA offshore cuttings discharge rules.

Abstract: Heavy crude oil containing at least 1% by weight water is hydrotreated and upgraded while being produced downhole in a production well. During production the heavy crude oil containing water is subjected to sonic energy at a low frequency of 400 Hz to 10 kHz downhole in the presence of a metal hydrogenation catalyst that causes the water in the crude oil to react and form hydrogen which then hydrotreats and upgrades the heavy crude oil during production. In another embodiment, if the heavy crude oil does not contain water, the hydrogen may be formed in-situ by contacting the heavy crude oil downhole with a chemical compound comprising ammonia, hydrazine and formic acid that in the presence of a metal hydrogenation catalyst and sonic energy causes the chemical compound to react and form hydrogen which then hydrotreats the heavy crude oil during production. Suitable catalysts include nickel on zinc dust, platinum on carbon and palladium on carbon, preferably nickel on zinc dust.

Abstract: The present invention is directed to an aqueous foamed Drilling Fluid for drilling well bores into a subterranean formation, comprising water, at least one clay and at least one foaming agent. According to the invention, it further comprises at least one metal hydroxide. The invention further relates to a method for preparing said foamed drilling fluid.

Abstract: Aqueous structured surfactants, e.g., lamellar, or preferably spherulitic systems optionally containing suspended solids are used as functional fluids, such as drilling fluids, cutting fluids, hydraulic fluids, heat transfer fluids, construction muds and lubricants. A composition consisting essentially of: water; a surfactant or mixture of surfactants present in a concentration sufficient to form a mobile spherulitic or dispersed lamellar phase in the absence of an electrolyte; and a substantially water insoluble functional material, suspended in the composition, the composition being substantially free from electrolyte.

Abstract: A well drilling and servicing fluid comprising a brine having dissolved therein a formate salt selected from the group consisting of potassium formate, cesium formate, and mixtures thereof, a biopolymer viscosifier, and a pre-gelatinized amylopectin derivative, and optionally a bridging agent and magnesium oxide. The amylopectin starch derivative is a crosslinked amylopectin starch (waxy) which has been crosslinked to the extent that the viscosity of an aqueous amylopectin starch suspension undergoing crosslinking is within about 25% to about 60%, preferably from about 25% to less than about 50%, of the maximum viscosity which can be obtained, and gelatinized.A process of increasing the low shear rate viscosity at ambient temperatures of the aqueous formate brine which comprises adding to the brine a biopolymer and the pre-gelatinized crosslinked amylopectin starch in amounts such that they interact to synergistically increase the low shear rate viscosity of the brine.

Abstract: Lubricant composition containing spherical particles of a ceramic material dispersed in a supporting vehicle. The composition is used as a lubricant, metalworking cooling fluid, drilling fluid or drilling mud.

Abstract: The invention provides alkaline water base well drilling and servicing fluids which deposit an easily degradable and removable filter cake on the sides of a borehole during well drilling and servicing operations. The fluids contain one or more polysaccharide polymers, sized bridging particles, and a peroxide selected from the group consisting of alkaline earth metal peroxides, zinc peroxide, and mixtures thereof. The fluids deposit a filter cake containing the peroxide.

Abstract: Reduction of the adhesion of polyethercyclicpolyol (PECP) to metals by preparing the PECP by condensing polyol molecules by reactive distillation and replacing part of the polyol with an alcohol of lower hydroxyl content than the polyol.

Abstract: Disclosed are low solids, high density fluids useful as drilling, workover, and completion fluids and the like in oil and gas well operations. The fluids comprise a brine having dissolved therein a zinc salt such as zinc bromide, and optionally one or more additional water soluble salts, a viscosifier which is a high surface area silica, a biopolymer viscosifier, a fluid loss control additive which is preferably a starch derivative, zinc carbonate, and, optionally, an alkaline buffer, a polar additive, and a bridging agent.It has been found that zinc carbonate will increase the low shear rate viscosity of fluids containing a zinc salt dissolved therein. Additionally, the combination of zinc carbonate and zinc oxide as the alkaline buffer provides fluids having increased thermal stability as indicated by the low shear rate viscosity of the fluids.

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: 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: The present invention relates to a pseudoplastic fluid composition including water, a mixed metal layered hydroxide dispersed in the water to impart preselected rheological properties to the fluid and a fluid loss additive composition including one or more of a carboxymethyl substituted vegetable starch, a carboxymethylated cellulosic compound or mixtures thereof in an amount effective to inhibit loss of fluid and with the degree of substitution being selected so that the carboxymethyl substituted compound is soluble in the fluid at the concentration of use without materially adversely affecting the rheological properties of the fluid and so that the fluid is resistant to fermentation. The improved composition includes a crosslinked carboxymethylated vegetable starch which has a degree of substitution in the broad range from about 0.3 to about 0.8 and in a narrower range of about 0.4 to about 0.

Abstract: Reducing the adherence of polyethercyclicpolyol to metal by exposing the metal to a selected surfactant.

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: A process and composition are provided for permeability reduction in a hydrocarbon-bearing formation to improve hydrocarbon recovery therefrom. The process includes placement of a crosslinked polymer gel in the treatment region preceded by surface preparation of a gelation solution which is the gel precursor. The gelation solution contains a crosslinkable polymer, a chromium(III)/carboxylate complex crosslinking agent, a carboxylate salt delaying agent and an aqueous solvent. The gel is placed in the treatment region by injecting the gelation solution into a well bore in fluid communication with the formation, displacing it into the desired treatment region and gelling the solution to completion forming the permeability-reducing gel in situ. The gelation rate is retarded in a controlled manner by adjusting the composition or concentration of the delaying agent in the gelation solution.

Abstract: Aqueous compositions for use as drilling fluids or as workover fluids/completion fluids comprise calcium chloride and calcium nitrate. The compositions have a density of at least 1.35 g cm.sup.-3 and the weight ratio of calcium chloride to calcium nitrate is 5:95 to 95:5. The compositions may be formulated so as to have low crystallisation temperatures. Additional densifying agents such as calcium bromide and/or zinc bromide may also be included.

Abstract: The invention provides methods for (1) reducing the fluid loss of and (2) reducing the concentration of polymer required to provide a desired degree of fluid loss control to, a well drilling and servicing fluid which contains at least one polymeric viscosifier, at least one polymeric fluid loss control additive, and a water soluble bridging agent suspended in an a liquid in which the bridging agent is not soluble, the methods comprising adding to the fluids a particulate, water soluble, ultra fine filtrate reducing agent having a particle size distribution such that at least 90% of the particles thereof are less than 10 micrometers and the average particle size is from about 3 to about 5 micrometers, the ultra fine filtrate reducing agent being insoluble in the liquid.

Abstract: Zinc oxide and zirconium oxide are used as weighting materials for water and oil based drilling fluids for horizontal wells.

Abstract: Invert emulsion muds for drilling of gas and oil, which are environmentally safe, and which contain:A. a continuous oil phase composed predominantly of at least one monocarboxylic acid ester of a C.sub.2 -C.sub.12 monofunctional alkalol wherein the monocarboxylic acid contains from 16 to 24 carbon atoms and is olefinically mono- or poly-unsaturated,B. a disperse aqueous phase,C. at least one emulsifier,D. at least one weighing agent,E. at least one fluid loss additive, andF. a mild alkaline reserve.