Abstract: Disulfonate salts of 2,4-pentanedione and methods for making such salts are described. The disulfonate salts are useful as cement dispersants. Cement compositions including such salts, methods for making cement compositions including such salts, and methods for performing cementing operations using such cement compositions are also described.

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

Abstract: A process to substantially reduce fluid loss in which an appropriate amount of a non-flowing gel of sufficient strength is emplaced to substantially eliminate or reduce loss of the drilling fluid. The gel composition of the process includes: (1) a non-cellulose containing copolymer having vinyl phosphonate co-monomer units which may be incorporated into the polymer by copolymerization with the other co-monomer(s) comprising the polymer or by grafting upon an already existing polymer or co-polymer, (2) a crosslinking agent active upon the phosphonate groups, (3) a crosslinking initiator comprising a Bronsted Lowry base or Lewis base and (4) an aqueous solvent.

Abstract: Methods in which temperature is used to control the foaming and/or defoaming of foamed treatment fluids comprising an aqueous liquid, an ionic foaming surfactant, and a gas are provided. A method of treating at least a portion of a subterranean formation is provided, the method comprising: providing a treatment fluid having a foam transition temperature, the treatment fluid comprising an aqueous liquid, and an ionic foaming surfactant; foaming the treatment fluid to form a foamed treatment fluid; circulating the foamed treatment fluid in a well bore penetrating the subterranean formation; and defoaming at least a substantial portion of the foamed treatment fluid, the defoaming comprising lowering the temperature of the foamed treatment fluid to about at or below the foam transition temperature.

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

Abstract: A method for drilling a borehole employing a drilling fluid including an additive comprising a glucose derivative with pH lowering acid, buffers and surface active agents. The drilling fluid additive preferably exhibits the following properties: activity of approximately 30%–45% in water solution; pH of about 4.5 to 5.5; a light amber to clear liquid appearance and a density of approximately 1.200 grams per cubic centimeter.

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

Abstract: A method and composition is provided for sealing a subterranean zone penetrated by a well bore and restoring lost circulation, wherein the composition basically comprises a mixture of latex, melamine-formaldehyde resin, and a catalyst.

Abstract: A method for drilling a borehole employing a drilling fluid including an additive comprising a glucose derivative with pH lowering acid, buffers and surface active agents. The drilling fluid additive preferably exhibits the following properties: activity of approximately 30%-45% in water solution; pH of about 4.5 to 5.5; a light amber to clear liquid appearance and a density of approximately 1.200 grams per cubic centimeter.

Abstract: A process of boring a tunnel using an earth-pressure balance shield boring tunnelling machine having a cutting head, an excavation chamber for soil removed by boring and conveying means for removal of said soil from the excavation chamber; wherein there is injected into a stratum being bored at the cutting head a foamed aqueous solution, characterized in that (a) the aqueous solution contains two essential components which are (i) a sulphate- or sulphonate-containing anionic susfactant, and (ii) &bgr;-naphthalene sulphonate-formaldehyde condensate; and in that (b) there is applied to the soil removed by boring in at least one of the excavation chamber and the conveyor a second aqueous solution containing essentially a high molecular weight polyethylene oxide and optionally a sulphate- or sulphonate-containing anionic surfactant. The process allows easy removal of soil from the cutting head to the excavation chamber and from the excavation chamber out of the machine.

Abstract: Disclosed is a hydrophilic, water soluble polymer concentrate for addition to aqueous liquids to enhance the properties thereof, particularly to increase the viscosity or decrease the fluid loss of well drilling and servicing fluids, the concentrate comprising a hydrophobic, water insoluble liquid, an organophilic clay suspension agent, the water soluble polymer, and a stabilizing agent comprising one or more acids in an amount from about 0.001% to about 1.5%, one or more anionic surfactants in an amount from about 0.001% to about 1.0%, one or more nonionic surfactants in an amount from 0.001% to about 0.625% and, from about 0% to about 0.75% of one or more water soluble organic liquids, wherein the total concentration of the stabilizing agent is from about 0.1% to about 2.5%, these percentages being based on the weight of the concentrate.

Abstract: A method of electrically logging subterranean wells using a conductive double emulsion fluid includes a miscible combination of an oleaginous fluid, an emulsifier capable of forming a microemulsion, an emulsifier capable of forming an invert emulsion, and an electrolytic salt. A microemulsion is the continuous phase of an invert emulsion. The electrolytic salt or brine of the salt is present in a concentration sufficient to permit the electrical logging of the subterranean well. The fluid may additionally contain a polar organic solvent and a carbon dioxide buffer. The polar organic solvent may be an oil soluble glycol or glycol ether such as ethylene glycol, diethylene glycol, propylene glycol, polypropylene glycol, and the like.

Abstract: Present invention relates to high brine carrier fluid, said carrier fluid selected from the group consisting of organic acids, organic acid salts, inorganic salts and combination of one or more organic acids or organic acid salts, a co-surfactant and an amount of a zwitterionic surfactant. The invention also relates to methods of treating a subterranean wellbore, including drilling, hydraulic fracturing, gravel placement, scale removing, mud cake removing, using said high brine carrier fluid.

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: Methods of drilling well bores using an invertible oil external-water internal emulsion drilling fluid and then inverting the drilling fluid to a water external-oil internal emulsion are provided. The methods basically comprise the steps of contacting the oil external-water internal emulsion with an aqueous acid solution containing an anionic sulfonate surfactant for preventing aqueous acid solution-crude oil emulsions and crude oil sludging and a chemical for preventing the anionic sulfonate surfactant from reacting with the emulsifier in the oil external-water internal emulsion.

Abstract: An additive which increases the density of wellbore fluids used during the construction or repair of oil, gas, injection, water or geothermal wells comprises solid colloidal particles of weight average particle diameter (D50) of less than 2 microns, the particles being deflocculated by the action of a dispersant, preferably incorporated during the process of grinding or communication of the particles to the specified particle size. The additives may be used in any wellbore fluid such as drilling, cementing, completion, packing, work-over (repairing), stimulation, well killing and spacer fluids as well as in a dense media separating fluid or in a ship's ballast fluid.

Abstract: The present invention provides improved early-enhanced strength cement compositions and methods. The cement compositions can be utilized in surface construction projects as well as in the construction of oil, gas and water wells. The improved cement compositions of this invention are basically comprised of a hydraulic cement, water present in an amount sufficient to form a slurry and hydrophobic silica powder.

Abstract: A method of inhibiting or retarding formation of hydrates from water and a lower alkane, such as methane or ethane, involves adding additives which comprise (i) a corrosion inhibitor and (ii) a salt which is of formula [R1(R2)XR3]+Y−, wherein each of R1, R2 and R3 is bonded directly to X, each of R1 and R2, which may be the same or different is an alkyl group of at least 4 carbons, X is S, NR4 or PR4, wherein each of R3 and R4 which may be the same or different represents hydrogen or an organic group, with the proviso that at least one of R3 and R4 is an organic group of at least 4 carbons, and Y is an anion, the additives being added in an amount effective to inhibit or retard hydrate formation, to a medium susceptible to hydrate formation.

Abstract: This Invention relates to a novel reversible thickener, i.e., a fluid whose viscosity can be carefully modulated—from very low viscosity to sufficient viscosity to act as a barrier to further flow; particularly preferred embodiments are directed to fluids and methods for stimulating hydrocarbon low viscosity to sufficient viscosity to act as a barrier to further flow; particularly preferred-bearing formations—i.e., to increase the production of oil/gas from the formation. In particular, the Present Invention is directed to a family of fluids (and methods incorporating those fluids) intended to be pumped through a wellbore and into the hydrocarbon-bearing formation.

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

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: The invention relates to multiphase lubricant concentrates with improved properties for use in aqueous fluids for geological exploration by drilling which contain organic lubricating components which are solid and/or liquid at room temperature (O phase) together with emulsifiers finely dispersed in a continuous aqueous phase (W phase). These concentrates are characterized in that the system of O phase/W phase and emulsifiers has a phase inversion temperature (PIT) above room temperature and has been produced by heating the multiphase system to temperatures equal to or above the PIT and subsequent cooling to temperatures below the PIT. The present invention also relates to the use of the multiphase lubricant concentrates as an additive in water-based fluids for use in geological exploration by drilling and for the subsequent treatment of the resulting boreholes.

Abstract: The invention concerns a water based foaming composition and the method of making it. The composition is optimized in that it contains a surfactant specifically selected according to the polymer also present in the composition. The surfactant and the polymer are selected so that they are oppositely charged. The invention is very useful in drilling or treating wells.

Abstract: A 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: In the presence of certain crude oils, when ferric iron exists in very acidic fluid, it practically instantaneously forms precipitates known as sludges which lead to irreversible damage. Iron control compositions and acid fluids containing such iron control compositions are disclosed. For acid fluids containing up to 15% acid, the iron control composition includes a reducing agent selected from a substituted and unsubstituted thiourea compounds, and a reduction catalyst including a copper (cuprous or cupric) compound. When the acid fluid contains more than 15% acid, for example from 15 to 28% acid, the reducing agent is again selected from substituted or unsubstituted thiourea compounds, and the reduction catalyst is a combination of a copper (cuprous or cupric) compound and iodine (iodine or iodide ions).

Abstract: Polymeric well completion and remedial compositions which form highly pliable impermeable masses of desired rigidity and methods of using the compositions are provided. The compositions are basically comprised of water, a water soluble polymerizable monomer, a polymerization initiator and an oxygen scavenging agent. The composition is usually foamed and contains a gelling agent and a solid filler material to increase the density and/or rigidity of the impermeable mass formed.

Abstract: The present invention relates to a method and a solution for use in downhole drilling to reduce the torque necessary to rotate the drill string. The solution comprises a phosphate and a sulfonate according to the formula (RSO.sub.3).sub.x Me.sup.x, where R is selected from the group consisting of an alkyl group, an aryl group, an alkylaryl group, and mixtures thereof having a molecular weight between about 280 and about 650, x is the number of (RSO.sub.3) groups, and Me.sup.x is a metal ion having a valence x. The phosphate is preferably a phosphate ester, ether phosphate, or soluble phosphate having a molecular weight in the range of about 300 to bout 900. The phosphate is able to operate at temperatures prevailing in drilling mud systems. The solution is pumped down a drill string as a slug in order to coat solids which accumulate in the well and allow them to be removed along with the drilling fluid.

Abstract: The present invention is based on the discovery that viscosification agents selected from sulfonated and neutralized sulfonated ionomers can be readily incorporated into oil-based drilling muds in the form of an oil soluble concentrate containing the polymer. Thus, one embodiment of the present invention provides an additive concentrate for oil-based drilling muds comprising a drilling oil, especially a low toxicity oil, and from about 5 gm to about 20 gm of sulfonated or neutralized sulfonated polymer per 100 gm of oil. Indeed, oil solutions obtained from the sulfonated and neutralized sulfonated polymers used as viscosification agents are readily incorporated into drilling mud formulations.

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 present invention relates to an oil-based drilling fluid, a continuous phase for an oil-based drilling fluid, and additives for an oil-based drilling fluid. The drilling fluid, the continuous phase of the drilling fluid, and the additives for the oil-based drilling fluid are characterized by non-fluorescence (defined as a fluorescence intensity of 800 or less) when exposed to ultraviolet light. The continuous phase of the drilling fluid is composed of synthetic hydrocarbons selected from the group consisting of oligomers synthesized from one or more alphaolefins containing a C.sub.2 to C.sub.14 chain length, wherein the oligomers have an average molecular weight of from 120 to 100, and additives. The additives of the continuous phase include surfactants, wetting agents and/or emulsifiers.

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: 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: 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: The present invention relates to a method and a solution for use in downhole drilling to reduce the torque necessary to rotate the drill string. The solution comprises a phosphate and a sulfonate according to the formula (RSO.sub.3).sub.x Me.sup.x, where R is selected from the group consisting of an alkyl group, an aryl group, an alkylaryl group, and mixtures thereof having a molecular weight between about 280 and about 650, x is the number of (RSO.sub.3) groups, and Me.sup.x is a metal ion having a valence x. The phosphate is preferably a phosphate ester, ether phosphate, or soluble phosphate having a molecular weight in the range of about 300 to bout 900. The phosphate is able to operate at temperatures prevailing in drilling mud systems. The solution is pumped down a drill string as a slug in order to coat solids which accumulate in the well and allow them to be removed along with the drilling fluid.

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: An improved method for acidizing an oil bearing formation in the presence of water bearing zones having high permeability is described. An aqueous fluid is pumped into the formation preceding the injection of stimulation material. This fluid contains hydroxyethylcellulose, a fluorescent dye and an organic acid anhydride, which during hydrolysis reduces the pH and the viscosity of the solution making it retrievable without damage to the formation.

Abstract: The use of a water external micellar dispersion as a drilling fluid for rotary and horizontal drilling operations wherein the drilling fluid contains more than 50% oil in the internal phase, improved high temperature stability, high yield points, low gel strengths, and ultra low fluid loss.

Abstract: A well fluid emusion having a water phase and an oil phase of a sulfurized alcohol and a naturally occuring fat, oil or derivatives thereof. Also disclosed is a method of lubricating drilling equipment used in conjunction with the drilling, completion or workover of a subterranean well. The method includes introducing the above emulsified well fluid into the well for circulation through and out of the well, and further includes contacting the surface of the drilling equipment with the emulsified well fluid to provide an interface between the equipment surface and the water phase. Suitable naturally occurring fats and oils may be obtained from the following animal oils and fats: butter, lard, tallow, grease, herring, menhaden, pilchard and sardine; and from the following vegetable oils and fats: castor, coconut, coffee, corn, cottonseed, jojoba, linseed, liticica, olive, palm, palm kernel, peanut, rapeseed, safflower, soya, sunflower, tall and tung.

Abstract: An additive for a water-based fluid which is to be used when the likelihood of differential sticking is high and which reduces the sticking tendency of the fluid and mud cake. An additive according to the invention comprises a well dispersed-particulate phase such as an emulsion, a fine emulsion, a microemulsion, a micellar phase or a polymeric phase having a particle size comparable with the pore throat size of a mud cake and comprising a material which forms easily deformable particles and which reduces the sticking propensity of the mud. One embodiment of the invention comprises a microemulsion of an oil which is well dispersed, substantially stable and has a substantial portion of the particle size distribution in the range 5-500 nm. An alternative embodiment comprises a micellar phase comprising one or more surfactants. The additive is typically used at a level of about 5% by volume in the drilling fluid.

Abstract: A water based drilling fluid which is environmentally non-toxic containing a sodium alkylsufosuccinate and well drilling additives, said sodium alkylsulfosuccinate is water dispersible and imparts anti-bit balling, lubricity and environmentally non-toxicity properties to said drilling fluid and does not precipitate in the presence of the said well drilling additives.

Abstract: A drilling fluid composition comprising a mixture of a brine (A) an emulsifier, and (B) an oil soluble friction modifier of the following formula: ##STR1## where X=1 to 4,z=1 to 6,Q=0 to 2R.sub.1 and R.sub.2 are independently H or an aliphatic group containing from 1 to about 16 carbon atoms, provided that the sum of R.sub.1 and R.sub.2 is between 0 and about 16,R' is an aliphatic group containing an average of from about 8 to about 24 carbon atoms, andR" is selected from the group consisting of H, an aliphatic group containing between 1 and an average of about 18 carbons, and ##STR2## where Q, X, z, R.sub.1, R.sub.2, R' and R" are defined as set forth above, and Y is 0 to 5 is disclosed. The compositions of the present invention have beneficial lubrication properties. These compositions are useful in drilling, working and completing well bore holes.

Abstract: This invention relates to a composition comprising a water-in-oil emulsion formed from a brine, a liquid oil, (A) an emulsifier, (B) a friction modifier of the following formula: ##STR1## where X=1 to 4, z=1 to 6,Q=0 to 2R.sub.1 and R.sub.2 are independently H or an aliphatic group containing from 1 to about 16 carbon atoms, provided that the sum of R.sub.1 and R.sub.2 is between 0 and about 16,R' is an aliphatic group containing an average of from about 8 to about 24 carbon atoms, andR" is selected from the group consisting of H, an aliphatic group containing between 1 and an average of about 18 carbons, and ##STR2## where Q, X, z, R.sub.1, R.sub.2, R' and R" are defined as set forth above, and Y is 0 to 5. In a preferred embodiment, z is 1. In the most preferred embodiment, Q=0, R.sub.1 and R.sub.2 are both H, X, and z all equal 1, R' is n-dodecyl, and R" is H. The compositions of the present invention have beneficial lubrication properties.

Abstract: Hydrocarbon base drilling fluids which are selectively convertible to cementitious compositions that set into hard substantially impermeable masses and methods of using such drilling fluids are provided. The drilling fluids are basically comprised of a hydrocarbon liquid having particulate hydraulic cement suspended therein. The drilling fluids are converted to cementitious compositions by admixing water and a surfactant therewith.

Abstract: Subterranean oil-bearing formations are treated with aqueous acid solutions which include an effective amount of an alkoxylated alkyl substituted phenol sulfonate which exhibits both antisludge and demulsification properties.

Abstract: The present invention relates to a method and a solution for use in downhole drilling to reduce the torque necessary to rotate the drill string. The solution comprises a sulfonate according to the formula (RSO.sub.3).sub.x Me.sup.x, where R is selected from the group consisting of an alkyl group, an aryl group, an alkylaryl group, and mixtures thereof having a molecular weight between about 280 and about 650, x is the number of (RSO.sub.3) groups, and Me.sup.x is a metal ion having a valence x. The solution is pumped down a drill string as a slug in order to coat solids which accumulate in the well and allow them to be removed along with the drilling fluid.

Abstract: A process employing a polymer enhanced foam in a wellbore as a drilling fluid during a wellbore drilling operation. The polymer enhanced foam is formed from an uncrosslinked acrylamide polymer, a surfactant, an aqueous solvent, and an added gas.

Abstract: Described is the use of surface-active alpha-sulfofatty acid di-salts as ecologically compatible emulsifiers of the W/O type and O/W type, respectively, in fluid and pumpable drilling fluids and other fluid drilling-hole treatment agents which comprise a continuous or a dispersed oil phase together with an aqueous phase and which are suitable for an environmentally acceptable exploitation of geological resources, for example oil or natural gas deposits. The invention further relates to inverted drilling fluids based on a continuous oil phase and, present therein, a dispersed aqueous phase which, in addition to the emulsifiers, contain further conventional auxiliary agents such as thickeners, fluid-loss additives, weighting agents, water-soluble salts and/or alkali reserves.

Abstract: The present invention relates to an improved continuous phase for an oil based drilling fluid and specifically a synthetic hydrocarbon continuous phase which is non-polluting and minimally toxic. The invention provides excellent drilling fluid properties under a wide variety of drilling conditions. The synthetic hydrocarbons are selected from the group consisting of branched chain oligomers synthesized from one or more olefins containing a C.sub.2 to C.sub.14 chain length and wherein the oligomers have an average molecular weight of from 120 to 1000. In the drilling fluid compositions, suitable emulsifiers, wetting agents, viscosifiers, weight materials and fluid loss additives are utilized in conjunction with water and/or a brine phase for the desired rheological properties.

Abstract: The present invention relates to an improved water based drilling fluid and an improved spotting fluid utilizing unhydrogenated synthetic hydrocarbon compositions which are non-polluting and minimally toxic. The invention provides excellent drilling fluid properties under a wide variety of drilling conditions. The synthetic hydrocabons are selected from the group consisting of branched chain oligomers synthesized from one or more olefins containing a C.sub.2 to C.sub.14 chain length and wherein the oligomers have an average molecular weight of from 120 to 1000. The compositions of these hydrocarbons are free of aromatics and petroleum based toxic impurities. The synthetic hydrocarbons are unhydrogenated.