Abstract: Selectively cross-linked starches are disclosed that are useful as fluid loss control additives in subterranean treatment fluids comprising starches that cross-linked to a Brabender peak viscosity of about 800 to about 1250 Brabender units after about 40 to about 70 minutes at about 92° C. and provide good fluid loss control over a temperature range of from about 20° C. to about 160° C. (68° F. to 320° F.).

Abstract: Well drilling and servicing fluids for use in producing formations and methods of removing filter cake therefrom are provided. The methods basically comprise using a drilling or servicing fluid comprised of water, a density increasing water soluble salt, a fluid loss control agent, a hydratable polymer solid suspending agent and a particulate solid bridging agent which is soluble in an aqueous ammonium salt solution. Thereafter, the filter cake deposited by the drilling or servicing fluid is contacted with a clean-up solution comprised of water and an ammonium salt for a period of time such that the bridging agent is dissolved thereby.

Abstract: A new stable liquid suspension containing non-soluble particles dispersed in a non-aqueous liquid medium having a concentration of a suspension aid and a method of making and use thereof.

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: 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: Water based drilling fluid compositions which contain at least one viscosity builder and at least one rheological control agent wherein the rheological control agent is an amphoteric polymer, the cationic groups of the amphoteric polymer being quaternary ammonium groups.

Abstract: A salt water drilling mud comprising a mixture salt water, a solid phase such as pre-hydrated bentonite, attapulgite, sepiolite, and extended bentonite, among others and optionally a synthetic oil, which is mixed with at least one of five different modules. A first module contains caustic, a natural wax and a natural thinner. A second module contains components of the first module and an alkali metal aluminate prepared by reacting the first module with aluminum metal. A third module contains the components of the first module and an alkali metal phosphate and/or alkali metal silicate. A fourth module contains the components of the first module, a saturated or unsaturated carboxylic acid source, a surfactant, and a preservative. The fifth module contains a combination of the first, third and fourth modules.

Abstract: Selectively cross-linked starches are disclosed that are useful as fluid loss control additives in subterranean treatment fluids comprising starches that are cross-linked to a Brabender peak viscosity of about 800 to about 1250 Brabender units after about 40 to about 70 minutes at about 92° C. and provide good fluid loss control over a temperature range of from about 20° C. to about 160° C. (68° F. to 320° F.).

Abstract: The present invention comprises a stable hydrocolloid welan gum in which a hydrocolloid, preferably welan gum, is uniformly dispersed in a superplasticizer such as sulfonated naphthalene, sulfonated melamine, modified lignosulfate, their derivatives and mixtures thereof. This is then dispersed in a rheological control agent which is a microbially-produced cellulose fiber composition. The composition is rapidly hydratable and useful as a stabilizing additive in many cement and drilling fluid applications, insulation fluids and de-icer compositions.

Abstract: Selectively cross-linked starches are disclosed that are useful as fluid loss control additives in subterranean treatment fluids comprising starches that are cross-linked to a Brabender peak viscosity of about 800 to about 1250 Brabender units after about 40 to about 70 minutes at about 92° C. and provide good fluid loss control over a temperature range of from about 20° C. to about 160° C. (68° F. to 320° F.).

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 solution thereof. The mixture is wet milled to form an extremely fine particle size, from about 3 microns to about 500 microns distribution of the gum. The composition is rapidly hydratable and useful as a stabilizing additive in many cement and drilling fluid applications.

Abstract: Advantageous aqueous mixed salt systems viscosified with water-soluble or water-dispersable polymers which are superior to corresponding single salt systems of similar densities are provided. The mixed salt systems comprise water; a water-soluble or water-dispersable polymer capable of viscosifying an aqueous medium; one or more cations including a member selected from the group consisting of lithium, sodium, potassium, cesium, magnesium, calcium, zinc, or mixtures thereof; and one or more anions including a member selected from the group consisting of chloride, bromide, iodide, formate, nitrate, acetate, cyanate, thiocyanate, a zinc complex anion or mixtures thereof; there being present either at least two cations or at least two anions. Inventive viscosified mixed salt systems display--under such stressing factors as aging, heat, mechanical agitation, and shear--greater stability compared to the single salt systems of similar densities.

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: 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: 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: 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: The present invention relates to water-soluble, particularly ternary, preferably ionic, cellulose mixed ethers, more particularly to anionic water-soluble cellulose mixed ethers, as additives for drilling fluid applications.

Abstract: The present invention provides compositions useful for viscosifying aqueous fluids, methods for making them and methods for using them. In one aspect of the invention, inventive compositions comprise a prehydrating alcohol having at least two hydroxyl groups and having a molecular weight of from about 60 to about 600; an inorganic salt; and a polymer. In a preferred aspect of the invention, the viscosifier composition additionally comprises a solvent having a molecular weight of from about 75 to about 1000. According to another aspect of the invention, inventive compositions comprise a prehydrating alcohol; an inorganic salt; and a polymer; and the composition is essentially free from water. Inventive compositions find advantageous use in viscosifying fluids utilized in subterranean drilling activities such as, for example, drilling, drill-in, completion, hydraulic fracturing, work-over, packer, well treating, testing, spacer, or hole abandonment fluids.

Abstract: The present invention relates to a process for controlling the permeability of the walls of the geologic formations drilled. The circulating drilling fluid includes a determined amount of gellan used as a filtrate reducer.In the process, the viscosity of the fluid is mainly controlled by polymers, such as xanthan, scleroglucan or wellan.The invention further relates to a drilling fluid including gellan.

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: 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 present invention provides a method of controlling fluid loss to a permeable formation penetrated by a wellbore. A novel fluid loss agent is prepared by forming a crosslinked polymer gel which then is sheared to break the gel into discrete particles of a particular size range. A slurry then is formed of the particles by dispersing the particles in an aqueous fluid having a density similar to that of the gel particles. The slurry then is introduced into contact with the permeable formation and a filter cake of the particles is formed upon contact with the formation and loss of the slurrying fluid to the formation. The filter cake provides further fluid loss control to the permeable formation.

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: The invention provides brine based well drilling and servicing fluids containing a fluid loss control additive selected from the group consisting of (1) a crosslinked ether derivative of a partially depolymerized starch, (2) a partially depolymerized crosslinked ether derivative of starch, or (3) mixtures thereof. The fluid loss control additive provides decreased fluid losses at much lower viscosities than the corresponding starch derivatives which have not been partially depolymerized. This enables their use in fluids at concentrations sufficient to provide excellent filtration control, the fluids having a viscosity sufficient for circulation of the fluids in the borehole. The invention also provides a method of reducing the fluid loss of well drilling and servicing fluids utilizing the fluid loss control additives (1) and/or (2).

Abstract: A composition useful for viscosifying a water-based fluid is provided which comprises a polymer such as guar gum, a metal compound such as an aluminum compound. The composition can also contain a polymer such as guar gum, a magnesium compound such as magnesium oxide, a metal aluminate such as sodium aluminate or a metal compound such as an aluminum compound, and optionally a fatty acid or salts thereof. The water-based fluid can also contain a clay such as bentonite. A process for viscosifying a water-based fluid and for substantially retaining the viscosity of the water-based fluid is also provided which comprises contacting the fluid with the composition described herein. Also disclosed is a process for controlling water loss of a water-based drilling fluid wherein the process comprises contacting the fluid with the composition described herein.

Abstract: The invention provides (1) a method of increasing the thermal stability of an aqueous polysaccharide-containing fluid by adding thereto magnesia and a thiosulfate salt; (2) a drilling, completion, or workover fluid comprising an aqueous liquid, a water soluble polysaccharide, magnesia, and a thiosulfate salt; and (3) an additive for increasing the thermal stability of an aqueous polysaccharide-containing fluid which comprises magnesia and a thiosulfate salt in a weight ratio of magnesia to thiosulfate salt from about 0.15/1 to about 6.67/1. The preferred magnesia has an activity index less than 100, most preferably less than 50. The preferred thiosulfate salt is sodium thiosulfate. The preferred polysaccharide is selected from the group consisting of xanthan gum, epichlorohydrin crosslinked starch, carboxymethyl cellulose, and mixtures thereof. The preferred aqueous liquid is a saturated sodium chloride solution.

Abstract: The present invention provides a method of controlling fluid loss to a permeable formation penetrated by a wellbore. A novel fluid loss agent is prepared by forming a crosslinked polymer gel which then is sheared to break the gel into discrete particles. A slurry then is formed of the particles by dispersing the particles in an aqueous fluid having a density similar to that of the gel particles. The slurry then is introduced into contact with the permeable formation and a filter cake of the particles is formed upon contact with the formation and loss of the slurrying fluid to the formation. The filter cake provides further fluid loss control to the permeable formation.

Abstract: The addition of relatively small quantities of reticulated bacterial cellulose to well bore drilling muds improves their rheological properties. A preferred reticulated bacterial cellulose is one produced under agitated culture conditions using strains of a bacterium from the genus Acetobacter. Reticulated bacterial cellulose may be used in place of a conventional gellant or in combination with conventional gellants to provide improved drilling muds.

Abstract: The invention is a method for forming a high viscosity gel by mixing about 0.9% to about 3.0% by weight of hydroxy propyl cellulose having an average molecular weight greater than about 1,000,000 about 0.4% to about 3.0% by weight of an alkali metal dodecyl sulfate in the ratio of about 3:1 to about 1:1.5 of cellulose to sulfate, and a brine having a salinity greater than about 20,000 ppm TDS.