Abstract: Disclosed is a process for the deacetylation of chitin and a process for the treatment of chitinaceous materials to obtain chitin which processes are conducted in a non-saponifiable, non-aqueous, water insoluble liquid having a flash point greater than about 100° C., preferably a non-aromatic hydrocarbon. The process for the deacetylation of chitin comprises suspending chitin in the hydrocarbon liquid, preferably from about 0.02 g/cc to about 0.2 g/cc, mixing therewith an alkali metal hydroxide solution, and heating the suspension at a temperature at least about 70° C. for a period of time sufficient to obtain the desired degree of deacetylation. The concentration of alkali metal hydroxide in the alkali metal hydroxide solution is at least 30% by weight, preferably at least 40% by weight, and most preferably at least 50% by weight, and the quantity of alkali metal hydroxide is sufficient to provide an alkali metal hydroxide to chitin weight ratio from about (0.35)(AMHMW)/40 to about (2.

Abstract: The invention provides a fluid loss control additive for oleaginous liquids and oleaginous wellbore fluids containing the additive. The additive is the reaction product of a tannin compound, a polyamidoamine, a commercial lecithin, and an acid. The preferred tannins are derived from quebracho and wattle trees. The preferred acid is sulfuric acid. The preferred polyamidoamine is a long-chain fatty alkyl partial amide which is the reaction product of a polyalkylenepolyamine and a fatty acid containing from about 8 to about 30 carbon atoms, most preferably tall oil fatty acids, wherein at least one of the amino groups of the polyalkylenepolyamine is not amidated. The commercial lecithin contains from about 30% to about 50% of the vegetable oil from which the lecithin is concentrated, preferably soybean oil, and is present in the additive in an amount from about 1% to about 3% by weight, based on the weight of the tannin.

Abstract: The invention provides an organic diacid anhydride-modified chitosan and a method of preparing the same under high shear conditions which eliminates the use of solvents and excessive amounts of aqueous liquids. Also provided are organic diacid anhydride-modified chitosans containing an inorganic basic material which enhances the aging stability thereof. The invention also provides fluids useful in various well drilling and servicing operations comprising an alkaline aqueous liquid containing an organic diacid anhydride-modified chitosan, as well as a method of drilling wells therewith.

Abstract: The invention provides an organic diacid anhydride-modified chitosan and a method of preparing the same under high shear conditions which eliminates the use of solvents and excessive amounts of aqueous liquids. Also provided are organic diacid anhydride-modified chitosans containing an inorganic basic material which enhances the aging stability thereof. The invention also provides fluids useful in various well drilling and servicing operations comprising an alkaline aqueous liquid containing an organic diacid anhydride-modified chitosan, as well as a method of drilling wells therewith.

Abstract: Disclosed is a method and gellable composition for decreasing the loss of fluid during well drilling or servicing operations. The gellable composition comprises a superabsorbent polymer in an acidic aqueous liquid in which the superabsorbent is not swellable. Preferably the gellable composition also contains a viscosifier, preferably chitosan. The method is practiced by forming the gellable composition, placing it at the location of fluid loss in a well, and mixing it with a basic aqueous liquid to raise the pH and thus allow the superabsorbent to expand in volume. Advantageously, the superabsorbent, chitosan, and an acid, preferably a solid acid, preferably sulfamic acid, are admixed to form an additive for preparing the gellable composition.

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: 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: Disclosed are a process for the preparation of pseudoplastic, shear thinning chitosan-containing fluids, and a method of enhancing the thermal stability of such fluids. Pseudoplastic fluids useful oil and/or gas wells, particularly drilling fluids, drill-in fluids, workover fluids, completion fluids, perforating fluids, filter cake removal fluids, various pills, and the like, are prepared by solublizing chitosan in an acidic solution and thereafter raising the pH above about 7.0 by the addition of a basic compound thereto. The thermal stability of such fluids is enhanced by incorporating into the fluids certain aldose or ketose sugars, oligosaccharides of such sugars, and mixtures thereof, optionally together with a water soluble bisulfite compound.

Abstract: Aphron-containing oil based well drilling and servicing fluids are disclosed which seal microfractures and the like during drilling and well servicing operations, thus decreasing the volume of fluid lost to the formations contacted by the fluids.. The fluids comprise an oleaginous liquid as the continuous phase, a viscosifier which imparts a low shear rate viscosity to the fluids of at least 10,000 centipoise, an aphron-generating surfactant, and aphrons. The fluids are used in a conventional method of drilling an oil and/or gas well or in conventional methods of servicing or treating such wells, such as in completion, workover, sand control, and frac pack operations, and as spotting fluids to release stuck pipes or tools in a wellbore.

Abstract: Aphron-containing spotting fluids and their use in releasing pipe or tools stuck in the filter cake on the sides of a borehole are disclosed. The spotting fluids comprise a liquid, either aqueous, oleaginous, or mixtures thereof, a viscosifier which imparts a low shear rate viscosity to the fluids of at least 10,000 centipoise, an aphron-generating surfactant, and aphrons. The spotting fluids are used in a conventional method of releasing pipes or tools stuck in the filter cake on the sides of a borehole during conventional drilling or well servicing operations.

Abstract: Disclosed is a process of manufacturing a lightweight particulate cementitious composition particularly adapted to the sorption of liquids comprising adding to a foamed cement slurry a particle forming agent, and aging the treated foamed slurry for a period of time sufficient for the particles to form and harden for subsequent handling. The bulk density, particle size distribution, and concentration of the agent are selected such that the cementitious composition has the desired density and such that at least 65% of the particles obtained after aging have the desired particle size.

Abstract: The invention provides well working compositions containing a particulate additive to decrease the seepage loss of the fluid to fluid permeable formations contacted by the compositions.

Abstract: The invention provides well working fluid compositions containing cotton burrs ground to certain particle size ranges to decrease the seepage loss of the fluid to fluid permeable formations contacted by the compositions. Also provided is a seepage loss additive comprising the ground cotton burrs in combination with one or more of ground oat hulls, ground corn cobs, hydrophobic organophilic water wettable cotton, ground citrus pulp, ground peanut shells, ground rice hulls, and ground nut shells.

Abstract: The invention provides well working fluid compositions containing oat hulls ground to certain particle size ranges to decrease the seepage loss of the fluid to fluid permeable formations contacted by the compositions. Also provided is a seepage loss additive comprising the ground oat hulls in combination with one or more of ground corn cobs, hydrophobic organophilic water wettable cotton, ground citrus pulp, and ground cotton burrs.

Abstract: Organophilic polymer adducts which are effective fluid loss control additives for oil base well-working fluids are prepared from an anionic or cationic water soluble polymer and one or more phosphatides. Preferred phosphatides are phosphoglycerides obtained from vegetable oils, most preferably commercial lecithin. Preferred polymers comprise polysaccharides or derivatives thereof and synthetic polymers.

Abstract: The invention provides well working fluid compositions containing oat hulls ground to certain particle size ranges to decrease the seepage loss of the fluid to fluid permeable formations contacted by the compositions. Also provided is a seepage loss additive comprising the ground oat hulls in combination with one or more of ground corn cobs, hydrophobic organophilic water wettable cotton, ground citrus pulp, and ground cotton burrs.

Abstract: Organophilic clays which are effective fluid loss control additives for oil base well-working fluids are prepared from a swelling smectite clay and one or more phosphatides. Preferred phosphatides are phosphoglycerides obtained from vegetable oils, most preferably commercial lecithin such as soybean lecithin. The organophilic clays may also contain quaternary ammonium compounds.

Abstract: Organophilic polymer adducts which are effective fluid loss control additives for oil base well-working fluids are prepared from an anionic or cationic water soluble polymer and one or more phosphatides. Preferred phosphatides are phosphoglycerides obtained from vegetable oils, most preferably commercial lecithin. Preferred polymers comprise polysaccharides or derivatives thereof and synthetic polymers.

Abstract: Organophilic polymer adducts which are effective fluid loss control additives for oil base well-working fluids are prepared from an anionic or cationic water soluble polymer and one or more phosphatides. Preferred phosphatides are phosphoglycerides obtained from vegetable oils, most preferably commercial lecithin. Preferred polymers comprise polysaccharides or derivatives thereof and synthetic polymers.

Abstract: Organophilic polyphenolic materials which are effective fluid loss control additives for oil base well-working fluids are prepared from a polyphenolic material and one or more phosphatides. Preferred phosphatides are phosphoglycerides obtained from vegetable oils, most preferably commercial lecithin. Preferred polyphenolic materials comprise one or more of: humic acid; lignosulfonic acid; lignins; phenolic condensates; tannins, the oxidized, sulfonated, or sulfomethylated derivatives of these polyphenolic materials; and the water soluble or colloidally dispersible salts of these polyphenolic materials or these derivatives thereof.