Venture Innovations, Inc.

Nl Industries

Venture Chemicals, Inc.

Actisystems, Inc.

Baroid Technology, Inc.

Pet Care Systems, Inc.

Roy F House

Jack C Cowan

Lonnie D Hoover

Victor M Granquist

Tommy F Brookey

Andree H Harrington

Andree' H Harrington

James H Sladek

Tammy L Rodrigue

Forrest A Scearce

Diane M Smith

Kimely P Pitre

Ronald W Brown

John H Waggenspack

S Michael Hughes

Andree H Wilkinson

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.

Anhydride-modified chitosan, method of preparation thereof, and fluids containing same

The invention provides an organic diacid anhydride-modified chitosan containing a polar additive comprising water soluble compounds containing one or more hydroxyl groups or one or more amino groups, including compounds containing both hydroxyl and amine groups, having a molecular weight less than about 2000, preferably less than about 1000. The invention also provides fluids useful in various well drilling and servicing operations comprising an alkaline aqueous liquid containing an organic diacid anhydride, chitosan, and the polar additive therein, as well as a method of drilling wells therewith.

The invention provides a method and fluid for drilling or servicing a well in a subterranean formation, particularly containing lost circulation zones or depleted, low pressure reservoirs. A method of decreasing the density of the fluid circulated in a borehole, decreasing the invasion of fluid into formations contacted by the fluid, or decreasing the lost circulation potential of the fluid is provided by using as the fluid an aqueous liquid having dispersed therein a polymer which increases the low shear rate viscosity of the fluid to the extent that the shear thinning index of the fluid is at least about 10, a surfactant, and aphrons, wherein the aphrons are preferably generated by the turbulence and pressure drop as the fluid exits the drill bit in the vicinity of the formation, the fluid having a low shear rate viscosity of at least 40,000 centipoise. The fluid additionally contains an oligosaccharide mixture composed of pentosans and/or hexosans containing from one to about 10 combined sugar units selected from the group consisting of arabinose, mannose, galactose, glucose, xylose, cellobiose, and mixtures thereof Preferably the oligosaccharide mixture is the water soluble portion of thermally hydrolyzed lignocellulose.

Aphron-containing well drilling and servicing fluids of enhanced stability

The invention provides well drilling and servicing fluids comprising an alkaline aqueous liquid containing chitosan, an anhydride, and an aldehyde therein. The invention further provides a method of drilling a well wherein there is circulated in the wellbore during drilling a drilling fluid comprising an alkaline aqueous liquid containing chitosan and an anhydride, and optionally an aldehyde therein.

Viscosified aqueous chitosan-containing well drilling and servicing fluids

The invention provides aqueous viscous or gelled alkaline fluids particularly useful in oil and gas well operations, and a method of drilling a well therewith. The fluids contain chitosan, an amine reactive acid, and an aldehyde therein, whereby the amine reactive acid and the aldehyde react with the primary amino group on the chitosan to increase the viscosity and stability of the fluid. The fluids are also useful wherein other chitosan-containing fluids are utilized. The preferred amine reactive acid is glyoxylic acid, and the preferred aldehyde is lactose.

The present invention discloses a method of producing modified, derivatized chitosans which produce viscous aqueous liquids when dispersed (solublized) in compatible aqueous liquids. The method comprises reacting chitosan in an acidic solution with an aldehyde-group containing chemical modifier at an elevated temperature wherein the concentration of chitosan in the acidic solution and the reaction time at the elevated temperature are sufficient to produce a semi-solid gel. The preferred chemical modifier is one or more saccharides containing less than about 10 saccharide units, most preferably lactose. The preferred reaction temperature is greater than about 60&deg; C., and the preferred concentration of chitosan is at least about 1.43% w/v. The invention also discloses the acidic chitosan-containing concentrates prepared by the method, and the viscous acidic fluids prepared by dispersing/solubilizing the concentrates in aqueous liquids.

Viscosified aqueous fluids and viscosifier therefor

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.

Chitosan-containing well drilling and servicing fluids

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.

Oil-in-water emulsion

The invention provides a method and fluid for drilling or servicing a well in a subterranean formation, particularly containing lost circulation zones or depleted, low pressure reservoirs. A method of decreasing the density of the fluid circulated in a borehole, decreasing the invasion of fluid into formations contacted by the fluid, or decreasing the lost circulation potential of the fluid is provided by using as the fluid an aqueous liquid having dispersed therein a polymer which increases the low shear rate viscosity of the fluid to the extent that the shear thinning index of the fluid is at least about 10, a surfactant, and aphrons, wherein the aphrons are preferably generated by the turbulence and pressure drop as the fluid exits the drill bit in the vicinity of the formation, the fluid having a low shear rate viscosity of at least 10,000 centipoise. The fluid additionally contains an oligosaccharide mixture composed of pentosans and/or hexosans containing from one to about 10 combined sugar units selected from the group consisting of arabinose, mannose, galactose, glucose, xylose, cellobiose, and mixtures thereof. Preferably the oligosaccharide mixture is the water soluble portion of thermally hydrolyzed lignocellulose.

Aphron-containing well drilling and servicing fluids of enhanced

The present invention provides an improved method for sorbing aqueous fluids through the use of a biodegradable, clumping, low odor, low attrition, low swelling ground grain litter. The ground grain litter is composed of a ground grain selected such that when the ground grain is wetted it tends to swell in volume less than 100%. In preferred embodiment, the ground grain litter comprises ground hard red spring wheat used to sorb pet urine and fecal liquids voided by a pet into the litter.

Ground grain animal litter

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.

Method of increasing the LSRV of aqueous fluids and oil-in-water

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.

Polysaccharide-containing well drilling and servicing fluids

An improvement in the use of clumping, scoopable litter to sorb and remove the urine deposited in litter receptacles by utilizing as the litter a natural product which has been modified to render it cohesive when wetted with urine. The modified natural product has excellent cohesion, is biodegradable, and is completely non-dusting. The modified natural product is a farinaceous material having a bulk density in the range from about 500 kg/m.sup.3 to about 900 kg/m.sup.3, a reducing sugar content from about 0.5% to about 4.0%, and a cold water solubles content from about 40% to about 90%. The preferred particle size of the modified natural product is such that at least 75% of the particles thereof are from about 250 microns to about 2000 microns.

Scoopable cat litter and method

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.

Lightweight particulate cementitious materials and process for producing

The invention provides a method of increasing the sorption capacity of smectite clays which exhibit osmotic swelling such as montmorillonite clays having predominately sodium as the exchangeable cation. The invention further provides a clumping cat litter having excellent cohesiveness comprising certain mixtures of a clay which exhibits osmotic swelling, a cellulosic material, and optionally a density controlling material, the clay, the cellulose material, and the density controlling material having certain particle size distributions, and the cat litter having a bulk density in the range from about 0.54 to about 0.96 g/cc and a sorption capacity greater than about 1.0 cc/g, wherein the concentration of the smectite clay is such that upon wetting the litter the cohesiveness of the lump of wetted litter is sufficient to allow its removal from a litter box, and wherein the concentration of the smectite clay is insufficient to prevent the lump of wetted litter from disintegrating in water over time.

Growing community of inventors

Houston, TX, United States of America

Roy F House