Anhydride-modified chitosan, method of preparation thereof, and fluids containing same
AssigneeVenture Innovations, Inc.
InventorsRoy F. House, Diane M. Smith
Life of this patent
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Abstract
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.
Claims39
A method of drilling a well wherein a drilling fluid is circulated in the wellbore during drilling comprising circulating as the drilling fluid an aqueous alkaline, chitosan-containing fluid which additionally contains an anhydride modifier and 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 amino groups, wherein the polar additive has a molecular weight less than about 2000.
A well drilling and servicing fluid comprising an alkaline aqueous liquid, chitosan, an alkanedioic acid anhydride, and a polar additive comprising water soluble compounds containing one or more amino groups, including compounds containing both hydroxyl and amino groups, wherein the polar additive has a molecular weight less than about 2000.
An anhydride-modified chitosan-containing composition comprising chitosan, an alkanedioic acid anhydride, a polar additive, and water, wherein the polar additive comprises water soluble compounds containing one or more amino groups, including compounds containing both hydroxyl and amino groups, wherein the polar additive has a molecular weight less than about 2000.
The method of preparing a modified chitosan comprising mixing under high shear conditions chitosan, an organic diacid anhydride, water, and a polar additive wherein the concentration of the chitosan is from 20% to 60% by weight, the concentration of the anhydride is from 5% to 45% by weight, the concentration of water is from 10% to 30% by weight, and the concentration of the polar additive is from 10% to 25% by weight, and wherein the polar additive comprises water soluble compounds containing one or more hydroxyl groups or one or more amino groups, including compounds containing both hydroxyl and amino groups, wherein the polar additive has a molecular weight less than about 2000.
Dependencies are inferred from the claim text.