| 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. |