ANHYDRIDE-MODIFIED CHITOSAN, METHOD OF PREPARATION THEREOF, AND FLUIDS CONTAINING SAME

摘要

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