Application of a new family of amphoteric cellulose-based graft copolymers as drilling-mud additives

Abstract

A new family of amphoteric cellulose-based graft copolymers (CGADs), which were prepared by grafting acrylamide and dimethylaminoethyl methacrylate onto sodium carboxymethyl cellulose, have been investigated for their properties as multifunctional drilling-mud additives with respect to shale inhibition, rheological control and filtrate-loss control. For the CGADs investigated, the shale-inhibition ability improves but the filtration-control ability weakens with increasing content of cationic groups. An increase in the concentration of CGADs results in better inhibition and viscosity-building as well as lower fluid loss. The pH of the medium has an effect on the inhibitive property. A comparative study among CGADs and some commercial polymeric drilling-mud additives was also carried out.