Novel modified cellulosic polymers as drilling fluid additives with improved properties

Novel modified cellulosic polymers with amphoteric character were prepared by grafting 2-dimethylaminoethyl methacrylate (DM) and 4-vinylbenzene sulph onic acid sodium salt (VB) onto sodium carboxymerhylcellulose (NaCMC), and characterized by IR and composition analyses. Their properties as drilling- fluid additives in oilfields were investigated with respect to shale inhibi tion, filtration control and viscosity enhancement. It is found that the gr afting of DM enhances the shale-inhibition effectiveness and that the graft ing of VB increases the tolerances to salt and temperature. Different from commonly used anionic and cationic polymeric additives, the modified cellul osic polymer with suitable structural parameters has both good shale-inhibi tion and mud properties. (C) 1999 Society of Chemical Industry.