Structure‐Property Relationships of New Water‐Soluble Grafted Starches with Amphoteric Character

Abstract

AbstractIn an attempt to develop an environmentally friendly, multifunctional mud additive for oilfield drilling treatment, new water‐soluble grafted starches with amphoteric character were prepared by grafting the mixed monomer system of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and 2‐(dimethylamino)ethyl methacrylate (DMAEM) onto naturally occurring potato starch, and characterized by IR and composition analyses. Their structure‐property relationships with respect to the hydration suppression of the swellable clay and the control of mud rheology were studied with the help of clay hydration‐swelling test, mud rheology test, and SEM observation. It has been found that the grafting of DMAEM enhances the inhibition effectiveness of clay hydration‐swelling and that the grafting of AMPS increases the viscosity of the treated muds and the tolerance to added salt. Compared with the partially hydrolyzed polyacrylamide with a degree of hydrolysis of 16%, a typical polymeric additive used in current drilling fluids, such grafted starch with suitable grafting percentage and composition has some distinct advantages in the formulation of water‐based drilling muds.Swelling percentage (Sp) of the clay pellets as a function of hydration time (t) in water and various sample solutions.magnified imageSwelling percentage (Sp) of the clay pellets as a function of hydration time (t) in water and various sample solutions.