Carboxymethylation of Icacina trichantha Oliv.Tuber Starch and Its Use as a Viscosifier and Fluid Loss Control Agent in Water Based Mud

Abstract

Starch from a non-food wild plant- Icacina trichantha oliv.tuber was extracted, characterized and chemically modified by carboxymethylation to produce two new derivatives of two different degrees of substitution. The derivatives were used in the preparation of water based muds. The rheological and filtration properties of these new muds were compared to those of muds prepared with the underivatized native starch and a commercial drilling starch using viscometric and fluid loss methods. Experimental results showed that the new muds have better filtration control behavior and viscosity than those of the native and commercial drilling starches. The values of flow index of the new muds were found to be less than 1.0, showing non-Newtonian and Pseudoplastic flow behavior of drilling muds. Yield stress of the muds increased with the modification. Viscosity decreased with increasing shear rate, showing shear thinning behavior of drilling muds. The new muds were found to obey the API models for static filtration as well as Power law and Herschel–Bulkley models for fluid rheology.

Keywords: Icacina trichantha oliv.;Carboxymethyl starch; drilling mud; filtration; rheology.