Application of Starches from Selected Local Cassava ( Manihot Exculenta Crantz) as Drilling Mud Additives

Selected local cassava ( Manihot esculenta Crantz) starches were investigated as additives for water-based drilling mud. Cassava cultivars, TMS 30572, TMS 98/0505, TMS 98/0581, M98/0068, TMS 92/0057, TMS 96/1632, NR8082, TME 419, TMS 97/4779 and TMS 01/1412 were processed to starches and used for drilling mud treatment at 0.5, 1.0 and 2.0 percent. Polyanionic cellulose (PAC), xanthan gum (XG) and industrial starch-modified drilling muds served as controls. Physicochemical analysis of the starches showed significant differences in their properties. Viscosity and fluid loss profiles revealed that some of the local cassava starches had comparable performance with the commercial polymers. The optimal concentration of the industrial starch in the mud system was 0.5 percent, while that of the local starches were between 0.5 and 1.0 percent. PAC and XG performed best at 1.0 and 2.0 percent respectively. The highest viscosities were shown by muds treated with TMS 98/0581, XG, TMS 96/1632, M98/0068, TMS 92/0057 and PAC, arranged in decreasing order. And the lowest fluid losses were exhibited by muds with PAC, industrial starch, XG, TMS 98/0581 and M98/0068 in increasing order. Viscosity and fluid loss models as functions of cassava starch physicochemical properties were developed. Increase in starch content, amylose content, solubility index would readily increase viscosity, while high starch content, amylopectin content, solubility index and pH would reduce the fluid loss. Local starches from TMS 98/0581, TMS 96/1632 and M98/0068 and TMS 92/0057 could be used as a substitute in drilling mud as viscosity enhancers and fluid loss control agents in Nigeria.