USING LOCAL ADDITIVES TO IMPROVE THE RHEOLOGY OF DRILLING FLUID AND REDUCE FLUID LOSS

ABSTRACT

Cassava starch flour with bentonite in controlling viscosity and fluid loss in Water Based Mud (WBM) was investigated in this study. Various mud samples were formulated consisting of different masses of cassava starch flour (2g, 4g, 6g and 8g) and an additional one being the control bentonite (0g of cassava starch flour). Fluid loss and rheological tests were carried out to determine the plastic viscosity, yield point, gel strength among others. Results from this investigation showed that, increasing the amount of cassava starch flour in the WBM increased the viscosity of the mud samples due to its swelling ability. Mud samples with cassava starch flour exhibited greater suspension ability (gel strength) of cuttings than that of the control sample with the exception of 6g and 8g of cassava starch at 80 ℃ for the 10minutes gel strength. At the end of the fluid loss test, mud sample with cassava starch flour concentration of 2g recorded a filter cake thickness of 2 mm while that of 4g, 6g, and 8g gave 3mm thickness. In conclusion, introduction of cassava starch flour into the mud samples from concentrations of 2g to 8g reduced its fluid loss by an average of 8%. Based on the analyses, starch flour prepared from freshly uprooted local cassava has the potential to improve viscosity and also control fluid loss in WBM.