Factorial Design Validation of an Environmentally Benign Water-Based Drilling Fluid from Sweet Potato Peels at Elevated Temperatures

Abstract

In recent years, several research types have been carried out to produce environmentally-benign drilling fluid additives using locally sourced substances. Still, the formulation of a more effective and cheaper viscosifier for a better hole cleaning ability that lowers risk in lost circulation zones, especially at higher temperatures, remains a critical research subject. This study examines the use of Sweet Potato Peels Extract (PPE), a more readily available by-product, as a drilling fluid additive. A 23 factorial experiment that considers temperature, PPE and Xanthan Gum (X.G.) as factor variables and viscosity as a response variable was conducted for field optimisation. In this research, the PPE and other commercial polymers were measured at different concentrations and combined in a specified ratio of 1:1 by mass to verify the levels of interaction between the additives on the mud weight, yield point (Y.P.), and plastic viscosity (P.V.) of the formulated drilling mud. The additives’ effects were then recorded using a mud balance, a viscometer, and a heater for temperature variance. The results were then compared with the control mud to ascertain the additives’ effectiveness. Experimental results revealed that the PPE and X.G. increased the Y.P. and P.V. at 104 °F and 176 °F, respectively. On adding 6 g of X.G. to the control mud (8.97 ppg), at 104 °F and 176 °F, the Y.P. increased by 88% and 11%, respectively, and the 3 g PPE + 3 g X.G. gave a better inference at 104 °F and 176 °F with a 92% and 38% increase respectively. This increase is a result of higher potassium content in the PPE from chemical laboratory analysis. Apart from the optimum ratio by mass of 1:1 above, the combination effects or results are shown using the factorial design experiment. The factor variables were modelled into a mathematical equation that indicates PPE additive as the most significant parameter on the yield point. The second component of viscosity, plastic viscosity (P.V.), followed a similar trend. Furthermore, PPE and X.G.'s effect on plastic viscosity at 176 °F decreased slightly with an increase in the control mud's salinity. This novel combination offers a more cost-effective and better-performing viscosifier than the conventional X.G. from the above results. The model helps predict downhole conditions better as it shows the interactive effects of the various additives and can help inform decisions at the surface. A better hole cleaning ability, lower risk in lost circulation zones, and reduced Non-Productive Time would be the benefits of using this formulation.