Optimisation of Rheological Properties of Water-Based Mud (WBM) with Natural Additives by Using Response Surface Methodology (RSM)

Abstract

The rheological properties of drilling muds are critical for achieving optimal performances during drilling operations. In this study, bentonite, tannin, and xanthan gum were utilised as water-based drilling mud additives to enhance the rheological properties. The Response Surface Methodology (RSM) with Box-Behnken Design (BBD) was used to investigate the additive's effect on the rheological properties of the drilling muds. The concentration of bentonite, tannin and xanthan gum were considered as the independent variables, while plastic viscosity (PV), apparent viscosity (AV), and yield point (YP) as the responses in the design of experiment (DOE). The YP, AV and PV were determined using 9.0 ppg of drilling mud according to the API standard procedures. Response surface plots (3D) were used to analyse the effect of the independent factors on the rheological properties and resulting in R2 values of 0.9753 for PV, 0.9582 for AV and 0.9513 for YP, which indicates that the interaction between elements in the system were statistically significant as these R2 values were close to 1.0. Bentonite was observed to significantly increased the PV, AV, and YP, whereas it decreased as tannin concentration increased. The optimal rheological properties required for low PV and AV with a high YP could be achieved using WBM formulation of bentonite at 4.02 g, 7.29 g of tannin, and 0.53 g of xanthan gum. Meanwhile, xanthan gum had an insignificant effect on the PV, AV, and YP. This finding demonstrates that the RSM model is accurate and relevant tool; hence it may be utilised to optimise the experimental conditions of mud formulation and accurately predict the rheology parameters of drilling muds.