Optimizing filtration properties of water-based drilling fluids: Performance of PAC variants and synergistic effects

Abstract

Effective fluid loss control and mud cake optimization are critical for preventing drilling challenges such as pressure imbalances and pipe sticking in water-based drilling operations. While polyanionic cellulose (PAC) is a common additive for managing filtration properties, the comparative performance of its variants—PAC-R, PAC-L, and PAC-UL—remains inadequately studied. This experimental investigation evaluates these PAC variants and xanthan gum (as a benchmark) across a range of concentrations to determine the most effective option and optimal concentration for minimizing fluid loss, mud cake thickness, and permeability under Low Temperature Low Pressure (LTLP) conditions. The study further explores the potential of combining PAC-L and PAC-R to enhance filtration performance. Results indicate that each additive exhibits peak performance at specific concentrations, with 0.7 wt% frequently emerging as the optimal threshold for balancing fluid loss control and mud cake properties. Notably, the PAC-L and PAC-R combination at 0.7 wt% outperforms individual additives, achieving superior filtration characteristics through synergistic effects. These findings highlight the distinct capabilities of PAC variants and underscore the value of tailored additive combinations in optimizing drilling fluid formulations. By identifying effective strategies for filtration control, this study provides practical insights for improving drilling efficiency, enhancing wellbore stability, and supporting sustainable drilling practices, contributing significantly to the advancement of water-based drilling fluid technology.