DRILLING MUD SELECTION AND WELLBORE STABILITY: A PHYSICOCHEMICAL APPROACH

Abstract

Wellbore instability remains a significant challenge in drilling operations, particularly in geologically reactive formations such as those found in the Azerbaijani sector of the South Caspian Basin. This study focuses on the selection and optimization of drilling muds from a physicochemical perspective, with particular attention to their chemical composition and rheological properties and how these factors influence wellbore stability. The interaction between drilling fluids and reactive shale formations is examined in terms of hydration processes, ion exchange mechanisms, and osmotic effects, all of which contribute to changes in structural integrity and stability of the borehole. In addition, the use of glycol-based inhibitive drilling fluids and various chemical additives is evaluated for their effectiveness in mitigating clay swelling and reducing fluid loss during drilling operations. The findings highlight the critical role of chemical engineering approaches in the formulation of drilling muds, demonstrating that properly optimized fluid systems can significantly enhance wellbore stability and minimize drilling fluid losses, thereby improving overall drilling efficiency and operational safety.