Geomechanical Insights and Experimental Analysis of Mud Contaminants Effects on Developed High-Performance Clay-Free Water-Based Drilling Fluid for Horizontal wells

ABSTRACT: This study presents a comprehensive geomechanical analysis of the Permian Basin and evaluates the performance of a novel Contamination-Resistant High-Performance Water-Based Mud (CF-HPWBM) for drilling horizontal wells under challenging contamination conditions. Geomechanical modeling reveals a normal fault regime with a safe mud weight window of 8.5 to 10.6 ppg for the Spraberry and Wolfcamp formations, providing critical insights for safe and efficient drilling. The CF-HPWBM demonstrated exceptional adaptability, maintaining stable rheological properties across various mud contaminants. pH stability was observed in most scenarios, except for cement contamination, which elevated pH to 12. Rheological properties, including plastic viscosity and yield point, were minimally affected, with seawater causing minor reductions but remaining effective for wellbore cleaning. Low-end rheology at both 3RPM and 6 RPM and gel strength exhibited resilience to seawater and sand, while clay enhanced these properties due to flocculation. Cement contamination, however, slightly degraded these characteristics. Shale dispersion tests indicated an impressive 89% recovery rate, highlighting effective shale inhibition, even under contaminant exposure. The developed mud also maintained optimal sag factors (0.50-0.53), ensuring stable weighting material suspension. These findings underscore the CF-HPWBM's robustness and suitability for maintaining wellbore stability and operational efficiency in complex drilling environments, offering a reliable solution for challenging conditions.