Addressing Wellbore Stability Challenges of Horizontal Drilling in Unconsolidated Sandstones

ABSTRACT: The paper discusses the underestimated issue of wellbore stability in horizontal drilling within unconsolidated sandstone formations. Historically, mud weight designs were based on shale stability, leading to higher mud weights and increased risk of lost circulation. Recent Gulf of Mexico drilling activities highlight the need for tailored mud weight designs for horizontal drilling in depleted sand formations. The paper proposes a practical workflow integrating analytical solutions, laboratory measurements, and customized numerical simulations to determine appropriate mud weights for maintaining wellbore stability. The study reviews existing literature, identifies gaps in current methodologies, and develops a workflow reflecting the mechanical behavior of unconsolidated sandstones. Laboratory data calibrates numerical simulations, modeling various drilling scenarios to predict wellbore stability. The workflow's efficacy is validated against field data, confirming its robustness. The methodology enhances operational efficiency and safety, offering a valuable tool for the oil and gas industry.