Field-Based Drilling Fluid Design Optimization Methodology Successfully Mitigated Time-Dependent Shale Instability in Khafji Field

Al-Khafji Joint Operations is developing the offshore Khafji Field in the X-Neutral Zone by drilling horizontal wells. These<br>wells encounter shale formations namely Ahmadi Shale and Wara Shale before reaching the pay zones, and Intermediate<br>Shale between KB-1 and KB-2 Sands. While drilling these shale formations, severe time-dependent wellbore instability<br>problems due to shale sloughing were experienced. These problems have led to several stuck pipes and sidetracks.