MPD Deepwater Drilling: A Case Study of MPD Surface Back Pressure Implementation for a Sidetrack Exploration Well in the Gulf of Mexico

Abstract

Managed Pressure Drilling (MPD) was identified as the differentiating technology to successfully execute a sidetrack deepwater exploration prospect in the Gulf of Mexico. Conventional drilling efforts were suspended on the original hole due to multiple pressure management issues, such as losses, ballooning, and wellbore instability. MPD was selected as an enabler for overcoming these challenges. The sidetrack was planned to exit the existing 14-inch casing and run three additional strings of casing/liners to a planned total depth (TD) over 31,000 ft MD. MPD was strategically integrated to address operational hurdles and acquire valuable subsurface data. MPD enabled the liners' shoe to be set deeper in two sections than the original wellbore, increasing the probability of reaching well TD. Given the well's exploratory nature and lack of offset information, a statically underbalanced mud was used, giving maximum flexibility to manage and test the pressure profile. MPD techniques for real-time pressure estimation were successfully used to obtain critical reservoir information. This paper offers a comprehensive overview of the sidetrack design, delineating some operational challenges. It also delves into MPD's role in effective equivalent circulating density (ECD), mud weight (MW) management, and tripping strategies needed to comply with regulatory requirements. By presenting key highlights, lessons learned, and recommendations gathered from the operation, this case contributes to the understanding and application of MPD in deepwater exploration.