Managed Pressure Drilling Technique Commingled High Pore Pressure Section with Depleted Section, Eliminate Drilling Hazard and Pore Pressure Uncertainty Related High-Pressure High-Temperature in West Kuwait Jurassic Deep Wells

Abstract The main goal was to successfully drill a re-entry well in the Rahiyah Field, West Kuwait, overcoming the challenge of commingle drilling from the Najmah to Middle Marrat formations characterized by High-pressure High-Temperature (HPHT) conditions and significant pressure uncertainty. A high-level Managed Pressure Drilling (MPD) strategy was developed, involving the use of a 15.2 ppg mud weight with an Equivalent Circulating Density (ECD) of 16.9 ppg. The plan included performing Dynamic Pore Pressure Tests and MPD Build Up Pressure Tests at the bottom of the Dharuma Formation to accurately determine the pore pressure across transitional zones. Adjustments to mud weight and ECD were made based on real-time data, facilitating adaptation to varying well conditions. The application of MPD techniques allowed for efficient and safe drilling through a highly uncertain pressure window, reducing the drilling time of commingled sections to 10 days, compared to over 30 days typically required for re-entry wells. The conventional approach would have necessitated a higher mud weight of 16.9 ppg, potentially causing a cycle of fluid losses and differential sticking. The oil-based mud (OBM) for the well’s final total depth (TD) was modified to a lighter density of 12.6 ppg with an ECD of 14.0 ppg, mitigating common issues in HPHT environments. This resulted in significant time savings and reduced non-productive time (NPT), demonstrating substantial improvements over traditional methods. This case study demonstrates the effectiveness of combining MPD with real-time pressure assessments to manage significant pressure variations in deep well environments. The learnings from this pilot project are crucial for refining cost-effective field development strategies and could significantly influence well trajectory planning, completion designs, and recovery optimization in similarly challenging geological settings.