Application of Key Deepwater Lessons Learned in Marginal Deepwater Development, Offshore Malaysia
Authors: Khalid Aizuddin , Hamza Norashikin , A Rahim Mas Rizal , A Rahman Amir Ridzwan , Patma Nesan Thanavathy , M Sahid Norhayati 
Published: September 2022

L & B fields offshore Sabah, Malaysia will be the next deepwater development in Malaysia after Kikeh, Siakap North-Petai, Gumusut-Kakap & Malikai. However, in comparison, L & B are considered marginal in terms of recoverable volumes and size of project, making it crucial to design and execute the project sharply to ensure value delivery. 5 key deepwater lessons learned areas are discussed in this paper as applied to L & B Field Development Plan (FDP) to ensure technical robustness based on experience of surrounding deepwater fields.

The first key area is subsea production stability and flow assurance. Among critical evaluations conducted were techno-commercial comparison of dual-loop pipe-in-pipe against heated pipe-in-pipe, upfront artificial lift plans, and water injectors design to avoid hydrates formation as observed in another field. The second critical area is in drilling where key lessons were to conduct thorough geohazard analysis for hazard identification and avoid wellhead subsidence. Thorough geomechanics and fracture gradient were also assessed to identify requirements for managed-pressure drilling and for backup designs. The third key area is well integrity, productivity and injectivity where sand production and fines migration risks need to be addressed through well completion strategy. The reservoir management plan must also reflect realistic production and injection plans and data crucial for monitoring. The fourth key issue is with regards to subsurface complexity in deepwater turbidite environment with risks to production attainability vis-à-vis reservoir connectivity and compartmentalization issues. A no-stones-unturned approach was taken integrating available static and dynamic data to estimate a robust recoverable volume. The fifth critical area is well startup and unloading procedures, which is important for well productivity. Model iterations were needed to conduct methodical well bean-up to eliminate risk of fines movement.

Application of lessons learned in these 5 key areas led to robust development plans with mitigations for risks common to deepwater developments offshore north Borneo. For flow assurance strategy, the evaluation led to dual-loop design, proactive artificial lift strategy and optimum water injector locations. Drilling requirements are identified for MPD and backup slim-hole designs. To ensure productivity and injectivity, long highly deviated wells, with downhole sand mitigations, are designed for maximum contact and reduced required drawdown. Skin factors were applied in subsurface modeling as observed in other fields to risk the production targets. The model was also calibrated with dynamic data gained from well tests and pressure points to provide realistic production estimates, with a well sequence plan to observe actual performance and optimize next well locations if necessary. For well startup procedures, model iterations guided by analogue fields’ experiences led to optimum startup designs for L & B.

These 5 key lessons learned areas are critical in deepwater development plans to ensure technical robustness during development stage to protect high investment value.