Key Learning Experience in Managing Prolific High Temperature Wells in Offshore Malaysia

Abstract Well integrity management for High Temperature (HT) wells can be challenging due to stresses and cyclic behaviour during thermal expansion or corrosive stress cracking that may impact the fatigue life of wellhead, tubing and casing. The impact can be catastrophic and detrimental to production sustainability and surrounding asset. This paper discussed operator’s experience and case studies in managing well integrity issues while operating HT wells in two fields, Field X and Field Y, located in offshore Malaysia. Field X and Field Y in offshore Malaysia, consists of five prolific High Temperature (HT) gas producers respectively, with temperature exceeding 300⁰F. For Field X, since its first gas delivery in 2017, well integrity issues include the incident of wellhead seals failure, wellhead tilting, abnormal conductor growth, tubing leaks and Drive Pipe Housing Head (DPHH) sliplock issues, resulted in production deferment and loss of primary containment. Meanwhile, for Field Y, the wellhead growth issue was observed only recently, end of 2021, after wells were on production for almost 2 years since 2020. The sudden movement has impacted the flowline to bend and expose the surface system to disastrous situation. Subsequently, the platform was on total shut down for a few days and led to unplanned production deferment and penalty due to production commitment. Analysis for WELLCAT and wellhead design has shown minimal concern on the wellhead growth but restriction on the surface line has caused production curtailment. To-date, the only identified issue is on the relative pattern of Flowing Tubing Head Pressure (FTHP) vs the wellhead growth. Proactive and reactive measures are implemented including in-depth Root Cause Failure Analysis (RCFA) to understand gaps and mitigation required, which provide imperative insight and benchmark on strategies to manage HT wells. The key issues and observations based on operator’s experience in managing HT wells include: Impact of cement integrity and cyclic load on wellhead growth and axial load exerted on wellhead.Oxygen corrosion of tubing causing intergranular corrosion weakening the tubing wall due to wellhead failure.Possible stress corrosion cracking resulted from wellhead tilting and growth.Wellhead design and acceptance requires validation on cyclic load and analysis on the capacity of sliplock to cater axial load at 30" conductor.Surface system modification requirement including flowline to cater for the bending effect caused by the growth. This paper also highlighted preventive, monitoring practices and technology application to rectify well integrity issues in HT wells at Field X. Discussion on wellhead maintenance scope, nitrogen injection in annulus, tubing corrosion management and bracing support to address abnormal wellhead growth.