Wellhead Fatigue Monitoring During Subsea Well Plug and Abandonment Activities

摘要

Wellhead fatigue monitoring was performed during Plug and Abandonment (P&A) activities of a well inthe Gulf of Mexico (GOM). Fatigue monitoring was deemed necessary for several reasons: an older vintageof wellhead system with uncertain fatigue life consumption from previous drilling activities, excessivewellhead stick-up, potentially large rig motions from a moored drilling rig for P&A. Fatigue monitoringwas performed to ensure the integrity of the wellhead during P&A operations.The wellhead fatigue monitoring methods previously developed by several of the coauthors was appliedin the wave-dominated GOM environment. Motions of the Blow Out Preventer(BOP) stack were measuredand combined with a model of the riser/BOP/wellhead/casing system to reconstruct fatigue damage in thewellhead, conductor and surface casing. To measure wellhead motions, Subsea Vibration Data Loggers(SVDLs) were run with the riser and retrieved via Remotely Operated Vehicle (ROV). Fatigue damagereconstruction in the wellhead, conductor and surface casing was performed directly using the measuredmotion data and an analytical transfer functions obtained from the calibrated Finite Element (FE) model.Results were provided with fast turnaround time to support operations.