Malaysia's First Subsea Fields Abandonment

This paper covers the End-of-Field Life management and abandonment planning for four subsea fields. Scope includes end-to-end planning from confirming cessation of production with the Regulator, to Abandonment Planning, actual Implementation and Execution. PETRONAS Procedures and Guidelines for Upstream Activities (PPGUA), Company internal guidelines and Industry Practices are available for End-of-Field Life management, Abandonment Planning and Execution. These guidelines were used pragmatically in addressing both technical and non-technical challenges on these four fields, including but not limited to PSC Obligations and Regulatory Compliance, Selection of Abandonment Concept, Execution Strategy, etc. The lack of experience in subsea field abandonment provided a unique opportunity for collaboration among industry players, constructive challenges, and the acceptability of new ideas including ways of working, processes and implementation of rules/guidelines. There are six subsea wells in these four fields, in different water depths, some of which are in a cluster while others are not. The scope and timeline for each was evaluated on individual basis to draw alignment with its field and PSC-specific requirements; some are thereafter bundled together into a campaign to gain efficiency and savings via a broader synergy approach. Two broad scopes were considered: Wells Plug and Abandonment (P&A), and Subsea facilities decommissioning and abandonment. All wells P&A are aligned to industry practice and PPGUA. Field in shallower water was planned for full decommissioning and abandonment with subsea tree removed and recovered; a new diverless flushing tool (developed in collaboration with subsea vendor) was used to clean the pipeline that will be left in-situ. For field in deeper water (more than 100 meters), comparative assessment was carried out and the results support "leave in-situ" concept. Fit-for-purpose Marine Biology assessment was carried out by a local university to support this concept. The plan is to have this abandonment concept presented to the relevant Government Agencies for final approval.