Cap Rock Restoration in Well Abandonment: Fit-for-Purpose Well Abandonment Design through Workflow Optimization and Integrated Assessment

Due to sharp oil price downturn in last few years, operators have been looking for ways to reduce operating expenses, especially on non producing assets. Well abandonment is proposed for non producing wells to reduce long term operating expenses. For well abandonment, traditional practice was well abandonment at reservoir level, with the purpose of securing entire well integrity as safety was the main concern. However, due to huge amount of time and cost associated to traditional well abandonment method, operators have been looking for optimization on well abandonment.

Field B is located in offshore Sarawak, and has been producing since 1968. Currently, Field B is in second half of its life cycle, and some wells and facilities are currently planned for decommissioning and abandonment. Well abandonment studies were initiated for 3 wells in Field B, with the purpose of reducing long term operating expenditures and minimize operation complexity. The studies are conducted by integrated team, consists of Petrophysicist, Reservoir Engineer, Production Technologist and Workover Engineer.

Well abandonment studies adopted integrated assessment approach, with the focus of reducing the time and cost related to well abandonment without jeopardizing safety requirements. As results, proposed abandonment intervals are significantly reduced compared to what has been planned initially. With simplified well abandonment plan, fit-for-purpose rig is used, and well abandonment operation cost is reduced with reduction in rig day rate. This paper will chronicle well abandonment optimization through workflow optimization and integrated assessment for well abandonment proposal.