With most of the major fields in the western off-shore of India being mature, the niche domain of well decommissioning is all set to experience its peak. The recent trends in the decommissioning industry indicate operators around the globe shifting towards fit-for-purpose alternatives to the conventional rig based decommissioning. However, with the day rates of Jack-up rigs slashed down to 35-40% of that of the pre-downturn period, entails us to revisit the strategy regarding the selection of the method for decommissioning. Therefore, this paper presents a framework that encompasses various parameters which serve as a guide to select an optimal method for a platform based well decommissioning.
The paper initializes by detailing the associated parameter ‘Platform Specifications’ comprising of platform's layout (available free space and various Rigless packages’ footprint), load-bearing capacity and material handling capacity of the platform. Following which, the paper contrasts rig based and Rigless Well decommissioning on three critical domains of project management-  Operational constraints,  Time constraints and  Economic constraints, henceforth presenting a synthetic technoeconomic analysis for a platform based well decommissioning project.
Inferring from the synthetic techno-economic analysis, the paper concludes that there are no visible cost benefits of selecting Rigless decommissioning over rig based decommissioning. The time and cost involvement in platform modification (if any) for undergoing Rigless approach, assimilated with the principle of economies of scale (in terms of wells spread over large number of platforms in the field undergoing decommissioning) and the ability to handle known and unknown uncertainties due to limited firsthand experience, further supports the rig based approach for platform-based well decommissioning in the current market.
The paper re-establishes rig based approach as a potential solution for dry tree wells decommissioning and challenges the cost-effectiveness of Rigless solutions for decommissioning available in the market, owing to techno-economic viability and risk optimization in the current market scenario in the western Indian offshore region. Further, with subsequent knowledge sharing from operators having experience in both Rigless and Rig based abandonment on comparable platform layouts and well specifications in the region, the industry will tend to standardize and gain proficiency to develop a sustainable approach to well decommissioning.