Re-Entry Considerations to Achieve Production from Suspended Discovery Wells in Offshore Marginal Fields, Niger Delta

Abstract In a bid to increase the crude oil and gas production output from the Niger-Delta and encourage the participation of independent producers in hydrocarbon production, the Nigerian government conducted the 2020 marginal field bid round, in which 57 marginal fields were put on offer for acquisition. 29 of the 57 fields, 51%, are situated offshore, all of which have at least one exploratory or discovery well traversing hydrocarbon sands; whereas most of which are suspended subsea with a wet suspension/trash cap in open waters. To honor marginal economics and accelerate the field commercialization, some of these suspended wells become relevant for potential re-entry operations to attain first oil; as such, the thought-process for re-entering these aged wells is a critical factor for success. This paper attempts to discuss the key considerations to safely access and exploit these existing wells; including, a subsea inspection to confirm the health state of the subsea cap and its connection, a bathymetric and geotechnical survey, the application of casing risers and/or subsea tieback systems, the role of production loads on the casing, and the acquisition and analysis of the cased-hole logs to verify the integrity condition of the casing. This paper also attempts to bridge the knowledge gap for new independent operators who now own or operate offshore marginal fields, with insufficient experience in upstream offshore activities.