Bonga North Story: Beyond 1 Billion Barrels – Driving Growth with Subsea Tiebacks in Deepwater Nigeria

Abstract The Bonga North (BN) project is a greenfield oil development located in the Gulf of Guinea, approximately 130km offshore, in water depths ranging from 900m to 1300m. A Field Development Plan proposing a standalone Floating Production Storage and Offloading (FPSO) to develop the field was proposed but not supported due to a misalignment in the allowable number of FPSOs in the Oil Mining License (OML) 118 block. The block has an existing FPSO with a 20-year design life that ends in 2025 and an oil capacity of 220 Mbopd but has come off the initial production plateau and is producing below capacity, with further decline in production anticipated. This paper discusses the journey of the Bonga North project, highlighting the challenges and resolution strategies in a constantly changing environment. Post the demonstration of the feasibility of a 10 to 15-year extension of the design life of the Bonga Main (BM) FPSO, flow assurance studies confirmed the feasibility of an 18km tie-back of the Bonga North fluids. The Bonga North concept was then revised from a standalone FPSO to a tie-back to the Bonga Main FPSO in a risk-based, competitive, and scalable approach. As a result, the Bonga North project was tranched to take advantage of the available ullage in the Bonga Main FPSO. The first tranche of development initially consists of 7 producer-injector well pairs and associated subsea infrastructure to keep the FPSO full. Further subsurface studies incorporating learnings from recent drilling results from the analogous Bonga Main field, including improved understanding of reservoir behaviours, resulted in a BN Tranche-1 development that was not optimal to fill the ullage in the FPSO. Consequently, a study was initiated to accelerate some of BN Tranche-2 wells, while simultaneously integrating design flexibility and robustness during Front End Engineering Design (FEED) and incorporating the same within Invitation to Tender (ITT) as an optional scope. This strategy optimized field development, addressed schedule issues, and showcased the benefits of adaptable design and execution. Bonga North Tr1 has the potential to add over 100Kbopd to the Bonga Main FPSO. The project execution is via three Engineering, Procurement, and Construction (EPC) contracts and a Wells Drilling and Completion Contract. The P50 FID date is in Q3 2024, however, the project team is working assiduously to deliver FID in Q2 2024. In accordance with proactively meeting the requirements of the Production Sharing Contract (PSC), the Project team has been engaging the concessionaire and the regulators, in a collaborative manner. Issues resulting from macro-economic perspectives and challenges, such as inflation, supply chain disruptions, supply constraints, and elevated input costs from the tenderers, are being timely resolved. This paper is part of a Mega Project series at OTC 2024, and the other papers are listed in the references.