Successful Delivery of the Bonga North West (BNW) Project - Nigeria's First Major Brownfield Subsea Tieback
Authors: Uyanwune Joey , Oyeniyi Lola , Ejiofor Chiedu 
Published: April 2015

The Bonga North West (BNW) Project is a complex brownfield subsea tie-back to the moored floating, production, storage and offloading (FPSO) host facility entitled Bonga Main FPSO. The Bonga Main Field is situated approximately 120 km offshore Nigeria, in the Gulf of Guinea. The license is operated under a production sharing agreement with the Nigerian National Petroleum Corporation (NNPC) by Shell Nigeria Exploration and Production Company Limited (SNEPCo) in partnership with Esso E&P Nigeria Ltd, Nigeria Agip Oil Company (NAOC) and Total E&P Nigeria. The National Petroleum Investment Management Services (NAPIMS), a wholly owned subsidiary of the NNPC, has been delegated full authority to act on behalf of NNPC in all matters pertaining to the PSC. The BNW field is located approximately 10 km north west of the Bonga Main field.

Several development concepts were considered for BNW, but due to its proximity to Bonga Main and the ullage that was expected in the Bonga Main facilities from 2014 (mid case), the field could best be developed as a brownfield subsea extension to the Bonga Main hub. This was considered to be the most technically feasible and economically attractive concept that also provided considerable flexibility to manage the impact of remaining uncertainties. The selected development concept which was in two phases comprised a subsea system for up to 9 conventional wells (6 producers and 3 water injectors), with initially, 6 firm wells (4 deviated producers and 2 deviated/horizontal water injectors) targeting the central and southern fault blocks in the BNW 690 and 702 reservoirs. The initial 6 Phase-1 wells develop 129 MMstb from the 690 and 702 reservoirs. The concept required the installation of two 4-slot production manifolds which tied back to the existing PM-1 production manifold via a Cross Over Module (COM), and an extension of the Bonga western injection line with two injection T-junctions (4 slots total). Subsea facilities installed include 13 km of 10-inch × 12-inch pipe-in-pipe quad joints oil flowlines; 4 km of 12-inch diameter water injection flowlines; 15 km of electro/hydraulic umbilicals. Additional installed facilities on the Bonga Main FPSO facility were upgrades including existing Distribution Control System (DCS) to accommodate BNW; four methanol injection pumps and four corrosion inhibition pumps skids, and a new Subsea Controls and Switchgear Building.

This paper provides an overview of the development and execution of the project. Focus is given on several strategies applied by the Project Team to successfully manage Health, Safety, Security and Environment (HSSE), quality, the execution contracts, diverse stakeholders, costs, challenges, opportunities, risks and uncertainties, team integration, operational readiness and assurance, to achieve top project delivery performance in a very challenging environment.

Additional details can be found in the dedicated support papers generated for this OTC session and listed in the Reference section of this paper.