Abstract

In this paper, we present a mathematical programming approach to evaluate the conceptual study of regional integrated development for Alta-Gohta discoveries in the Barents Sea. Two alternative scenarios are investigated, the first considers to tieback Alta-Gohta to a field that is 60 km away, Johan Castberg, and the second to tieback the field to Goliat, another field at 100 km further. A sensitivity analysis in terms of CAPEX and OPEX is performed to assess the trade-off between selecting the host to be Johan Castberg or Goliat. The results indicate that the profitability and host selection for a tieback development plan of Alta-Gohta is highly dependent on the start time and the costs of the project.

Introduction

The planning of offshore field development is complex and time-consuming as it involves several disciplines such as drilling, infrastructure location, processing capacity, wells scheduling, production planning, among others. This paper addresses conceptual studies from DG1 (feasibility) to DG2 (concept selection) of regional integrated field development alternatives of real-world fields. In this work, the feasibility and profitability of two different business concepts are assessed through a mathematical-programming based approach.

The Barents Sea is the largest sea area on the Norwegian Continental Shelf (NCS) and with the largest potential for finding oil and gas reservoirs. Field development in the Barents Sea is challenging due to stricter safety and environmental regulations, Arctic weather season limitations and a lack of mature facilities and infrastructure as only a few fields are currently in production there. The Snøhvit (gas) and Goliat (oil) fields came on stream in 2007 and 2016, respectively. The oil field Johan Castberg is another field in the area currently under development and has the first oil planned to 2023. Gohta and Alta, two nearby offshore oil discoveries in 2013 and 2014, respectively, are currently under consideration for being developed. Recently, the operator reported that a standalone development of Alta and Gohta is no longer considered to be commercially viable, Staalese (2020). The main reason is that the deployment of new host facilities in the Barents Sea is too costly, and the recent fall in oil prices.

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