Title: Risk-informed decision-making with an improved risk-based approach to evaluate plug and abandonment designs

Authors: Henrik Langdalen; Eirik Bjorheim Abrahamsen; Jon Tømmerås Selvik; Hans Petter Lohne

Addresses: Department of Safety, Economics and Planning, University of Stavanger, Kjølv Egelands hus, Kristine Bonnevies vei 22, 4021 Stavanger, Norway ' Department of Safety, Economics and Planning, University of Stavanger, Kjølv Egelands hus, Kristine Bonnevies vei 22, 4021 Stavanger, Norway ' Department of Safety, Economics and Planning, University of Stavanger, Kjølv Egelands hus, Kristine Bonnevies vei 22, 4021 Stavanger, Norway; Norwegian Research Centre (NORCE), Prof. Olav Hanssensvei 15, 4021 Stavanger, Norway ' Norwegian Research Centre (NORCE), Prof. Olav Hanssensvei 15, 4021 Stavanger, Norway

Abstract: A risk-based approach has been established to evaluate the quality of plug and abandonment oil and gas well designs that differ from the regulatory requirements on the Norwegian continental shelf. A move away from the prescriptive requirements to a more performance-based approach implies a reliance on the risk-based approach's ability to treat and reflect all the relevant uncertainties. The quality measure in this context is the leakage risk, expressed in terms of failure probability and the associated leakage rate, where uncertainties are treated by probability distributions. It is reasonable to question whether the probability distributions provide adequate representations of all the relevant uncertainties. To improve the current risk-based approach, we propose an improved approach that complements the probability distributions by highlighting the uncertainties rather than the probabilities, assesses the risk of deviation from the assumptions and reflects the knowledge-base.

Keywords: risk assessment; leakage risk; probability of failure; leakage rate; plug and abandonment; P&A; assumption deviation risk; ADR; uncertainty; assumption; background knowledge; risk management; strength of knowledge; SoK.

DOI: 10.1504/IJBCRM.2019.100415

International Journal of Business Continuity and Risk Management, 2019 Vol.9 No.3, pp.226 - 250

Received: 13 Aug 2018
Accepted: 26 Oct 2018
Published online: 28 Jun 2019 *

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