Optimising Offshore Structures Decommissioning - A Multicriteria Decision Approach

Abstract

Decommissioning activity is being delayed due to cash flow constraints in most companies, others are taking advantage of the low oil prices to expedite decommissioning activity as some associated cost becomes cheaper. Nevertheless, decommissioning is an emerging and growing market. There is a forecasted increase in global decommissioning projects from about $2.4 billion in 2015 to $13 billion per year by 2040, with an estimated 2000 offshore structures to be decommissioned between 2021 and 2040. These costs are very high considering decommissioning is an activity that does not necessarily bring in an income to producing companies. Thus, companies are seeking ways to optimize the process of decommissioning so as to reduce overall cost. This work identifies and evaluates the various decommissioning options and criteria for decision making and proposes a multicriteria decision making approach that will optimise decommissioning process and efficiency savings.

Environmental Sustainability and Efficiency of Offshore Platform Decommissioning: A Review

“…This section provides a system for decommissioning considering environmental impact, where topsides, wells, substructures, and subsea infrastructure are among the key equipment items slated for removal during decommissioning, with topsides and substructures being the largest [27,28]. If the process is to be successful and cost-effective, the choice of a suitable decommissioning option is critical.…”

“…In addition to meeting all environmental and technical criteria, it was the most cost-effective and efficient option. Eke et al [27] summarized the analysis of decommissioning the Hermosa Platform located offshore of California using a technique of multi-criteria decision analysis (MCDA) called AHP, or Analytic Hierarchy Process. Five criteria were adopted in their analysis: safety, environmental impact, technical feasibility, cost, and public perception.…”

Identificação e valoração dos critérios de decisão em projetos de descomissionamento offshore

“…Adotou-se a equação (1) na ordem de preferência dos critérios. Como não se percebeu alteração na ordem de preferência entre critérios, a Tabela 6 representa a ponderação para o caso global, que considera todas as respostas, bem como para profissionais Jr e Sr. Na ordem de preferência dos subcritérios relativos a Meio Ambiente (Tabela 5), obtém-se ponderações diferentes para os agrupamentos de profissionais Jr e Sr após aplicação da equação (1), conforme Tabela 7. principalmente quando comparados a outras fases do ciclo de vida de uma plataforma offshore (Eke et al, 2020).…”

“…O descomissionamento de instalações de exploração e produção de petróleo e gás natural (oil and gas -O&G) tem sido tema de estudo de muitos autores (Bull & Love, 2019;Eke et al, 2020;Ekins et al, 2006; bem como uma preocupação relevante de diversas empresas do setor (Repsol, 2017;Shell, 2017b). A aplicação de métodos multicritérios de apoio à tomada de decisão também pode ser vista em uma quantidade significativa de estudos (Fowler et al, 2014;Henrion et al, 2015;Marfatia, 2019;.…”

“…Apesar da forte presença do método AHP, 35% dos estudos de descomissionamento já realizados, ao segmentar os descomissionamentos destinados à indústria de O&G percebe-se forte relevância de métodos de Avaliações Comparativas (Repsol, 2017;Shell, 2017b (Repsol, 2017;Shell, 2017b), quanto em estudos científicos (Eke et al, 2020;Ekins et al, 2006;Fowler et al, 2014; (Edwards & Barron, 1994).…”