Engineering and environmental studies for decommissioning of subsea infrastructure
Petrina Raitt A , Allison Selman B C and Céline Lanoëlle BA Green Light Environmental, Unit 19/210 Queen Victoria Street, North Fremantle, WA 6159, Australia.
B Atteris Pty Ltd, Level 3, 220 St Georges Terrace, Perth, WA 6000, Australia.
C Corresponding author. Email: allison.selman@atteris.com
The APPEA Journal 59(1) 277-288 https://doi.org/10.1071/AJ18107
Submitted: 31 December 2018 Accepted: 4 March 2019 Published: 17 June 2019
Abstract
Decommissioning of subsea infrastructure requires input from engineering and environmental studies, as well as the stakeholders, so that informed decisions can be made. This paper discusses the technical and environmental considerations relating to the decommissioning of subsea infrastructure for the full range of subsea components, including structures, rigid pipelines, flexible flowlines and control systems. Example engineering and environmental assessments that could be performed are discussed, such as stability, corrosion, lifting, materials degradation, net environmental benefit assessment (NEBA) and marine and fishing studies. The stakeholder engagement process is also presented. The paper discusses processes leading up to the decommissioning decision and what operators can do, to ensure that there is adequate information to support decisions that need to be made on transitioning into the final stage of the asset lifecycle. The paper will provide guidance on execution of the decommissioning works, how to ensure success and considerations for material handling, management and disposal of potentially hazardous and contaminated material and other environmental impacts. The technical aspects will be presented using case studies on past and present decommissioning projects in Australia. Solutions for in situ, recovery and repurposing that have been adopted will be presented, as well as alternative solutions that are currently being developed.
Keywords: decommission, engineering studies, environment, environmental plan, flowlines, NEBA, pipelines, stakeholder, structures, trees, umbilicals.
Petrina Raitt is the Director of Green Light Environmental, a specialised environmental consultancy that provides environmental support and value-adding solutions to the oil and gas industry. Petrina has over 20 years professional experience in environmental roles within government agencies, oil and gas and mining industries Australia. Her experience has included managing large-scale and complex impact assessments of both offshore and onshore activities and obtaining approvals of significant projects with both technical and stakeholder challenges. She has also served as project manager for various projects on behalf of APPEA and its members; including delivering a Scientific Literature Review of Decommissioning Options and Industry Shared Methodology for Stakeholder Engagement and Consultation. Petrina is also founder and Managing Director of eBase, a cloud-based environmental-impact assessment platform that aims to support more efficient consistent and thorough EIA and project approvals. |
Allison Selman is a Director of Atteris Pty Ltd and the Business Manager for Asset Lifecycle services. Allison graduated from the University of Western Australia in 1998 with a Bachelor of Engineering in Materials Engineering and a Bachelor of Commerce in Management and Marketing. She is a Chartered Professional Engineer and a Fellow of Engineers Australia. Her professional career has been spanned work for consultants, operators and contractors in Australia, Indonesia and Thailand. Her main interests are asset and integrity management of offshore infrastructure. She contributes on the board of Subsea Energy Australia and is the founder of the Women in Subsea Engineering (WISE) network. |
Celine Lanoëlle is a Lead Engineer at Atteris and the SME for Flexible Risers. Her main expertise lies in configuration design of flexible risers, installation, operation support and integrity management. Her experience in operation support exposed her to ageing assets and the considerations for field-life extension, with the inherent requirement for material-degradation assessment associated with flexible riser cross-sections. Céline has a background in Mechanical and Ocean Engineering. She contributed to the Offshore Pipeline Engineering Decommissioning Guideline for the Energy Pipelines Cooperative Research Centre (EPCRC). She is also an active member of the Women in Subsea Engineering (WISE) network. |
References
Department for Business Energy and Industrial Strategy (2018). ‘Guidance Notes: Decommissioning of Offshore Oil and Gas Installation and Pipelines.’ (Offshore Decommissioning Unit, Offshore Petroleum Regulator for Environment and Decommissioning, Department of Business, Energy and Industrial Strategy: UK.)ISO (International Organisation for Standardisation) (2009). ‘Risk Assessment – Principles and Guidelines.’ ISO31000:2009. (ISO.)
Kueppers, L. M., Baer, P., Harte, J., Haya, B., Koteen, L. E., and Smith, M. E. (2004). A decision matrix approach to evaluating the impacts of land-use activities undertaken to mitigate climate change. Climatic Change 63, 247–257.
| A decision matrix approach to evaluating the impacts of land-use activities undertaken to mitigate climate change.Crossref | GoogleScholarGoogle Scholar |
MacLeod, I. D. (1990) Conservation Management of Iron Steamships – The SS Xantho (1872). In ‘Proceedings of the Fifth National Conference on Engineering Heritage’, Perth, 2–5 December 1990. Vol. 16. No. 1, pp. 45–51.
McMaster, S. Y., Jensen, C. H., and Hayes, D. T. (2018). ‘[Confidential Project] Decommissioning – Semi Quantitative Degradation Study.’ (Atteris Pty Ltd: Australia.)
National Offshore Petroleum Titles Administrator (NOPTA) (2017). ‘Offshore Petroleum Decommissioning Guideline.’ Available at: https://www.nopta.gov.au/_documents/guidelines/decommissioning-guideline.pdf [Verified 21 March 2019].
Selman, A. G. L., and Jas, E. P. (2017). ‘Project 6.3-11: Offshore Pipelines Decommissioning Engineering Guideline.’ (Energy Pipelines Cooperative Research Center (EPCRC): Australia.)
Shaw, J. L., Seares, P., and Newman, S. J. (2018). ‘Decommissioning Offshore Infrastructure: a Review of Stakeholder Views and Science Priorities.’ (WAMSI: Perth, WA, Australia.)
Subsea World News (2018). ‘Webtool in Pipeline Decom Tool Project for Chevron”. Available at: https://subseaworldnews.com/2018/11/27/webtool-in-pipeline-decom-tool-project-for-chevron/ [Verified 30 April 2019].
Sumer, B., and Fredsoe, J. (2002). ‘The Mechanics of Scour in the Marine Environment. Advanced Series on Ocean Engineering, Vol. 17.’ (Technical University of Denmark: Denmark.)
WA Today (2018). “King Reef’ sunk off Exmouth to bring in big fish”. Available at: https://www.watoday.com.au/national/western-australia/king-reef-sunk-off-exmouth-to-bring-in-big-fish-20180815-p4zxog.html [Verified 30 April 2019].
