2-Year Review of Project To Repurpose Steel Tubulars To Create Marine Havens

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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 228583, “Repurposing Decommissioned X To Reef: A Review—2 Years After Repurposing Steel Tubulars To Create Marine Havens,” by Sogo Kuroiwa, SPE, Teck Hua Goh, and Wayne F.H. Foo, Sumitomo, et al. The paper has not been peer-reviewed.

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In October 2023, a proof of concept (POC) to repurpose industry end-of-life materials into an artificial reef was undertaken in Malaysia as a collaboration between Sumitomo Corporation; Petronas; and the Department of Fisheries, Malaysia (DOFM). For the POC, surplus oil-country tubular goods (OCTG) casing pipes were used in the fabrication of artificial reef structures for the enhancement of biodiversity and commercial fisheries. This paper shares a brief overview of this initiative, monitoring results, and replication of this concept in a subsequent project.

Introduction

As the demand for decommissioning activities increases, an increasing need exists to seek options for the treatment of decommissioned materials. Traditionally, rigs-to-reefs (RTR) is an environmentally sustainable approach toward offshore decommissioning whereby offshore platforms are repurposed as artificial reef structures to enhance marine biodiversity. RTR initiatives also reduce costs for removal and logistics by reefing parts of the decommissioned structure that have been assessed to be free of contaminants on the seabed at the actual decommissioning site or transported and reefed at a designated site. RTR initiatives have been ongoing in Malaysia since at least 2004. All artificial reefing activities are performed under strict regulatory requirements, including environmental impact assessments and navigation safety checks, and are in accordance with international guidelines and policies.

X-to-Reef (XTR) Proof of Concept

Conventional RTR projects generally involve the deployment of decommissioned offshore structures in their as-is condition, without structural alterations or extensive removal of contaminants and residues. For the XTR initiative, no limitation exists on the material types or categories used in the fabrication of artificial reef structures. Additional elements also were incorporated to promote the growth of targeted marine species. XTR strives to enable a more scientific and targeted approach to biodiversity enhancement than is often perceived in RTR projects.

Apart from supporting local fisheries enhancement through the XTR structures, opportunities also exist in supplementing traditional RTR projects to develop the reefing site into an aquatic “garden city” that can increase the biomass of commercial fish exponentially as well as that of crustaceans, mollusks, corals, seagrass, and seaweeds.

In early 2023, preliminary discussions were held to implement the XTR concept through engagements with the DOFM and Petronas to review proposed artificial reef designs based on desired outcomes, identify suitable deployment sites, and establish performance objectives for a POC. Under this collaboration, the operator supplied surplus OCTG casing pipes, which were repurposed into artificial reef structures.

A total of 10 structures were fabricated and installed: six around Pulau Kapas (Terengganu) to promote local fisheries and enhance fish biodiversity, and four at Pulau Sibu (Johor), also to enhance biodiversity and concurrently support seagrass protection and restoration. As part of the POC, periodic post-installation monitoring was conducted to assess the ecological effects associated with the deployment of the XTR structures.