Large-scale SURF recovery using AHTS

An independent Brazilian operator launched a tender for a SURF removal and disposal campaign, covering Engineering, Preparation, Removal and Disposal (EPRD) services across three offshore platforms. The scope included 760 km of flexible pipelines, umbilicals and associated subsea infrastructure in water depths ranging from 100 to 500 metres. The scale of the campaign, combined with varying product diameters (up to 400 mm) and differing lengths, required careful consideration of recovery methods to ensure compliance with project requirements while optimising operational efficiency and minimising risk.

MDL’s feasibility study assessed deck layout and equipment requirements based on the available product data. It included an evaluation of maximum recovery loads and packing volumes across a range of recovery scenarios. Four recovery methodologies were developed, including direct recovery to high-tension reels, recovery using a Horizontal Lay System (HLS) onto standard reels or high-tension reels, and recovery to deck with cutting and storage in containers. Each option considered deck space requirements, recovery capacity and estimated campaign duration, alongside technical, operational and safety factors, as well as associated commercial implications.

The study provided a clear comparison of recovery methodologies, enabling an informed selection of the preferred execution approach. MDL presented the findings to the client in a workshop, addressing key technical considerations and supporting selection of the preferred execution approach. In subsequent phases, MDL further supported the project by developing vessel-specific deck layouts - helping to progress the campaign with increased confidence and a defined, efficient decommissioning strategy.