OSV conversion for deepwater SURF recovery

A Brazilian field operator identified an opportunity to use an Offshore Support Vessel already under charter to recover flexible flowlines, umbilicals and jumpers across two Campos Basin fields. The scope covered 21 subsea products, ranging from 2.5-inch gas-lift risers to 9.5-inch gas-export flowlines, in water depths of approximately 770m. The vessel owner engaged MDL to determine whether the OSV could be repurposed for the decommissioning campaign and to define a suitable recovery methodology and back-deck configuration.

MDL completed a FEED study to assess the vessel's suitability and develop the recovery methodology and back-deck configuration. The study defined the handling requirements, providing the technical basis for the vessel owner and field operator to progress the proposed approach. Following the study, MDL was selected to deliver the complete back-deck spread. The package combined MDL's award-winning Wheeled Horizontal Lay System (WHLS), Generation 3 Reel Drive System, an offshore-rated reel and high-capacity assets from its Winches & Lifting Solutions range. MDL field personnel from the UK and Brazil operated the spread, while the Rio-based MDL do Brasil team managed the vessel mobilisation in B-Port, acting as the single point of contact between the client and third-party contractors.

The recovery campaign was completed 19 days ahead of the client's forecast. MDL's modular equipment facilitated an efficient mobilisation, while the WHLS's wheeled overboarding arrangement reduced the capstan effect during retrieval. This enabled a single 110Te tensioner to handle recovery loads of up to 105Te. Most notably, by combining the FEED study, equipment spread and project delivery within one package, MDL enabled the operator to use a vessel already under charter rather than source a specialist decommissioning asset, such as a PLSV. The approach reduced vessel sourcing and mobilisation requirements while successfully completing the recovery scope.