AHTS conversion into a flexlay vessel

A client was undertaking enhancement works across two producing fields in the Santos Basin, including the installation and relocation of flowlines and umbilicals. To reduce mobilisation costs, the operator sought to utilise its existing infield anchor handling tug supply (AHTS) vessel for the installation activities. The vessel was not designed for flex-lay operations and was equipped only with a gantry crane, creating challenges for handling end fittings and ancillaries.

MDL conducted a feasibility study to assess whether the installation could be executed using the existing vessel configuration with a suitable flex-lay spread. An installation methodology was developed covering first-end initiation, normal lay operations and second-end abandonment. The study assessed onboard handling, gantry crane capability, winch utilisation and wire routing. MDL also developed a preliminary deck layout and carried out an integration structural assessment for the proposed lay equipment, including the RDS, tensioner and chute, alongside a risk and opportunity matrix.

The findings confirmed the viability of converting the vessel into a flex-lay asset and included recommendations for further detailed engineering where required. This enabled the client to progress the project with increased confidence, supporting a cost-effective and operationally efficient installation strategy using its existing vessel fleet.