Subsea Engineering – Single Vessel Solution

Samphire Subsea Case Study

Gas service and two production risers were at the end of their design life and required to be replaced to ensure the facilities could be supported until end of field life. Selection of the subsea engineering solution for the riser replacement works was critical and would largely dictate project costs.


Samphire was engaged to manage the engineering and execution of the replacement risers. The work required shallow diving under the FPSO turret, winch operations for product recovery / installation and sat diving for the subsea connection to the riser base.

Traditional selection criteria would dictate a two vessel solution; DSV for install and sat works and a support vessel for the air diving operations.

Samphire completed a technical evaluation of the work at the subsea contractor selection stage to consider if a DSV with a larger deck could accommodate all equipment to provide a one vessel solution. This resulted in the selection of a mid-size DSV as the installation vessel.


Further efficiencies and optimisations were made following review of deck layouts, equipment footprints, installation schedules and vessel operations.

As a result three gas service and two production risers were replaced over two campaigns with one vessel creating an overall safer solution and delivering significant cost savings for the Client.

Work Screening / Evaluation Equipment Criticality Review Risk Management Caisson Investigation Study/Repairs Subsea IRM - General Subsea Support Brownfield Project Execution Work Execution Pigging Campaign Management Subsea Engineering - Single Vessel Solution Subsea Controls Obsolescence Package Management Subsea Facilities Life Extension Subsea Decommissioning Services