BOP Setback Structure

Stena Carron / Drillmax 2nd BOP Setback Structure

Background

Stena Drilling awarded Cadherent the contract to engineer the design of a secondary setback structure on-board the Stena Carron and Stena Drillmax drilling vessels to accommodate a new 15K 6 Ram BOP Stack.

In order to accurately design all structural interfaces and to ensure a clash free installation we utilised our in-house dimensional survey services.

Stage 1 - Initial 3D Laser Surveys (offshore)

Our team mobilised to the vessel to carry out detailed 3D laser scans of the existing setback structures, moon pools and riser laydown areas.

A target control system was established to allow any future vessel surveys to seamlessly integrate with the captured data. On completion of survey fieldwork the data was returned to Cadherent head office for processing and interrogation by our engineering design team.

Stage 2 - Design Phase and Clash Check

Through integration with the latest CAD packages and specialist software LFM (Light Form Modeller) our engineering design team could undertake the required structural modifications utilising the surveys accurate as built data, whilst ensuring the new structure remained clash free.

Stage 3 - Setting out (Stena Drillmax)

On completion of the design phase our survey team mobilised to the Drillmax in Las Palmas (Gran Canaria) to set-out the primary structure and BOP Gripper interface plates. Using proven survey techniques we continually monitored the 65Te structure throughout assembly to ensure tolerances +4 -0mm were achieved

Key project benefits of the surveys:-

– By undertaking the initial laser scan, all critical interfacing points were captured with high accuracy and in full detail.

– Using 3D point cloud software with AutoCAD interface, the engineering design team could virtually visit the site for measurements at any stage in the project.

– Easy to clash check scan data with local equipment, structure and design model.

– Controlling the setting out of the primary structure was critical to ensure correct alignment for the interface with secondary steelwork.