Top Tensioned Risers

Our TTR engineers have a thorough understanding of the interface complexities involved in top tensioned risers, and the technical expertise and project management skills to design, procure and deliver even the most complex systems.

TTR’s are probably the most challenging riser systems to engineer. The challenges stem from the many interfaces that must be accommodated, firstly, from interaction between production, injection and drilling risers, in-place as well as during installation and workover operations, and secondly, the need to minimise wellbay footprint and accommodate wellbay interfaces with the tensioners, jumpers and offtake piping while providing safe access for personnel.

We have unrivalled experience in the design, analysis and specification of dry tree production and surface BOP drilling riser systems for TLP, spar, semi-submersible and barge production vessels. Our project experience covers a wide range of TTR diameters, services, water depths and environments, including the North Sea, Gulf of Mexico, West Africa, and Brazil. Our experience includes procurement of TLP riser systems and the detailed design of spar riser systems for the Gulf of Mexico.

The many different components in TTR’s are manufactured by a range of vendors. Successful delivery of these systems has its foundation in fit-for-purpose specification of each equipment package and clear definition of the interfaces between packages. Appropriate qualification testing of connectors and fabrication methods is then needed and stack-up integration testing to ensure successful delivery in the field. 2H have the required experience and understanding to ensure these systems are successfully designed and delivered.

Key Services

• Feasibility studies and FEED including wellbay and seabed layout
• Single/dual casing riser risk assessment
• Detailed global analysis of strength, fatigue and clearance response
• Development of welding, material, corrosion and riser component specifications
• Component hardware specification, procurement and delivery management
• Component qualification and testing
• Riser system drawings and contractor interface management
• Integration management and system integration test procedures
• Installation procedures and offshore installation support
• Monitoring and integrity management

Project Experience

• Chevron – Big Foot TLP TTR Detailed Design & Delivery Management
• Total – Moho Nord TLP TTR FEED, Detailed Design and Delivery Management
• ATP – Mirage MinDOC TTR CVA
• Dominion (ENI) – Devils Tower Spar TTR Detailed Analysis and Sidetrack Drilling Feasibility Assessment
• Maersk – Chissonga TLP Single versus Dual Casing Riser Risk Assessment
• Exmar Offshore – OPTI-EX Semi-Submersible TTR Tensioner Feasibility Assessment
• BP – Horn Mountain TTR Design Verification and Production Riser Coupling Qualification
• BP – Holstein TTR & Conductor Fatigue Monitoring