Dry Tree Semi-Submersible for Drilling and Production - A Review of Design Drivers Available to Purchase

Development of Dry Tree Semi-submersible has been evolving for over ten years. It gained accelerated momentum in the last three years. Several engineering houses have proposed different concepts, performed engineering studies, conducted scaled model tests, and published results in Joint Industry Project reports and technology forums. This paper takes a critical review of design philosophies for concept selection, and addresses the most important design drivers to integrate Semi-submersible hull and riser tensioners for a system ready for field application. Global performance and motion characteristics are compared, and followed by riser stack-up and tensioning system. Critical aspects of the tensioners, trees, and riser systems are discussed in depth for conditions ranging from operating to survival. The paper continues to review wellbay layout scenarios in relation to riser arrangement and, in particular, to drilling riser elevations. Operations of wellbay systems are outlined, with keen attention to the drilling operations. Differences in applications for three oil provinces, Gulf of Mexico, Offshore West Africa, and Offshore West Australia are identified. The paper aims at providing a state-of-art review of the Dry Tree Semi-submersible development status for the offshore industry, and highlighting further work that shall enable sufficient maturity for a first project execution.