Subsea Vessel Riser Storage Horizontal Pre-Assembly
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Solution Overview
Problem
The existing process for assembling and disassembling riser strings in subsea wellbore operations is time-consuming due to the need for extensive connection-making between riser sections, which slows down the deployment and requires significant effort and testing.
Innovation Solution
The implementation of a vessel with a riser storage system that stores pre-assembled riser stands, allowing connections to be made and tested before loading, significantly reducing the assembly time by storing multiple riser stands connected end-to-end in horizontal orientation, and using a strongback assembly for efficient handling and alignment during deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If riser sections are stored individually and assembled on-demand, then flexibility in deployment is improved, but assembly time and operational complexity increase significantly
Solution Approach 1:
Riser sections are pre-assembled into complete riser strings onshore before deployment. The pre-assembly process includes connecting multiple riser sections with connector fittings, installing satellite pipes, and performing integrity testing in advance. This preliminary preparation eliminates time-consuming assembly operations at sea, reducing deployment time while maintaining deployment flexibility.
Solution Approach 2:
The riser string is divided into modular sections that can be pre-assembled independently onshore. Each section can be tested and certified separately, then quickly deployed as complete modules. This segmentation allows parallel preparation of multiple sections, improving overall deployment efficiency while maintaining system flexibility.
2Loss of time
If riser sections are assembled and tested onshore before deployment, then deployment time is reduced, but storage requirements and logistical complexity increase
Solution Approach 1:
Multiple riser sections are nested within each other in a telescopic arrangement during storage and transport. The sections are stacked vertically or horizontally in a compact configuration, reducing storage space requirements. This nesting approach allows complete pre-assembled riser strings to be stored in a space-efficient manner without requiring complex external support structures.
3Productivity
If traditional on-site assembly process is used, then equipment and storage space requirements are reduced, but operational efficiency and productivity decrease
Solution Approach 1:
All connection making, satellite pipe installation, and integrity testing are performed in advance onshore where facilities and expertise are readily available. This preliminary action transfers operational complexity from the marine environment to the onshore facility, simplifying on-site operations to merely deploying pre-tested complete assemblies, thereby improving operational efficiency.
Data Source
AI summary
A vessel (1) adapted to perform subsea wellbore related operations involving a riser string between the subsea wellbore and the vessel, e.g. drilling and/or wellbore intervention. The vessel (1) has a hull (2) and a riser storage (40) adapted to store therein of multiple risers in horizontal orientation. The riser storage (40) is adapted to store therein, or has stored therein, multiple pre-assembled riser stands (60), e.g. at least 25 riser stands, each riser stand being assembled from multiple riser sections (60, 61) connected end-to-end, e.g. each riser stand (62) consisting of two riser sections (60, 61), each riser section comprising a riser pipe and optionally one or more satellite pipes on the outside of and along the riser pipe, each riser section (60, 61) comprising a connector fitting arrangement at each end thereof, and each riser section (60, 61) comprising preferably one or more buoyancy members, wherein in a riser stand the connector fitting arrangement of one riser section is connected to a connector fitting arrangement of another riser section.