Buoyant System Reduces Riser Stress
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Solution Overview
Problem
Current methods for disconnecting and reconnecting risers from floating offshore platforms are expensive, complex, and prone to stress due to repetitive bending, especially in hostile environments, and existing solutions do not adequately address the need for a cost-effective and reliable system.
Innovation Solution
A buoyant system that allows rigid or flexible risers to be coupled and decoupled from a subsea buoyant extension, reducing the need for spool pieces, arch supports, and flexible joints, enabling risers to slide through a guide tube between elevations on the platform and the seabed, thereby minimizing bending stress and facilitating platform movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible risers are used to accommodate flex, then the risers can handle movement, but they are more expensive and less reliable long-term than rigid pipe segments
Solution Approach 1:
The system divides the riser support function into separate components: rigid riser segments and a dedicated guide tube assembly. The guide tube is segmented into multiple sections that can move independently, allowing the rigid riser to maintain its structural integrity while the guide tube accommodates the flex and movement.
Solution Approach 2:
The guide tube acts as an intermediary between the rigid riser and the floating platform. It absorbs the movement and flex that would otherwise be transmitted to the rigid riser, allowing the riser to remain rigid while still accommodating platform motion through the guide tube's independent movement.
2Reliability
If rigid pipe segments are used, then reliability improves, but they cannot accommodate flex and movement
Solution Approach 1:
The guide tube is divided into multiple rigid segments that can move independently relative to each other. This segmentation allows the guide tube assembly to accommodate flex and movement while maintaining the rigidity of individual pipe segments, combining the reliability of rigid construction with the adaptability needed for movement.
Solution Approach 2:
The guide tube assembly is designed with dynamic capabilities, allowing it to move independently from the floating platform and riser. This dynamic movement accommodates platform flex and wave motion while the rigid pipe segments maintain their structural integrity and reliability.
3Object-affected harmful factors
If the floating platform is disconnected and moved to avoid icebergs or hurricanes, then damage is avoided, but the time to disconnect and reconnect is lengthy and expensive
Solution Approach 1:
The guide tube assembly is pre-configured with buoyancy modules and connection mechanisms that are ready for rapid deployment. When platform movement is needed to avoid hazards, the buoyancy modules can be quickly activated to provide immediate lift, and the connection mechanisms are designed for rapid attachment and detachment, significantly reducing the time required for disconnection and reconnection operations.
Solution Approach 2:
The system incorporates dynamic buoyancy control through buoyancy modules that can be rapidly deployed or adjusted. This allows the platform to quickly change its position or disconnect from the riser when hazardous conditions are anticipated, reducing the time window needed for safe disconnection and reconnection operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The buoyant system reduces riser stress, lowers costs, simplifies connections, and enhances reliability by allowing rigid risers to be used without the need for expensive flexible joints, while enabling efficient repositioning of the floating platform.
Implementation Method 1
a buoyant extension having a buoyancy and configured to be detachably coupled with the offshore floating platform
Data Source
AI summary
The present invention provides a buoyant system and method for a hydrocarbon offshore floating platform to be coupled and decoupled from a subsea buoyant extension with risers slidably coupled thereto. The buoyant system can allow rigid risers to be coupled and decoupled and alternatively move between a first elevation below the offshore floating platform, such as at the buoyant extension, and a higher second elevation at the offshore floating platform independent of a spool piece, arch support, and flexible joint for the risers. The buoyant system can reduce riser stress by reducing bending required for the riser to form a catenary or other curved shape even as a rigid riser.