Subsea Overload Release System Using Collapsible Reservoir
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Solution Overview
Problem
Existing subsea connection systems lack a reliable and resettable overload release mechanism that can override tension overload conditions without requiring surface-based repairs, leading to potential damage or rupture of connections between offshore platforms and the seafloor.
Innovation Solution
A subsea overload release system utilizing a collet sleeve and overload piston mechanism, where an overload reservoir collapses to disengage members when tensile stress exceeds a predetermined value, allowing for in-situ reset and reconnection without surface intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed subsea connection system is used to maintain reliable connections between platform and seafloor, then connection strength is improved, but the system becomes vulnerable to overload damage and requires expensive surface repairs
Solution Approach 1:
The connection system is divided into a permanent subsea base portion and a removable overload relief portion. The overload relief portion includes a collet sleeve with fingers that can disengage from the base portion when overload occurs, allowing the damaged components to be replaced independently without recovering the entire connection system to the surface.
Solution Approach 2:
A collet mechanism acts as an intermediary between the permanent base portion and the platform-connected member. The collet sleeve with flexible fingers provides a releasable connection that can override under overload conditions, serving as a protective intermediary that sacrifices itself to protect the more critical permanent infrastructure.
2Ease of repair
If an overload release mechanism is added to allow in-situ release, then ease of repair is improved, but device complexity increases
Solution Approach 1:
The overload relief portion is designed to automatically disengage when overload occurs through the collet mechanism's inherent mechanical properties. The flexible fingers naturally override and release from the base portion grooves under excessive load without requiring external control systems, sensors, or active intervention, thereby limiting complexity while achieving self-protecting functionality.
Solution Approach 2:
The connection strength parameter is made variable through the collet mechanism. During normal operation, the fingers maintain a strong engaged connection. Under overload, the mechanical parameters change as the fingers override and release, transitioning the system from a high-strength state to a released state without requiring active control.
3Loss of time
If a reusable overload release system is implemented, then loss of time is reduced by avoiding surface repairs, but manufacturing precision requirements increase
Solution Approach 1:
The collet sleeve incorporates flexible fingers that can elastically deform during engagement and disengagement. This flexibility compensates for minor manufacturing tolerances and misalignments between the collet sleeve and base portion, allowing reliable operation without requiring extremely tight manufacturing precision while still enabling quick in-situ replacement.
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
Enables controlled release and reconnection of subsea elements during overload conditions, reducing the need for surface repairs and allowing for in-situ maintenance and reset of the system, thereby minimizing downtime and costs.
Implementation Method 1
an overload piston acting on fluid in an overload reservoir causes an overload pressure
Implementation Method 2
an overload pressure member adapted to allow fluid to exit the overload reservoir when the pressure of the fluid exceeds a pre-established value
Implementation Method 3
causing the overload reservoir to at least partially collapse. The collapse allows the system to extend and force open the fingers
Data Source
Figure 1
Figure 2
AI summary
The disclosure provides a subsea overload release system and method. The disclosure provides a releasable connection system that can be overridden during an overload condition, and is resettable in a subsea location in situ. During normal operation, a collet sleeve is slidably engageable with a collet having one or more fingers that can releasably couple a first member with a second member. During an overload condition, an overload piston acting on fluid in an overload reservoir causes an overload pressure and a rupture or other release of fluid through an overload pressure member, causing the overload reservoir to at least partially collapse. The collapse allows the system to extend and force open the fingers to disengage the second member from the first member. When the overload symptom is rectified, the overload reservoir can be reset and the overload pressure member reset or replaced without requiring repairs above sea surface.