Offshore Tower Elevation System for Deck Acceleration Control
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Solution Overview
Problem
Existing offshore systems for subsea wellbore activities face safety hazards due to unintentionally large accelerations of the mobile working deck caused by sudden changes in load, which the heave compensation system cannot quickly counteract, leading to potential damage.
Innovation Solution
An offshore system with a separated elevation and heave compensation system, where an overload protection system detects undesirably large accelerations and controls the elevation system to counteract them, thereby limiting the acceleration of the mobile working deck and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heave compensation system is used to compensate heave motion of the mobile working deck, then the deck remains stable during normal operation, but the system cannot quickly counteract sudden load changes causing dangerously large accelerations
Solution Approach 1:
The system divides the single heave compensation function into two separate systems: a heave compensation system for normal wave motion compensation, and an elevation system for sudden load change protection. This segmentation allows each system to be optimized for its specific function without the limitations of a combined system.
Solution Approach 2:
The elevation system acts as an intermediary protective layer between the mobile working deck and sudden load changes. When a sudden load change is detected, the elevation system intervenes by moving the deck in the opposite direction to counteract the acceleration, giving the heave compensation system time to adjust.
2Reliability
If the heave compensation system tension is maintained to compensate waves, then the deck is stabilized during wave motion, but the tension cannot be lowered quickly enough when load suddenly changes
Solution Approach 1:
The elevation system is pre-positioned and ready to act before sudden load changes occur. When a load change is detected, the elevation system immediately activates to counteract the acceleration, providing a preliminary protective action while the heave compensation system adjusts its tension.
Solution Approach 2:
The system transitions from a static heave compensation tension to a dynamic response where the elevation system actively adjusts deck position in real-time based on detected acceleration, allowing rapid response to load changes while maintaining wave compensation.
3Reliability
If the mobile working deck is elevated to a higher position for heave compensation, then wave motion compensation is effective, but the deck becomes more vulnerable to sudden acceleration damage
Solution Approach 1:
The elevation system provides a protective cushioning mechanism that activates before damage can occur from sudden accelerations. By detecting load changes and counteracting accelerations immediately, the system cushions the deck against the full impact of sudden events like drill string release.
Data Source
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AI summary
The present invention relates to an offshore system comprising: • - a tower to be positioned on a floating body (3) and defining a substantially vertical firing line (9); • - a mobile working deck (15) which is moveable along the firing line within a motion range which is the sum of an elevation motion range and a heave compensation motion range; • - a heave compensation system to provide heave compensation of the mobile working deck within the heave compensation motion range; • - an elevation system to position the mobile working deck within the elevation motion range; and • - an overload protection system configured to detect an undesirably big acceleration of the mobile working deck, and - in the event of a detected acceleration - to control the elevation system such that the mobile working deck motion in the elevation motion range is opposite to the motion in the heave compensation motion range.