Internal Caisson Leg Cutter for Offshore Platform Removal
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Solution Overview
Problem
Existing methods for removing offshore marine platform jacket legs below the mud line are inefficient and hazardous, requiring trench digging and maintaining stability, which can lead to trench collapse and equipment damage.
Innovation Solution
An internal caisson/jacket leg cutter apparatus with rotary cutters supported by a frame that engages the interior wall of the caisson/jacket leg, allowing for a 360-degree cut without the need for trench digging, using extendable/retractable arms and a cutting mechanism with milling devices that travel along an arc-shaped path, monitored by resistance feedback for stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trench digging is used to remove jacket legs below mud line, then complete removal is achieved, but operation complexity and safety risks increase
Solution Approach 1:
Instead of approaching the jacket leg from the outside by digging a trench, the invention inverts the approach by inserting a cutting apparatus from the interior of the jacket leg. The apparatus is lowered through a pre-made opening at the top of the jacket leg and performs cutting operations from within, eliminating the need for trench excavation and associated safety risks.
Solution Approach 2:
The cutting apparatus is designed to be inserted into and operate within the hollow interior space of the jacket leg. The apparatus includes nested components such as the cutting head positioned within the stabilizing arm assembly, which itself is contained within the jacket leg's internal volume, allowing compact deployment and retrieval.
2Productivity
If trench digging is performed, then jacket leg removal is possible, but time and resource consumption increase
Solution Approach 1:
A small access opening is created at the top of the jacket leg before inserting the cutting apparatus. This preliminary action enables the apparatus to be lowered into position without requiring extensive trench excavation, significantly reducing the time and resources needed for the overall removal operation.
Solution Approach 2:
The cutting apparatus extracts only the essential access opening needed to insert the tool, rather than removing large volumes of soil through trench digging. This minimal extraction approach maintains productivity while reducing time loss compared to traditional trenching methods.
3Reliability
If trench stability is maintained during cutting, then safety is improved, but operational complexity increases
Solution Approach 1:
The invention eliminates the trench stability problem entirely by inverting the approach: instead of cutting from outside a trench, the cutting apparatus operates from inside the jacket leg through a small opening. This removes the need for trench support structures and stability monitoring, greatly simplifying the operation while maintaining safety.
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 solution enables safe and efficient removal of caisson/jacket legs by maintaining stability and control during cutting, reducing the risk of accidents and equipment damage, while allowing for precise cutting of tubular members embedded in the seabed.
Implementation Method 1
cutting mechanism employing one or more milling devices that are rotary cutters. These rotary cutters cut the caisson/jacket leg wall as the cutter travels along horizontal plane perpendicular to the central axis of the cutter.
Data Source
AI summary
An internal caisson/jacket leg cutter and method provides a frame having upper and lower end portions. The upper end portion has rigging that enables the frame to be lifted. Extensible arms are movably supported upon the frame. The arms extend and retract along generally radially extending lines. Extension of the arms enables them to contact the inside surface of a caisson/jacket leg and thus center and anchor the frame within the caisson/jacket leg interior. A cutting mechanism at the lower end portion of the frame includes one or more rotary cutters or milling devices that cut the caisson/jacket leg wall as these cutters traverse an arc shaped path, tracking the caisson/jacket leg wall.