Subsea Wellhead Locking Mechanism for Deepwater Drilling
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Solution Overview
Problem
The existing continuous drilling method using a wellhead running tool is limited to shallow depths due to difficulties in rotation control at greater depths, where the drill string rotation and seabed rotation do not match, leading to issues with torque application and the risk of underwater camera cables being caught.
Innovation Solution
A continuous drilling system that allows the subsea wellhead and tool body to be attached and detached using hydraulic pressure without rotating the drill string, employing a locking mechanism with protrusions and plugs to secure and release the wellhead, preventing cable entanglement even with underwater cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the drill string is rotated to separate the shaft portion and main body of the wellhead running tool, then the separation can be achieved, but the underwater camera cable wraps around the drill pipe and becomes entangled
Solution Approach 1:
The patent replaces the mechanical rotation-based separation system with a hydraulic pressure-based separation system. Instead of rotating the drill string to separate components, hydraulic pressure is applied through flow paths to move the separation piston, which in turn separates the shaft portion from the main body. This substitution eliminates the need for drill string rotation during separation, preventing cable entanglement while achieving the same separation function.
Solution Approach 2:
The patent employs hydraulic pressure to drive the separation mechanism. Fluid is supplied through flow paths to the separation piston, utilizing hydraulic force to move the piston and achieve separation of the wellhead running tool components. This hydraulic approach replaces the mechanical rotation method and allows separation without rotating the drill string, thereby preventing underwater camera cable entanglement.
2Length of stationary object
If the drill string length is increased to reach deep seabed, then the drilling depth is extended, but the rotation control becomes very difficult due to mismatched rotation numbers
Solution Approach 1:
The patent replaces the rotation-based separation mechanism with a hydraulic pressure-based mechanism. By using hydraulic pressure to drive the separation piston instead of rotating the drill string, the system eliminates the rotation control problem entirely. This allows the use of long drill strings for deep seabed drilling without the complexity of matching rotation numbers between the ship/floating rig and the seabed release point.
3Ease of operation
If the wellhead running tool is separated from the subsea wellhead by rotation, then the separation can be achieved, but this method is not suitable for deep water of 3,000 m or more
Solution Approach 1:
The patent replaces the rotation-based separation system with a hydraulic pressure-based separation system. By using hydraulic pressure to drive the separation piston, the system achieves separation without rotating the drill string. This makes the system adaptable to deep water conditions (3,000 m or more) where rotation control is difficult, thereby improving depth adaptability while maintaining ease of separation operation.
Solution Approach 2:
The patent changes the operating parameter from mechanical rotation to hydraulic pressure. Instead of using rotational motion to separate components, the system uses hydraulic pressure as the driving parameter. This parameter change enables the separation mechanism to function effectively at great depths where rotation control is problematic, thereby improving adaptability to deep water environments.
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 efficient drilling at deep water depths without the need for rotation control, preventing cable entanglement and improving work efficiency by allowing secure attachment and detachment of the wellhead without rotating the drill string.
Implementation Method 1
when a fluid has flowed into the insertion hole, the locking protrusion protrudes and is locked to the inner surface of the subsea wellhead and the projection protrudes and is locked to the tool stem
Data Source
AI summary
A lock plug (7A) is inserted into a plug installation position of an insertion hole (5a) of a tool stem (5) connected to a drill string (10), and when a fluid has flowed to the insertion hole (5a), a stopper (62) protrudes radially outward from a tool body (6) and is locked to a subsea wellhead (4) and an internal stopper (66) protrudes radially inward from the tool body (6) and is locked to the tool stem (5) in a lock state. An unlock plug is inserted into the plug installation position of the insertion hole (5a), and when the fluid has flowed into the insertion hole (5a), the stopper (62) is separated from the subsea wellhead (4) and the internal stopper (66) is separated from the tool stem (5) to release the lock state.