Drill Pipe Coupling Apparatus for Controllable Weak Link
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Solution Overview
Problem
Existing coupling systems for drill pipes in offshore operations face challenges such as high tension issues due to heave compensator failures or vessel drifting, leading to potential drill pipe breakage or damage to critical equipment, and existing weak links or disconnecting systems are complex, unreliable, or difficult to retrieve.
Innovation Solution
A coupling apparatus with flanges and bolts that resist rotation and axial movement, allowing the breaking load to be determined by the tensile capacity of the bolts, and a selectively releasable carrier sleeve to adjust the axial-load-carrying capacity, enabling a controllable weak connection to manage bending moments and tensile forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a weak link is provided in the drill pipe to prevent fatal damage, then the risk of catastrophic failure is reduced, but the tensile capacity is limited and retrieval becomes difficult
Solution Approach 1:
The drill string is segmented into an upper part and a lower part by the coupling apparatus, which acts as a discrete weak link component. This segmentation allows the weak link function to be isolated to a specific location while maintaining the integrity of the rest of the drill string, and enables easier retrieval of the lower part after failure.
Solution Approach 2:
The coupling apparatus serves as an intermediary element between the upper and lower drill pipe sections. It provides the weak link functionality through its controlled breaking mechanism while facilitating easier retrieval operations compared to traditional weak links that are integrated into the pipe structure itself.
2Reliability
If traditional disconnecting systems are used to prevent drill pipe breakage, then safety is improved, but the system complexity increases and technical reliability decreases
Solution Approach 1:
The weak link functionality is extracted from complex disconnecting systems and implemented through a simple coupling apparatus with controlled breaking mechanism. This extraction eliminates the need for complex control systems, sensors, and actuation mechanisms while maintaining the safety function.
Solution Approach 2:
The coupling apparatus is designed as a simple, replaceable component with a controlled breaking mechanism. Rather than using complex, expensive disconnecting systems, the invention employs a simpler structure that can be easily replaced after activation, reducing overall system complexity and cost.
3Strength
If the drill pipe is designed with high tensile capacity throughout, then the risk of breakage is reduced, but the ability to create a controlled weak link is lost
Solution Approach 1:
The coupling apparatus introduces a localized variation in tensile capacity within the otherwise high-strength drill string. The controlled breaking mechanism creates a specific weak point with reduced tensile capacity at the coupling location, while the rest of the drill pipe maintains its full strength. This local quality change enables controlled weak link functionality without compromising the overall strength of the drill string.
Data Source
AI summary
A coupling apparatus and a method are for connecting two drill-pipe sections in a string of drill-pipe sections joined together by tool joints. The coupling apparatus comprises: a first pipe with a first end portion and a second end portion, the first end portion being provided with a tool joint for connection to a drill-pipe section; a second pipe with a first end portion and a second end portion, the first end portion being provided with a tool joint for connection to a drill-pipe section.