Multi-position Mechanical Spear for Tension Cuts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current tubular cutting tools face challenges in making multiple cuts in a single trip while providing well control and maintaining circulation during cutting, often resulting in the tubular being cut in compression, which impedes the cutting process and lacks effective well control in case of a kick.
Innovation Solution
A cut-and-pull spear mechanism that mechanically sets slips to grip the tubular under tension, with an annular seal for well control and an internal bypass for circulation, allowing for multiple cuts and emergency release features to reset the tool for subsequent cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the tubular is left open for circulation during cutting, then fluid circulation is maintained, but well control capability is lost in case of a kick
Solution Approach 1:
The spear is pre-positioned inside the tubular before cutting begins, ready to seal the bore immediately if needed. The seal element is prepared in advance within the spear structure, so that well control can be activated instantly without delaying the cutting operation or requiring additional steps.
Solution Approach 2:
The spear acts as an intermediary device between the open tubular bore and the cutting operation. It provides a sealed environment within its structure that allows circulation to continue through designated pathways while maintaining the capability to isolate the wellbore if a kick occurs.
2Stability of the object's composition
If the tubular is cut in compression, then the structure remains stable, but the cutting process is impeded and blade rotation becomes more difficult
Solution Approach 1:
The spear applies a tensile force counteracting the compressive weight of the tubular column. By gripping the tubular interior and pulling upward, the spear creates tension that offsets the downward compressive force, putting the tubular in a state of reduced compression or light tension during the cutting operation, thereby facilitating blade rotation.
3Device complexity
If a single cut location is used with stop ring, then the tool can be set simply, but multiple cuts require tripping out and reconfiguring the tool
Solution Approach 1:
The spear is designed with a resettable locking mechanism that allows it to be set, released, and re-set at different locations. The drag blocks and locking dogs provide dynamic positioning capability, enabling the tool to be repositioned and re-engaged multiple times during a single trip, transforming a static single-cut tool into a dynamic multi-cut system.
Solution Approach 2:
Instead of discarding the tool after one cut, the spear is designed to be recovered and repositioned. The resettable locking feature allows the spear to be released from its set position, moved to a new location, and re-engaged, enabling multiple cuts to be made with the same tool assembly during one trip.
4Reliability
If the spear is set to grip the tubular, then well control is provided, but the tool cannot be repositioned for another cut
Solution Approach 1:
The locking mechanism featuring locking dogs and drag blocks is designed to be both secure when set and releasable when needed. The dogs engage with the drag blocks to provide firm gripping for well control, but can be disengaged by applying sufficient force in the opposite direction, allowing the spear to be repositioned for additional cuts or removed from the wellbore.
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 multiple cuts in a single trip with well control and circulation, preventing debris from entering the bypass and allowing for easy reset and repositioning of the tool, enhancing operational efficiency and safety.
Implementation Method 1
A cut-and-pull spear mechanism that mechanically sets slips to grip the tubular under tension
Implementation Method 2
with an annular seal for well control
Implementation Method 3
with an internal bypass for circulation
Implementation Method 4
The lock can be defeated with an axial force that retracts a spring-loaded dog
Data Source
AI summary
A cut-and-pull spear is configured to obtain multiple grips in a tubular to be cut in tension. A lock feature holds the set position of the slips and seal. The lock can be defeated with an axial force that retracts a spring-loaded dog, and the lock can be reset to the run-in position, with the slips and seal retracted, so that the assembly can be repositioned in the same trip for another cut. A cam surface prevents setting the slips and seal until the spear is relocated to the next desired cut location or removed from the wellbore. The lock can be defeated with picking up or with a pressuring up on a dropped ball for an emergency release. A surface signal of the release is provided by a stack of disc springs that have to be compressed to release the lock.