Resettable Collet Mechanism for Well Abandonment Tools
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Solution Overview
Problem
Current well abandonment and casing recovery techniques require multiple trips into the well, leading to inefficiencies and increased costs, as existing tools struggle to maintain circulation during cutting and require precise rotation to switch between cutting and testing modes, and are prone to accidental actuation on floating rigs.
Innovation Solution
A resettable mechanism with a high overpull tension-set packer and a casing cutting and removal assembly that includes an anchor, cutter, and retrievable packer, allowing for multiple circulation tests and safe operation on a single trip, using a collet and collet ring to prevent accidental actuation and maintain circulation paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inflatable packer is used to seal the annulus after cutting, then circulation can be tested, but the well remains open during cutting making it vulnerable to kicks and the packer cannot be set quickly
Solution Approach 1:
The mechanical packer is pre-positioned in the assembly before entering the well. The packer elements are held in a retracted state by a mechanical locking mechanism (collet and collet ring) until actuation signal is received, at which point the lock releases and the packer elements are immediately deployed to seal the annulus. This preliminary positioning enables rapid response to kicks during cutting operations.
2Reliability
If a drop ball mechanism is used to actuate the packer, then the packer can be set, but high velocity flow at the choke causes erosion and potential washout
Solution Approach 1:
The hydraulic drop ball actuation system is replaced with an electrical actuation system. An actuation signal transmitted through the drill string activates an actuator (such as a shape memory alloy element or electromagnetic actuator) that mechanically releases the collet lock, allowing the packer elements to deploy. This substitution eliminates the need for high-velocity fluid flow through the choke, preventing erosion and washout while maintaining reliable packer actuation.
3Ease of operation
If measured rotation of the string is required to switch the tool between modes, then cutting and testing can be performed, but such manipulation cannot reliably be achieved when a cut is made far from surface
Solution Approach 1:
The mechanical mode switching mechanism requiring measured rotation of the drill string is replaced with an electrical actuation system. Electrical signals transmitted through the drill string activate actuators that control the cutting mechanism and packer deployment independently of string rotation. This substitution enables reliable operation even when cuts are made far from the surface where string manipulation becomes difficult or impossible.
4Productivity
If the annulus is left open during cutting to allow circulation, then cuttings can return to surface, but the well is vulnerable to kicks and circulation cannot be forced through the cut
Solution Approach 1:
The system dynamically transitions between two states: during cutting, the annulus remains open for cuttings removal; immediately upon completion of cutting, the packer is actuated to seal the annulus and force circulation through the cut. This dynamic state change, controlled by the electrical actuation system, maintains both cuttings removal capability and well control without compromising either function.
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 and safe casing recovery with multiple circulation tests on a single trip, preventing accidental tool actuation and maintaining well control, even on floating rigs, by using a resettable mechanism and high overpull tension-set packer.
Implementation Method 1
The packer elements (240) are typically made from a material capable of radially expanding when it is axially compressed such as rubber or other elastomeric material.
Data Source
AI summary
A resettable mechanism for preventing the accidental actuation of a load set downhole tool and method of use. The resettable mechanism provides a collet (52) and a detent (56) with a collet ring arranged to ride over the detent under a load in excess of the operating load of the downhole tool and the collet load. Reversing the loading resets the mechanism and the downhole tool. A disengagement assembly (66) is described to disenable the detent (56) and operate the downhole tool at the operating load. Embodiments to a retrievable mechanical tension-set packer and a casing cutting and removal system are described which prevent premature actuation of the packer when run from floating structures.