Packer Shear Screw Isolation Mechanism for Premature Release Prevention
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Solution Overview
Problem
Straight pull release (SPR) mechanisms for packers are limited by the shear strength of shear screws, leading to potential premature release under high pressure differentials, which restricts the tensile and pressure ratings of the packers.
Innovation Solution
A protective mechanism is introduced to isolate shear screws from tensile forces, which can be selectively unlocked to allow shearing when necessary, ensuring the screws are only exposed to shearing forces when the pressure differential exceeds a threshold, thereby preventing premature release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If shear screws are directly loaded by tensile forces and pressure-induced hydrostatic forces, then the SPR mechanism can be realized without additional equipment, but the tensile rating and pressure rating are limited by the shear strength of the screws
Solution Approach 1:
The patent divides the load-bearing function into two separate components: shear screws for lateral positioning and a protective mechanism (holding collar with locking lugs) for axial tensile load bearing. This segmentation allows each component to be optimized for its specific function, enabling the packer to achieve higher tensile and pressure ratings without increasing SPR mechanism complexity
Solution Approach 2:
The holding collar acts as an intermediary component between the upper and lower cone assemblies, intercepting tensile forces before they reach the shear screws. The locking lugs on the holding collar engage with corresponding features to create a load path that bypasses the shear screws during retrieval operations, protecting them from premature shearing while maintaining the simple SPR mechanism design
2Reliability
If shear screws are protected from tensile forces, then premature release is prevented, but the mechanism requires an additional protective structure
Solution Approach 1:
The protective mechanism is merged with the existing cone assembly structure. The holding collar is integrated into the lower cone assembly, and the locking lugs are formed as part of the cone finger structure. This merging approach provides reliable protection against premature release while minimizing additional structural complexity, as the protective features are incorporated into components that already exist in the packer design
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
This solution allows SPR packers to operate at higher pressure and tensile ratings without compromising their setting or retrieval capabilities, by protecting the shear screws from undesired shearing until it is safe to release them, thus enhancing the packer's performance in applications like gravel packing and frac-packing.
Implementation Method 1
the tensile rating and pressure rating of the SPR packers are frequently limited by the shear strength of these screws
Implementation Method 2
means for isolating the shear screw from tensile force and wherein the means for isolating is selectively unlockable to expose the shear screw to the force
Data Source
AI summary
Disclosed herein are methods and apparatus for releasing a releasable packer. The apparatus may include shear screws, a mechanism for isolating the shear screw from a shearing force. The mechanism for isolating the shear screw from a shearing force is selectively unlockable to expose the shear screw to the shearing force. The methods may include unlocking a mechanism protecting at least one shear screw, applying a shearing force to the at least one shear screw, and shearing the at least one shear screw.