Pressure Balanced Floating Piston for Mechanical Lock
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Solution Overview
Problem
Shear pins in subterranean tools often break prematurely or at inappropriate times due to pressure differentials, leading to unwanted tool activation and costly repositioning, as they are sensitive to variations in tubing or annulus pressure and can jam between moving parts.
Innovation Solution
The use of captive collets held by a pressure-balanced piston, where ports are isolated to build pressure and move the piston downhole to release the collet, allowing relative movement and tool actuation, eliminating the need for shear pins and ensuring pressure balance across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shear pins are used to hold components in position, then the components can be securely retained until actuation, but the shear pins may break prematurely or at inappropriate times due to pressure differentials and impacts
Solution Approach 1:
The patent removes the shear pin component entirely from the system and replaces it with a pressure-balanced piston mechanism. This extraction eliminates the harmful factor of shear pin sensitivity to pressure differentials and impacts, while maintaining the function of securing components until actuation through the piston-collet assembly
Solution Approach 2:
The pressure-balanced piston serves as an intermediary mechanism between the pressure environment and the collet retention system. The piston with its balanced ports isolates the retention mechanism from direct pressure effects, mediating the transition from pressure-sensitive shear pins to pressure-insensitive collet retention
2Stability of the object's composition
If shear pins are used to secure parts, then the parts remain fixed in position, but the shear pins can jam between moving parts when they break
Solution Approach 1:
By removing the shear pin and replacing it with a collet held by a pressure-balanced piston, the patent eliminates the source of jamming remnants. The collet mechanism provides secure retention without the risk of broken pin fragments interfering with moving parts
Solution Approach 2:
The invention transitions from a static shear pin retention system to a dynamic piston-controlled collet system. The collet can be actively released by piston movement, allowing controlled part separation without the unpredictable behavior of broken shear pins
3Reliability
If pressure-balanced piston with isolated ports is used to release collet, then controlled tool actuation is achieved, but the device complexity increases
Solution Approach 1:
The pressure-balanced piston serves multiple functions: it maintains pressure balance during normal operation, enables controlled collet release when ports are isolated, and can drive the actuating sleeve. This multi-functionality justifies the added complexity by consolidating several functions into a single component
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 prevents premature tool activation and reduces the risk of collet jamming, ensuring reliable and cost-effective operation by maintaining pressure balance and controlled release mechanisms, thereby avoiding the need for costly repositioning.
Implementation Method 1
The piston is exposed to tubing pressure on opposed ends to be in pressure balance despite variations of pressure in the tubing
Implementation Method 2
one of the ports to the piston is isolated from the other and pressure drives the piston in a downhole direction to release the collet
Data Source
AI summary
Parts that need to be retained against relative movement are held with at least one collet that is captured in a groove with sleeve that acts as a piston. The piston is exposed to tubing pressure on opposed ends to be in pressure balance despite variations of pressure in the tubing. When it is desired to allow relative part movement to actuate the tool, one of the ports to the piston is isolated from the other and pressure drives the piston in a downhole direction. This releases the collet and drives a sleeve in an opposite direction to actuate a tool. The parts can be optionally rotationally locked.