Frangible Disk Isolation Tool Piston Activation
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Solution Overview
Problem
Existing downhole pressure isolation tools face challenges in reliably opening using limited differential hydrostatic pressure, especially in varying wellbore fluid pressures, and require accurate shear force activation which is often inaccurate with shear pins, particularly in horizontal or highly deviated wells.
Innovation Solution
The tool employs a piston assembly with a rupturable membrane and multiple fingers to apply a transverse force to a frangible disk, using a sudden increase in pressure to cause complete collapse, and allows for on-site selection of rupture membrane assemblies to match specific well conditions, eliminating the need for external activation tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shear pins are used for activation, then the device can be activated by hydrostatic pressure, but the shear force activation is often inaccurate particularly in horizontal or highly deviated wells
Solution Approach 1:
The patent replaces the mechanical shear pin system with a pressure-sensitive membrane system. The membrane is designed to rupture at a specific pressure threshold, providing more accurate and reliable activation compared to shear pins which rely on friction and mechanical strength that vary with well orientation. This substitution eliminates the dependency on gravitational forces and mechanical friction, achieving consistent activation pressure regardless of well deviation.
Solution Approach 2:
The patent changes the activation mechanism from mechanical shear strength to pressure-sensitive membrane rupture. By selecting membranes with specific rupture pressure ratings, the system can be precisely tuned to activate at desired pressure differentials. This parameter-based approach allows for accurate control of activation pressure by selecting appropriate membrane materials and thicknesses, rather than relying on mechanical assembly variations.
2Adaptability or versatility
If limited differential hydrostatic pressure is applied to open the isolation tool, then the tool can operate in varying wellbore fluid pressures, but the pressure may be insufficient to reliably cause complete collapse of the frangible disc
Solution Approach 1:
The patent segments the disk collapse process into multiple stages through the use of multiple fingers that sequentially puncture the disk. Instead of requiring one large force to collapse the entire disk at once, the system uses multiple smaller force applications through individual fingers. This segmentation allows the limited differential pressure to be effectively distributed and amplified, achieving reliable complete collapse even with restricted pressure differentials across varying wellbore conditions.
Solution Approach 2:
The patent introduces fingers as intermediary elements between the pressure source and the frangible disc. These fingers act as force concentrators that translate the limited differential hydrostatic pressure into focused puncture forces. The fingers amplify the available pressure by concentrating it onto small contact areas of the disk, enabling reliable penetration and collapse that would not be achievable with the differential pressure alone applied directly to the disk surface.
3Reliability
If multiple fingers are used to puncture holes in the frangible disc, then complete collapse can be achieved, but the device complexity increases
Solution Approach 1:
The patent designs the finger assembly to serve multiple functions simultaneously: the fingers act as force concentrators for puncturing the disk, as structural support elements, and as pressure distribution mechanisms. By making the fingers multi-functional, the system achieves reliable complete disk collapse without proportionally increasing overall device complexity. The same structural elements that provide mechanical support also perform the critical puncture function, eliminating the need for separate specialized components.
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 ensures reliable and accurate opening of the isolation tool across a range of pressures, reducing the risk of incomplete disk fracture and debris interference, and allows for precise adaptation to varying well conditions without the need for interventionist tools.
Implementation Method 1
a rupturable membrane in fluid communication with and the bore above the dome and the upper face of the piston, the membrane rupturable at a first hydrostatic pressure on the membrane
Implementation Method 2
flowing an upper zone fluid through the ruptured membrane to the upper face of the piston... causing the piston to move from its first position to the second position
Implementation Method 3
The piston includes piston walls. A rupturable membrane is provided, the rupturable membrane rupturing at a membrane rupture pressure. The piston is slideable between a first position and a second position with respect to the inner walls of the housing of the piston assembly
Data Source
AI summary
A downhole pressure isolation tool is disclosed for use in a tubing string or casing string. The tool includes a frangible disk or seal within a housing having a bore. The disk has a dome section and a cylinder section and the dome of the disk is transverse to the bore. A piston is located between the housing and the cylinder of the disk, the piston movable between a first position and a second position, the second position, engaging a set of fingers which push into the cylinder of the disc to break it, causing the entire disk the cause and the entire disk to fail. A rupturable membrane is provided which, when it ruptures places the piston in fluid communication with a fluid within the bore.