Pressure Activated Perforating Switch Support
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Solution Overview
Problem
Existing downhole perforating systems face challenges in reliably transmitting electrical signals for detonating shaped charges due to the need for reliable electrical connections that can withstand pressure and maintain insulation from tool components in contact with the casing.
Innovation Solution
A pressure-activated switch assembly is used in a gun string, where each detonator is connected to a pressure switch that closes only upon receipt of explosive energy from a previous detonation, allowing sequential firing of shaped charges and ensuring reliable electrical signal transmission through a feed-thru puck assembly and bushing mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical connections are made to transmit detonation signals through the tool string, then shaped charges can be detonated, but the electrical connections must maintain insulation from tool components in contact with the casing while withstanding pressure
Solution Approach 1:
The tool string is divided into discrete modules (tandem subs, guns, switches) with isolated electrical connection points. Each detonator has its own isolated electrical connection, allowing independent firing control while maintaining insulation integrity throughout the tool string assembly.
Solution Approach 2:
A feed-thru puck assembly acts as an intermediary component between the electrical signal source and the detonators. This mediator provides a sealed, pressure-resistant electrical connection point that isolates the electrical circuit from the external tool string casing and downhole environment.
2Adaptability or versatility
If a pressure switch is used to close only upon receipt of explosive energy, then selective sequential firing is enabled, but the switch mechanism must reliably distinguish between legitimate detonation signals and other pressure events
Solution Approach 1:
The pressure switch is pre-configured with a piston and spring mechanism that is initially in the open position. The piston is designed to move to the closed position only when subjected to the specific pressure profile and magnitude of a legitimate detonation wave, preventing premature or false activation.
Solution Approach 2:
The pressure switch piston has a specific surface area and spring constant calibrated to respond only to the localized high-pressure impulse of a detonation. This local quality differentiation ensures the switch responds selectively to genuine explosive events rather than general pressure changes in the wellbore.
3Productivity
If multiple shaped charges are fired sequentially through a gun string, then selective perforation is achieved, but the system must confirm detonation to surface and maintain electrical signal integrity through multiple components
Solution Approach 1:
The pressure switch serves a dual function: it controls the electrical circuit closure for detonator activation and simultaneously provides feedback confirmation to the surface system. When the piston closes the switch, it completes the electrical circuit and sends a confirmation signal back up the tool string, verifying successful detonator activation.
Solution Approach 2:
The electrical connection components (feed-thru puck, bushing, electrical connector) are merged into a single integrated assembly that maintains signal integrity throughout the tool string. This consolidated design reduces connection points and potential failure modes while ensuring reliable electrical signal transmission from surface to each detonator.
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 enables reliable and selective detonation of shaped charges in a downhole environment by ensuring that each perforating gun is armed and signals surface confirmation of detonation, improving the efficiency and reliability of the perforating process.
Implementation Method 1
A pressure switch is positioned at a second end of the firing pin. The pressure switch includes a piston that is movable in response to pressure
Implementation Method 2
The bushing may frictionally engage with the firing piston to constrain movement of the firing piston
Data Source
Figure 1
Figure 2
Figure 3~4b
AI summary
A method, system, and apparatus for restraining a firing pin using a bushing for use in a downhole switch that is armed using the explosive energy of a previously detonated shaped charge.