Electronic Time Delay Apparatus for Downhole Tools
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Solution Overview
Problem
Existing downhole wellbore tools lack a reliable and efficient mechanism for introducing a predetermined time delay between triggering events, such as opening a valve or firing a perforating gun, which is essential for testing and preventing hang fire conditions in oil and gas extraction operations.
Innovation Solution
A low-power electronic circuit with a timer and a fusible link is used to create a predetermined time delay, where the circuit automatically initiates the degradation of the fusible link after the timer expires, releasing a spool valve to open a valve or activate a downhole tool, allowing for controlled and delayed activation of downhole tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fluid restriction with microscopic passages is used as a time delay mechanism, then time delay is achieved, but the system complexity increases
Solution Approach 1:
The patent replaces the complex mechanical fluid restriction system with a simpler electronic timer circuit. The electronic timer uses standard electronic components (microcontroller, crystal oscillator, capacitors, resistors) to generate precise time delays without requiring complex microscopic fluid passages, thereby reducing mechanical complexity while maintaining time delay functionality.
Solution Approach 2:
The patent uses pneumatic pressure as the triggering mechanism for the electronic timer. Pressure-sensitive switches detect pressure changes in the wellbore environment and activate the electronic timer circuit, allowing the system to respond to downhole conditions while using simpler electronic timing rather than complex fluid restriction mechanisms.
2Adaptability or versatility
If pressure-activated percussion initiation is used to detonate, then electrical conductors are not required, but the ability to implement controlled time delays is reduced
Solution Approach 1:
The patent introduces an electronic timer circuit as an intermediary between the pressure-activated percussion initiation system and the final detonation event. The timer receives pressure activation signals and uses them to trigger the percussion initiation mechanism after a predetermined time delay, thus maintaining the benefits of electrical-conductor-free activation while restoring precise time delay control capability.
Solution Approach 2:
The system performs preliminary pressure sensing and timer activation before the actual detonation event. When pressure reaches a threshold, the pressure-sensitive switch activates the timer in advance, which then triggers the percussion initiation mechanism after the calculated time delay, allowing controlled sequencing of events without requiring continuous electrical conductors.
3Productivity
If multiple downhole tools are activated in sequence, then operational efficiency improves, but the complexity of coordination increases
Solution Approach 1:
The patent divides the coordination of multiple downhole tools into independent, modular timer circuits. Each tool or tool group has its own timer module that can be independently programmed with specific delay intervals. This segmentation allows multiple tools to be activated in sequence without requiring a single complex centralized control system, reducing overall coordination complexity while maintaining operational efficiency.
Solution Approach 2:
The electronic timer system uses periodic timing cycles to activate multiple downhole tools in a predetermined sequence. Each timer is programmed with specific time intervals that create a periodic activation pattern, allowing tools to fire in controlled succession (e.g., perforating guns at different depths, valve openings at different stages) without requiring complex real-time coordination between them.
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 provides a reliable, cost-effective, and repeatable time delay mechanism that is independent of wellbore conditions, enabling predictable activation of downhole tools, including perforating guns, and allows for the activation of multiple tools within specified intervals, ensuring efficient well operations.
Implementation Method 1
the fusible link is configured to burn (degrade) for a predetermined time interval
Data Source
AI summary
A time delay apparatus for use with a downhole tool in a wellbore casing. In an exemplary embodiment, the apparatus includes an electronic circuit comprising a timer, a fusible link, a split spool device that includes a center pin held in place in a restrained position with a spool and a spring element surrounding the spool, A pressure applied to a trigger device, such as a rupture disk, activates a pressure switch and starts a timer, configured with a preset countdown time, in the electronic circuit. On expiration of the timer, the timer block of the electronic circuit generates a signal to cause breaking of the fusible link and releasing of the spring element such that the center pin of the split spool travels to a functional position and activates the downhole tool.