Sneak Path Eliminator for Diode Multiplexed Downhole Control
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Solution Overview
Problem
Existing systems for remotely actuating downhole well tools require a large number of wires and complex electronics, which are unreliable and prone to issues like improper actuation and current draw, especially when extending through hostile environments like high temperatures and pressures.
Innovation Solution
A system that uses a small number of conductors to selectively actuate multiple downhole well tools by controlling current flow direction, eliminating the need for complex electronics and reducing the number of lines required, with under-voltage lockout devices preventing current flow through unintended control devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of wires and complex electronics are used to remotely actuate multiple downhole well tools, then the ability to selectively control each tool is improved, but the reliability deteriorates due to hostile environments like high temperatures and pressures
Solution Approach 1:
The patent extracts the electronic control components from the downhole environment and relocates them to the surface. The system uses purely passive downhole components (control devices, diodes, lockout devices) that can withstand hostile environments, while all active electronics remain on surface where conditions are controlled. This resolves the reliability issue by removing vulnerable electronics from the harsh downhole environment.
Solution Approach 2:
The patent replaces complex electronic control systems with a passive electrical switching mechanism using diodes and lockout devices. Instead of relying on downhole electronics to process signals, the system uses the directional conductivity of diodes and voltage-dependent switching of lockout devices to selectively actuate tools. This mechanical/electrical substitution eliminates the need for unreliable downhole electronics while maintaining selective control capability.
2Adaptability or versatility
If many lines are extended and sealed through bulkheads, packers, hangers, wellheads, etc., then the ability to transmit control signals to multiple tools is improved, but the device complexity increases
Solution Approach 1:
The patent makes the conductors universal by having each conductor serve multiple functions: it is part of the control circuit for multiple different tools and can be used in combination with different other conductors to control different tools. This multi-functionality reduces the total number of conductors needed compared to dedicated one-to-one wiring, thereby reducing installation and sealing complexity.
Solution Approach 2:
The patent merges multiple control functions into a single conductor by using it in series with different lockout devices for multiple tools. Instead of requiring separate dedicated wires for each tool, the same conductor is shared across multiple control circuits, with selection achieved through the diode/lockout device configuration. This combining approach significantly reduces the number of lines required.
3Ease of operation
If voltage is applied across conductors to select a control device, then the ability to actuate a specific well tool is improved, but current may flow through unintended control devices causing unnecessary current draw
Solution Approach 1:
The patent applies preliminary anti-action by using diodes to prevent current from flowing in unintended directions before the problem occurs. The diodes are positioned to block current flow paths that would otherwise allow sneak paths through unintended control devices. This preventive blocking ensures that current only flows through the intended control device when voltage is applied, eliminating unnecessary current draw and energy loss.
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 approach allows for precise and reliable actuation of multiple well tools with fewer lines and no unnecessary current draw, improving control and reducing the risk of device failure in harsh downhole environments.
Implementation Method 1
The control device 50 may include a solenoid 58 and a diode 62. The diode 62 may be connected in series with the solenoid 58 between the two conductors 52a, b
Implementation Method 2
There may be provided at least one under-voltage lockout device 72 for each of the control devices 50, whereby the under-voltage lockout devices 72 prevent current from flowing through the respective control devices 50 if the voltage potential across the respective predetermined pair of conductors 52 is less than a predetermined minimum
Data Source
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AI summary
Sneak path elimination in diode multiplexed control of downhole well tools. A system for selectively actuating multiple well tools includes a control device for each tool, a well tool being operable by selecting a respective control device; conductors connected to the control devices, which are selectable by applying a predetermined voltage across a respective predetermined pair of the conductors; and at least one lockout device for each control device, the lockout devices preventing current from flowing through the respective control devices when voltage across the respective predetermined pair of the conductors is less than a predetermined minimum. A method includes selecting a well tools for actuation by applying a predetermined minimum voltage to a set of conductors; and preventing actuation of another well tool when the predetermined minimum voltage is not applied across another set of conductors, at least one conductor being common to the two sets of conductors.