Wireline Release Tool Current Limiting for Safe Ohmic Testing

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Solution Overview

Problem

Existing wireline release tools (WRTs) do not support ohmic testing for switches and detonators located behind an open pass-through switch, which is essential for ensuring the safety and effectiveness of downhole perforating operations.

Innovation Solution

Incorporating a current limiter device with depletion mode transistors and a resistor between the electrical input and output of the WRT, allowing a test current to pass while preventing larger currents from activating the pass-through switch, enabling safe ohmic testing without detonating the detonators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pass-through switch is kept open to prevent accidental detonation, then safety is improved, but ohmic testing capability is lost

Engineering Contradiction:

ImprovesafetyVSAvoidohmic testing capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

A current limiter device is introduced as an intermediary component between the electrical input/output and the pass-through switch. This device allows controlled leakage current to pass through the open switch for testing purposes while preventing sufficient current from reaching the detonators to cause accidental detonation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the electrical parameters by introducing a current limiter that allows small test currents to pass while blocking larger detonation currents. This parameter-based control enables the system to support ohmic testing without compromising safety by changing the current magnitude threshold.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the pass-through switch is closed to enable electrical communication, then ohmic testing is enabled, but the risk of accidental detonation increases

Engineering Contradiction:

Improveohmic testing capabilityVSAvoidaccidental detonation risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The current limiter acts as a protective intermediary that sits between the electrical input and the pass-through switch, allowing testing current to reach the switch while limiting the maximum current that can flow to safe levels regardless of switch state.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The current limiter is positioned upstream to preemptively limit current before it can reach dangerous levels. This preliminary anti-action prevents the harmful effect (accidental detonation) from occurring in the first place by ensuring current never exceeds safe thresholds.

Inventive Principle:

Principle #9Preliminary anti-action

3Device complexity

If a traditional switch configuration is used, then simple electrical control is achieved, but testing behind the switch is prevented

Engineering Contradiction:

Improveelectrical control simplicityVSAvoidtesting capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent merges the functions of the pass-through switch and the current limiter into a single integrated assembly. The switch maintains its simple control function while the current limiter is added in parallel to provide testing capability, combining both functions in one device.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The modified WRT assembly becomes multi-functional, supporting both traditional electrical control through the pass-through switch and ohmic testing through the current limiter pathway. This universal design allows the same device to perform multiple functions without requiring separate systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables safe and effective ohmic testing of downhole tools by allowing a small test current to pass through the current limiter device while preventing accidental detonation, ensuring the integrity and readiness of the gun string assembly.

Implementation Method 1

The circuit includes a first depletion mode transistor and a second depletion mode transistor

Methodology Applied

Scientific EffectDepletion mode transistor operation:

Implementation Method 2

a pass-through switch located inside the housing and electrically connected between the electrical input and the electrical output

Methodology Applied

Scientific EffectElectrical switching:

Implementation Method 3

a resistor connected between the source and the drain of the second transistor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS12038264B2Current feed-through wireline release tool and method

Publication Date: 2024.07.16 GEODYNAMICS INC

AI summary

A wireline release tool for downhole intervention, the tool including a housing having an electrical input and an electrical output; a pass-through switch located inside the housing and electrically connected between the electrical input and the electrical output; and a current limiter device located inside the housing and electrically connected between the electrical input and the electrical output. The pass-through switch is connected in parallel to the current limiter device, between the electrical input and the electrical output.