Toroidal Winding Formation Fluid Resistivity Measurement

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Solution Overview

Problem

Formation testers face issues with electrode corrosion and shorting due to the corrosive nature of formation fluids, as well as electrolysis caused by direct current, which affects the accuracy of resistivity measurements.

Innovation Solution

The use of electrical windings, specifically toroidal windings, that are not electrically coupled to the formation fluid, allowing for the measurement of electrical properties such as resistivity and dielectric constant without direct contact, and the implementation of a dual-chamber piston pump for fluid sampling and analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct current voltage is applied to button electrode in electrical contact with formation fluid, then resistivity measurement is obtained, but electrode corrosion and shorting occur

Engineering Contradiction:

Improveresistivity measurementVSAvoidelectrode performance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A toroidal winding is introduced as an intermediary component that couples to the formation fluid without direct electrical contact. The winding induces eddy currents in the fluid, and the secondary voltage induced in a second winding provides the resistivity measurement. This mediator approach eliminates electrode corrosion and shorting while maintaining measurement capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the direct electrical contact system (button electrode) with an electromagnetic induction system (toroidal windings). Instead of applying voltage directly through contact, the system uses alternating current in the first winding to induce eddy currents in the fluid, which then induce voltage in the second winding. This substitution eliminates the harmful direct current contact while achieving the same measurement goal.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If direct current flows through formation fluid, then resistivity is measured, but electrolysis adversely affects measurement performance

Engineering Contradiction:

Improveresistivity measurementVSAvoidelectrolysis

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the direct current flow method with an alternating current electromagnetic induction method. The first winding carries alternating current that induces eddy currents in the formation fluid, and the second winding detects the induced voltage. This substitution eliminates electrolysis while maintaining resistivity measurement capability through the relationship between the induced voltages and currents.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses periodic alternating current in the first winding instead of continuous direct current. The alternating current periodically induces eddy currents in the formation fluid, which in turn periodically induces voltage in the second winding. This periodic action prevents the continuous electrochemical reactions that cause electrolysis, while still allowing measurement of the fluid's electrical properties.

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If button electrode is surrounded by focusing electrodes, then current flow is focused for better measurement, but electrode complexity and corrosion risk increase

Engineering Contradiction:

Improvecurrent flow focusingVSAvoidelectrode structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex multi-electrode structure (button electrode with surrounding focusing electrodes) with a simpler toroidal winding configuration. The toroidal winding naturally focuses the electromagnetic field and induced eddy currents in the formation fluid without requiring multiple separate electrodes. This substitution reduces structural complexity while maintaining or improving measurement precision through the inherent geometry of the toroidal shape.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 accurate and reliable measurement of formation fluid electrical properties without electrode corrosion or shorting, improving the precision and consistency of data collected during oil and gas exploration.

Implementation Method 1

a first electrical winding is provided an alternating current signal that creates an electric field. A current flow is induced in a second electrical winding based on the electric field.

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8581591B2Method and system of determining an electrical property of a formation fluid

Publication Date: 2013.11.12 HALLIBURTON ENERGY SERVICES INC

AI summary

Determining an electrical property of a formation fluid. At least some of the illustrative embodiments are methods comprising drawing formation fluids into a tool within a borehole, applying a swept frequency electric field to the formation fluids by way of a first winding, inducing a current flow in a second winding based on the swept frequency electric field, and determining a property of the formation fluids based, at least in part, on the current flow in the second winding.