Geological Sample Measuring Device with Coplanar Electrodes
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Solution Overview
Problem
Current measuring devices for the electric properties of geological samples, such as rocks from gas or oil reservoirs, face issues with systematic errors and over-estimation of substrate resistance in two-electrode measurements and inaccurate high-frequency measurements with four-electrode techniques due to contact resistance and electrode polarization effects.
Innovation Solution
A measuring device with a cylindrical design featuring two half-shells, coplanar contacts, and elastic means to ensure good contact with the sample surface, allowing for rapid application of both two- and four-electrode techniques without configuration changes, using gold-plated brass and gold electrodes with deformable noble metal sheets and springs to adapt to sample surfaces, and a liquid sample-holder device for precise impedance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two-electrode measurement technique is used, then device simplicity is improved, but measurement precision deteriorates due to contact resistance and polarization effects
Solution Approach 1:
The device is segmented into two independent measurement systems: a two-electrode measurement system and a four-electrode measurement system. Each system can be independently activated based on measurement requirements. The four-electrode system segments the current injection and voltage measurement functions to different electrode pairs, eliminating contact resistance effects from the measurement.
Solution Approach 2:
The measuring device is designed with multi-functionality to perform both two-electrode and four-electrode measurement techniques using the same physical apparatus. The device includes electrode arrangements that support both measurement modes, allowing users to switch between techniques based on sample characteristics and measurement requirements without needing separate devices.
2Measurement precision
If four-electrode measurement technique is used, then measurement precision is improved, but device complexity worsens due to multiple electrodes and configuration requirements
Solution Approach 1:
The device merges the two-electrode and four-electrode measurement systems into a single integrated apparatus. The electrode structure is designed so that the same physical electrodes can serve both two-electrode and four-electrode configurations. The control system automatically selects and configures the appropriate measurement mode based on the selected technique.
3Productivity
If rapid succession measurements are required, then productivity is improved, but device complexity worsens due to configuration changing requirements
Solution Approach 1:
The device incorporates dynamic switching capability that allows rapid transition between two-electrode and four-electrode measurement modes. The electrode connections and measurement circuitry are designed to be dynamically reconfigurable through electronic switching rather than physical reassembly, enabling quick mode changes without manual intervention.
4Measurement precision
If contact resistance is reduced through electrode treatment, then measurement precision is improved, but manufacturing complexity worsens due to additional processing steps
Solution Approach 1:
The device uses a conductive gel as an intermediary substance between the electrodes and the rock sample. This gel fills in surface irregularities and provides consistent electrical contact, reducing contact resistance without requiring complex electrode surface treatments. The gel acts as a mediator that improves contact quality while keeping the electrode manufacturing simple.
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 accurate and rapid measurement of electric properties with minimal systematic errors and resistance over-estimation, maintaining precise contact even at high frequencies, and accommodating various sample sizes and types.
Implementation Method 1
elastic means, preferably in the form of compression springs
Implementation Method 2
deformable noble metal sheets to adapt to sample surfaces
Implementation Method 3
measurement of the low-frequency complex impedance, i.e. lower than 100kHz
Implementation Method 4
configuration used for cylindrical samples is that of a capacitor whose parallel and flat plates are in contact with the faces of said sample
Data Source
AI summary
The present invention relates to a measuring device (10) of the electric properties of solid or liquid geological samples, such as, for example, rocks, preferably from oil or gas reservoirs, and saturation fluids of the same, comprising a hollow body (11, 12) consisting of a first upper half-shell (11) and a second lower half-shell (12), the upper and lower half-shells (11, 12) coaxially sliding one inside the other, inside the body (11, 12) there being a housing seat (23) for a substantially cylindrical sample, two pairs of electrodes (13, 14) being envisaged facing the housing seat (23) for the injection of current into a sample and for the measurement of the voltage at the ends of the sample, characterized in that the pairs of electrodes (13, 14) are pairs of coplanar electrodes, each situated at one end of the housing seat (23).