Resistivity Measurement Using Curved Electrodes on Plunger Cores
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Solution Overview
Problem
Current methods for measuring rock resistivity in anisotropic reservoirs require cumbersome core sample preparation and are inefficient for obtaining vertical resistivity measurements, particularly for plunger-type cores.
Innovation Solution
A resistivity measurement system and method utilizing a displacement loop with curved electrodes and a confining pressure pump to measure resistivity in a vertical direction without altering core preparation techniques, using a formula that calculates resistivity based on current, voltage, arc length, and core dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional plunger-type core measurement method is used, then the measurement process is simple and quick, but the measured resistivity represents horizontal direction only and cannot obtain vertical direction resistivity for anisotropic reservoirs
Solution Approach 1:
The patent introduces a new measurement dimension by placing electrodes on the lateral surface of the core sample. Instead of measuring only along the vertical axis (conventional method), the invention measures resistivity along the radial/horizontal direction by applying voltage between two points on the cylindrical surface, thereby obtaining resistivity data in an additional spatial dimension that reveals anisotropic properties
2Adaptability or versatility
If cuboid rock sample preparation method is used to test vertical resistivity, then vertical resistivity can be measured, but the preparation process becomes troublesome with wire cutting taking long time and being tedious
Solution Approach 1:
The invention makes the conventional cylindrical core holder and plunger-type core preparation method multi-functional. By adding lateral surface electrodes to the standard core holder configuration, the same simple cylindrical preparation process can now serve both conventional vertical resistivity measurement and the new lateral resistivity measurement for anisotropic analysis, eliminating the need for special cuboid preparation
Solution Approach 2:
The invention segments the measurement function by separating the voltage application points onto the lateral surface of the core, distinct from the conventional end-face electrode placement. This segmentation allows independent measurement of resistivity in different directions using the same core sample without requiring complex multi-directional electrode arrangements
3Adaptability or versatility
If lateral surface electrodes are added to the core holder, then the device complexity increases, but this enables resistivity measurement in previously inaccessible directions
Solution Approach 1:
The invention adapts to the cylindrical geometry of the core sample by placing electrodes on the curved lateral surface rather than using flat surfaces. The electrodes are positioned at specific angular intervals around the circumference, utilizing the rotational symmetry of the cylindrical shape to achieve directional resistivity measurement without complex three-dimensional electrode arrangements
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 efficient resistivity measurement in the vertical direction for plunger-type cores, suitable for anisotropic reservoirs, without changing core preparation methods, and provides accurate resistivity data for guiding reservoir identification and development.
Implementation Method 1
two opposite curved electrodes are disposed on the sleeve, an inner surface of the curved electrode is matched with an outer surface of the sleeve... a voltmeter configured to measure a voltage between the two curved electrodes, and an ammeter configured to measure a current flowing between the two curved electrodes
Data Source
AI summary
The present disclosure discloses a resistivity measurement method, device and system. The method comprises: placing a core to be measured into the core holder after a 100% saturated water treatment, and injecting a predetermined confining pressure by the confining pressure pump; turning on the displacement source to carry out a displacement, and at an interval of a predetermined time period, acquiring a current value by the ammeter and a voltage value by the voltmeter; determining a resistivity of the core according to the current value, the voltage value, an arc length of the curved electrode, and a radius and a length of the core. The present disclosure can realize a rock resistivity measurement in a vertical direction under formation conditions for a plunger-type core, without needing to change the core preparation technology or method.