Three-Electrode Borehole Sensor for Simultaneous Capacitance and Resistance
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Solution Overview
Problem
Existing borehole fluid measurement technologies require separate sensors for resistance and capacitance, which occupy more space and prevent simultaneous measurements at the same depth, leading to reduced resolution and accuracy due to fluid droplets skewing measurements.
Innovation Solution
A single sensor probe with three electrodes forming two pairs, one with an insulative layer, and an RC oscillator circuit for capacitance measurement, and another pair for resistance measurement, allowing for simultaneous and high-resolution measurements of both characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate capacitance and resistance probes are deployed, then each probe can be optimized for its specific measurement function, but the probes occupy more space and cannot measure the same fluid simultaneously
Solution Approach 1:
The patent combines capacitance and resistance measurement functions into a single probe assembly. The probe includes capacitive electrodes for capacitance measurement and resistive electrodes for resistance measurement, all integrated within one housing. This merging allows both measurements to be taken from the same fluid sample at the same location, eliminating the need for separate probes and reducing overall space requirements while maintaining measurement accuracy.
Solution Approach 2:
The single probe assembly performs multiple measurement functions simultaneously. It includes capacitive electrodes for measuring fluid capacitance, resistive electrodes for measuring fluid resistance, and can optionally include temperature sensing capabilities. This multi-functional design allows one probe to replace what would traditionally require multiple separate probes, optimizing space utilization while providing comprehensive fluid characterization.
2Measurement precision
If more sensors are deployed in a small borehole, then measurement resolution increases, but the space constraint prevents deploying enough sensors
Solution Approach 1:
By merging capacitance and resistance sensors into single integrated probes, the patent reduces the number of separate devices that need to be deployed. Each compact probe contains both measurement functionalities, allowing more probes to be positioned within the limited borehole space. This integration directly increases measurement resolution by enabling closer spacing of measurement points while simplifying the deployment process.
Solution Approach 2:
The probe design nests multiple functional components within a compact structure. The capacitive electrodes and resistive electrodes are arranged in a nested or closely integrated configuration within a single probe housing, maximizing the use of available space. This nested arrangement allows multiple probes to be deployed in close proximity within small-diameter boreholes without excessive complexity.
3Reliability
If separate capacitance and resistance probes are used, then each probe can be independently optimized, but fluid droplets hanging between probes skew the measurements
Solution Approach 1:
The patent eliminates measurement skewing by combining capacitance and resistance measurements into a single probe assembly that samples the same fluid simultaneously. Since both measurements are taken from the identical fluid sample at the same location, there are no fluid droplets hanging between separate probes to cause measurement errors. This integrated approach ensures that both measurements reflect the true properties of the same fluid, significantly improving measurement reliability.
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 more sensors to be deployed in a small borehole, providing higher resolution and accurate, simultaneous measurements of resistance and capacitance, eliminating measurement skewing issues and increasing the understanding of fluid distribution and production in wells.
Implementation Method 1
A RC oscillator circuit in which the capacitance of the circuit is determined at least in part by the electrode pair with the electrically insulative layer disposed in the gap between the electrodes
Implementation Method 2
A RC oscillator circuit in which the capacitance of the circuit is determined at least in part by the electrode pair with the electrically insulative layer disposed in the gap between the electrodes. The sensor may also include a counter (optionally implemented in hardware or software) to count the oscillations and thereby provide a measure of the frequency of the oscillation
Implementation Method 3
A resistance sensor may include a probe comprising a source and a return electrode, electronics to drive a current from the source through the borehole fluid to the return, and electronics to measure the current and the voltage difference across the electrodes (which provides a measure of resistance of the fluids between the electrodes)
Implementation Method 4
electronics to drive a current from the source through the borehole fluid to the return, and electronics to measure the current and the voltage difference across the electrodes (which provides a measure of resistance of the fluids between the electrodes)
Data Source
AI summary
A sensor comprising three electrodes forming two electrode pairs, each pair having a gap between the electrodes, is disclosed. An electrically insulating layer is disposed in the gap of one electrode pair. The sensor may include a RC oscillator circuit connected to the electrode pair having the insulating layer such that the electrode pair contributes to the capacitance of the circuit. The sensor may include a power supply connected to the other electrode pair to provide a voltage across and current through material in the pair's gap. The sensor may be disposed in a borehole to allow borehole fluid to enter the gaps and the RC oscillator circuit and power supply may be operated to provide a measure of capacitance and resistance characteristics of the borehole fluid.