Multi-Frequency Capacitance Measurement for Formation Water Resistivity
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Solution Overview
Problem
Current methods for determining formation water resistivity in subsurface samples are costly, time-consuming, and often destructive, with limitations due to sample variability and unavailability, as well as geochemical reactions that can alter measured results.
Innovation Solution
The method involves using multi-frequency complex resistivity measurements to derive a salinity index, which is empirically correlated with formation water resistivity, allowing for non-destructive determination of resistivity or conductivity without the need for destructive testing or geochemical models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive testing methods are used to determine formation water resistivity, then measurement precision may be improved, but the sample is destroyed and cannot be reused
Solution Approach 1:
The patent replaces destructive mechanical/chemical testing methods with non-destructive electrical impedance spectroscopy measurements. By using multi-frequency electrical signals to measure the subsurface sample, the system determines formation water resistivity without physically altering or destroying the sample, thus resolving the contradiction between measurement precision and sample preservation
Solution Approach 2:
The patent changes the measurement parameter from direct resistivity measurement requiring sample destruction to impedance spectroscopy measurements across multiple frequencies. This parameter change allows extraction of formation water resistivity information through mathematical modeling of frequency-dependent impedance responses, achieving accurate measurements without sample destruction
2Measurement precision
If traditional resistivity measurement methods are used, then formation water resistivity can be determined, but the process is time-consuming and requires extensive sample preparation
Solution Approach 1:
The patent performs preliminary actions by measuring impedance across multiple frequencies simultaneously and using pre-established theoretical models to directly calculate formation water resistivity. This eliminates the need for time-consuming sequential testing and sample preparation steps required by traditional methods, significantly reducing measurement time while maintaining precision
Solution Approach 2:
The patent creates an electrical impedance spectrum copy of the subsurface sample's properties across multiple frequencies. By analyzing this spectral copy rather than physically manipulating the sample, the system rapidly determines formation water resistivity without time-consuming sample preparation or sequential measurements
3Ease of operation
If produced water analysis is used to determine formation water resistivity, then direct measurement is possible, but sample variability and contamination affect reliability
Solution Approach 1:
The patent uses electrical impedance spectroscopy as an intermediary measurement method that indirectly determines formation water resistivity through the subsurface sample's frequency-dependent impedance response. This intermediary approach avoids direct water sampling and analysis, eliminating contamination issues and sample variability problems while maintaining ease of operation and improving reliability
Solution Approach 2:
The patent replaces the mechanical/chemical process of water sampling, filtration, and laboratory analysis with an electrical measurement system. By substituting the entire water analysis workflow with impedance spectroscopy, the system achieves reliable formation water resistivity determination without exposure to contamination sources that affect produced water analysis
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 approach enables quick and accurate determination of formation water resistivity or conductivity, independent of water saturation, rock type, and temperature, facilitating more efficient hydrocarbon exploration and production without sample preparation or geochemical interference.
Implementation Method 1
a first capacitance value of the subsurface sample at a first frequency is measured; a second capacitance value of the subsurface sample at a second frequency is measured
Implementation Method 2
Systems and methods for the determination of formation water resistivity and conductivity
Data Source
AI summary
According to various embodiments, a method may include measuring a first capacitance of a sample at a first frequency using a measurement system, measuring a second capacitance of the sample at a second frequency using the measurement system, calculating a ratio of the first capacitance to the second capacitance, and determining a formation water resistivity or conductivity of the sample using the ratio.