Multi-frequency Electromagnetic Tensor Logging for Complex Formations
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Solution Overview
Problem
Conventional electromagnetic logging methods fail to accurately account for dielectric permittivity, dielectric permittivity anisotropy, conductivity anisotropy, and interfacial polarization phenomena in geologically complex formations like shaly sands and organic-rich mudrocks, leading to inaccurate hydrocarbon estimation.
Innovation Solution
A triaxial electromagnetic measurement tool that transmits and receives electromagnetic energy at multiple frequencies, processing real and imaginary components to compute complex conductivity, dielectric permittivity, and anisotropy, enabling precise resistivity and mineralization analysis, including differentiation between pyrite and graphite inclusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electromagnetic logging methods are used, then the measurement process is simple, but the measurement precision deteriorates due to neglecting dielectric permittivity, conductivity anisotropy, and interfacial polarization effects
Solution Approach 1:
The patent applies parameter changes by measuring electromagnetic response at multiple frequencies rather than a single frequency. This allows the system to capture frequency-dependent effects such as dielectric permittivity variations, conductivity anisotropy, and interfacial polarization phenomena, thereby improving measurement precision in complex formations without requiring complex additional hardware
Solution Approach 2:
The patent segments the electromagnetic measurement into multiple frequency components. By analyzing the response at different frequencies separately and then combining the results, the system can isolate and quantify specific physical effects (dielectric permittivity, conductivity anisotropy, interfacial polarization) that would be indistinguishable in a single-frequency measurement, improving precision while maintaining reasonable device complexity
2Reliability
If single-frequency electromagnetic measurements are taken, then the measurement time is short, but the reliability deteriorates due to inability to account for frequency dispersive characteristics
Solution Approach 1:
The patent uses periodic action by implementing a time-multiplexed measurement sequence where the tool sequentially transmits electromagnetic energy at multiple distinct frequencies and measures the response at each frequency. This periodic switching between frequencies allows comprehensive data collection for reliable characterization of frequency-dispersive formations while minimizing total measurement time through efficient sequencing
3Measurement precision
If conventional electromagnetic measurements neglecting anisotropic effects are used, then the device complexity is low, but the measurement precision deteriorates in anisotropic formations
Solution Approach 1:
The patent applies universality by designing an electromagnetic measurement tool that can operate in both isotropic and anisotropic formations using the same hardware configuration. The multi-frequency measurement capability provides a universal solution that automatically adapts to different formation types, capturing anisotropic effects when present while maintaining simplicity in isotropic cases, thereby improving precision across all formation types without proportionally increasing device complexity
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
The tool provides accurate multi-frequency, full-tensor complex conductivity measurements, enhancing hydrocarbon estimation and mineral identification in complex formations by accounting for anisotropic and dispersive properties, improving the accuracy of resistivity and dielectric properties analysis.
Implementation Method 1
cause the triaxial transmitter to transmit electromagnetic energy into the formation sample at four or more distinct and sequential frequencies
Implementation Method 2
cause the triaxial receiver to receive said transmitted electromagnetic energy each of the four or more frequencies
Implementation Method 3
compute at least a dielectric permittivity, a conductivity anisotropy, or a permittivity anisotropy of the formation sample
Implementation Method 4
compute at least a dielectric permittivity, a conductivity anisotropy, or a permittivity anisotropy of the formation sample
Data Source
AI summary
An electromagnetic measurement tool for making multi-frequency, full tensor, complex, electromagnetic measurements includes a triaxial transmitter and a triaxial receiver deployed on a tubular member. An electronic module is configured to obtain electromagnetic measurements at four or more distinct frequencies. The measurement tool may be used for various applications including obtaining a resistivity of sand layers in an alternating shale-sand formation; computing a dielectric permittivity, a conductivity anisotropy, and/or a permittivity anisotropy of a formation sample; and/or identifying formation mineralization including discriminating between pyrite and graphite inclusions and/or computing weight percent graphite and/or pyrite in the formation sample.