Non-linear Acoustic Micro-seismic Characterization
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Solution Overview
Problem
Conventional methods for interrogating materials rely on linear acoustic interactions, which are inadequate for characterizing non-linear properties of materials, limiting the ability to generate enhanced multi-dimensional image information of non-linear properties using non-linear acoustic interactions.
Innovation Solution
A remote sensing system with two acoustic sources and detectors that generate primary acoustic waves intersecting in a medium, producing a third wave by non-linear interaction, which is processed to emulate micro-seismic events and generate 3D images of non-linear properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear acoustic interaction methods are used to interrogate materials, then the measurement process is simple and conventional, but the ability to characterize non-linear properties of materials is inadequate
Solution Approach 1:
The system divides the material interrogation process into multiple stages: generating primary acoustic waves at different frequencies, allowing them to propagate through the medium, detecting the resulting non-linear interaction signals, and processing the data to generate multi-dimensional images. This segmentation allows complex non-linear characterization to be achieved through a structured sequence of operations.
Solution Approach 2:
The invention transitions from conventional linear acoustic measurements to multi-dimensional imaging of non-linear properties by incorporating frequency domain analysis, spatial distribution mapping, and temporal characterization. The system generates 3D or 4D images that reveal non-linear properties throughout the material volume, adding dimensional information beyond simple point measurements.
2Loss of information
If non-linear acoustic interactions are used to generate enhanced multi-dimensional image information, then the characterization capability is improved, but the difficulty of detecting and measuring non-linear properties increases
Solution Approach 1:
The system uses primary acoustic waves as intermediary carriers to probe the material's non-linear properties. By generating controlled acoustic waves at specific frequencies and observing their non-linear interaction products, the system indirectly measures material properties that would be difficult to detect directly. The acoustic waves serve as mediators between the measurement system and the material's non-linear characteristics.
Solution Approach 2:
The invention creates virtual copies or representations of micro-seismic events through non-linear acoustic interactions. By generating acoustic signals that replicate the characteristics of natural micro-seismic sources, the system can study material properties under controlled conditions while obtaining information equivalent to what would be obtained from actual seismic events, thereby reducing measurement difficulty.
3Measurement precision
If conventional linear interaction methods are used, then the system operation is straightforward, but the generated image information lacks multi-dimensional characterization of non-linear properties
Solution Approach 1:
The acoustic interrogation system is designed with multi-functionality to perform both conventional linear acoustic measurements and advanced non-linear interaction measurements using the same hardware platform. The system can operate in multiple modes (different frequency combinations, different detection schemes), providing universal applicability while maintaining operational simplicity through integrated control.
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 the characterization of non-linear properties of materials by generating emulated micro-seismic events at specific locations, providing 3D images of non-linear properties and propagation velocities, improving the accuracy of material characterization.
Implementation Method 1
generating a first primary acoustic wave in the medium from a first acoustic source; generating a second primary acoustic wave in the medium from a second acoustic source; the first and second primary acoustic waves intercepting in the medium to produce a third acoustic wave by non-linear interaction
Implementation Method 2
receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies
Data Source
Figure 1
Figure 2
Figure 3a~3d
AI summary
A method and system for generating a micro-seismic event in a medium from a non-linear interaction to characterize the medium is provided. The method includes generating, by a first acoustic source (SI, 12), a first coded acoustic signal comprising a first plurality of pulses arranged as a time sequence, each pulse comprising a modulated signal at a central frequency; and generating, by a second acoustic source (S2,14), a second coded acoustic signal comprising a second plurality of pulses arranged as a time sequence, wherein each pulse comprises a modulated signal and a central frequency of the modulated signal within each pulse in the second plurality of pulses is a selected fraction d of the central frequency of the modulated signal for the corresponding pulse in the first plurality of pulses. The method further includes receiving, by a receiver (R), a detected signal including a third signal being generated by a non-linear mixing process from the first acoustic signal and the second acoustic signal in the mixing zone; performing, by a processor, data processing on the received signal, or correlating with a coded signal template, or both, to extract the third signal generated by the non-linear mixing process over noise or over signals generated by a linear interaction process, or both, to obtain an emulated micro-seismic event signal occurring at the mixing zone; and characterizing properties of the medium or creating a 3D image of the properties of the medium, or both, based on the emulated micro-seismic event signal.