3D Imaging of Non-Linear Acoustic Properties via Three-Wave Mixing
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Solution Overview
Problem
Current seismic interrogation methods for rock formations are limited by the size and power of acoustic sources, leading to restricted penetration and inability to effectively create three-dimensional images of non-linear properties and compressional to shear velocity ratios in regions remote from a borehole.
Innovation Solution
A method involving two sources in a borehole configured to generate steerable beams of elastic energy at different frequencies, which intersect away from the borehole, producing a third wave through a three-wave mixing process, detected by sensors to create three-dimensional images of non-linear properties and compressional to shear velocity ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high frequency signals are used, then measurement precision is improved, but penetration distance is reduced
Solution Approach 1:
The system segments the acoustic energy transmission by using multiple sources at different frequencies (high frequency for precision, low frequency for penetration) rather than relying on a single frequency source. This allows the high frequency signals to provide measurement precision while low frequency signals ensure adequate penetration distance into the formation.
Solution Approach 2:
The system changes the frequency parameter by employing multiple sources operating at different frequencies simultaneously. The high frequency sources provide detailed measurement precision for non-linear properties, while low frequency sources ensure sufficient penetration distance, resolving the contradiction between these two parameters.
2Length of stationary object
If low frequency signals are used, then penetration distance is improved, but source size must be increased
Solution Approach 1:
The system segments the acoustic energy transmission by using multiple sources at different frequencies (high frequency for precision, low frequency for penetration) rather than relying on a single frequency source. This allows the high frequency signals to provide measurement precision while low frequency signals ensure adequate penetration distance into the formation.
Solution Approach 2:
The system transitions from a single-frequency approach to a multi-frequency dimensional space, allowing simultaneous optimization of penetration distance and source size constraints by operating in the frequency domain rather than being limited to a single frequency parameter.
3Use of energy by moving object
If acoustic sources are clamped to the borehole wall, then energy transfer to formation is maximized, but device complexity increases
Solution Approach 1:
The system employs dynamic beam steering capabilities that allow acoustic energy to be directed and focused toward the formation without requiring physical contact or clamping to the borehole wall. This dynamic control of acoustic beam direction maintains effective energy transfer while avoiding the mechanical complexity of clamping mechanisms.
Solution Approach 2:
The system uses the borehole fluid as an intermediary medium to transmit acoustic energy from the sources to the formation. This eliminates the need for direct mechanical coupling or clamping to the borehole wall, reducing device complexity while maintaining effective energy transfer through the fluid path.
4Measurement precision
If multiple sources at different frequencies are used, then three-dimensional imaging capability is improved, but device complexity increases
Solution Approach 1:
The system merges multiple acoustic sources operating at different frequencies into a single integrated logging tool assembly. This combining of multiple frequency sources and their associated beam steering mechanisms into one unified device enables three-dimensional imaging capability while managing the overall device complexity through integrated design.
Solution Approach 2:
The system implements multi-functionality by designing a single logging tool that performs both high-frequency detailed imaging and low-frequency deep penetration imaging, as well as beam steering and three-dimensional characterization. This universal design approach enables comprehensive three-dimensional imaging capability without requiring separate specialized devices for each function.
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 creation of detailed three-dimensional images of non-linear properties and compressional to shear velocity ratios, enhancing the characterization of rock formations and reservoir properties, with improved penetration and accuracy compared to existing methods.
Implementation Method 1
producing a third wave through a three-wave mixing process
Data Source
AI summary
In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; 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 and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.