Nonlinear Harmonic Wave Formation Property Estimation
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Solution Overview
Problem
Current formation evaluation methods, such as acoustic logging, face limitations in accurately estimating mechanical properties like porosity and saturation due to their reliance on linear wave modes, which are not sufficiently sensitive to the non-linear properties of earth formations.
Innovation Solution
The method involves generating and analyzing non-linear harmonic waves by transmitting linear guided waves into a borehole, using an acoustic tool with a processor to measure and estimate formation properties based on the detected harmonics, which are highly sensitive to the non-linear properties of the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear guided wave modes are used for formation evaluation, then the acoustic logging method can operate at low frequencies with good penetration, but the sensitivity to non-linear formation properties (porosity and saturation) is insufficient
Solution Approach 1:
The patent applies mechanical vibration by transmitting linear guided waves at specific frequencies that resonate with the formation, causing non-linear harmonic responses. The acoustic source generates vibrations that interact with the formation's mechanical properties, producing higher harmonic waves that are sensitive to porosity and saturation. This resolves the contradiction by using vibration-based measurement to achieve high sensitivity without increasing device complexity.
Solution Approach 2:
The patent changes the measurement parameter from linear wave amplitude to non-linear harmonic wave amplitudes. By analyzing the amplitudes of higher harmonics generated in response to linear guided waves, the system achieves enhanced sensitivity to formation properties. This parameter transformation allows the measurement system to detect non-linear properties more effectively while maintaining the same acoustic tool configuration.
2Measurement precision
If traditional acoustic logging methods are used, then the measurement process is simple and direct, but the accuracy of estimating mechanical properties like porosity and saturation is limited
Solution Approach 1:
The patent uses non-linear harmonic waves as an intermediary to indirectly measure formation properties. Instead of directly measuring porosity and saturation, the system measures the amplitudes of higher harmonic waves generated by the formation in response to linear guided waves. These harmonic waves serve as intermediaries that carry information about the formation's mechanical properties, resolving the difficulty of direct measurement while improving accuracy.
Solution Approach 2:
The patent replaces traditional mechanical measurement approaches with acoustic wave-based measurement. Instead of using direct mechanical contact or simple acoustic amplitude measurement, the system uses the generation and detection of non-linear harmonic waves to infer formation properties. This substitution enables more accurate measurement of mechanical properties like porosity and saturation by leveraging the formation's non-linear acoustic response.
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 provides more accurate and sensitive measurements of formation properties, including porosity and saturation, by leveraging the high amplitude of non-linear harmonics generated at low frequencies, overcoming the limitations of traditional methods.
Implementation Method 1
measuring non-linear harmonic waves generated by the formation in response to the linear guided wave mode
Data Source
AI summary
An embodiment of a method of estimating a property of an earth formation includes: disposing an acoustic tool in a borehole in an earth formation, the acoustic tool including an acoustic source and at least one acoustic receiver; transmitting acoustic signals into the borehole by the acoustic source, the acoustic signals having at least one linear guided wave mode that propagates along a surface of the borehole; receiving the acoustic signals by at least one receiver; analyzing, by a processor, the acoustic signals to measure non-linear harmonic waves generated by the formation is response to the at least one linear guided wave mode; and estimating a property of the formation based on the measured non-linear harmonic waves.