Passive Seismic Re-Datuming Using Ambient Noise Deconvolution
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Solution Overview
Problem
Current seismic exploration methods rely on traditional sources like air guns or controlled explosions, which are disruptive to marine life and produce unwanted ambient noise that interferes with seismic data acquisition, necessitating a more environmentally friendly and efficient approach to utilize ambient noise for subsurface imaging.
Innovation Solution
A method utilizing ambient noise, such as propeller noise, is acquired as a continuous wavefield and processed through multidimensional deconvolution (MDD) to estimate the emitted source, separate up/down propagating wavefields, and interpolate point spread functions to image the subsurface without needing to know the source characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional seismic sources like air guns are used, then seismic waves can be generated for subsurface exploration, but environmental disruption to marine life and unwanted ambient noise occur
Solution Approach 1:
The patent converts harmful ambient noise from marine vessels into useful seismic signals through cross-correlation processing. By treating the noise as a source of information rather than interference, the system extracts subsurface reflection data without requiring traditional seismic sources, thereby eliminating environmental disruption while maintaining measurement capability
Solution Approach 2:
The system uses the marine vessels' own operational noise (propellers, engines) as the seismic source, eliminating the need for separate seismic source deployment. The vessels serve dual purposes: transportation and seismic signal generation, reducing overall system complexity and environmental impact
2Object-affected harmful factors
If ambient noise is used as seismic source, then environmental impact is reduced and cost is decreased, but the source characteristics are unknown and signal processing becomes more complex
Solution Approach 1:
The patent introduces cross-correlation as an intermediary mathematical operation between the recorded noise signals and the Green's function. This intermediary process extracts the subsurface reflection information by correlating the ambient noise with the expected wavefield, effectively filtering out the complexity of unknown source characteristics while retrieving useful geological information
Solution Approach 2:
The system replaces traditional mechanical seismic sources with a computational approach using cross-correlation processing. Instead of physically generating controlled seismic waves, the system uses mathematical correlation of ambient noise signals to extract subsurface information, substituting mechanical complexity with computational processing
3Quantity of substance
If cross-correlation techniques are used to image subsurface structures, then the need for additional seismic sources is reduced, but processing the continuous wavefield into usable signals becomes more challenging
Solution Approach 1:
The patent makes the marine vessels universal by enabling them to perform both transportation and seismic data acquisition functions. The same vessels that transport equipment and personnel also generate and record the seismic signals needed for subsurface imaging, eliminating the need for dedicated seismic source vessels and reducing the overall quantity of equipment required
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 reduces the need for additional seismic sources, minimizes environmental impact, and provides accurate subsurface imaging by leveraging existing noise sources, allowing for cost-effective monitoring of stored carbon leakage.
Implementation Method 1
using cross-correlation techniques to image subsurface structures
Implementation Method 2
multidimensional deconvolution (MDD) where data are separated into an up/down propagating wavefield
Implementation Method 3
interpolating the products of MDD, correlation functions and point spread functions
Data Source
AI summary
Systems and methods for determining Green's function between known receiver positions based upon seismic data from an unknown source, the unknown source having unknown source positions and unknown source characteristics. The systems and methods include estimating an up-going component and a down-going component of the seismic data at receivers of the seismic data by combining particle motion characteristics of the seismic data, assigning geometry to the unknown source by computing a point spread function (PSF) based on a conjugate transpose of the down-going component at the receivers and the down-going component at the receivers, and computing a cross-correlation function (CF) based on the conjugate transpose of the down-going component and the up-going component at the receivers, interpolating the PSF and the CF across the receivers, estimating a Green's function based on the interpolated CF and the interpolated PSF, and taking an action based on the Green's function.