Passive Source Wavefield Reconstruction for Marine Seismic Imaging
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Solution Overview
Problem
Existing marine seismic surveys face challenges in accurately imaging subsurface structures using ambient acoustic energy from passive sources due to the lack of direct knowledge of the source wavefield, leading to incomplete and inaccurate imaging results.
Innovation Solution
A method is developed to identify a presumed location of the passive source and isolate the direct wavefield from sensor recordings, followed by backpropagating this wavefield to generate an estimated passive source wavefield, which is then used to create a subsurface image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ambient acoustic energy from passive sources is used for marine seismic surveys, then environmental impact and cost are reduced, but imaging accuracy deteriorates due to lack of direct knowledge of the source wavefield
Solution Approach 1:
The patent introduces an intermediary process (wavefield separation and backpropagation) to bridge the gap between passive source recordings and accurate subsurface imaging. By separating the direct wavefield from recorded signals and backpropagating it to the source location, the method creates an estimated source wavefield that serves as a mediator, enabling accurate imaging without requiring direct access to the actual source wavefield
Solution Approach 2:
The patent replaces the mechanical/physical system of active seismic sources with a computational system that processes ambient acoustic energy. Instead of physically generating controlled acoustic waves, the method uses signal processing techniques (wavefield separation, backpropagation, deconvolution) to extract imaging information from passive recordings, substituting physical source generation with computational wavefield reconstruction
2Measurement precision
If actively controlled seismic sources are used to produce acoustic energy, then imaging accuracy is improved through known source wavefields, but environmental impact and cost increase
Solution Approach 1:
The patent enables the ambient acoustic energy from passive sources to serve itself for imaging purposes. By processing the direct wavefield component of the passive source recordings through backpropagation and deconvolution, the method allows the ambient noise to provide its own imaging signal without requiring external active sources, making the passive acoustic energy self-sufficient for seismic imaging
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 enables accurate imaging of subsurface structures using ambient acoustic energy by effectively utilizing passive source wavefields, improving imaging accuracy and reducing environmental impact and costs.
Implementation Method 1
acoustic energy that was emitted in the body of water by a passive source
Implementation Method 2
isolating, from the recorded signals, a direct wavefield arriving at the sensors from a direction of the identified point
Data Source
AI summary
Methods and apparatus are described for using ambient acoustic energy as a passive source in marine seismic surveys. An example embodiment includes (a) accessing signals that were recorded by sensors in the presence of acoustic energy that was emitted by a passive source during a marine seismic survey; (b) identifying a point to represent a location from which the acoustic energy was emitted; (c) isolating, from the recorded signals, a direct wavefield arriving at the sensors from a direction of the identified point; and (d) generating an estimated passive source wavefield at the identified point by backpropagating the isolated direct wavefield to the identified point. The estimated passive source wavefield may be used, together with signals recorded by the sensors, to generate an image of a subsurface earth volume without the use of active seismic sources.