Seismic Wavefield Separation for Incidence Angle Determination
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Solution Overview
Problem
Current seismic exploration methods face challenges in determining the three-dimensional directional propagation attributes of seismic events, particularly in marine surveys, where the interference between upgoing and downgoing waves limits the useful bandwidth and makes it difficult to accurately determine incidence angles and azimuths, especially in deep water environments.
Innovation Solution
The method involves processing seismic data from multi-component seismic sensors to decompose wavefields into up and down going components, using techniques such as wavefield separation and cepstral analysis, to determine the three-dimensional incidence angle and azimuth of seismic events, even with a single streamer, by analyzing the time delay between the primary wave and its ghost wave and applying polarization analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wavefield separation techniques are applied to determine three-dimensional directional propagation attributes, then measurement precision of incidence angles and azimuths is improved, but device complexity increases due to the need for multi-component sensors and complex processing algorithms
Solution Approach 1:
The wavefield is segmented into upgoing and downgoing components through mathematical decomposition. The seismic data is separated into distinct wavefield components that can be independently analyzed, allowing precise determination of directional propagation attributes without requiring complex hardware modifications.
Solution Approach 2:
An intermediary processing system is introduced that uses multi-component sensor data to compute wavefield separation. The system employs intermediate calculations involving particle motion vectors and polarization analysis to bridge the gap between raw sensor data and final directional attributes, managing complexity through structured intermediate steps.
2Ease of operation
If traditional seismic processing methods are used in deep water environments, then ease of operation is maintained, but measurement precision of directional propagation attributes deteriorates due to interference between upgoing and downgoing waves
Solution Approach 1:
The interference between upgoing and downgoing waves, which traditionally degrades measurement quality, is converted into a beneficial effect. By analyzing the interference pattern and applying wavefield separation, the system extracts precise directional information that would otherwise be obscured, turning the harmful interference into a source of additional information.
Solution Approach 2:
The processing method changes key parameters by separating the wavefield into distinct upgoing and downgoing components. This parameter transformation allows the system to operate effectively in deep water environments by fundamentally changing how the seismic data is processed and interpreted.
3Measurement precision
If bandwidth is increased to improve signal quality, then measurement precision improves, but loss of energy increases due to the broader frequency range requiring more processing power
Solution Approach 1:
The system applies partial wavefield separation, focusing computational energy on the specific frequency ranges and wavefield components most relevant to determining directional propagation attributes. Rather than processing the entire bandwidth uniformly, the method selectively processes portions of the signal that contribute most to measurement precision.
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 allows for the accurate determination of three-dimensional incidence angles and azimuths of seismic events, overcoming the limitations of existing methods and enabling more effective seismic data analysis in deep water environments, thereby improving the identification of subterranean geological formations and potential hydrocarbon deposits.
Implementation Method 1
Some seismic sensors are sensitive to pressure changes (hydrophones)
Implementation Method 2
others to particle motion (e.g., geophones)
Implementation Method 3
The sources generate seismic waves, which propagate into the geological formations creating pressure changes and vibrations along their way
Implementation Method 4
the interference between the upgoing plane wave and its reflection, called a 'ghost,' at the free surface
Data Source
AI summary
A technique includes obtaining seismic data acquired by at least one seismic sensor. The technique includes processing the seismic data to determine a value that is indicative of a three-dimensional directional propagation attribute of a seismic event based on the seismic data.