Seismic Data Correction for Variable Air-Water Interface
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Solution Overview
Problem
Existing methods for correcting seismic data for a variable air-water interface during non-impulsive emission, such as those using vibratory sources, require continuous measurements or substantial modifications to the acquisition setup, which are undesirable and ineffective for accurately generating high-resolution images of the subsurface.
Innovation Solution
A method that calculates a free surface reflection operator based on the position of the seismic source and the air-water interface datum, allowing for the correction of recorded seismic data to generate an improved image of the subsurface, without the need for continuous measurements or setup modifications, by accounting for the changing air-water interface during the emission process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous measurements or substantial modifications to the acquisition setup are implemented to correct for variable air-water interface, then the measurement precision of seismic data improves, but the device complexity and ease of operation deteriorate
Solution Approach 1:
The system uses the vibratory source itself to generate reference signals that enable estimation of the air-water interface position. The source serves dual purposes: generating seismic waves for subsurface imaging and providing reference signals for interface characterization, eliminating the need for separate measurement systems
Solution Approach 2:
The patent introduces a reference sensor that detects signals from the vibratory source as an intermediary means to estimate the air-water interface position. This reference sensor acts as a mediator between the source and the processing system, enabling indirect measurement of interface variations without direct contact or complex instrumentation
2Reliability
If continuous measurements are implemented to track air-water interface variations, then the reliability of seismic imaging improves, but the use of energy and measurement complexity increase
Solution Approach 1:
The system performs interface estimation at specific time points during the vibratory source emission rather than continuously. By updating the interface position estimate periodically at key moments in the emission cycle, the system maintains imaging reliability while significantly reducing energy consumption compared to continuous measurement approaches
3Ease of manufacture
If the air-water interface is assumed constant during emission, then the device complexity is reduced, but the manufacturing precision and image quality deteriorate
Solution Approach 1:
The system transitions from assuming a static air-water interface to dynamically estimating interface position at different time points during source emission. By updating the interface model to reflect temporal variations, the system improves image resolution and correction accuracy while maintaining computational feasibility through efficient estimation algorithms
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 correction of seismic data for a variable air-water interface, improving the quality of seismic imaging by accounting for the dynamic changes in the air-water interface, thereby enhancing the resolution and accuracy of subsurface images without requiring additional setup modifications or continuous measurements.
Implementation Method 1
seismic source configured to generate an acoustic wave. Acoustic wave propagates downward and penetrates the seafloor
Implementation Method 2
the reflected acoustic wave propagates upward and is detected by detector. Since the interface between the water and air is well approximated as a quasi-perfect reflector, the reflected wave is reflected back toward the detector
Data Source
AI summary
Computing device, computer instructions and method for correcting an image, of a surveyed surface, due to a free-surface reflection. The method includes calculating a free surface reflection operator for a seismic source displaced in water based on a position of the source, and an air-water interface datum; receiving recorded seismic data d recorded with seismic sensors (r), wherein the recorded seismic data is associated with a pressure and/or a particle motion produced by a seismic wave in earth; correcting the recorded seismic data d based on the free surface reflection operator to obtain transformed seismic data; and generating an image of the surveyed subsurface, based on the transformed seismic data, wherein the image is indicative of various layers of the earth. The free surface reflection operator varies while a source signal is being emitted by the source.