Direct Arrival Signal Estimation via Transfer Function
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In marine seismic surveys, there is a lack of information recorded at short offsets due to the impracticality of towing streamers directly under seismic sources, limiting the processing of seismic data, and making it challenging to estimate direct arrival signals at locations without seismic receivers.
Innovation Solution
A method is described to estimate direct arrival signals at locations without seismic receivers by determining a transfer function based on predicted direct arrival signals and near-field measurements, allowing for the extrapolation of these signals using notional source signatures and seismic receiver measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If streamers are towed directly under seismic sources to record short offset data, then measurement precision of direct arrival signals is improved, but device complexity and operational impracticality increase
Solution Approach 1:
The patent applies preliminary action by measuring the signature of the seismic source in advance using near-field measurements taken when the streamer is at a known position relative to the source. This pre-measured signature is then used to estimate direct arrival signals at short offsets without requiring the streamer to be physically positioned there, thus maintaining measurement precision while avoiding operational complexity
Solution Approach 2:
The patent uses copying by creating a notional source signature that replicates the actual seismic source characteristics. This notional signature is derived from near-field measurements and is used to generate predicted direct arrival signals at short offsets, effectively copying the source behavior without requiring physical presence at the target location
2Loss of information
If seismic receivers are positioned at short offsets to capture direct arrival signals, then information completeness is improved, but device complexity and operational difficulty increase
Solution Approach 1:
The patent introduces an intermediary approach by using a transfer function that mathematically connects near-field measurements to short offset direct arrival signals. This transfer function acts as a mediator that translates readily available near-field data into the desired short offset information without requiring complex physical reconfiguration of the seismic survey equipment
Solution Approach 2:
The patent replaces the mechanical system of physically positioning streamers at short offsets with a computational system. By using signature-based prediction and transfer functions, the method substitutes complex mechanical positioning operations with mathematical transformations of measured data, thereby maintaining information completeness while reducing device complexity
3Productivity
If near-field measurements are used to estimate direct arrival signals, then productivity of seismic data processing is improved, but measurement precision at short offsets may be compromised
Solution Approach 1:
The patent applies feedback by using the measured signature from near-field measurements to continuously refine the estimation of direct arrival signals. The process incorporates feedback loops where the predicted signals are compared with actual measurements, and the transfer function is adjusted accordingly to improve accuracy while maintaining productivity
Solution Approach 2:
The patent uses parameter changes by transforming the seismic data through mathematical operations that change the parameters of the signals. The transfer function performs parameter transformations that convert near-field measurement parameters into short offset direct arrival signal parameters, maintaining precision through controlled parameter changes while improving processing productivity
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 improves the quality and accuracy of geophysical data products by enabling the estimation of direct arrival signals at short or near-zero offsets, aiding in the imaging of primaries and multiples, and deconvolving the seismic source ghost, thereby enhancing the processing of seismic data.
Implementation Method 1
The seismic source control may cause the one or more seismic sources, which can be air guns, marine vibrators, etc., to produce acoustic signals at selected times. Each acoustic signal is essentially a sound wave that travels down through the water and into the subterranean formation.
Implementation Method 2
The seismic receivers thereby measure a wavefield that was ultimately initiated by the actuation of the seismic source.
Data Source
AI summary
Estimation of direct arrival signals based on predicted direct arrival signals and measurements can include obtaining notional source signatures for notional sources that correspond to source elements in a seismic source. A first predicted direct arrival signal at a first location and a second predicted direct arrival signal at a second location can be determined. The first location corresponds to a seismic receiver and the second location does not correspond to a seismic receiver. A transfer function can be determined based on the first predicted direct arrival signal at the first location and the second predicted direct arrival signal at the second location. An estimated direct arrival signal at the second location can be determined based on the transfer function and a measurement by the seismic receiver corresponding to the first location. The estimated direct arrival signal represents what a measured direct arrival signal would be at the second location.