Zero Offset Seismic Data from Near-Field Hydrophones
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Solution Overview
Problem
Current marine seismic surveying techniques, particularly in 3D geometries, face challenges in recording zero-offset seismic traces due to source and receiver geometries, leading to obscured subsurface reflections by direct air gun arrivals, which hinders accurate data interpolation and identification of near-surface features.
Innovation Solution
A method that estimates and removes the common signal from near-field hydrophone data recorded by sensors embedded in air gun arrays, treating them as receivers to generate zero-offset seismic data, by computing the median or average signal over a significant spatial distance, thereby isolating the most coherent signals and attenuating direct air gun arrivals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If near-field hydrophones are used to monitor source signature, then source signature verification is improved, but direct air gun arrivals obscure subsurface reflections
Solution Approach 1:
The patent extracts and removes the direct air gun arrival signals from the near-field hydrophone data through signal processing. By identifying and subtracting the common signal component (direct arrivals) from the recorded data, the method isolates the subsurface reflection signals that would otherwise be obscured, enabling both source verification and subsurface imaging.
Solution Approach 2:
The patent converts the harmful direct air gun arrivals into a useful tool for source signature verification. By using the predictable direct arrivals as a reference signal, the method can actually verify source functionality and then subtract this known signal to reveal the useful subsurface reflection data, turning the obstruction into a verification tool.
2Measurement precision
If zero-offset data is recorded, then trace interpolation accuracy is improved, but conventional 3D geometry prevents zero-offset recording
Solution Approach 1:
The patent creates a virtual zero-offset data set by processing near-field hydrophone recordings. Instead of physically positioning receivers at zero offset, the method copies and reconstructs zero-offset traces from the near-field data through signal processing, effectively creating the desired data geometry without changing the physical acquisition setup.
Solution Approach 2:
The patent replaces the mechanical constraint of physical receiver positioning with a signal processing approach. Rather than requiring receivers to be positioned at zero offset to achieve accurate interpolation, the method uses digital signal processing to extract and reconstruct zero-offset traces from near-field data, substituting mechanical positioning requirements with computational methods.
3Quantity of substance
If many shots are used to generate zero-offset volumes, then data density is improved, but acquisition time increases
Solution Approach 1:
The patent makes the near-field hydrophone data serve multiple functions simultaneously. The same near-field recordings used for source signature verification are also processed to generate zero-offset seismic data, eliminating the need for separate acquisition campaigns and maximizing the utility of each shot while building high-density data volumes.
Data Source
AI summary
Method for acquiring zero offset data from a marine seismic survey. Seismic data are recorded using source signature monitor receivers located very near the air guns or other sources (81). The recorded data are sorted into common-source gathers (82). A common trace is computed that is common to each gather (83). The common trace is subtracted from each trace in each gather (84), resulting in approximately zero-offset data.