Marine Seismic Source Configuration for 4D Repeatability
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Solution Overview
Problem
In marine seismic surveys, achieving repeatability while adopting new surveying techniques or equipment to improve efficiency and data quality is challenging, as it often undermines the consistency needed for effective 4D surveying by introducing changes that reflect survey methods rather than subsurface changes.
Innovation Solution
The use of asymmetric or symmetric source configurations, transitioning from dual to triple source layouts, and employing additional shot points and dithering patterns in monitor surveys to enhance crossline resolution and data quality while maintaining repeatability by replicating or modifying baseline survey configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If new surveying techniques or equipment are adopted to improve efficiency and data quality, then productivity and measurement precision are improved, but repeatability deteriorates due to changes in survey methods
Solution Approach 1:
The survey area is divided into multiple zones with different source configurations. Some zones use traditional dual-source layouts to maintain repeatability, while other zones employ triple-source or asymmetric configurations to improve data quality and efficiency. This segmentation allows simultaneous achievement of both goals.
Solution Approach 2:
Different regions of the survey area are assigned different source configurations based on local requirements. Areas where repeatability is critical use conventional setups, while areas benefiting from enhanced resolution use advanced configurations. This local optimization resolves the contradiction between improvement and consistency.
2Measurement precision
If source configurations are changed to improve crossline resolution, then measurement precision is improved, but repeatability deteriorates due to deviation from baseline survey
Solution Approach 1:
Asymmetric source configurations are employed in monitor surveys to achieve improved crossline resolution. By strategically positioning sources at asymmetric locations relative to the baseline survey, the patent enhances measurement precision while maintaining sufficient repeatability for meaningful 4D comparison.
Solution Approach 2:
The patent introduces additional source positions (third source) beyond the traditional dual-source baseline configuration. This dimensional expansion from two sources to three or more sources enables improved crossline resolution while maintaining repeatability through careful selection of source positions that preserve baseline comparability.
3Measurement precision
If additional shot points are employed to enhance data quality, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The additional sources and shot points serve multiple functions: they improve crossline resolution, provide redundant data for quality enhancement, and maintain repeatability when configured appropriately. This multi-functionality justifies the increased complexity by delivering multiple benefits from the additional equipment.
Data Source
AI summary
Methods and apparatus are described for performing a 4D monitor marine seismic survey that repeats a previous survey. A number of sources may be used during the 4D monitor survey that differs from a number of sources that were used during the previous survey. Shot points from the previous survey are repeated by the 4D monitor survey, and additional shot points may be produced during the 4D monitor survey that were not produced during the previous survey. Embodiments enable efficiency and data quality improvements to be captured during 4D survey processes, while preserving repeatability.