Marine Seismic Source Array Azimuth Distribution
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Solution Overview
Problem
Current seismic data acquisition methods, including wide-azimuth and rich-azimuth surveys, face challenges in achieving accurate and high-resolution subsurface imaging due to poor azimuth distribution and ghost reflections, which affect the final image quality.
Innovation Solution
The proposed system involves a streamer vessel towing plural streamers with a central source and multiple source vessels positioned along the traveling direction, including front and large offset sources, with specific offset distances and configurations to enhance azimuth distribution and illumination, such as parallel, dovetail, or asymmetric arrangements, allowing for simultaneous or sequential activation of sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional source array placement in front of streamers is used, then the acquisition system is simple to operate, but the azimuth distribution is poor
Solution Approach 1:
The source array is segmented into multiple independent source vessels positioned at different locations (front, large offset front, and other positions) relative to the streamers. Each source vessel can be independently controlled and activated, allowing for optimized azimuth distribution without requiring a single complex source configuration.
Solution Approach 2:
The source vessels are positioned in multiple dimensions relative to the streamers, including front sources at various cross-line offsets and large offset front sources. This multi-dimensional arrangement creates comprehensive azimuth coverage by distributing sources across different spatial positions rather than a single linear arrangement.
2Measurement precision
If wide-azimuth acquisition with multiple sources and streamers is used, then substructure illumination is improved, but ghost reflections and notches affect the final image
Solution Approach 1:
Different source vessels are positioned at specific locations optimized for their function: front sources for primary illumination and large offset front sources for extended azimuth coverage. Each source location is strategically chosen to minimize ghost reflections while maximizing subsurface illumination in specific areas, creating local optimization of image quality.
Solution Approach 2:
The source array configuration uses asymmetric positioning of sources relative to the streamers, with sources placed at unequal offsets and distances. This asymmetric arrangement helps break the symmetry that causes ghost reflections and notches, thereby improving the final image quality by reducing these harmful artifacts.
3Measurement precision
If rich-azimuth acquisition with multi-azimuth shooting is used, then azimuth coverage is improved, but the number of passes and sources increases
Solution Approach 1:
Multiple source vessels are merged into a single coordinated system that operates simultaneously. The front sources, large offset front sources, and other source vessels can be activated in combination during the same survey pass, merging their contributions to achieve rich azimuth coverage without requiring multiple separate passes, thereby improving acquisition efficiency.
Solution Approach 2:
The source vessels are pre-positioned at optimal locations before the survey begins, with front sources and large offset front sources placed at predetermined cross-line offsets. This preliminary positioning allows for immediate azimuth coverage during the survey without requiring repositioning or multiple passes, maintaining productivity while achieving comprehensive azimuth coverage.
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 configuration improves the accuracy and resolution of seismic data acquisition by providing enhanced azimuth coverage and offset distribution, reducing ghost reflections and improving the overall quality of the subsurface image.
Implementation Method 1
The seismic waves generated by the source arrays propagate downward and penetrate the seafloor, eventually being reflected by a reflecting structure (not shown) back to the surface
Implementation Method 2
The reflected seismic waves propagate upwardly and are detected by detectors provided on the streamers 14
Implementation Method 3
The reflected seismic waves propagate upwardly and are detected by detectors provided on the streamers 14
Data Source
AI summary
Method and system for improving offset/azimuth distribution. The system includes plural streamers towed by a streamer vessel; a central source towed by the streamer vessel; first and second front sources located in front of the plural streamers along a traveling direction of the streamer vessel; and first and second large offset front sources located in front of the first and second front sources along the traveling direction. The offset distance between the first and second large offset front sources, along a cross-line direction, is larger than an offset distance between the first and second front sources.