Seismic Source Geometry With Variable Shot Spacing for Continuous Surveys
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Solution Overview
Problem
Existing seismic data acquisition methods, particularly in marine surveys, are inefficient due to linear shooting patterns that lead to spatial discontinuities in sampling, requiring multiple vessels and being prone to artifacts in the final image, and are challenging in obstructed areas with ocean currents.
Innovation Solution
Deploying seismic receivers in laterally spaced lines and using a seismic energy source that traverses a path circumscribing a center with varying distances and directions, allowing for variable source spacing to optimize sampling density and reduce line change times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear shooting patterns are used with constant source spacing, then the survey geometry is simple to implement, but spatial discontinuities in sampling occur leading to artifacts in the final image
Solution Approach 1:
The patent applies parameter changes by varying the source spacing along the survey line. Instead of using constant source spacing, the invention implements variable source spacing where the distance between successive sources changes according to a predetermined pattern. This allows denser sampling in certain areas and sparser sampling in others, eliminating spatial discontinuities while maintaining survey efficiency. The variable spacing parameter is optimized to provide uniform spatial sampling coverage.
Solution Approach 2:
The patent implements dynamics by transitioning from static constant spacing to dynamic variable spacing. The source positions are determined by a variable spacing function that adapts the distance between sources based on their position along the survey line. This dynamic approach allows the survey geometry to optimize sampling density continuously along the line, preventing the spatial discontinuities that occur with constant spacing.
2Productivity
If multiple vessels are used to acquire simultaneous lines of data, then productivity increases, but device complexity and cost increase
Solution Approach 1:
The patent applies segmentation by dividing a single survey line into multiple segments acquired by one vessel. Instead of using multiple vessels to acquire simultaneous lines, the invention uses one vessel to acquire multiple lines sequentially with optimized variable spacing that effectively samples the same area that would require multiple vessels. This segmentation approach maintains productivity while reducing the number of vessels needed.
Solution Approach 2:
The patent implements universality by making a single vessel perform the function that would otherwise require multiple vessels. The variable spacing technique allows one vessel to achieve the same sampling coverage and data quality that would require multiple vessels using constant spacing, thereby reducing device complexity and operational cost while maintaining productivity.
3Ease of manufacture
If constant source spacing is used, then the survey geometry is simple to design, but line change time increases reducing survey efficiency
Solution Approach 1:
The patent applies parameter changes by implementing variable source spacing that optimizes the transition between survey lines. The spacing parameter varies along the line to position sources more efficiently near line turnarounds, reducing the distance the vessel must travel during line changes. This variable spacing parameter is designed to minimize non-productive line change time while maintaining adequate sampling density.
Solution Approach 2:
The patent implements preliminary action by pre-planning the variable spacing pattern along each survey line to anticipate and optimize line change positions. The spacing is predetermined to position sources in a way that minimizes the vessel's travel distance when transitioning to the next line, effectively preparing the survey geometry in advance to reduce line change time.
4Manufacturing precision
If dense sampling is used throughout the entire survey area, then image quality is maximized, but the total number of shots and time required increases significantly
Solution Approach 1:
The patent applies local quality by implementing variable source spacing that provides denser sampling in certain local areas and sparser sampling in others. The spacing is optimized to provide high sampling density where it is most needed for image quality while reducing density in areas where it is less critical. This local optimization maintains overall image quality while significantly reducing the total number of shots required.
Solution Approach 2:
The patent implements parameter changes by varying the source spacing parameter along the survey line to optimize the balance between sampling density and acquisition time. The spacing parameter is adjusted continuously or in segments to provide adequate sampling for image quality while minimizing the total number of shots. This parameter optimization reduces survey acquisition time while maintaining necessary image quality standards.
Data Source
AI summary
A method for seismic surveying comprises deploying a plurality of seismic receivers proximate an area of subsurface to be surveyed. At least one seismic energy source moves in a path that circumscribes a center, wherein positions of the plurality of seismic receivers remain fixed. At least one of a distance between the path and the center changes monotonically as seismic energy source traverses the path, or the center moves in a selected direction as the seismic energy source traverses the path. The source is actuated at selected times as the at least one seismic energy source traverses the path, such that a spacing between positions of the source along the source path and transverse to the source path varies between successive actuations of the source. Seismic energy is detected at the plurality of seismic receivers resulting from actuating the at least one seismic energy source.