Distributed Seismic Sources for Wider Common Midpoint Width
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Solution Overview
Problem
Geophysical surveys in marine environments face challenges with seismic energy attenuation and limited common midpoint width, especially in shallow water and for shallow underground reflectors, due to the attenuation of higher frequency seismic energy and the inability to effectively utilize outer sensor streamers.
Innovation Solution
A marine geophysical survey system that distributes seismic sources into high-frequency, mid-frequency, and low-frequency sources across the width of a streamer spread, with varying source densities, allowing for a wider common midpoint width and improved signal coverage by optimizing source placement and towing configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If seismic sources are concentrated in a single location, then towing force requirements are reduced, but common midpoint width is limited and outer sensor streamers cannot be effectively utilized
Solution Approach 1:
The patent divides the seismic source into multiple distributed sources (high-frequency, mid-frequency, and low-frequency sources) positioned at different locations across the streamer spread. This segmentation allows the common midpoint width to be extended to utilize outer sensor streamers while distributing the towing force requirements across multiple smaller units rather than one large concentrated source
Solution Approach 2:
The patent transitions from a single-point source configuration to a distributed linear array of sources across the width of the streamer spread. This dimensional change from concentrated to distributed positioning enables simultaneous achievement of wider common midpoint coverage and reduced individual towing force requirements through spatial distribution
2Measurement precision
If high-frequency seismic sources are used, then resolution of shallow reflectors is improved, but attenuation of seismic energy increases in shallow water
Solution Approach 1:
The patent applies different source types (high-frequency, mid-frequency, low-frequency) at different positions across the streamer spread, matching source characteristics to local survey requirements. High-frequency sources are positioned to target shallow reflectors where resolution is critical, while low-frequency sources handle deeper targets where attenuation is less of a concern
Solution Approach 2:
The patent changes the frequency parameter of seismic sources based on position and target depth. By using a combination of high-frequency sources for shallow imaging and low-frequency sources for deeper penetration, the system optimizes the frequency parameter to balance resolution requirements against attenuation losses in different survey zones
3Reliability
If source density is increased across the streamer spread, then signal coverage is improved, but towing complexity and force requirements increase
Solution Approach 1:
The patent implements varying source densities at different positions across the streamer spread, with higher density in zones requiring better signal coverage and lower density where coverage is sufficient. This localized optimization improves overall signal reliability without uniformly increasing complexity across the entire spread
Solution Approach 2:
The patent applies a pragmatic approach to source density by distributing sources sufficiently to achieve adequate signal coverage without over-densifying the array. This partial action approach provides acceptable signal reliability while avoiding the exponential increase in towing complexity that would result from excessive source density
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 enhances the effective width of seismic surveys, reduces data gaps, and improves signal quality by distributing seismic sources to minimize attenuation and towing force issues, thereby increasing the usable near-source receiver offset and data quality.
Implementation Method 1
seismic sources... producing seismic energy... sensors... detect energy reflected from underground formations
Implementation Method 2
detect energy reflected from underground formations below the water bottom
Data Source
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AI summary
Marine geophysical surveys with distributed seismic sources. At least some of the example embodiments are methods including performing a marine geophysical survey by: towing a plurality of high-frequency sources spread along a width of an array of sensors, the high-frequency sources having a first source density with respect to the width; and towing a plurality of mid-frequency sources spread along the width, the mid- frequency sources have a second source density with respect to the width, the second source density lower than the first source density; and towing a low-frequency source along the width; activating the high-frequency, mid-frequency, and low-frequency sources.