Marine Seismic Source Blending with Random Timing
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Solution Overview
Problem
Seismic data acquisition using blended sources faces challenges in separating individual seismic sources due to overlapping reflections, particularly in wide-azimuth towed streamer surveys, which complicates subsurface imaging and increases costs.
Innovation Solution
A method involving the use of multiple seismic sources activated at random times, with overlapping shots separated using an inversion-type process, allowing for faster and more cost-effective seismic surveys by making interference between sources incoherent while maintaining coherent reflections from each source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple seismic sources are activated simultaneously or with overlapping timing to increase productivity, then the survey speed improves, but the difficulty of separating individual source reflections increases
Solution Approach 1:
The patent applies periodic action by using random time delays between source activations. Multiple seismic sources are activated in a periodic sequence with randomized timing intervals, allowing the sources to overlap in time while maintaining distinguishable patterns. This periodic activation with random timing enables faster survey acquisition while preserving the ability to separate individual source contributions through pattern recognition in the overlapping reflections.
2Measurement precision
If random time delays are introduced between source activations to make interference incoherent, then source separation becomes easier, but the complexity of the acquisition process increases
Solution Approach 1:
The patent applies parameter changes by modifying the time delay parameter between source activations. Instead of using fixed or zero time delays, the system introduces random time delay values that change from one source activation sequence to another. This parameter variation transforms the coherent interference pattern into an incoherent one, making source separation easier while managing complexity through controlled randomness in the timing parameter.
3Measurement precision
If conventional sequential source activation is used to maintain clear source separation, then measurement precision is maintained, but productivity decreases due to slower acquisition
Solution Approach 1:
The patent applies merging by combining multiple seismic source activations within overlapping time windows. Instead of strictly sequential activation, the system merges the output of multiple sources that are activated with random time delays, allowing their reflections to overlap in the recorded data. This merging approach enables parallel processing of multiple sources, significantly increasing survey speed while the random timing patterns preserve source separation capability.
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 enables faster and cheaper seismic data acquisition, potentially providing better resolution and improving the chances of discovering economic hydrocarbon deposits by effectively separating overlapping seismic sources.
Implementation Method 1
The source of the down-going sound energy might come, for example, from explosions or seismic vibrators on land, or air guns in marine environments. Each time the source is activated, it generates a seismic signal that travels downward through the earth, is reflected, and, upon its return, is recorded at a great many locations on the surface.
Implementation Method 2
waiting a random length of time following the first seismic source activation and then activating the second seismic source where the random length of time is selected such that recorded seismic energy from said second source activation interferes with recorded seismic energy from the first source activation
Data Source
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AI summary
This is a method of acquiring marine wide azimuth towed streamer seismic data. Preferably, a recording boat which tows a plurality of seismic streamers and at least one source may be accompanied by a plurality of source boats that each tow at least one source. The source boats may preferably activate their respective sources such that the subsurface reflections generated by each source interfere. The time separation between successive shots may preferably be a random variable related to the lowest frequency of interest in the data. Additionally, the source boats may preferably be alternatively fired from the head and tail of the recording streamers.