Marine Seismic Source Firing Sequence for Cross-Line Resolution
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Solution Overview
Problem
Traditional marine seismic data acquisition methods face challenges in reducing the cross-line bin size, which affects the resolution of subsurface imaging, and increasing the number of sources or streamers is not feasible due to cost and operational limitations.
Innovation Solution
Actuating multiple marine acoustic sources in a firing sequence with overlapping activations and varying time delays, allowing for simultaneous or near-simultaneous firing of sources laterally offset from each other, thereby reducing the cross-line bin size and improving coverage without increasing waiting times or the number of streamers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sources is increased to reduce cross-line bin size, then cross-line resolution is improved, but cost and operational complexity increase
Solution Approach 1:
The patent employs periodic action by implementing a flip-flop firing sequence where sources are activated in alternating periods. During one period, the first source fires while the second is inactive; during the next period, the second source fires while the first is inactive. This periodic activation pattern allows multiple sources to be used effectively without requiring all sources to be active simultaneously, thereby reducing operational complexity and cost while maintaining improved cross-line resolution through the reduced bin size.
2Measurement precision
If the number of streamers is increased to reduce cross-line bin size, then cross-line resolution is improved, but cost and drag increase
Solution Approach 1:
The patent applies dimensionality change by shifting the solution from the streamer dimension to the source dimension. Instead of increasing the number of streamers (one dimension), the invention increases the number of sources and uses temporal sequencing in the time dimension. This allows the system to achieve reduced cross-line bin size and improved resolution by manipulating source activation patterns rather than adding more streamers, thereby avoiding the associated costs and drag increases.
3Productivity
If simultaneous firing of multiple sources is used to reduce waiting time, then productivity is improved, but signal separation becomes difficult
Solution Approach 1:
The patent resolves this contradiction by implementing periodic action through the flip-flop firing sequence. Sources are activated in alternating periods rather than simultaneously, which maintains signal separability. The first source fires during its active period while the second is inactive, then they switch. This periodic pattern allows the system to achieve high productivity by minimizing idle waiting time between shots while preserving the ability to separate signals during processing, since each source's contribution occurs during distinct time windows.
Solution Approach 2:
The patent applies preliminary action by pre-planning and pre-coordinating the firing sequence of multiple sources. The system establishes a predetermined flip-flop pattern where the activation timing of each source is carefully scheduled in advance. This preliminary coordination ensures that sources fire in an optimized sequence that minimizes waiting time while maintaining signal separability, allowing the processing system to anticipate and correctly attribute signals from each source based on the known firing pattern.
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 quality of subsurface imaging by reducing data gaps and improving cross-line resolution, allowing for more effective seismic data acquisition with fewer streamers and lower operational costs.
Implementation Method 1
The seismic source is towed by a vessel under water, and the generated acoustic energy propagates toward the subsurface
Implementation Method 2
the generated acoustic energy propagates toward the subsurface where the energy is reflected from various formations of the subsurface
Data Source
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AI summary
System and method for actuating first and second marine acoustic sources in a firing sequence, the firing sequence including at least a first actuation of the first source followed by a first actuation of the second source followed by a second actuation of the first source and a second actuation of the second source. The method includes towing the first source at a depth in water substantially equal to a depth of the second source; establishing a series of reference time instants; actuating the first source with a variable first time delay relative to the series of reference time instants; and actuating the second source with a variable second time delay relative to the series of reference time instants such that time intervals between consecutive activations of the first and second sources are also variable.