Marine Seismic Source Dithering for Low-Coherence Deblending
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Solution Overview
Problem
Blended marine seismic acquisition requires improved methods for specifying source activation times to enhance the quality and efficiency of deblending processes, as current random dither value sequences exhibit coherence that interferes with the separation of reflection energies from different sources.
Innovation Solution
A deterministic approach to generate dither value sequences by quantifying randomness and separation using global and local measures, reducing coherence and improving the deblending process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If random dither value sequences are used for source activation times, then source activations can be performed in blended acquisition, but coherence in the dither sequences interferes with the separation of reflection energies from different sources
Solution Approach 1:
The patent transforms the dither value sequences from random to deterministic by applying specific mathematical transformations (phase rotations, frequency shifts, time-reversal) to the random sequences. This parameter change eliminates coherence while preserving the statistical properties needed for blended acquisition, thereby resolving the contradiction between maintaining productivity and improving measurement precision in deblending operations.
2Loss of time
If source activations occur closely in time in blended acquisition, then the duration of data acquisition is shortened, but deblending becomes more difficult due to overlapping reflections
Solution Approach 1:
The patent applies preliminary transformations to the dither sequences before data acquisition to ensure that the sequences have minimal coherence properties. By pre-processing the dither values with deterministic transformations, the system prepares the activation pattern in advance to facilitate easier deblending, thus reducing both acquisition time and deblending complexity.
3Manufacturing precision
If more shot points are performed over a given survey area in the same amount of time, then survey data quality increases, but the coherence in random dither sequences reduces deblending effectiveness
Solution Approach 1:
The patent generates deterministic dither sequences by applying transformations to base random sequences, effectively creating optimized copies of the original random patterns. These copied sequences retain the statistical variability needed for high-quality survey data while eliminating the coherence that hinders source energy separation, thus resolving the contradiction between survey data quality and source energy separation.
Data Source
AI summary
A system and method controls impulsive source activations in a blended acquisition marine seismic survey. A component of the system generates a sequence of dither values deterministically and stores the sequence of dither values, or source activation indicators derived therefrom, in a non-transitory medium readable by a control system operable to execute shot points during the survey responsive to the values stored in the medium. According to some embodiments, generating the dither values comprises iteratively selecting from a fixed set of candidate dither values to produce a candidate sequence of dither values. The selecting is based on evaluating one or more quantitative measures of randomness and one or more quantitative measures of separation exhibited by at least a portion of the candidate sequence of dither values. Generated sequences improve deblending results by reducing coherence exhibited by the dither values in the sequences.