Subsurface Imaging Wave Field Separation via Coherent Energy Analysis
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Solution Overview
Problem
Current subsurface imaging methods using multiple seismic sources face challenges in accurately separating and refining wave fields, leading to incomplete or noisy subsurface images due to overlapping wave fields from multiple sources with varying time delays.
Innovation Solution
The method involves organizing signals from multiple firing sequences into gathers, processing these to form initial estimates of wave fields, and then refining them by separating the contributions of each source using coherent/incoherent energy separation techniques, allowing for the derivation of a more accurate subsurface image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple seismic sources are employed to expedite the survey process, then productivity is improved, but wave field separation accuracy deteriorates due to overlapping wave fields
Solution Approach 1:
The patent divides the complex wave field into separate source components by segmenting the signal based on coherent energy patterns. Each seismic source contribution is isolated into distinct wave field estimates through coherent/incoherent separation, allowing individual source effects to be analyzed independently despite simultaneous activation.
Solution Approach 2:
The patent employs an iterative refinement process where initial wave field estimates are used to generate correction terms that are fed back into the separation algorithm. This feedback loop continuously improves the accuracy of source separation by using the results of previous iterations to enhance subsequent separations.
2Productivity
If multiple seismic sources are actuated with variable time delays, then survey efficiency is improved, but signal coherence and separation reliability deteriorate
Solution Approach 1:
The patent changes the temporal parameters of the seismic sources by actuating them with variable time delays between successive firings. This parameter variation creates distinguishable wave field patterns that can be separated through coherent energy analysis, allowing multiple sources to be activated simultaneously while maintaining separability.
Solution Approach 2:
The patent employs dynamic adjustment of source activation timing and iterative refinement of wave field estimates. The system adaptively adjusts processing parameters based on the variable time delay patterns, enabling reliable separation despite the dynamic and varying nature of the source actuation sequence.
3Loss of time
If initial wave field estimates are used without refinement, then processing time is reduced, but image accuracy deteriorates
Solution Approach 1:
The patent performs preliminary coherent/incoherent separation to generate initial wave field estimates quickly, then applies refinement only to the critical components. This preliminary action provides a rapid first pass that can be visually inspected and adjusted, balancing processing speed with final accuracy requirements.
Solution Approach 2:
The patent applies full refinement only when necessary, using partial refinement for most cases. The iterative process can be stopped early when sufficient accuracy is achieved, avoiding unnecessary computational effort while maintaining adequate image quality for the specific application requirements.
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 accuracy and clarity of subsurface imaging by effectively separating and refining wave fields from multiple sources, resulting in improved subsurface structure visualization.
Implementation Method 1
The seismic waves propagate from a source down into the earth and reflect from boundaries between subsurface structures. Surface receivers detect and record reflected seismic waves
Implementation Method 2
The seismic waves propagate from a source down into the earth and reflect from boundaries between subsurface structures
Implementation Method 3
processing these to form initial estimates of wave fields, and then refining them by separating the contributions of each source using coherent/incoherent energy separation techniques
Data Source
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AI summary
A disclosed subsurface imaging method begins by obtaining initial signals from a geophysical survey that has been acquired with multiple geophysical energy sources actuated in a plurality of firing sequences, each sequence having a known time delay between the firing times of each source. The initial signals are grouped into gathers of signals acquired from multiple firing sequences. For each gather, initial estimates of the first and second source wave fields are determined. Quieted signals for the first source are then generated to represent the initial signals minus a current estimate of the second source wave field. A coherent energy separation operation is applied to the quieted signals to obtain a refined estimate for the first source wave field.