Visco-acoustic RTM for TTI Seismic Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current seismic data processing methods fail to accurately compensate for visco-acoustic effects in tilted transverse isotropy (TTI) media, leading to inadequate imaging of complex geological regions with strong velocity contrast and substantial attenuation, due to difficulties in estimating the Q factor and lacking a well-established technology for migrating seismic data using visco-acoustic equations.
Innovation Solution
A computer-implemented method and apparatus for reverse time migration (RTM) that compensates for anelastic effects by using a visco-acoustic wave propagation model in a TTI medium, incorporating Q estimation and compensation phases to correct frequency-dependent energy attenuation and phase distortion, employing a two-way wave equation and conjugate medium propagation to stabilize time reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional migration methods treat the underground formation as a lossless acoustic medium, then the device complexity is reduced and ease of manufacture is improved, but the imaging precision deteriorates due to inability to compensate for frequency-dependent energy attenuation and phase distortion
Solution Approach 1:
The patent changes the physical parameters of the wave propagation model by introducing frequency-dependent attenuation coefficients and phase velocity corrections. The visco-acoustic wave equation incorporates frequency-dependent terms that account for energy attenuation and phase distortion, transforming the conventional lossless acoustic model into a visco-acoustic model that accurately represents real geological conditions while maintaining computational feasibility
Solution Approach 2:
The patent introduces an intermediary visco-acoustic wave equation that acts as a bridge between the simple lossless acoustic model and the complex anelastic wave equation. This intermediary model incorporates essential visco-acoustic effects (frequency-dependent attenuation and phase velocity) without requiring full anelastic theory, providing a practical compromise that improves imaging precision while avoiding excessive computational complexity
2Loss of energy
If inverse Q-filtering methods are used to compensate for seismic absorption, then the amplitude attenuation is corrected, but the imaging precision deteriorates because these methods cannot correctly handle real geological complexity and phase distortion
Solution Approach 1:
The patent converts the harmful effects of visco-acoustic propagation (attenuation and phase distortion) into beneficial information by incorporating frequency-dependent attenuation coefficients and phase velocity corrections directly into the migration imaging process. Instead of attempting to reverse these effects after migration, the method uses them to weight and correct the imaging results, transforming the degradation mechanisms into correction factors that enhance imaging precision
Solution Approach 2:
The patent performs preliminary correction for visco-acoustic effects by incorporating frequency-dependent attenuation and phase velocity into the migration imaging process itself. Rather than applying post-migration corrections, the method integrates these corrections during the imaging process, allowing for more accurate reconstruction of subsurface structures by accounting for energy loss and phase distortion as the seismic waves propagate through the earth
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
The method effectively enhances imaging resolution and amplitude preservation by accurately accounting for absorption effects, improving the accuracy of subsurface structure imaging in complex geological settings with strong velocity contrast and attenuation.
Implementation Method 1
using a visco-acoustic wave propagation model in a TTI medium, incorporating Q estimation and compensation phases to correct frequency-dependent energy attenuation and phase distortion
Implementation Method 2
the anelastic effects (e.g., anelastic attenuation, which is characterized by seismic quality factor Q that is inversely proportional to attenuation) cause seismic energy to decrease along the path and wavelet distortion
Implementation Method 3
Waves 22a propagate down toward the seafloor 24 penetrate it and are then partially reflected and/or refracted at interfaces between layers where the wave propagation velocity changes
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A method for survey data processing compensates for visco-acoustic effects in TTI medium in an RTM method. This method employs propagating in conjugate medium to yield correct phase, and acoustic wave propagation to yield correct amplitudes through adaptive matching filtering.