FWI and Seismic Stack Integration for Reservoir Characterization
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Solution Overview
Problem
Current methods for characterizing subsurface reservoirs, such as full wavefield inversion (FWI) and seismic stacks, face limitations in accurately inferring petrophysical rock properties like porosity and shale content due to computational costs and ambiguous angle definitions, especially in complex geologies like sub-salt reservoirs, leading to compromised property estimation.
Innovation Solution
A computer-implemented method integrating a full wavefield inversion (FWI) solution with a non-FWI solution over extended bandwidths, combining FWI properties with non-FWI properties to generate a model estimate, comparing it with statistical or rock physics models, and iteratively refining it to improve accuracy beyond the limited FWI bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full wavefield inversion (FWI) is used to characterize subsurface reservoirs, then measurement precision of petrophysical properties is improved, but computational cost increases and bandwidth is limited
Solution Approach 1:
The patent segments the bandwidth into different frequency ranges, applying FWI to lower frequencies where it is computationally feasible and effective, while using alternative methods for higher frequencies. This segmentation allows the system to achieve broad bandwidth coverage without requiring computationally prohibitive full-bandwidth FWI, thus resolving the contradiction between measurement precision and computational complexity.
Solution Approach 2:
The patent applies FWI partially, only to the frequency band where it provides significant benefit and remains computationally manageable. By using FWI for lower frequencies and complementary methods for higher frequencies, the system achieves sufficient overall accuracy without the excessive computational cost of applying FWI across the entire bandwidth, resolving the trade-off between precision and computational complexity.
2Measurement precision
If FWI bandwidth is extended to improve property estimation, then measurement precision is improved, but computational cost increases
Solution Approach 1:
The patent segments the frequency bandwidth into lower and higher frequency components, applying computationally intensive FWI only to the lower frequency range where it is most effective. For higher frequencies, it uses alternative processing methods that consume less computational energy. This segmentation enables extended bandwidth coverage with improved precision while controlling computational energy consumption.
Solution Approach 2:
The patent changes the processing parameters by switching between different methods (FWI vs. non-FWI) based on frequency band. This parameter change allows the system to achieve extended bandwidth and improved precision while managing computational energy consumption by using the most efficient method for each frequency range.
3Device complexity
If conventional seismic inversion is used, then device complexity is reduced, but reliability of property estimation deteriorates due to ambiguous angle definitions in complex geologies
Solution Approach 1:
The patent introduces FWI as an intermediary method that operates in the frequency domain to bypass the ambiguous angle definition problem that plagues conventional seismic inversion in complex geologies. By using FWI for lower frequencies and combining it with non-FWI methods for higher frequencies, the system achieves reliable property estimation without requiring complex angle-based processing, thus resolving the contradiction between simplicity and reliability.
Data Source
AI summary
A computer-implemented method for integrating a full wavefield inversion (FWI) solution with a non-FWI solution. Computational costs for generating a large bandwidth FWI solution, such as to 50 Hz, may be considerable. However, limiting the FWI solution to a narrower frequency band, such as up to 20 Hz, renders the FWI solution less useful. To remedy this, an FWI solution that is band limited, such as up to 20 Hz, is integrated with a non-FWI solution. The non-FWI solution may comprise seismic stacks or non-seismic data, and is directed to a different frequency band, with at least part of the non-FWI solution frequency band being greater than 20 Hz. In this way, bandwidth extension may be performed for at least one subsurface physical property parameter by combining a band limited FWI solution with a non-FWI solution.