Geophysical Data Frequency Extrapolation for FWI Cycle Skipping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Full Wavefield Inversion (FWI) methods often fail to accurately represent subsurface structures due to cycle skipping, which occurs when low-frequency data is missing, leading to incorrect hydrocarbon exploration and development decisions.
Innovation Solution
A computer-implemented method that decomposes geophysical data into frequencies and slowness, estimates a filter across known frequencies, extrapolates or interpolates missing frequencies using a Wiener prediction filter, and recomposes the data to generate updated geophysical data, preventing cycle skipping and improving subsurface modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard inversion algorithms are used, then processing is simpler, but low-frequency data is lost leading to cycle skipping
Solution Approach 1:
The patent applies preliminary action by performing frequency extrapolation on the seismic data before the inversion process. The system extrapolates low-frequency components from higher-frequency data using predictive algorithms, thereby preparing the data in advance to prevent cycle skipping during inversion. This preliminary frequency restoration ensures that the inversion algorithm has access to the necessary low-frequency information without requiring actual low-frequency measurements.
2Measurement precision
If FWI is run with no low frequency data, then the residual is zero, but the starting model is incorrect
Solution Approach 1:
The patent introduces an intermediary process between data acquisition and inversion: frequency extrapolation. This intermediary step generates synthetic low-frequency data that acts as a mediator, allowing the inversion to proceed with complete frequency coverage. The extrapolated frequencies serve as a bridge, enabling the inversion algorithm to achieve both zero residual (data matching) and accurate model recovery by providing the missing low-frequency constraints.
3Productivity
If cycle skipping occurs, then inversion converges, but the result is an inaccurate representation of subsurface
Solution Approach 1:
The patent applies preliminary anti-action by preventing cycle skipping before it can occur during inversion. By extrapolating low-frequency components beforehand, the system counteracts the condition that leads to cycle skipping (missing low-frequency data causing traveltime mismatches). This preventive measure ensures that the inversion converges to the correct global minimum rather than a cycle-skipped local minimum, maintaining both productivity and reliability.
Data Source
AI summary
A computer-implemented method for generating missing frequencies within geophysical data, said method including: decomposing, with a computer, geophysical data into frequencies and slowness or wavenumber along time and one or more spatial dimensions; estimating, with a computer, a filter across known frequencies within the geophysical data for each time, spatial dimension, and slowness or wavenumber sample; extrapolating or interpolating, with a computer, the missing frequencies from the known frequencies by applying the filter; recomposing, with a computer, the known frequencies and the missing frequencies back into time and the one or more spatial dimensions; and prospecting for hydrocarbons with geophysical data that includes the missing frequencies.