Full Wavefield Inversion Using Time Varying Filters
First Claim
1. A method for inverting measured seismic data to infer a physical property model of a subsurface region, comprising successively updating the model by performing iterative, multi-scale inversion of the measured seismic data on a computer using local-minimum optimization of an objective function that computes misfit between model-simulated seismic data and the measured seismic data, wherein a changing low-pass filter, hereinafter called the filter, is used to successively alter the objective function from scale to scale by filtering the measured and simulated seismic data in the misfit computation, said filter being time-varying wherein the filter'"'"'s low-pass cutoff frequency varies with traveltime of the seismic data being filtered at one or more scales of the inversion.
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Abstract
An improved method for reducing the accuracy requirements on the starting model when performing multi-scale inversion of seismic data (65) by local objective function optimization (64). The different scales of inversion are brought about by incorporating a low-pass filter into the objective function (61), and then decreasing the amount of high-frequency data that is filtered out from one scale to the next. Moreover, the filter is designed to be time varying, wherein the filter'"'"'s low-pass cutoff frequency decreases with increasing traveltime of the seismic data being filtered (62). The filter may be designed using Pratt'"'"'s criterion for eliminating local minima, and performing averages (or other statistical measure) of the period and the traveltime error only with respect to source and receiver location but not traveltime (63).
140 Citations
23 Claims
- 1. A method for inverting measured seismic data to infer a physical property model of a subsurface region, comprising successively updating the model by performing iterative, multi-scale inversion of the measured seismic data on a computer using local-minimum optimization of an objective function that computes misfit between model-simulated seismic data and the measured seismic data, wherein a changing low-pass filter, hereinafter called the filter, is used to successively alter the objective function from scale to scale by filtering the measured and simulated seismic data in the misfit computation, said filter being time-varying wherein the filter'"'"'s low-pass cutoff frequency varies with traveltime of the seismic data being filtered at one or more scales of the inversion.
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21. A computer program product, comprising a computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method for full wavefield inversion of measured data to infer a model of a propagating medium for the wavefield, said method comprising:
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successively updating the model by performing iterative, multi-scale inversion of the measured data using local-minimum optimization of an objective function that computes misfit between model-simulated data and the measured data; wherein a changing low-pass filter, hereinafter called the filter, is used to successively alter the objective function from scale to scale by filtering the measured and simulated data in the misfit computation, said filter being time-varying; wherein the filter'"'"'s low-pass cutoff frequency varies with wavefield traveltime through the medium corresponding to the data being filtered at one or more scales of the inversion. - View Dependent Claims (22, 23)
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Specification