A hybrid local Born/Rytov Fourier migration method: Implementation of a stable scheme
- Los Alamos National Lab., NM (United States). Earth and Environmental Sciences Div.
- Conoco, Inc., Ponca City, OK (United States)
Two efficient Fourier migration methods termed the extended local Born Fourier (ELBF) method and the extended Rytov Fourier (ELRF) method were developed recently for imaging 3D complex structures. They are based on local applications of Born and Rytov approximations within each marching interval. The ELBF method becomes unreliable when the lateral slowness variations are large and/or the frequency is high, while the ELRF method is reliable for these cases. However, the ELRF method is approximately 30--40% slower than the ELBF method because the ELRF method requires one more step where exponentials of complex numbers are calculated than the ELBF method during wave extrapolation within each marching interval. The authors investigate the stability condition of the ELBF method and propose an implementation scheme using variable marching intervals to make the ELBF method stable for all lateral slowness variations and frequencies. The variable marching interval depends on the lateral slowness variations within a given extrapolation region and the frequency, and consequently, the computational time of the ELBF with variable marching intervals increases with the lateral slowness variation and frequency. To take advantage of the faster computational speed of the ELBF method compared to the ELRF method and the better stability feature of the ELRF method than the ELBF method, the authors propose a hybrid local Born/Rytov Fourier migration method. In the hybrid method, the ELBF method is used for regions with small lateral slowness variations and/or low frequencies, otherwise, the ELRF method is used. Two synthetic datasets for complex structures are used to demonstrate the capabilities of the ELBF with variable marching intervals and the hybrid method for imaging complex structures with strong lateral slowness variations. Computational speeds of the split-step Fourier method, ELRF method, hybrid method, and ELBF method with single marching interval and variable marching intervals are compared with each other. The results demonstrate that the hybrid method can save more than 10% of the CPU time required by the ELRF method.
- Research Organization:
- Los Alamos National Lab., Earth and Environmental Sciences Div., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 677168
- Report Number(s):
- LA-UR-98-2067; CONF-980731-; ON: DE99000769; TRN: AHC29821%%303
- Resource Relation:
- Conference: 43. international symposium on optical science, engineering, and instrumentation, San Diego, CA (United States), 19-24 Jul 1998; Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
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