Variance-based Salt Body Reconstruction
79th EAGE Conference and Exhibition 2017
Seismic inversions of salt bodies are challenging when updating velocity models based on Born approximationinspired gradient methods. We propose a variance-based method for velocity model reconstruction in regions complicated by massive salt bodies. The novel idea lies in retrieving useful information from simultaneous updates corresponding to different single frequencies. Instead of the commonly used averaging of single-iteration monofrequency gradients, our algorithm iteratively reconstructs
... ively reconstructs salt bodies in an outer loop based on updates from a set of multiple frequencies after a few iterations of full-waveform inversion. The variance among these updates is used to identify areas where considerable cycle-skipping occurs. In such areas, we update velocities by interpolating maximum velocities within a certain region. The result of several recursive interpolations is later used as a new starting model to improve results of conventional full-waveform inversion. An application on part of the BP 2004 model highlights the evolution of the proposed approach and demonstrates its effectiveness. Topics: Full Waveform Seismic Inversion, Seismic Imaging -Theory, Velocity and Seismic Velocity Parameter Estimation -Theory Main objectives: Introduce a computationally inexpensive semi-automated method for inverting salt bodies. New aspects covered: We consider updates from different single frequencies through several iterations instead of commonly used single-iteration single-frequency gradients averaging. We propose a computationally inexpensive way to build an initial model for full-waveform inversion from relatively high frequencies.