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15th Biennial International Conference SPG 2025

Stabilizing FWI with both OBN and streamer seismic data: Implications to exploration in shallow marine carbonates

Published in GEOHORIZONS - 2025

S. P. Das 1, Weizhong Wang 2 , Neha Pandey 1 , Anil Kumar 3 , Nikhil Singh 1, & Puneet Saxena 1, 1GEOPIC, ONGC Dehradun, 2M/s GeoTomo LLC, Houston, 3 SPIC, ONGC Mumbai

Abstract


FWI stability is a primary concern in building an accurate velocity model using seismic waveforms. This study discusses a stabilized workflow using two shallow marine seismic datasets: a conventional streamer dataset and an OBN dataset. The study optimizes the utilization of the two datasets, ensuring accuracy in the estimation process and efficiency in computation and disk space management. A comprehensive workflow is designed with a major focus on reducing cycle-skipping by low-frequency enhancements of the input data and extracted wavelet. The workflow uses refraction and reflection tomography to generate an initial model, a cascaded loop of FWI iterations to stabilize the velocity updates, and a joint traveltime-FWI for the final velocity model. The result indicates a successful delineation of carbonate mounds and compensation of pseudostructures in the pay zone. The study also unearths the possibility of a shallow, high anisotropic layer just below the seafloor, which resulted in potential mismatch of the depth markers in earlier imaging. This study highlights the importance of considering joint datasets and a combination of inversion methodologies to unravel mysteries from a well-acquainted area

Keywords


FWI, OBN, streamer, non-linear refraction tomography, common reflection angle migration, 3D consistent layer-flooding velocity model building.

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