Solving fault-related imaging issues: A case study comparing conventional processing and multiparameter FWI imaging

Abstract Seismic imaging of faulted reservoirs presents a challenging task. Faults cause diffractions that need to be preserved, but their multiples (diffracted multiples) must be attenuated without damaging primaries to avoid a noisy image. Additionally, conventional tomography may not adequately model the complex velocity structure caused by faulting. These fault-related imaging issues were addressed in an offshore Western Australian field, covered by a narrow-azimuth streamer data set, using two strategies. First, conventional seismic data reprocessing was performed with careful noise reduction and fault-guided tomography. The noise reduction process included detailed surface-related multiple elimination model generation and mild premigration Radon demultiple. Fault-guided tomography was performed using interpreted faults as a guide for tomography velocity updates. The results showed significant improvements over existing seismic images. Second, a test was performed to leverage multiparameter full-waveform inversion (FWI) using the full unprocessed wavefield, including refractions, multiples, and intact diffractions, to derive a velocity model and FWI-reflectivity for seismic imaging of faulted reservoirs. The results of multiparameter FWI imaging were comparable, if not superior, to the results from the conventional processing using tomography-based velocity and migration, achieving comparable results in a shorter timeframe. These studies suggest that multiparameter FWI imaging has the potential to serve as an alternative solution with quicker turnaround time to conventional processing for accurately imaging faulted reservoirs.