Fault Shadow Removal over Timor Trough Using Broadband Seismic, FWI and Fault Constrained Tomography

Abstract

Thrust-complex imaging in the Timor Trough suffers from fault shadows due to strong lateral velocity variation. We demonstrate a new workflow to tackle this. Broadband seismic data were acquired with high signal-to-noise ratio for the low frequency content. With broadband input, FWI derived a better velocity model in the shallow water thrust area where the reflection tomography has limitations. Compared to conventional tomography which has difficulty in addressing the sharp velocity boundary properly, fault constrained tomography (FCT) uses the interpreted fault planes as constraint for inversion. FCT also benefited from the better low frequency content in the broadband data which provided better imaging penetration in the severe fault shadows. Broadband seismic and depth imaging with FWI and FCT made a step change in the image quality to improve the understanding of the thrust-complex structures and the underlying potential reservoirs.