Publication Name: PESA's Eastern Australasian Basin Symposium II
Authors: P.J. Lyon, P.J. Boult, A. Mitchell and R.R. Hillis
Date Published: December 2004
Number of Pages: 29
Reference Type: Book Section
Abstract:
Accurate interpretation of fault geometry is essential to the assessment of fault seal integrity in the Penola Trough, Otway Basin. Fault geometries in the Penola Trough are variable with complex kinematic interactions between younger, Early Cretaceous and older, Late Cretaceous fault populations. This complexity, combined with issues of seismic data quality, makes interpretation of fault geometry particularly difficult.A laterally invariant velocity function was applied to the seismic time data of the area to redisplay the seismic in a form that gives a better representation of depth, here termed 'pseudo-depth' conversion. This technique appears to work well in the Penola Trough where lateral velocity variation, as revealed by well data and stacking velocities, is minimal. This new pseudo-depth seismic data set has shown that many of the apparent listric fault geometries in time data are in fact planar. Pseudo-depth conversion has also improved the clarity of the seismic data and shows almost identical depth matching of structure and horizon interpretation when compared with pre-stack depth-migrated sections.
The insights into fault geometry, which pseudo-depth seismic data provides, is having significant impact on a new structural interpretation of the Penola Trough. Different structural styles and the kinematic relationships of different fault populations are more clearly discernable on pseudo-depth seismic sections. This paper therefore demonstrates how depth conversion of time seismic data has provided a better domain in which to view, analyse and interpret fault geometry than the conventional time domain.