Seismic imaging of Foothills structures: A numerical and field data study of the effects of statics on pre-stack depth migration (Alberta)

Seismic imaging in the southern Alberta Foothills can be difficult due to effects associated with topography, thrust fault and fold geometries, and velocity variations resulting from a variable near-surface low velocity layer and variable subcropping units.; Numerical models were generated to replicate two Foothills structures; a fault-bend fold and a fault-propagation fold. The models are used to address imaging concerns related to: (a) impact of the low-velocity layer on imaging quality; (b) the effects of structural scale on interpretation; and (c) impact of noise on both imaging quality and interpretability.; A field data study was completed on a 2D line in the Foothills to determine the effects of the near surface on pre-stack depth migration. Two static correction methods were employed; (a) generalized linear inversion and (b) tomostatics. These methods determined that an accurate statics solution coupled with pre-stack depth migration from topography, yielded a seismic image that is inferior to that obtained by incorporating the low-velocity layer into the depth velocity model, followed by pre-stack depth migration from topography.