An Interferometric Solution for Non-stationary Shear-wave Statics

Converted-wave data processing requires the computation of shear-wave statics for the receiver side.

Conventionally this is done under the assumption of surface consistency. However, if the velocity change between the low velocity layer (LVL) and the medium underneath is smooth, or if the base of the LVL is structurally complex, the vertical raypath assumption that supports the surface consistent approach is no longer valid. This feature results in a non-stationary change of the statics that needs to be addressed in order to properly solve the problem. In this work the radial-trace (R-T) transform is used for moving the data to a raypath consistent framework where the statics change was showed to be approximately stationary. In this domain traveltime interferometry was applied to retrieve the delays caused by the near surface. Cross-correlation of the delayed traces with a model trace free of statics was showed to return a cross-correlation function that carries the statics information. These functions were convolved with the original traces to remove the delay caused by the near surface. Stacked sections computed using surface-and raypath-consistent solutions showed how the latter one effectively removed the statics by addressing the non-stationarity of the problem.