CMP Traveltime Approximation in 3D Media as a Function of Wavefront Attributes

In seismic data processing and analysis the construction of an accurate and reliable traveltime moveout formula is of prime importance owing to its use in producing stacked sections. The most famous moveout expression is the normal moveout (NMO) intended to describe the traveltime reflections of common-midpoint (CMP) data. In this paper we present a new 3-D traveltime moveout time correction formula as a function of wavefront attributes such as the velocity of wave propagation near the earth's surface, two principal wavefront curvatures, azimuth angle and refervxe velocity. The formula is a traveltime approximation based second-order Taylor series expansion around a reference ray. Being a function of three parameters, the traveltime formula presented is expected to provide a better approximation than the conventional CMP NMO time correction. This formula was obtained by manipulating geometrical properties of the wavefront, adapting the principles of differential geometry and using the eikonal equation only . Using synthetic examples, we comment on the performance of this traveltime formula.