  Surface-consistent deconvolution is a standard processing technique in land
data to uniformize the wavelet across all sources and receivers. The required
wavelet estimation step is generally done in the homomorphic domain since this
is a convenient way to separate the phase and the amplitude spectrum in a
linear fashion. Unfortunately all surface-consistent deconvolutions make a
minimum-phase assumption which is likely to be sub-optimal. Recent developments
in statistical wavelet estimation demonstrate that nonminimum wavelets can be
estimated directly from seismic data, thus offering promise to create a
nonminimum phase surface-consistent deconvolution approach. Unfortunately the
major impediment turns out to be phase unwrapping. In this paper we review
several existing phase unwrapping techniques and discuss their advantages and
inconveniences.
