Abstract
Wide-angle multicomponent ocean-bottom cable (OBC) data should further
enhance sub-basalt imaging by using both compressional and converted
shear wavefields. The first step in analysing multicomponent OBC
data is to decompose the recorded wavefields into pure P- and pure
S-wavefields, and extract the upgoing P- and S-waves. This paper
presents a new scheme to separate P- and S-wavefields from wide-angle
multicomponent OBC data in the tau-p domain. By considering plane-wave
components with a known horizontal slowness, the P- and S-wavefields
are separated into the directions of observed P- and S-wave oscillations
using the horizontal and vertical components of the data. The upgoing
P- and S-waves are then extracted from the separated P- and S-wavefields.
The parameters used in the separation are the seismic wave velocities
and the density at the receiver location, which can be estimated
from the first reflection phase observed on the horizontal and vertical
components. Numerical tests on synthetic data for a plane-layered
model show good performance and demonstrate the accuracy of the scheme.
Separation of wavefields from a basalt model is performed using synthetic
wide-angle multicomponent OBC data. The results show that both near-offset
and wide-angle reflections and conversions from within and below
basalt layers are enhanced and clearly identified on the separated
wavefields.
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