Enhancing Seismic Interpretation with CDP Gathers
Ayorinde Adekanle, John P. Benoit, and Rex A. Hanson
ChevronTexaco, Lagos,
Nigeria
Historically, stacking common midpoint (CMP) data along the offset direction has
been the most frequent method of removing noise from seismic data. Because of this
technique, most seismic interpretation is done using stacked data. More recently,
with the successful use of amplitude variation with offset (AVO) data, limited
angle rather than full stacks are being used in many projects. Interpreters can
take this process an important step further by viewing interpreting the
gathers directly. Inspecting gathers allows deeper understanding of seismic
events and recognition of noise (multiples, residual moveout, imaging problems,
etc.) as well as the AVO response of key reflectors. Amplitude anomalies can only
be understood by referring to the AVO behavior seen in gathers.
Using a technique provided by Jim Magill (ChevronTexaco's Energy Technology Company), Chevron Nigeria Ltd. (CNL) has begun to create projects that organize stacked data and gathers in a convenient way. These projects use the 3D/3D Merge capability in Seisworks to link the gather and stack geometry, so that interpreters can view an event and the pre-stack traces simultaneously. An enhancement of this technique involves using the visualization features of Voxelgeo, to move rapidly manipulate and view the gathers. Key to both techniques is the use of linked cursors in gather and stack space to show the geometrical relationships. The authors strongly encourage CNL interpreters to use these techniques in their work.