Page 414 - Acquisition and Processing of Marine Seismic Data

CHAPTER

8

CDP Sort and Binning

OUTLINE

8.1 CDP Geometry 405 8.3 Binning in 3D 411
8.2 CDP Fold 409 8.4 QC in Sort and Binning 415

Seismic data consists of specific signals of process is known as CDP sorting, which requires
earth response, generated by an acoustic source, trace geometry to be defined prior to the sort
propagated through the subsurface, and process. Seismic recording with the CDP
recorded at the receiver locations. Considering method was realized in the 1950s and it signifi-
a pair of point source and receiver geometry, a cantly improved the quality or signal-to-noise
particular time sample on a seismic trace in a ratio (S/N) of the seismic data. In the stacking,
seismic line can be defined by three quantities: the traces in each CDP gather are linearly
summed up after normal moveout (NMO) cor-
• Location of source
rection so that each CDP becomes a stacked
• Location of receiver
trace. Each trace in a CDP contributes to increase
• Recording time of seismic sample
the S/N of this trace, and the S/N is directly pro-
Seismic data is collected in source-receiver portional to the square root of the number of
coordinates; however, the recorded trace is traces in a CDP gather.
reflected from the midpoint of source and
receiver, assuming a horizontal seabed and sub-
bottom layers. The source-receiver midpoint is 8.1 CDP GEOMETRY
termed the common depth point (CDP), provid-
ing a horizontal layered earth. After assigning For multichannel seismic acquisition, several
the geometry to the seismic data, traces from traces reflected from the same midpoint location
the same reflection point are collected in a on the seabed as well as subbottom layers are
group, which is termed a CDP gather and this recorded. Although these traces originate from

Acquisition and Processing of Marine Seismic Data 405 # 2018 Elsevier Inc. All rights reserved.
https://doi.org/10.1016/B978-0-12-811490-2.00008-6