Page 468 - Acquisition and Processing of Marine Seismic Data

CHAPTER

10

Normal Moveout

Correction and Stacking

OUTLINE
10.1 Normal Moveout Time 461 10.2 NMO Stretching 469
10.1.1 NMO Time for Single 10.3 Stacking 472
Horizontal Interface 462
10.1.2 NMO Time for Several 10.4 Specific Stacking Methods 475
Horizontal Interfaces 463 10.4.1 Partial Stack 475
10.1.3 NMO Time for Dipping 10.4.2 Median Stack 477
Interfaces 465 10.4.3 Trimmed Stack 480
10.1.4 NMO Corrections for Long 10.4.4 Common Reflection
Offsets 465 Surface Stack 481
10.1.5 NMO Velocity in Azimuthally
10.5 QC in NMO Correction and Stacking 486
Anisotropic Medium 467

In a shot or common depth point (CDP) hyperbola, and equals the difference of arrival
gather, reflection signals arrive earlier at the time t(x) at offset x for a specific reflection and
receivers close to the source point (near offsets) zero-offset arrival time t(0). NMO correction
than the reflections recorded at distal locations removes the normal moveout times of each
(far offsets). The time difference between the reflection hyperbola on every CDP gather, using
arrival time of a reflection at a specified offset the root-mean-square (RMS) velocities obtained
and the zero-offset time of that reflection is from velocity analysis. After NMO correction,
defined as the normal moveout (NMO) time of all primary reflection hyperbolas in the CDPs
that reflection event. The NMO time varies for are expected to be flattened so that all reflection
each receiver for a particular reflection events are repositioned at their zero-offset

Acquisition and Processing of Marine Seismic Data 459 # 2018 Elsevier Inc. All rights reserved.
https://doi.org/10.1016/B978-0-12-811490-2.00010-4