New Zealand Journal of Geology and Geophysics abstracts
Accurate elevation and normal moveout corrections of seismic
reflection data on rugged topography
Jiangping Liu1
Jiangchai Xia2,*
Chao Chen1
Guo Zhang1
1Department of Geophysics
China University of Geosciences
Wuhan, Hubei, 430074, PR China
2Kansas Geological Survey
The University of Kansas
1930 Constant Ave
Lawrence, Kansas 66047, USA
jxia@kgs.ku.edu
*Author for correspondence.
Abstract The application of the seismic reflection
method is often limited in areas of complex terrain. The problem is the
incorrect correction of time shifts caused by topography. To apply
normal moveout (NMO) correction to reflection data correctly, static
corrections are necessary to be applied in advance for the compensation
of the time distortions of topography and the time delays from
near-surface weathered layers. For environment and engineering
investigation, weathered layers are our targets, so that the static
correction mainly serves the adjustment of time shifts due to an
undulating surface. In practice, seismic reflected raypaths are assumed
to be almost vertical through the near-surface layers because they have
much lower velocities than layers below. This assumption is acceptable
in most cases since it results in little residual error for small
elevation changes and small offsets in reflection events. Although
static algorithms based on choosing a floating datum related to common
midpoint gathers or residual surface-consistent functions are available
and effective, errors caused by the assumption of vertical raypaths
often generate pseudo-indications of structures. This paper presents
the comparison of applying corrections based on the vertical raypaths
and bias (non-vertical) raypaths. It also provides an approach of
combining elevation and NMO corrections. The advantages of the approach
are demonstrated by synthetic and real-world examples of multi-coverage
seismic reflection surveys on rough topography.
Keywords seismic; elevation correction; normal
moveout; velocity analysis
G04045; Received 30 November 2004; accepted 8 July 2005; Online
publication date 13 October 2005
New Zealand Journal of Geology & Geophysics, 2005, Vol. 48:
707–716
0028–8306/05/4804–0707 © The Royal Society of New Zealand 2005
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