My PhD Thesis, PDF 3MB - Stanford University

Chapter 4
Attenuation Estimation Using the Centroid
Frequency Shift Method
In the previous two chapters, two forward modeling methods are developed to
simulate elastic waves in complex boreholes. Because of their efficiency, stability, and
accuracy, these new approaches have many applications to borehole seismic problems.
In the following chapters, I apply these methods to investigate seismic attenuation
estimation from borehole seismic data.
It has long been believed that attenuation is important for the characterization of
rock and fluid properties, e.g., saturation, porosity, permeability and viscosity, because
attenuation is more sensitive than velocity to some of these properties (e.g., Best et. al.,
1994). Measurements of both velocity and attenuation provide complementary
information about rock properties. Although attenuation is important, its reliable
measurement is much more difficult than the velocity, since attenuation information in
seismic data is easily contaminated by many factors. In this chapter I present a new
method for estimating seismic attenuation based on frequency shift data. In comparison
to some other methods of estimating attenuation, the frequency shift method is relatively
insensitive to geometrical spreading, reflection and transmission effects, source and
receiver coupling, radiation patterns, and instrument responses.
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