We discuss, in a two-part article, the benefits of 90°-phase wavelets in stratigraphic and lithologic interpretation of seismically thin beds. In Part 1, seismic models of Ricker wavelets with selected phases are constructed to assess interpretability of composite waveforms in increasingly complex geologic settings. Although superior for single surface and thick-layer interpretation, zero-phase seismic data are not optimal for interpreting beds thinner than a wavelength because their antisymmetric thin-bed responses tie to the reflectivity series rather than to impedance logs. Nonsymmetrical wavelets (e.g., minimum-phase wavelets) are generally not recommended for interpretation because their asymmetric composite waveforms have large side lobes. Integrated zero-phase traces are also less desirable because they lose high-frequency components in the integration process. However, the application of 90°-phase data consistently improves seismic interpretability. The unique symmetry of 90°-phase thin-bed response eliminates the dual polarity of thin-bed responses, resulting in better imagery of thin-bed geometry, impedance profiles, lithology, and stratigraphy. Less amplitude distortion and less stratigraphy-independent, thin-bed interference lead to more accurate acoustic impedance estimation from amplitude data and a better tie of seismic traces to lithology-indicative wireline logs. Field data applications are presented in part 2 of this article.
[1]
M. B. Widess.
HOW THIN IS A THIN BED
,
1973
.
[2]
R. Bracewell.
The Fourier Transform and Its Applications
,
1966
.
[3]
H. Zeng,et al.
Facies Mapping from Three-Dimensional Seismic Data: Potential and Guidelines from a Tertiary Sandstone-Shale Sequence Model, Powderhorn Field, Calhoun County, Texas
,
1996
.
[4]
P. Schultz,et al.
Fundamentals of geophysical data processing
,
1979
.
[6]
Alistair R. Brown.
Interpretation of three-dimensional seismic data
,
1986
.
[7]
R. E. Sheriff,et al.
Application of Amplitude, Frequency, and Other Attributes to Stratigraphic and Hydrocarbon Determination: Section 2. Application of Seismic Reflection Configuration to Stratigraphic Interpretation
,
1977
.
[8]
Milo M. Backus,et al.
Interpretive advantages of 90°-phase wavelets: Part 2 — Seismic applications
,
2005
.
[9]
A. Nur,et al.
Effects of porosity and clay content on wave velocities in sandstones
,
1986
.
[10]
P. L. Lawrence,et al.
INTERPRETATION OF SYNTHETIC SEISMOGRAMS
,
1961
.
[11]
Hongliu Zeng,et al.
High-frequency sequence stratigraphy from seismic sedimentology: Applied to Miocene, Vermilion Block 50, Tiger Shoal area, offshore Louisiana
,
2004
.