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Conceptual models and real three-dimensional (3-D) seismic data show that in progradational carbonate platform margin and slope deposits of the Kingdom Abo reservoir of the Permian basin, west Texas, primary seismic reflection events do not necessarily follow clinoformal geologic-time surfaces. The seismic frequency content of the data controls the dip and architecture of seismic reflection events. High-frequency seismic data tend to follow thinner, time-bounded clinoform depositional elements (time-stratigraphic units), whereas low-frequency seismic data tend to image thicker, low-angle lithofacies units (time-transgressive units). In seismic data of moderate frequency, both clinoform units and flat lithofacies units are imaged, creating complex interference patterns that are difficult to interpret.
Experiments with models and real data demonstrate that seismic data can be selectively filtered in the signal bandwidth to help distinguish time-stratigraphic units from lithostratigraphic units. Selective filtering alters the dominant frequency of the data to match a desired scale of geologic objects. If there are enough high-frequency components in the seismic data, true clinoform stratigraphy can be imaged even if the data are dominated by lower frequency components.
Seismic modeling of outcrop of the Abo sequence in Apache Canyon, Sierra Diablo, west Texas, indicates that a dominant frequency of 100 Hz is needed to recover true clinoform stratigraphy using seismic data. The interpretation of available 3-D seismic data can only partially distinguish time-stratigraphy from lithostratigraphy because of the lack of frequency components greater than 70 Hz in the data. Application of this outcrop model in seismic modeling avoids interpretational pitfalls that can occur if the dominant frequency of the seismic data is not matched to the unit thicknesses that need to be resolved.
Hongliu Zeng has been a research scientist for the Bureau of Economic Geology, University of Texas at Austin since 1997. His research interests include seismic sedimentology, seismic stratigraphy, and special seismic processing, applied to petroleum prospecting. He earned his B.S. (1982) and M.S. (1985) degrees in geology from the Petroleum University of China and his Ph.D. (1994) in geophysics from the University of Texas at Austin.Charlie Kerans has been a senior research scientist at the Bureau of Economic Geology, University of Texas at Austin since 1985. His research emphasis is on the construction of sequence-stratigraphic frameworks for carbonate-reservoir characterization. He has been an AAPG Distinguished Lecturer and has won seven awards for best paper, including PBS-SEPM, West Texas Geological Society, and the Pratt Memorial Award from AAPG.