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Abstract: Seismic Resolvability of Individual Sand-Filled Channels in the Lower Pennsylvanian Jackfork Formation, Arkansas: Model Applicability for the Gulf Coast
Gerald J. Kuecher (1), Arnold H. Bouma (1)
Measurements on width and thickness of individual channel sandstone bodies in the Lower Pennsylvanian Jackfork Formation at Haig Quarry (upper-middle fan) and at Big Rock Quarry (middle fan), Arkansas, provide a model to test the seismic resolvability of such submarine fan channels at various depths in the Gulf of Mexico. These channelized sandstone bodies, as well as their bounding facies types were assigned porosity and density values, consistent with typical Gulf Coast counterparts, in order to obtain reflection coefficients at the top and base of the channels at both locations.
Two hypothetical cases of vertical seismic resolvability were examined, i.e., a shallow case (2000 feet depth) and a deep case (10,000 feet depth). At neither location could these channels be seismically resolved (/4), but they could be seismically detected (/30) from their channel axis to within 6 feet of pinchout in the shallow case, and only in the thickest part of the channel in the deep case. Concave-upwards raypath focusing should increase the amplitude of the base channel reflection. Horizontal seismic resolution is affected in the deep case due to the limited areal dimensions of these channels.
Although these Jackfork Formation channels do not reflect the scale of Gulf Coast Tertiary and younger submarine fans, this study points to one of the potential pitfalls of seismic stratigraphy when similar fans are interpreted, unconstrained by ground truth.
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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES
(1) Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana 70801
Copyright © 1999 by The Gulf Coast Association of Geological Societies