W.L. Chapman, C.J. Schafers, 1983. "Shallow Sand Channel, Coal Exploration, Illinois Basin", Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces, A. W. Bally
Download citation file:
The seismic line in Figure 1 is a high-frequency data example applied to a coal exploration problem. The location of the line is shown on the map of the Illinois basin. The line was recorded with two objectives in mind. First, to seismically map a shallow coal seam at a depth of 530 ft (161 m). Second, to map sand channels in the coal seam, before mining, in order to plan an efficient mine layout. The data was recorded using a sweep of 260-50 Hz, and as is certainly apparent, the line met both objectives. On the right side of Figure 2 (a marked version of Figure 1) the reflection from the low velocity (8,000 ft/sec, 2,438 m/sec) coal seam is uniform and moderately high in amplitude. As the low velocity is replaced by high velocity (13,000 ft/sec, 3,962 m/sec) sandstone, the coal event i reduced in amplitude, virtually disappearing on most of the left half of the line. The data does an excellent job of defining the 12-ft (3.6-m) coal seam.