Lithology and Fluids: Seismic Models of the Brushy Canyon Formation, West Texas
Lithology and fluid information can be extracted from seismic data of deepwater clastics if their relative contribution to the signal is understood. Brushy Canyon Formation outcrop seismic models are constructed for the Western Escarpment of the Guadalupe Mountains using properties from outcrop, normal, and overpressured Gulf of Mexico and North Sea basins to test seismic sensitivity to lithology, fluid, and pressure. Large, clean, gas-saturated, and overpressured sandstones have the best resolution. Hydrocarbon saturation does not necessarily enhance seismic response. Lithology and fluid effects can reduce impedance contrast, resulting in low amplitudes (dim spots). Elevated geopressures preserve porosity producing low velocities and high amplitudes (bright spots). Even in low-impedance contrast intervals, offset-dependent amplitudes increase resolution and indicate hydrocarbons.