Facies mapping from three-dimensional seismic data: Potential and guidelines from a tertiary sandstone-shale sequence model, Powderhorn field, Calhoun County, Texas
- Univ. of Texas, Austin, TX (United States)
We generated a set of three-dimensional (3-D) seismic models of a lower Miocene progradational microtidal shore-zone system at the Powderhorn field, Calhoun County, Texas. These models were based on detailed lithological mapping of 250 m of stratigraphic section over an area of 13 x 9 km. The mapping was guided by detailed facies analysis based on wireline logs from 115 wells. Fourteen sandy depositional units averaging 3-30 m in thickness are encased in 15 shale units. Density-neutron and spontaneous potential (SP) logs in five recently drilled wells were used to calculate effective porosity and shaliness, which correlate well with P-wave velocity and bulk density logs. The results show how the depositional facies at reservoir scale might be illustrated by 3-D seismic data, and how the seismic resolution of depositional facies changes with seismic frequency, stratigraphic position, and facies patterns. The Powderhorn reservoir sequence is interpreted as a barrier bar/lagoon depositional system associated with coastal stream plains, bayhead deltas, and small wave-dominated deltas corresponding to frequent relative changes of sea level. To detect these types of deposits, the seismic frequency should be selected such that the seismic data are tuned to the maximum thickness to establish a linear relationship between seismic amplitude and facies, and to achieve the best signal-to-noise ratio. The resulting ambiguity may be reduced by careful analysis of facies relationships if some well data are available, and probably by the amplitude vs. offset (AVO) method. The stratal resolution of seismic imagery depends not only on wavelet frequency, but also on the stratigraphic position of a given reservoir, or the magnitude of geological interference.
- OSTI ID:
- 223580
- Journal Information:
- AAPG Bulletin, Vol. 80, Issue 1; Other Information: PBD: Jan 1996
- Country of Publication:
- United States
- Language:
- English
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