Abstract: Outcrop Analogs for South Timbalier 295 Turbidite Sands: Development of a Turbidite Channel Complex and Implications for Fluid Flow, Brushy Canyon Formation, West Texas

HOOVER, ANDREW R.

We compare and contrast an amalgamated turbidite system within the Brushy Canyon Formation with the K40 sand of South Timbalier Block 295, offshore Louisiana. These observations, applicable to subsurface interpretation of turbidite sands, demonstrate the lateral variability of gravity flow deposits in a restricted basin and the influence of topography on turbidite deposition.

We observe channel elements including erosional surfaces, silt drapes, and initial and subsequent fill. Sands thicken and coarsen toward the axis of the channel complex where they are very thickly bedded, medium-grained with large rip-ups. Channel margins preserve silts and medium-to-very fine sands displaying complete Bouma sequences. Topography controlled distribution of sands and steered channels toward the axis of the depositional low where coarser amalgamated sands accumulated. Flanks of the depositional low preserved less energetic events and were less prone to amalgamation by subsequent turbidite events.

These observations are similar to observations from wireline logs of the K40 sand, deposited in a Pliocene slope minibasin. Downdip K40 sands, closer to the basin axis, are thicker and amalgamated. Levee and channel margin deposits of thinner sands are preserved on the flank of the minibasin. From outcrop observations, we predict good lateral and vertical permeability with even water sweep in axial (basinward) sands. Marginal sands with limited vertical permeability due to interbedded shales will have variable water sweep influenced by proximity to producing wells.   

AAPG Search and Discovery Article #90940©1997 AAPG Foundation Grants-in-Aid