Seismic Geomorphology of Coal-Bearing Fluvial-Lacustrine Successions in Intracratonic Basins, Australia

Takeshi Nakanishi¹ and Simon Lang^2
1 INPEX Corporation, Tokyo, Japan
² University of Adelaide, Adelaide, Australia

3D seismic datasets reveal high-resolution seismic attributes reflecting paleo-geomorphologic elements of fluvial-lacustrine depositional systems. These can be recognised using seismic amplitude visualisations combined with judicious application of sequence stratigraphic concepts as they can be applied to continental successions. Datasets used are from the intracratonic basins of central and eastern Australia, in particular the coal-bearing Cooper and Eromanga basins. Seismic geomorphic elements recognised include: incised valley fills, amalgamated and isolated fluvial channel belts (low to high sinuosity), floodplain, peat mires, crevasse splay complexes, lacustrine delta mouth bars and associated distributary channels. A key part of the recognition of these geomorphic elements is the use of modern and ancient analogues to provide reality checks for recognising internal and external geometry, matching real scale versus seismic resolution of composite elements. These can be used in combination with the sequence stratigraphic position (systems tract) to assess the preservability of isolated individual elements versus palimpsest (eg. amalgamated and residual) elements depending on the balance of sediment supply versus accommodation, and hence a predictable pattern of reservoir and seal connectivity. A key process is a reality-check of the actual lithology imaged by various seismic atttributes using a combination of well log, core, outcrop, and in some cases production data.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005