Molasse Basin, Austria
The Oligocene to Early Miocene Molasse Basin in Austria was developed between the Alpine fold and thrust belt to the south and the Bohemian massif to the north. Channels ran along the axis of the narrow basin and were fed sediment derived mainly from large deltaic systems to the west and partially from the Alpine thrust front to the south. Smaller intraslope basins were developed along this front and some of the major sand reservoirs in the basin are intraslope basins located on this structurally complex southern slope, as studied by Jake Covault (2008). Stratigraphic and structural traps in the main channel complex also contain significant amounts of natural gas. Steve Hubbard worked on the bed-scale sedimentology of the Puchkirchen Formation, with an emphasis on tying core facies to seismic response (Hubbard, 2005 ; 2007). A comprehensive dataset of >2000 m of core and >2000 km 2 of recently acquired 3-D seismic data make this research possible. Steve also studied the provenance of the formation with the intention of resolving the paleogeographic configuration of the basin (Hubbard, 2004).
Current studies in the Molasse Basin, sponsored by SPODDS and RAG, an Austrian petroleum company, include those of Anne Bernhardt, who is tying detailed turbidite and debris-flow-deposit sedimentology in the axial channel to the origin of specific reservoir sands, and Lisa Stright, who is utilizing seismic approaches to characterize and identify deep-water lithofacies.
Larisa Masalimova's project will address the depositional mechanisms, environment and evolution of the sediments in Atzbach, Schwanenstadt and Zell-am-Pettenfirst gas fields in the Upper Austrian Molasse Basin. The gas-bearing sandstones of these fields were interpreted to be crevasse-splay and overbank deposits to main axial channel (de Ruig and Hubbard, 2006; Hubbard et al., 2009). The goal is to interpret the depositional setting, document the spatial variation of main bodies and the lithological heterogeneity of out-of-channel deposits. Thin-bedded hydrocarbon reservoirs are attracting more and more attention of the petroleum geoscientists. This research will expand our knowledge of overbank deposits and crevasse-splays through integration of core, well logs and seismic data.
