Evolving Exploration Methods in the Hydrocarbon Play Within the Patchawarra Formation on the Western Flank, Cooper Basin

Abstract

The hydrocarbon play in the Patchawarra Formation lies within a Permian age, high latitude, fluvial sand and coal measure system that is up to 300m thick in the Cooper Basin of Central Australia. Fluvial channel belt sands, ranging from 1 to 20m thick, form a conventional reservoir. Seal and source play components are in the inter-bedded overbank, silts, clays and coal seams. The low seismic reflectivity sands combined with the numerous, high seismic reflectivity coals makes standard seismic interpretation difficult. These factors combined with the thin, irregular geometry of the reservoir, make exploring for hydrocarbon traps challenging. The largest fields in the Western Flank, discovered to date, are considered to have a stratigraphic trap component that is combined with a structural influence. Each field has a single main pay zone located in a different clastic package compared to the other fields in the play. An evolving exploration method is reviewed that uses the coals as local timelines with trap limits defined using structural and stratigraphic indications from the seismic. This method combined with ideas of source and trap has recently proved successful in extending the play. Examples of some of the hydrocarbon traps and concepts are shown that may help with evolving ideas and future exploration methods in this basin and other basins with similar fluvial plays.