Seismic and Well Interpretation of Fluvial Clastic and Coal Packages for Stratigraphic Traps Within the Patchawarra Formation, Cooper Basin

Abstract

Several stratigraphic traps have been discovered within the Permian-aged Patchawarra Formation on the western flank of the Cooper Basin. These traps contain gas within fluvial sandstones deposited within a sequence of mixed clastic and coal beds. From an area containing 866 km² of 3D seismic and 27 wells, selected seismic and well data are used to show practical interpretation techniques used to define existing and potential stratigraphic traps. A practical use of seismic scale reflectivity and well correlation results in the Patchawarra Formation being divided into two component packages: - A clastic package that typically shows a high seismic acoustic impedance (“Hard”) and comprises of fluvial channel, point bar and proximal crevasse splay sandstones and flood-plain muds. Target reservoirs are relatively discontinuous sandstones that can be encased by mud facies and thick coals. - A coal package characterised by relatively low seismic acoustic impedance (“Soft”) sequences that are identified in wells as coals and coaly muds. These are interpreted to be deposited as relatively continuous, topographically raised areas of peat-mire and organic rich muds with rare coarse clastics. Stratigraphic trap potential is interpreted where defined coal packages split, and an example is illustrated at outcrop scale. Seismic attribute maps are integrated with package thicknesses, well log character, interpreted facies and depth structure to define trap geometries. The techniques illustrated provide a practical work flow to integrate well and seismic data in the search for stratigraphic trap geometries within fluvial and coal measures sequences.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015