Characterizing carbonate facies using high-definition frequency decomposition: Case study from North West Australia

Abstract

Carbonate facies identification is difficult using conventional seismic attributes due to subtle lithologic changes that cannot be easily recognized. Therefore, there is a need to develop new methodologies to study their evolution and their associated sedimentary processes, which will eventually lead to better prediction for reservoir-quality rocks. New insights into the Cenozoic carbonates in North West Australia have been captured with the application of a high-definition seismic attribute workflow. The workflow starts with conditioning of the seismic volume using structurally oriented noise attenuation filters to remove any random and coherent noise from the input data. It also benefits from a high-definition frequency decomposition that matches the original seismic resolution without smearing interfaces using a “matching pursuit” algorithm. A color blend of multigeometric attributes, such as semblance and conformance, has also been used in the workflow to define edges and discontinuities present in the data within carbonate deposits that are attributed to depositional geometries, such as barrier reefs. Our workflow has been developed to investigate the geomorphology and the sedimentary processes affecting Cenozoic successions in the Northern Carnarvon Basin in North West Australia. Geomorphological and sedimentological observations have been documented such as an Eocene rounded carbonate ramp with evidence of slump blocks and scarps, Middle Miocene accretions generated due to longshore drift, and the presence of Pliocene-Pleistocene patch and barrier reefs. These observations were extracted as geobodies to allow for visualization, and they can be used in an automated seismically based facies classification scheme. The new appreciations are not only useful for understanding the carbonate evolution but can also be used to identify geohazards such as slumps ahead of future drilling.