Adhari, Muhammad Ridha.1 Wilson, Moyra E. J.1
1School of Earth Sciences, The University of Western Australia, Perth, Australia
The Upper Permian Beekeeper Formation is a proven reservoir in the Woodada field, Perth Basin, Western Australia, yet the nature and sedimentary features of this formation are not well understood. The Beekeeper Formation is about 20 km wide and 70 km long and the thickness of this sedimentary unit is up to 134 m. This formation is interpreted to be deposited in a cool-water ramp setting and has been identified not only in the Woodada field, but also in the Beharra Spring field, Perth Basin. This study aims to better understand the characteristics of the Beekeeper platform and the diagenetic processes that occurred during its evolution. Sixty metres of conventional cores are available from five wells from the Perth Basin and 127 thin sections were made from those cores. Sedimentary logging, acetate peels, thin section petrography, and acid digestion have been conducted on the available dataset. Results from this study show that the Beekeeper Formation is a mixed carbonate-siliciclastic system, with both coeval and reciprocal mixing during sequence development. Bryozoas, brachiopods, and crinoids are the main bioclasts in packstones, grainstones, and rudstones. Primary matrix porosity is minimum in the Beekeeper Formation, but the secondary fracture porosity is of the highest quality. The fracture system is interpreted to be generated through tectonic activity on the basis of the relative timing of the paragenetic events, offset along the fractures, common sub-vertical fracture orientations, multi-size and multi-episode fracture development, and multi-phase fracture cements. The main diagenetic processes affecting the Beekeeper Formation include micritisation, boring, mechanical compaction, syntaxial overgrowth, granular-blocky calcite cementation, chemical compaction, dolomitisation, recrystalisation, and replacement, whereas bioclast and calcite vein dissolution are as minor features. These findings are expected to advance our understanding of this Upper Permian mixed carbonate-siliciclastic system and reservoir.
Keywords: Upper Permian, Mixed carbonate-siliciclastic, Beekeeper Formation, Fracture porosity
Muhammad Ridha Adhari is a student at the School of Earth Sciences, UWA sponsored by AAS. Adhari holds a bachelor degree from Institut Teknologi Bandung, Indonesia and a master degree from Curtin University, Australia. Currently, he is conducting a research on fractured carbonate-siliciclastic reservoir from the Perth Basin, Australia.