Spatio-temporal characterisation of the Beekeeper Formation of Australia: facies development, mixing of carbonate and siliciclastic materials, and influencing factors

The Beekeeper Formation, a mixed carbonate-siliciclastic reservoir, has long been known as a proven gas reservoir in the northern Perth Basin, Australia. However, its characteristics, and spatio-temporal distribution are still not well understood. There are two main objectives of this study: (1) to identify the main cutting facies groups/subgroups, and electrofacies of the Beekeeper Formation; and (2) to understand spatio-temporal characteristics, and development of the Beekeeper Formation. Integrated multi analyses have been conducted to achieve these objectives including cutting, wireline logging, and XRF analyses. Fifteen types of cutting components, and nine electrofacies were identified forming the Beekeeper Formation. The Beekeeper Formation consists of nine facies sub-groups, and these are classified into carbonate-dominated facies group, siliciclastic-dominated facies group, and mixed carbonate-siliciclastic facies group. Furthermore, this formation can vertically be divided into three parts on the basis of the main facies groups: the lower, middle, and upper parts. The lower and upper parts consist predominantly of siliciclastic materials, while the middle part is dominated by carbonate materials. In the north of the study area, the Beekeeper Formation consists predominantly of siliciclastic materials with minor carbonate materials, whereas in the central to south it consists mainly of carbonate material with minor-moderate siliciclastic materials. Various processes have influenced the evolution of the Beekeeper Formation including influx of siliciclastic components, mixing of carbonate and siliciclastic materials, suitable environment for the growth of carbonate biotas, sea level fluctuation, and tectonic activities. It is expected that findings from this study will provide new insights into characteristics of mixed carbonate-siliciclastic reservoirs in general, and will have regional and global applicability.