X-ray diffraction data of shales from the greater McArthur Basin

Abstract

The Northern Territory Geological Survey (NTGS) has been assessing the unconventional hydrocarbon potential of the greater McArthur Basin. A component of this assessment is understanding the bulk and clay mineralogy of shales from the basin succession to determine their heterogeneity, brittleness, and thermal maturity.

Between 2015 and 2017, NTGS contracted Weatherford Laboratories (Australia) Pty Ltd to undertake X-ray diffraction (XRD) analyses on shales from various stratigraphic units across the greater McArthur basin. This Record includes tabulations of XRD data for 469 shale samples from 71 drill cores and one outcrop site; it also includes the associated diffractograms for 158 of those samples.

The results highlight the differences in bulk and clay mineralogy between each of the different shale units across the McArthur Basin. This is reflected in differences in the calculated brittleness indices and the Kübler index. Each shale unit also contained internal variations, with the brittleness index ranging from moderately ductile to brittle. This demonstrates heterogeneity within each formation. The Kübler index was also varied between each shale unit; however, some units had a wide range in values while others were more closely constrained.

The data from the Velkerri and Kyalla formations presented herein was used as a part of the unconventional petroleum resource assessment of the Roper Group (Revie 2017). Tabulated raw data for all of the formations across the greater McArthur Basin is included in NTGS’s DIP 014 (Revie et al 2021) and will be used for future resource assessments.