Resource potential of the Carrara Sub-basin from the deep stratigraphic well NDI Carrara 1

Abstract

NDI Carrara 1 is a deep stratigraphic well completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI), in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first stratigraphic test of the Carrara Sub-basin, a newly discovered depocentre in the South Nicholson Region. The well intersected Proterozoic sediments with numerous hydrocarbon shows, likely to be of particular interest due to affinities with the known Proterozoic plays of the Beetaloo Sub-basin and the Lawn Hill Platform, including two organic-rich black shales and a thick sequence of interbedded black shales and silty-sandstones. Alongside an extensive suite of wireline logs, continuous core was recovered from 283.9 m to total depth at 1750.8 m, providing high-quality data to support comprehensive analysis. Presently, this includes geochronology, geochemistry, geomechanics and petrophysics. Rock-Eval pyrolysis data demonstrate the potential for several thick black shales to be a source of hydrocarbons for conventional and unconventional plays. Integration of these data with geomechanical properties highlights potential brittle zones within the fine-grained intervals where hydraulic stimulation is likely to enhance permeability, identifying prospective Carrara Sub-basin shale gas intervals. Detailed wireline log analysis further supports a high potential for unconventional shale resources. Interpretation of the L210 and L212 seismic surveys suggests that the intersected sequences are laterally extensive and continuous throughout the Carrara Sub-basin, potentially forming a significant new hydrocarbon province and continuing the Proterozoic shale play fairway across the Northern Territory and northwest Queensland.

Thermal history of the Carrara Sub-basin: insights from modelling of the NDI Carrara 1 drill hole

“…For full list of author affiliations and declarations see end of paper Age information was assigned based on recently acquired SHRIMP zircon U-Pb geochronology (Kositcin and Carson 2022), and formation picks and lithology information were assigned based on chemostratigraphy and well log analysis (Bailey et al 2022). The amount of uplift and erosion was estimated through analysis of newly acquired seismic data (Carr et al 2019) and calibrated using equivalent vitrinite reflectance calculated from bitumen reflectance data (Ranasinghe and Crosdale 2022).…”

Petrophysical interpretation and reservoir characterisation on Proterozoic shales in National Drilling Initiative Carrara 1, Northern Territory

“…Below the Widdallion Sandstone Member, the Lawn Hill Formation was further divided into three intervals referred to as the lower Lawn Hill Formation (1430.1 m to total depth), Lawn Hill shale (1126.3-1430.1 m) and upper Lawn Hill (687.9-1126.3 m) (Bailey et al 2022a;Wang et al 2023;Fig. 2).…”

“…The Carrara Sub-basin spans 129 km by at least 190 km from north to south and accommodates thick deposits (up to 8 km) formed in both the early Palaeozoic (Georgina Basin) and Proterozoic era (Carson et al 2022a). The Proterozoic sedimentary rocks, particularly the shales, are considered equivalent to the prospective rocks of the greater McArthur Basin, Lawn Hill Platform and Mount Isa Province (Bailey et al 2022a;Grosjean et al 2022).…”

“…Two stages of continuous coring were carried out from 283.9 m to total depth. As part of the EFTF program, a variety of laboratory tests were conducted for organic and inorganic geochemical properties (Carson et al 2021), geochronological age (Carson et al 2022a), as well as petrophysical and geomechanical properties (Bailey et al 2022a(Bailey et al , 2022b. Wireline logging was undertaken and pre-processed by Weatherford Logging, including spectral gamma ray (concentrations of potassium (GRPON,%), thorium (GRTHN, ppm) and uranium (GRURN, ppm)), compressional wave slowness (DTCN, µs/ft), bulk density (DENNN, g/cm3), limestone neutron porosity (NPRLNC, m3/m3), photoelectric factor (PDPEN, b/e), shear wave slowness (DTSXXN, µs/ft), Stoneley wave slowness (DTDTXN, µs/ft), spontaneous potential (SPCGN, mv), deep (RTAFN, ohmm) and shallow resistivity (FEFEN, ohmm) logs, array induction resistivity and micro-imager logs (Geoscience Australia 2021).…”

Exploring for the Future: new geomechanical data in frontier Australian basins

“…Under EFTF, new geomechanical work has been undertaken, including stress modelling (e.g. Bailey et al 2019Bailey et al , 2021bBailey et al , 2022a, shale brittleness studies (e.g. Jarrett et al 2020a;Bailey et al 2022b) and the acquisition of extensive new rock property data through a program of laboratory analysis of both newly acquired and legacy rock samples in several frontier regions (e.g.…”