b'AEGC 2023Short abstractsconsider the environment a top national concern. Nationally, the2D forward seismic modelling at the Thunderbox gold environment is protected through the Environment Protectionmine, Western Australia, using laboratory petrophysical and Biodiversity Conservation Act (EPBC) which was firstdata.introduced in 1999 and has been amended numerous times since. The EPBC act is primarily concerned with protecting areasAndre Eduardo Calazans Matos de Souza 1 Stephanie Vialle2, of national environmental significance and similar legislationJoel Sarout3 and Mustafa Sari3exists at the state level. Coupled with an increasing emphasis on environmental protection is an increased awareness of the1 Qeye-labs effects of climate change. A 2021 survey by the Australia Institute2 Curtin University found that the proportion of respondents who thought that3 CSIROfossil fuel producers should pay for the costs of dealing withSeismic methods are not widely deployed in the mining climate change had increased from 38% to 51% in just 4 years.industry. However, the increasing interest in deeper gold Similarly, 61% supported a levy on fossil fuel exports to pay fordeposits, especially in Australia where the deposits are climate disasters. concealed under a thick cover of sediments, makes seismic To support the energy transition, there is a need for extractivemethods an appealing tool for gold exploration and mining industries to supply the critical resource required. These activitiesplanning due to their capacity to couple resolution and depth must be performed under increasing regulatory compliance andof investigation. At Brownfield gold deposits, such as the consider community concerns. Effectively doing so requires theThunderbox gold mine, seismic methods could be integrated application of exploration technologies, particularly geophysicalwith the existing geological knowledge of the mine to help techniques, that both minimise geological uncertainty andestablish new exploration opportunities that extend the known adhere to environmental requirements. mineralisation at depth. However, seismic interpretation remains largely speculative in hard-rock environments due to: As the requirements for geophysical imaging increase(1) highly complex geologic structures, (2) scarcity of boreholes (particularly the increased popularity of the seismic methodlogs, (3) poor database documenting the petrophysical for mineral exploration), their potential direct environmentalproperties of gold-bearing host rocks. In this study, we present impact also increases. In this paper we outline the currenta 2D seismic forward modelling of the Thunderbox gold mine, environmental restrictions applied to the acquisition of onshoreWestern Australia that was built using 2D geological section of geophysical (in particular seismic) surveys. We then discussthe mine along with laboratory petrophysical measurements how the environmental impact can be reduced through theperformed on over 100 whole core samples from the mine. application of new technology and careful survey planning. Laboratory measurements include bulk and grain densities, and ultrasonic P- and S-wave velocities at ambient conditions. In Seismic facies and rock properties prediction usingaddition, four samples were selected to investigate the pressure Direct Probabilistic Inversion: case studies fromdependence of P-wave velocity. We found that the seismic reflectivity between the lithological units is low, except for Australian basins. the massive basalt and the talc schist (shear zone) that show a Andre Eduardo Calazans Matos de Souza, Rob Ross, Henriknotable acoustic impedance contrast with all lithologies. Given Hansen and Ask Jakobsen that most of the gold-host rocks at the mine seem to be only economically mineralised when they are in the vicinity of the Qeye-labs shear zone, the delineation of this structure at high resolution Direct Probabilistic Inversion (DPI) is a single-step inversioncan be attractive for Thunderbox mine planning.process that inverts pre-stack seismic data directly for seismic facies. DPI formulates the inversion problem in a BayesianGeophysical response and exploration methods for framework, in which you can integrate geological knowledgeCallie-style targets in Tanami, NT, Australia.such as stratigraphic and fluid gravitational ordering, possible lithologies and fluids within each stratigraphic layer, distributionTim Doheyof unit thicknesses, and transition probability between one facies and the next. The injection of this valuable geologicNewmont Mininginformation, previously ignored in standard deterministic AVOCallie is a world-class vein-hosted orogenic gold deposit inversions, helps mitigate ambiguities inherent in the seismiclocated 650 km NW of Alice Springs, within a conformable method. First, all possible geologic solutions (prior model) arePaleoproterozoic sequence of sedimentary rocks. Gold is primarily created based on the geologic knowledge of the basin, andcontained within several preferential stratigraphic host units, then their modeled seismic responses are compared with theand within parasitic folds of the moderately ESE plunging Dead observed seismic in a moving neighbourhood rather than tryingBullock Soak anticlinorium. Geophysics has proven to be valuable to solve the full joint posterior distribution. This approach allowsin mapping stratigraphic markers and fold geometry which act a robust handling of uncertainty and non-uniqueness, whichas controls on gold mineralisation in the near mine environment. are essential for risk analysis. The outputs of DPI are probabilisticModern geophysical techniques have also been key in exploring facies and rock properties (porosity, the volume of clay, etc.)for similar under-cover signatures across the larger brown-fields which accurately propagate uncertainty into the solution. Insearch-space, particularly when guided by a petrophysical this study, DPI is applied to different 3D datasets across differentcharacterisation of the conformable stratigraphic sequence.Australian basins to show the efficiency of the method in predicting seismic facies and reservoir properties even for thinHigh resolution airborne magnetics allow for lithostructural reservoirs and coal layers despite being at the limit of resolutioninterpretation across the region, which is predominantly under in the seismic. We have also compared the inverted facies tocover, as well as 3D modelling to guide drill targeting. Recent results from the standard deterministic AVO inversion. low-noise airborne gravity gradiometry surveys have provided FEBRUARY 2023 PREVIEW 92'