b'AEGC 2021Short abstracts236: Practical aspects of wavefield decomposition for239: Targeting fractured rock aquifers using magnetic permanent seismic rotatory sources dataMr Roman Isaenkov1, Dr SINEMYAVUZ 1, Prof Roman Pevzner1,Mrs Heather Ballantyne 1 and Ms Karen Gilgallon2Dr Konstantin Tertyshnikov, Dr Julia Correa2 and Dr Barry Freifeld31 SGC1 Curtin University 2 Southern Geoscience Consultants Pty Ltd2 Lawrence Berkeley National Laboratory3 Class VI Solutions Fractured Rock Aquifers are an important source of water, providing supply for mining, irrigation, town water and stock Continuous and automated reservoir monitoring has thewatering. Approximately 40% of groundwater in Australia is potential to bring a new level of longevity and data qualitypresent in fractured rock, with one third of all water extraction into seismic monitoring. In addition, compared to surfacebores located in fractured rock systems.seismic, borehole-based monitoring has higher repeatabilityImportant aspects of exploring for Fractured Rock and is much less invasive. In this approach, distributedAquifers include the ability to assess the size and fracture acoustic sensing can serve as permanent receiver for the entireinterconnectedness of a potential aquifer and being able to length of the well, while surface orbital vibrators can provideaccurately identify sites for bore targeting.a continuous alternative to mobile Vibroseis sources. In the Stage 3 of the Otway Project, the 15 000-tonne CO2 injectionAirborne magnetic data is a highly effective tool for identifying will be continuously monitored with multi-well offset DASthe location of faults, fractures and potential water traps along VSP. To test this approach, the continuous acquisition of thedykes and other aquatards. Existing free or low-cost airborne multi-well DAS VSP data using SOVs was commenced in Maymagnetic data previously acquired by government geological 2020. We optimise the multi-well DAS VSP data processing foragencies and mining-exploration companies covers large parts automated data processing and imaging. The sections for 2Dof Australia and is readily available for download. The survey line transects of each well-SOV pair are consistent with 3D VSP. Thespacing varies from wide-spaced 400m to very detailed 25m sections for 2D transects of each well-SOV pair provide goodand can be imaged in a variety of ways to highlight relevant illumination of the subsurface. features using filtering such as vertical and tilt derivatives.Case studies illustrate the use of magnetic data to identify 238: Estimate elastic moduli of arenites from micro- the location of potential Fractured Rock Aquifers. A 25 m line tomographic images with digital rock physics spaced survey in the Pilbara was used to determine the most prospective drill sites for a water bore to supply a mining-Mr Jiabin Liang, Prof Boris Gurevich1, Prof Maxim Lebedev1,related processing plant. The interpretation was completed in Dr Stephanie Vialle1, Mr Alexey Yurikov1 and Dr Stanislavcollaboration with the company and hydrologists. An 80m line Glubokovskikh1 spaced survey in southwest Western Australia was interpreted 1 Curtin University to identify priority drilling targets close to existing infrastructure for town supply.Numerical computation from high resolution 3D micro- In summary, magnetic data filtering and interpretation is a tomographic images of rocks (known as digital rockhighly cost-effective solution for identifying targets for fractured physics) has the potential to predict elastic properties morerock aquifer exploration by drill targeting.accurately. However, successful examples are limited to samples with simple structure and mineralogy. The physical size of sample is often too small to present heterogeneities242: Laboratory measurements of seismic properties and at a larger scale and the image resolution is insufficient toforward seismic modelling at the Thunderbox gold minecharacterize the details of rocks. Also, the greyscale valuesMr Andre Eduardo Calazans Matos de Souza , Dr Stephanie of different minerals in micro-tomographic images are often1similar, and previous attempts to segment them as separateVialle1, Dr Joel Sarout2 and Dr Mustafa Sari2phases are not very successful. Here, we propose a practical1 Curtin Universitydigital rock physics workflow for somewhat more complex2 CSIROand ubiquitous rocks, namely, sandstones that contain mostly quartz and a small fraction of dispersed clay (knownSeismic methods are not widely deployed in the mining as arenites). Based on a set of images, we obtain a suite ofindustry. However, the increasing interest in deeper gold post-computation corrections to compensate for the effectsdeposits, especially in Australia where the deposits are of sample size and resolution of the micro-tomographicconcealed under a thick cover of sediments, makes seismic images. Furthermore, we build a segmentation workflow thatmethods an appealing tool for gold exploration and mining effectively detects feldspar and clay minerals, despite theirplanning due to their capacity to couple resolution and depth grey-scale similarity to quartz. A moduli-porosity trend isof investigation. At Brownfield gold deposits, such as the derived from the subsamples of the original digital images.Thunderbox gold mine, seismic methods could be integrated Bulk moduli agree well with the ultrasonic measurementswith the existing geological knowledge of the mine to help on the dry samples at 40 MPa. Shear moduli remainestablish new exploration opportunities that extend the known overestimated, which is likely caused by poor knowledge ofmineralization at depth. However, seismic interpretation the mineral stiffness. We compensate for this effect using aremains largely speculative in hard-rock environments due to: heuristic correction to the matrix moduli. The final version(1) highly complex geologic structures, (2) scarcity of boreholes of the workflow provides accurate elastic moduli trends withlogs, (3) poor database documenting the petrophysical porosity and clay content based on only two samples ofproperties of gold-bearing host rocks. To better understand Bentheimer sandstone. the seismic properties at the Thunderbox gold mine, we 103 PREVIEW AUGUST 2021'