b'AEGC 2023Short abstractssignificant unprecedented increases in salinities in late summerhorizontal and gradually dipping segments. These data indicate and autumn in 2020, prior to winter rainfall and groundwatera complex bedrock surface, possibly caused by a series of sub-recharge. vertical faults as the bedrock slumped across the Darling Fault.Airborne electromagnetic (AEM) survey was planned to improve the understanding of the likely causes of rising salinity within theLeveraging legacy data: An onshore reprocessing case borefield and assisting in water source planning. The secondarystudy from the Bowen Basin.aims were to map the extent of the saline water interface and to improve understanding of the hydrogeology of the area. Anthony Goodall 1 Bahaa Soliman1, Catalina Ocampo1, Oscar Garcia1, Andy Walz1, Emily Guidry2 and Gabriele Busanello1The 2021 AEM survey successfully mapped the extent of the saline water interface and delineated the other major1 Schlumberger hydrogeological features. The saline water interface was2 Shellmapped as approximately 200 to 300 meters west of theWe present a seismic reprocessing and seismic reservoir production borefield. It was interpreted that the increasedcharacterisation case study for a legacy onshore dataset salinity in the production bores was more likely due to the thinacquired in the Bowen Basin, Australia, in 2003. The study freshwater aquifer being impacted by upconing of underliningdemonstrates the benefits of using contemporary signal brackish groundwater from the Woodada Formation, and notprocessing and imaging technologies to maximise the value in the inland movement of the coastal SWI. The AEM survey alsolegacy seismic acquisition datasets. These modern techniques confirmed the presence major faults and fresh groundwateraddress the complex geophysical challenges posed by coal in the deeper aquifers such as the Lesueur Sandstone. Thisreflectivity responses including noise and multiple generation. information will be crucial in planning for future water sources. The study achieved the sub-surface geological objectives to accurately estimate the rock properties for use in seismic Mapping a palaeochannel on the edge of the Darlingreservoir characterisation lithology mapping, specifically to distinguish between sand and coal lithologies.Fault in Western Australia using airborne EM and passive seismic. The signal-processing incorporated surface-wave analysis, modeling and inversion, and controlled-amplitude and Karen Gilgallon 1, Remke L. van Dam1, Greg Maude1 and controlled-phase processing. This was followed by anisotropic Peter Pring2 velocity modeling, depth imaging and a workflow to attenuate multiples using extended interbed multiple prediction. These 1 Southern Geoscience Consultantscombined techniques resulted in optimal noise attenuation, 2 Caravel Minerals bandwidth extension, improved imaging, and multiple energy In recent years, horizontal-to-vertical spectral ratio (HVSR)attenuation relative to the legacy 2014 processing.analysis of passive seismic data has gained acceptance asThe modern processing offered significant uplift in signal-to-an efficient method for assessment of bedrock depth. Thenoise ratio, temporal and spatial resolution, fault definition, HVSR approach has become increasingly popular thanksand stratigraphic termination in the reservoir interval. The to the availability of lightweight and mobile 3-componentbandwidth enhancement at target depth provided higher seismometers. resolution and an additional octave of usable low-frequency Here, we report on a palaeochannel investigation in the Wheatsignal offering an improved data input for pre-stack inversion. Belt of Western Australia aimed at de-risking groundwaterInverted rock properties of acoustic impedance and Vp/Vs from drilling for mine development. Available datasets includedseismic showed a high correlation with well logs. A unique an airborne EM survey and drilling data that identifiedsignature was observed in these rock properties for both sands palaeochannel sediments to depths of around 190 m belowand coal lithologies providing a means to delineate lithologies ground level (bgl). The narrow channel extended westward tofrom the seismic data and map potential reservoir extent.the Darling Fault where it disappeared from the EM dataset. Reprocessing included the latest technology for denoise and A passive seismic survey programme was designed to define thedemultiple designed around the specific challenges posed channel morphology in greater detail. Multiple transects wereby thin sand and interbed coal layers. This added value to the collected using SARA GeoBox instruments across the channelseismic dataset for geological interpretation without the need structure, both east and west of the fault. All HVSR frequenciesto acquire further seismic data. AVO fidelity was preserved and were converted to depth using a constant velocity which wasenhanced, making the legacy acquisition dataset suitable for obtained from a borehole control survey. high-resolution accurate quantitative reservoir characterisation.East of the scarp, a clear HVSR resonance peak, representative of the bedrock transition, was identified in the data, with depths toSeismic uncertainty analysis from the Pinhoe model bedrock up to 210 m bgl. The identified channel responses werebuilding study.used for hydrogeological modelling and follow-up drill planning. In transects crossing the Darling Fault, the primary resonanceYuelian Gong, Lianping Zhang, Dominic Fell, Nigel Seymour horizon dips strongly westward as bedrock dips below the Perthand Sherman YangBasin (lowest bedrock resonance frequency: 0.46 Hz). West ofSchlumbergerthe scarp, no channel signature was evident. A weak but laterally continuous resonance peak was observed at depth of aroundThe Pinhoe field is located in the Northern Carnarvon basin 150 to 200 m bgl. One transect, oriented sub-parallel with andin the North-West Shelf, offshore Exmouth Plateau of Western slightly east of the mapped fault, identified multiple sub- Australia, approximately 200 km northwest of Exmouth. The FEBRUARY 2023 PREVIEW 100'