b'AEGC 2021Short abstracts41: UAV magnetic survey planning, QAQC and dataearthquakes to be occurring in this area as it is in the middle of processing an Archean cratonic region although the scarps from surface rupturing events, such as the Meckering event, mainly trend Mr Brendan Ray 1 approximately north-south and appear to lie along trends in the magnetic data (Dentith et al 2009).1 Southern Geoscience Consultants (SGC)UAVs have been deployed increasingly to collect magnetic data,Until mid-2020 the ANSN had a fairly sparse coverage of however acquisition using these systems often lacks QAQCthe area. A secondary Public Seismic Network (PSN) is also checks that are typically expected from fixed-wing or helicoptermonitoring in the area. Inclusion of the PSN data has quite an based acquisition. Furthermore, survey parameters such as lineeffect on the calculated locations, as exampled by the tighter spacing and mean terrain clearance are often not given enoughclustering of the Beacon swarm of 2009 (Dent, 2009) rather than thought, leading to data that is unnecessarily over-sampledthe linear trend from just using the ANSN data.(line spacing much closer than flying height) or flying heightsIn mid-2020 four more semi-permanent stations were installed that are too low, leading to data that is littered with spuriousin the area and one in the Goldfields and added to the data surface noise. streaming into the National Earthquake Alerts Centre (NEAC) and UAVs are not immune to system noise, instrument noiseincorporated into the location algorithm. This presentation looks and GPS issues that also arise in their larger, fixed-wing andat seismicity of the area, the small swarms that have been detected helicopter counterparts and these need to be addressedsince then and the relationship of the seismicity to the geology.prior to acquisition. Due to the commercial infancy of these systems, delivered products are often sub-optimal as they lack contractual agreements of data quality and noise levels. Factors47: Multi-purpose utility of constructing 3D static such as deviation from planned survey height, deviation fromgeomechanical model in the Ichthys field, Browse Basinplanned lines, noise levels above a threshold etc. need to be pre-agreed on in a way thats fair and transparent to both theMr Partha PratimMandal 1, Ms Iman Essa1, Mr Sankhajit Saha2 UAV operator, as well as the client. and Prof Reza Rezaee1Processing of UAV data from its raw state can be thought of in1 Curtin Universitytwo stages, the first being spatial data processingchecking2 Baker Hughesand correcting for GPS positioning errors as well as altitude information, breaking up the data into unique lines or blocks,The petroleum industry progressed significantly to develop etc. The second stage is the assessment and correction of3D/4D geomechanical models (GMs) to make efficient field magnetic dataremoval of spikes, dropouts, correction of basedevelopment planning which reduces the uncertainty of 1D station data etc. UAV data tends to be delivered as grids, images,GM in the field scale. In this paper, we demonstrated how and ASCII line data which oftentimes, have only undergoneto build a high-resolution 3D static GM in a stratigraphic the minimum processing in this two-stage process. The datastructural setup with a combination of wireline logs, drilling needs to be further enhanced to reduce the appearance ofdata, structural objects, and laboratory rock mechanical near-surface noise, or artefacts in the grids which are related todata from 21 core samples in the Ichthys field of the Browse line-directionality to allow for clearer interpretation of the dataBasin, North West Shelf so that spatial distribution of pore without adversely affecting the underlying geology. pressure and stress behaviour can be understood across the Brewster Member sandstone reservoir. The workflow incorporates calibrated 1D GM of seven wells. 1D GM 44: Earthquake monitoring in the Southwest Seismicanalysis confirmed strike-slip faulting regime throughout Zone, Western Australia the stratigraphic column and the orientation of maximum principal stress is nearly towards the E-W direction. The 1D Dr Ruth Murdie 1, Ms Lucy Brisbout1, Dr Hugh Glanville2, Drmodel also indicates a sharp pressure ramp within Jamieson Trevor Allen2, Dr Craig Bugden2 and Mr Vic Dent3 reaching a maximum to the middle of the layer and then 1 Geological Survey of Western Australia regressed below Aptian and near to hydrostatic pressure 2 Geoscience Australia at top of the upper Vulcan formation. 3D modelling is 3 Curtin University Associate performed by incorporating interpreted seismic surfaces and unconformities in line with the geological understanding of Five new seismic monitoring stations have been added tothe subsurface and stratigraphic variation from the seabed to the Australian National Seismograph Network (ANSN) inlower Vulcan formation. A geostatistical technique is adopted Western Australia with the aim of better locating the smallto map and interpolate rock properties throughout the grid earthquakes of the Southwest Seismic Zone of southwestwhich is tied with the fields stratigraphic unit. A seismic Western Australia. velocity cube is used to compute density profile based on The Southwest Seismic Zone, one of the most seismicallyacoustic-density correlation and thereafter vertical stress. active onshore areas in Australia, is an area known for itsPore pressure is modelled by defining the pressure depth seismicity by the local people who regularly experiencerelationship from the 1D reference pore pressure profile small cupboard rattlers. These often occur in swarms asand honouring the structural layering. Due to its inherent documented by Dent (e.g. 2009, 2014, 2017, 2019, 2020). Itproperty of structural consistency, this 3D model efficiently is more widely known for the M6.5 Meckering earthquake ofcaptures the lateral heterogeneity over the 1D model 1968 which destroyed many houses in Meckering, producedvalidated at Prelude-1A well location.a 37 km long and 2 m high fault scarp and dramaticallyKey words: Geomechanical model, stress regime, rock strength, bent the railway line. There is no obvious tectonic reason forpore pressure, strutural grid, Ichthys69 PREVIEW AUGUST 2021'