b'ASEG newsCommitteesThis year, our focus shifts to the in- entire borehole profiles instantaneously,the integration of thermal properties depth analysis of the divergent armand has a potential for conducting in- derived from drill cuttings provided by of the triple junction that spans thesitu thermal conductivity assessmentsthe Geological Survey of South Australia. Mesozoic depocenters of the Otwayduring active operations. Nonetheless,Simultaneously, we are set on inferring Basin. Were employing a novel approach,it demands a more intricate calibrationthe land surface temperature history amalgamating petrophysical samplesprocess, necessitating additionalusing temperature data from a single from 180 wells with high-resolutionlabour, processing, extended setup, andborehole with a substantial air-filled gravity and magnetic data, to generatelogistical considerations. section in the Gippsland Basin. To address 2D and 3D models of the Otway Basin.The project targets accessible boreholesthe air-filled section our methodology We plan to analyse these 3D models,in the Gippsland and Murray Basinsmerges both DTS and thermistor-produced through combined 2Dfor sensor deployment. It aims tobased logs in this borehole, which seismic constrained forward and inverseexamine these sensor technologiesmutually complement each other, and models, to delineate the rift domainscollectively to optimise operationalincorporates the thermal conductivity and examine the major tectonic factorsefficiency, accuracy, precision, andand diffusivity data previously acquired steering the evolution of the divergentin-situ calibration techniques for DTS.from cores courtesy of the Geological and transform arms of the triple junction.Gaining this understanding is pivotalSurvey of Victoria. We sincerely thank Seismic interpretation combined withfor applications within boreholethe ASEG Research Foundation for the 2D forward models of intersectinggeophysics that rely on temperaturefinancial support bestowed by the grant, traverses covering Otway Basin has beenmeasurements. These applicationswhich has been critical for meeting the completed. Our final endeavour is tospan fundamental lithospheric researchcosts associated with our fieldwork and produce constrained 3D models of the(heat flow measurements), geothermalnecessary equipment.Otway Basin. exploration, monitoring of groundwater We wish to express our profoundtemperatures, and the reconstruction ofRF22P01. University of Adelaide, PhD gratitude to the Members of thepast land surface temperatures. student Kosuke Tsutsui (supervisor Australian Society of ExplorationThe project has advanced, thanks toProfSimon Holford).Geophysics (ASEG). Their ASEG Researchpartnerships between the University Foundation grant has been instrumentalof Melbourne, AuScope, GeoscienceGeophysical-geomechanical in facilitating a significant portion of thisAustralia, CSIRO, and the geologicalcharacterisation of igneous rocks in the PhD project. surveys of Victoria and South Australia,Browse Basin: implications for exploration, which have provided crucial access todevelopment, and gas storage in volcanic-DTS equipment, boreholes, and relatedrich basins.RF21P02. University of Melbourne,core samples and cuttings. We secured MScstudent Youssef Hamad (supervisorhigh-precision, lab-calibrated thermistor-Dr Graeme Beardsmore). Introductionbased logs from eight boreholes in the Utilisation and comparison of conventionalGippsland Basin, and two more fromExploration in sedimentary basins wireline precision temperature sensing,the Murray Basin in South Australia. Weimpacted by magmatic activity faces DTS, and aDTS to detect and quantifyimplemented DTS in five of those eighta significant challenge in accurately subsurface geothermal anomalies in theboreholes using passive sensing, and onepredicting the presence of igneous on-shore Gippsland Basin. of the Murray Basin boreholes with activerocks within sedimentary sequences sensing. In three of those boreholes,(e.g. Planke et al. 2000; Schofield et al. This project integrates three temperaturewe also deployed button-style loggers2017; Watson et al. 2020). These igneous measurement technologies, all tailoredas in-situ calibration sensors alongsiderocks can profoundly impact various for borehole geophysical logging, andDTS to enhance the accuracy of the DTSaspects of petroleum systems, such investigates how they can complementlogs, particularly when encounteringas influencing reservoir deposition by each other. The sensors includedata noise. Collectively, these loggerscontrolling sediment fairways, working thermistor-based instruments, self- demonstrated robust performance,as fluid migration pathways or barriers, contained button-style loggers, andcapturing subsurface temperatures downand forming trapping systems (e.g. fibre optic distributed temperatureto depths of 1 km and up to temperaturesHolford et al. 2012; Senger et al. 2017). sensors (DTS), each with its distinctof approximately 65oC. An active DTSAdditionally, igneous rocks can add advantages and disadvantages.trial was carried out in a borehole in thecomplications to drilling operations such Conventional thermistor instruments,Murray Basin to acquire in-situ thermalas low rates of penetration, rapid drill bit while known for precision, contendconductivity data, facilitated by CSIRO.wear, drilling mud losses, and wellbore with drawbacks such as slow loggingFurthermore, we secured legacy rockcollapse, leading to unforeseen costs speeds, heavy and costly wirelinecores from the Geological Survey ofand complexities (e.g. Millett et al. 2016; cables, and extended equilibrationVictoria core library in Werribee andWatson et al. 2020; Curtis et al. 2022).times in air-filled bore sections,conducted thermal conductivity and diminishing their accuracy. In contrast,diffusivity measurements. The Browse Basin, covering an area self-contained button-style loggersof~140 000 km on Australias North offer a more economical alternative,The next stage of our project involvesWest Shelf, typifies many of these but not without compromising theapplying numerical modelling to derivechallenges, with the presence of igneous resolution of temperature and depthin-situ thermal conductivity from therocks having been recognised since its measurements. DTS uniquely capturesactive DTS data from South Australia.early exploration in the 1970s. Despite time-series spatial-temporal data, logsThis model is set for refinement throughbeing one of several major hydrocarbon FEBRUARY 2024PREVIEW 9'