b'AEGC 2021Short abstractsBorehole magnetic resonance (BMR) is a wireline loggingIn the near future, the probe will be tested across a series of technique used to provide in-situ formation evaluation. BMRfield trials. Further work involves extending the measurement responds to both the volumes of fluids present in a rock, andcapabilities of the probe and looks towards commercialisation the geometry of the pores in which this water resides. Asof the tool.such, it is a powerful addition to any borehole geophysical characterisation aimed at evaluating the storage and flow189: In-situ stress pattern along the Jellinbah Fold capacity of subsurface formation or aquifer.Thrust Belt in the Bowen Basin, AustraliaBMR is highly advantageous due to its ability to provide a lithology independent measurement of formation porosity.Mr Saswata Mukherjee 1, Dr Mojtaba Rajabi1, Prof Joan Esterle1 A further application of BMR is to estimate the formationand Dr Renate Sliwa2permeability. Semi-empirical models have been developed1 School of Earth and Environmental Sciences, The University of which quantify the relationship between the pore sizeQueenslanddistribution captured using BMR and formation permeability.2 Integrated Geoscience Pty LtdThe parameters which are used within these models are formation dependent. Thus, the parameters must be calibratedThe Permo-Triassic Bowen Basin hosts numerous thick to the geology of interest to ensure that the BMR permeabilitycoal seams, and it is a prolific basin for coal mining and model is tuned to provide appropriate permeability estimates.gas production. The development of coal seam gas (CSG) Historically this has been through coring programmes, howeverreservoirs in different parts of the Bowen Basin emphasizes this is often not available in a hydrogeological context duethe potentiality of the basin as the next major gas province ability to retrieve core in unconsolidated formations and thein eastern Australia, albeit with challenges for permeability. availability of pump test data on existing bores. This paperThe Jellinbah Fold Thrust Belt in the Bowen Basin is one such reviews a process that uses a combination of packer tests, pumparea, and the current CSG development in this structurally tests and lugeon tests to calibrate the coefficients to calculatecomplex area shows the significant influence of in-situ stress hydraulic conductivity from a T2 distribution. The process will beon the wellbore stability, gas production and well completion discussed and its applications to set of data will be presented. design. Therefore, a comprehensive analysis of in-situ stress pattern is required in order to better understand the localised stress perturbations for further appraising CSG reservoirs 188: Designing a magnetic resonance Logging-While- potentiality in this part of the basin. Herein, we compile and Drilling tool for reverse-circulation minerals exploration analyse different datasets including conventional well logs, borehole image logs and seismic data to understand the in-situ Dr Keelan ONeill 1, Mrs Sravani Mukkisa2, Prof Michael Johns1stress field across the study area and characterise the role of and Dr Timothy Hopper2 geological structures on the stress pattern within the Bowen Basin sedimentary sequences.1 University of Western Australia2 RIG Technologies International Pty Ltd Analysis of 19.3 km of borehole image logs from 29 vertical wells corroborated an overall NE-SW for the maximum We outline a nuclear magnetic resonance (NMR) logging-whilst- horizontal stress (S Hmax ) orientation within the study area. drilling (LWD) tool targeted at the minerals exploration industry.Although in-situ stress data showed a predominant thrust The tool allows real-time geological assessment during reverse- faulting stress regime in most parts, evidence of strike-slip stress circulation (RC) drilling. NMR logging captures the porosity,regime was also observed within the region. Significant stress pore size and permeability in the formation of interest enablingrotations were observed spatially and along depth, highlights advanced formation evaluation. This information can then bethe influence of folds, faults, fractures, and lithological contrast used to assist real-time decisions for drilling operations (e.g.on the present-day stress pattern at local scales. This suggests geo-steering) and resource evaluation. that existing geological structures are one of the key controlling In this work we outline the challenges involved in designingparameters on the in-situ stress patterns observed within the the prototype NMR LWD tool. The mechanical structure ofstudy area.the tool needs to be highly robust to survive the shocks and vibrations experienced during RC drilling operations, whilst190: A new method for determining drill-bit signal ensuring there is minimal impact on magnetic resonanceemission timemeasurements. The tool magnetic physics must ensure that the probe is measuring at the appropriate depth into theDr Zixing Qin 1, Prof Milovan Urosevic1, Mr Andrej Bona1, Prof adjacent formation at sufficient accuracy. The measurementRoman Pevzner1 and Dr Konstantin Tertyshnikovmust also be designed to be insensitive to the array of1 Curtin Universitymotions experienced during drilling operations. The device requires high-powered electronics which must be capable ofIn 2019, we acquired the first ever seismic while drilling (SWD) handling the tool power supply as well as signal excitationdata with distributed acoustic sensing (DAS) fibre optic cable and detection requirements The resultant design optimisespermanently installed behind the casing. After analysing the the inherent trade-offs which exist between each of thesesignal characters, we utilized shift and stack technique to physical components: (mechanical structure, magneticincrease signal strength at selected waveform locations. Data components and electronic hardware) to fit within the dual- quality obtained is encouraging after such an initial processing wall drill-rod in the RC drill string without compromisingstep. However, a fundamental problem inherited from the the drilling operation. Current experimental analysis of theraw SWD dataset still remains, which relates to unknown zero prototype is ensuring that the probe is demonstrating thetiming. This limits the applicability of the drill bit technique for required measurement specifications and is field-ready. investigations of the geological space between two or more AUGUST 2021 PREVIEW 94'