Vertical seismic profiling (VSP) is commonly used in the oil and gas industry for better subsurface imaging and characterisation, as well as for providing depth calibration for surface seismic. The use of VSP in mineral exploration and mine planning is not very common mostly due to the small diameter and stability of the boreholes, as well as the relatively high cost of such surveys. These issues can be mitigated by using cheap and potentially disposable borehole sensors, such as fibre-optic cables utilised in distributed acoustic sensing (DAS). The questions we want to answer in this work are how the quality of DAS data compares to other types of borehole measurements and what are the operational benefits and constraints for the use of this technology in mineral exploration settings. To this end, we have tested performance of DAS measurements in one of the boreholes of the Mineral Systems Drilling Program in South Australia and compared them to hydrophone measurements. The DAS measurements provide data quality that is much better than a hydrophone string, in particular it has consistent amplitudes at different depths, shows less cable and tube waves, and the reflections are much clearer. The acquisition of DAS data is quicker than any other borehole measurements that require multiple pulls of the receivers. The reduction of the acquisition time increases with the depth of the borehole. This case study demonstrates that DAS measurements show big potential for mineral exploration and exploitation.

Relatively stringent accuracy and precision requirements for well casing surveys and associated water-level measurements are generally difficult to achieve. Field experience and research indicate that the achieved accuracy is commonly less than expected. Realistic accuracy expectations require that the investigator know what is achievable for a site and how to convey the proper information to the surveyor. The point-difference accuracy of vertical surveys is calculated, based on the measured inaccuracy of the vertical survey divided by the square root of the length of the survey, and therefore by the size of the study area and number of wells surveyed. The accuracy of water-level measurements and contour maps is determined primarily by the equipment and procedures used for measuring the depth to water in the well casings. When setting accuracy requirements for water-level measurements and contour maps, the investigator must consider the end use of the data. Composite error from the two primary sources of error determines how much precision and accuracy are reasonably achievable.