Underground » Exploration
This report presents the research for a wireless survey tool that provides high data-rate, bi-directional wireless communication between the borehole assembly and the drill rig in the hazardous conditions of underground in-seam (UIS) drilling.
Phase1 (C21019) involved the research required to understand the performance of high frequency communications techniques inside an inseam borehole, with the power limitations required for an intrinsically safe design. Based on the previous results, this project focused on developing a prototype for trials in cross-panel drilling, or more generally, for holes in the 400-500m range. This system was also used to conduct further research to assess and optimise the performance in the 600m-1200m range; which is where the technology needs to operate for cross measure drilling and exploration holes.
Two versions of the system have been developed and tested. One version is a low power design with electronics and algorithms that are optimised for operating on battery powered systems with maximum battery life. On the low power version both the borehole assembly (BHA) tool and the drill rig unit (DRU) are battery powered, so that it can be operated where electrical power is not available at a mine. The second system that was designed requires higher battery capacity at the borehole assembly (BHA) for transmitting larger data packets that are structured for overcoming electrical noise and requires a powerful computer at the drill rig for running powerful algorithms. Both systems were tested, and the system that was manufactured and tested at the mine site is the streamlined low-power version. This stand-alone system is designed for 400-500m boreholes and was tested at Tahmoor mine inside a 600m deep cross measure borehole. The results were quite close to the expected outcomes, and in fact were very good.
During the field trial, raw data was logged to flash memory which was later used to test the enhanced version of the system. This version uses algorithms that require the computation power of a computer. We were hoping to test the computer-based system at the mine site trials, but the manufacturer did not have certification ready in time, so instead our effort went into maximising the performance of the stand-alone system. Post-analysis of the raw data with the high-power algorithms demonstrated that it is possible to manufacture a system capable of high resolution, high bandwidth communication in most typical UIS boreholes (in the 600-1200m range).
The prototype contains a survey sensor and is hazardous area certified. The tool architecture is open so that it can also integrate with Mining3's other designs as well as third-party tools, to provide geo-sensing measurement-whilst-drilling (MWD) and logging-whilst-drilling (LWD) capabilities. The tool is available for further testing under different conditions, subject to more battery units being manufactured and certified. The drill rig unit on the prototype is currently not certified, however, can be used underground subject to a risk-assessment being conducted.