drillGEO is a magnetic resonance (MR) logging-whilst drilling (LWD) tool targeted at the minerals exploration industry. drillGEO allows real-time geological assessment during reverse-circulation (RC) drilling. Magnetic resonance logging captures the porosity, pore size and permeability in the formation of interest enabling advanced formation evaluation. This information can then be used to assist real-time decisions for drilling operations (e.g. geo-steering) and resource evaluation. In this work we outline the challenges involved in designing the prototype drillGEO tool. The mechanical structure of the tool needs to be highly robust to survive the shocks and vibrations experienced during RC drilling operations, whilst ensuring minimal impact on magnetic resonance measurements. The tool magnetic physics must ensure that the probe is measuring at the appropriate depth into the adjacent formation at sufficient accuracy. The measurement must also be designed to be insensitive to the array of motions experienced during drilling operations. The resultant design optimises the inherent trade-offs which exist between each of these physical components: (mechanical structure, magnetic components and electronic hardware) to fit within the drill-string without compromising the RC drilling operation. Current experimental analysis of the prototype is ensuring that the probe is demonstrating the required measurement specifications and is field-ready.

Open-Access Online Publication: March 03, 2023