Forensic geology and gas reservoir data from the bit: new learnings from Yabby technology
New geosensing and gas reservoir technology (the ‘Yabby’) can be directly applied to Underground In-Seam (UIS) drilling to improve confidence in underground operational interpretation. The methodology uses various pressure sensors mounted on a rig and separator system, coupled with analytical software that produces real-time data from which 3D spatial attributes can be accurately determined. Soft and weak zones can be identified, and structures can be located confidently. The system includes formation flow analysis, drill performance management and reporting functions. This paper describes the technology and demonstrates its application with recent case studies. It also introduces new developments associated with the technology, including a colour sensor that improves geosensing interpretation and applications from surface boreholes designed to assist fugitive emission gas reservoir assessments.
This technology provides geological certainty for longwall mining in structurally challenging terrains. Any disruption to the longwall's continuous operation can result in production loss, costing millions of dollars in lost revenue. Certainty regarding the geological integrity of a longwall panel is an integral part of modern mining. In mines that need to drain gas for safety purposes, up to 200,000m per year of UIS drilling can be undertaken, and this data is sporadically used (or not at all) to inform the geological model, and with significant caveats due to the uncertainty of the data currently supplied by UIS drilling. Yabby changes this paradigm by providing accurate, quantitative, high-resolution data from UIS drilling.
The Yabby also incorporates an instrumented separator system that measures formation flow metrics during drilling, enables pressure build-up tests, and provides unparalleled insight into the variances present in the gas reservoir. Potential outburst-prone zones can be located in advance of the face, areas of high and low permeability identified, and detailed down-hole flow data provided within and between individual boreholes. Quantitative knowledge is now in the hands of the gas drainage engineer, and decision-making can now be based on facts rather than experience or ‘gut feel’.
The Yabby operates as a passive data collector on the drilling rig and has no tangible impact on drilling operations. It can be fitted to any drilling rig in about a day and removed at the end of a project or transferred to another rig if desired. An enormous amount of valuable drilling performance data is gathered, which can be directly applied to improve drill metrics or mitigate issues relating to drilling dysfunction. Work is underway to incorporate aspects of the drill metrics into a visual display to assist drillers in maintaining their position in-seam and provide feedback on drilling dysfunction, cuttings clearance, and other desired drilling-related feedback loops.
The Yabby has been commercially operational for over four (4) years. It has logged and reported more than 500,000m of continuous data in underground and surface applications. Yabby systems are now operational in NSW, QLD, and North America.