Jeffrey, RG & Zhang, X 2008, 'Hydraulic Fracture Growth in Coal', in Y Potvin, J Carter, A Dyskin & R Jeffrey (eds), SHIRMS 2008: Proceedings of the First Southern Hemisphere International Rock Mechanics Symposium, Australian Centre for Geomechanics, Perth, pp. 369-379, https://doi.org/10.36487/ACG_repo/808_79 (https://papers.acg.uwa.edu.au/p/808_79_Jeffrey/) Abstract: A significant number of hydraulic fracture treatments in coal seams have been mined and the propped fracture geometry mapped. Efforts to monitor fracture growth remotely or by measuring pressure in offset wells have added to the database on fracture growth in coal. Despite this considerable body of work, fracturing coal still can result in unexpected response and model predictions of fracture pressure and extent are unreliable, unless considerable empirical experience is available and used to calibrate the model for any new site. This state of affairs is a result of the layered and naturally fractured nature of coal. This paper will present selected data from lab and field experiments and modelling results that together provide an insight into the main factors contributing to high treating pressure and shorter than expected length development for hydraulic fracture treatments in coal.