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Spontaneous heating in the active goaf area during normal mining processes poses increased threats to mine productivity and safety, as evidenced in events induced by spontaneous combustion of coal. To control and mitigate this engineering problem, there is a need to gain critical knowledge of spontaneous combustion in the longwall goaf area, which can be achieved through a combination of field tests and numerical modeling. This paper introduces the spontaneous combustion management system widely used in Australia and presents Computational Fluid Dynamics (CFD) models for the simulation of gas flow dynamics in the goaf area, based on the site conditions of an underground coal mine where coal seam gas is predominantly comprised of carbon dioxide. The models were validated with gas monitoring data and used to conduct parametric studies for proactive goaf inertisation optimization. Qualitative and quantitative analysis of simulation results indicated that better goaf inertisation could be achieved when nitrogen was injected via cut-through at 250 m on the maingate (MG) side and surface boreholes at 100 m and 700 m on the tailgate (TG) side, with a total injection rate greater than 1750 1/s. The oxygen concentration on the MG and TG side dropped below 5% at distances of 120 m and 75 m behind the longwall face, with an oxidation zone area of 35375 m2, which was approximately one-third of the oxidation zone area of the scenario without inert gas injection. Simulation results help shed light on improving current goaf inertisation practices to effectively reduce the risk of heating in goaf areas and improve mining process safety based on Australian conditions and practices. [ABSTRACT FROM AUTHOR]

There has been an exponential increase in both the production and exploration of coal seam gas (CSG) in Australia and many other regions in the world. Amajor issue associated with the production of CSG is the management of produced water. CSG is usually mixed with water in the coal seam, to recover the gas, the water must be first extracted from the coal seam to reduce pressure. This water -- known as co-produced water or CSG water -- is typically quite saline, large in volume and may contain heavy metals and other trace elements of concern. The management of this produced water is of paramount importance to the oil and gas industry. This paper reviews the key characteristics of CSG water and its possible beneficial uses. A specific focus is on the role of reverse osmosis (RO) membranes in the treatment of produced water for beneficial uses or safe discharge into the environment. Recent examples involving the use of RO membranes for the treatment of produced water are systematically summarised and discussed. Opportunities and challenges associated with sustainable management of produced water currently presented to the water industry are also highlighted and discussed in detail. [ABSTRACT FROM AUTHOR]