Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable condit...Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.展开更多
This paper highlights a reliable goaf gas capture system developed and used at Ravensworth Under-ground Mine since its trial in 2009. The method utilises horizontal holes drilled from underground sites and connected t...This paper highlights a reliable goaf gas capture system developed and used at Ravensworth Under-ground Mine since its trial in 2009. The method utilises horizontal holes drilled from underground sites and connected to an underground gas pipeline. This system incorporates a gas suction and flaring plant designed specifically for this method. The current method has captured effectively a total longwall, and adjacent goaf gas accounts for over 85%. The design of the holes drilled has been the success of the gas flow reliability. The flow is extraordinarily consistent and predictable. The management of the under-ground pipeline determines the overall reliability of flow. The design has resulted in Ravensworth Man-agement being confident to remove a gas bearing bleeder roadway and still manage the existing tailgate roadway for allowing access as required. The reduction of CO2 equivalent emissions recorded is approx-imately 0.35 ？ 106 tons annually. This design has further improvements to be added to allow use at any other site with gas in the overlying strata.展开更多
文摘Directional drilling has been established in the coal industry as a viable means of gas drainage, exploration and water management. But the environment in and around coal seams is not always conducive to stable conditions while drilling and borehole stability after the drilling has been completed. This paper identifies the conditions which cause unstable drilling conditions and the various means which are used to attempt to manage or bypass those conditions. Ultimately, equipment does become bogged in these adverse environments and requires recovery by over-coring.
文摘This paper highlights a reliable goaf gas capture system developed and used at Ravensworth Under-ground Mine since its trial in 2009. The method utilises horizontal holes drilled from underground sites and connected to an underground gas pipeline. This system incorporates a gas suction and flaring plant designed specifically for this method. The current method has captured effectively a total longwall, and adjacent goaf gas accounts for over 85%. The design of the holes drilled has been the success of the gas flow reliability. The flow is extraordinarily consistent and predictable. The management of the under-ground pipeline determines the overall reliability of flow. The design has resulted in Ravensworth Man-agement being confident to remove a gas bearing bleeder roadway and still manage the existing tailgate roadway for allowing access as required. The reduction of CO2 equivalent emissions recorded is approx-imately 0.35 ？ 106 tons annually. This design has further improvements to be added to allow use at any other site with gas in the overlying strata.
