The evolution in coal mine gas extraction - a response to economic, environmental and community pressures

Effective gas management is vital to the success of the longwall mines operating in the Bulli seam, located in the Southern Sydney Basin, Australia. High gas emissions are characteristic of the region with specific gas emissions typically in the order of 30-45 m3/t. The mines that operate in this area have, since 1980, relied on the use of extensive underground to inseam (UIS) drilling to drain gas both ahead of advancing roadway development and following longwall coal extraction. With the ever increasing production capacity of modern mining machinery the UIS methods are struggling to drain sufficient gas from the coal ahead of mining to avoid gas related production delays. A further consideration for the operations in this region is the rapid rate of urban development extending to the south of Sydney and the increasing pressure to reduce greenhouse gas emissions. This paper discusses the evolution of gas drainage methods in the Southern Sydney Basin along with a range of developments that have the potential to significantly reduce both the community impact and mine green house gas (GHG) emissions.