News and Events and FAQ’s on Coal Seem Gas
What is Coal Seam Gas?
Coal Seam Gas (CSG) is a gas consisting of around 98% methane and is formed from the degradation of plant matter over millions of years. CSG is trapped by water and ground pressure against the surface of coal in underground coal seams and is also located within pores inside the coal. The spaces between the coal are known as fractures or cleats. Some of the fractures are interconnected and permeable which allows water and gas to move between the fractures.
How is Coal Seam Gas extracted?
CSG is extracted via CSG wells that are drilled into the coal seams to release the gas trapped within the coal. For economic extraction of CSG, coals seams in Australia are generally between 200metres – 1,000m metres deep. The CSG wells are cased with steel and cement. In situations where coal seams are very deep and of low permeability, the use of hydraulic fracturing or ‘fraccing’ may be employed to increase permeability. This process involves pumping fluid comprising water, sand and other additives such as BTEX (BTEX is an acronym for benzene, toluene, ethylbenzene and xylene compounds) at high pressure down the cased CSG well and into the coal seam. This action fractures the coal seam and provides a pathway to facilitate gas flow through the coal.