What is Fracking?
Fracking is a form of unconventional oil and gas extraction. This online explainer briefly outlines what's involved in fracking and how it works. On the mainland fracking is mainly used to explore for and extract coal seam gas (CSG). Tasmania is considered prospective for two types of unconventional gas: shale gas and tight gas. Shale gas is found in shale rocks. Tight gas is found in low permeability sandstone rocks.
If fracking is permitted in Tasmania, drilling would be more similar to fracking operations in the US, which has very large shale gas deposits. The Bakken Shale and the Marcellus Shale gas 'plays' are two examples of fracking for shale gas.
Shale gas deposits lie between 2000 and 4000 metres underground. Because shale gas deposits are deeper than coal seam gas deposits, horizontal wells are drilled off the vertical well. As a result, the fractures caused by horizontal drilling are vertical, instead of horizontal. Subterranean rock fractures range from a few metres to tens of metres in length.
Fracking to release tight gas also requires acidation. This means that acids, usually hydrochloric acid, are pumped into the formation to dissolve some of the rock material to enable the gas to flow more readily. There are other ways to fracture wells and sometimes gases such as propane or nitrogen are injected to create fractures.
The industry frequently claims that fracking is a proven technology that's been in use for over 60 years. Fracking as we know it today is very different to the practice used in conventional gas wells for decades. Before 1997, when technological advances made unconventional gas extraction commercially viable, fracking was only done on vertical wells. Last century fracking also involved much lower pressures and fewer chemicals.