- Depending on the subsurface formation, a technique called hydraulic fracturing is required to release the gas trapped deep underground
- Hydraulic fracturing involves pumping a fluid down the well at high pressure to open tiny cracks in the target rock reservoir
- A CSG well will probably be fractured once in its production lifetime
- Hydraulic fracturing can be traced back over 40 years in Australia
The hydraulic fracturing process – also referred to as ‘fraccing’ or ‘fracking’ – is used to increase the flow of oil and gas to a well, increasing production and reducing the total number of wells needed to develop a resource. It allows commercialisation of low permeability reservoirs in which oil and gas do not easily flow. It can also be used with other natural resources, such as to access geothermal energy, and to increase water production.
Hydraulic fracturing involves pumping a fluid down the well at high pressure to open tiny cracks in the target rock reservoir. This fluid contains ‘proppants’, primarily sand, which is used to hold the fissures open and improve the flow of gas or oil. Most fluid contains less than 1% of chemical additives to make the technique more efficient.
While the proppants remain behind in the rock formation, most of the injected fluid either breaks down into harmless materials (such as starch or water) or flows back to the surface.
All recovered fluids are isolated in sealed storage areas designed to prevent leakage, including specially designed and constructed dams or above-ground holding tanks. Depending on regulatory conditions, these fluids are then reused in subsequent well stimulation activities, treated for other uses or disposed of through an approved facility.
Hydraulic fracturing isn’t used automatically in the exploration and production process. The process occurs after the actual drilling of a well and is considered a separate process in the development of an oil and gas field.
A CSG well will probably be fractured once in its production lifetime while a shale or tight gas well will undergo a series of fractures of the same well which are carried out in multiple stages. Multistage hydraulic fracturing, when combined with horizontal drilling, is a prime example of the importance of innovation in the oil and gas industry.
The combination of these techniques has resulted in fewer wells needing to be drilled to access large reserves of oil and gas, resulting in less environmental impact at a surface level.
History in Australia
In Australia, hydraulic fracturing can be traced back over 40 years where it was used in the production of energy resources, including conventional natural gas.
For example, natural gas wells in South Australia’s Cooper Basin have been fracture stimulated since the 1970s, while in Western Australia, the Department of Minerals and Petroleum reports that almost eight hundred fracture stimulations have been carried out in that State since 1958 – with no observed or reportable adverse consequences.
A majority of the hydraulic fracturing undertaken in Western Australia has occurred on Barrow Island since 1965.
Located off the coast of Western Australia, Barrow Island has been identified as an ‘A’ Class nature reserve – the highest level of environmental protection afforded in the State.