Hydraulic fracturing or “fracking” is a well established, tightly regulated technology. It has been used safely to enhance oil and gas production for 65 years in more than 2 million wells worldwide.
Fracking increases the flow of oil and gas to wells, which increases production per well and reduces the total number of wells needed to develop resources. It also allows commercialisation of “tight” (low permeability) reservoirs in which oil and gas do not easily flow.
This technology is now used in about 90% of new US gas wells – including all shale gas wells. Shales have low permeability. This mean the pores in the rocks are not well connected with each other, so oil and gas do not flow easily. Fracking is used to increase permeability.
Other industries also use reservoir stimulation – artificial geothermal energy production relies on fracking and even water bores are sometimes fracced to increase water production.
The Cooper Basin (in northeast south Australia and southwest Queensland) has for 50 years been one of Australia’s premier oil and gas regions. Since 1969, about 700 wells have been hydraulically fractured in the Cooper without problems. Some of these wells have been fracked several times.
Fracking involves stimulating tiny fractures in a rock layer in order to increase the flow of gas, oil or other substances, such as geothermal fluids.
Fluid is pumped down the well at high pressure to produce cracks in the target rock reservoir.
Hydraulic fracturing fluid is mostly water and sand or ceramic beads (between 96 and 99.9 per cent). The sand or beads (known as “proppants”) enter the fissures and hold them open to make the fracturing process more effective.
The chemicals in the fluid reduce friction, remove bacteria from the formation, dissolve some minerals, prevent build-up of scale and enhance the fluid’s ability to transport sand.
The chemical additives used are familiar products found in most households. They are subject to similar strict regulations applying to responsible chemical use on farms or in factories.
The industry is committed to open and transparent disclosure of the chemicals used in exploration or production. Planning for each well involves preparing an environmental management plan with details of the chemicals used in hydraulic fracturing and the management strategies in place to protect the environment. This information is available to the public on company websites.
|Acids||Helps dissolve minerals, initiate fissure in rock (pre-fracture) and manage pH Levels||Swimming pool cleaner|
|Sodium Chloride||Allows a delayed breakdown of the gel polymer chains||Table salt|
|Polyacrylamide||Minimises the friction between fluid and pipe||Water treatment, soil conditioner|
|Ethylene Glycol||Prevents scale deposits in the pipe||Automotive anti-freeze, de-icing agent, household cleaners|
|Borate Salts||Maintains fluid viscosity as temperature increases||Laundry detergent, hand soap, cosmetics|
|Sodium/Potassium Carbonate||Maintains effectiveness of other components, such as cross-linkers||Washing soda, detergent, soap, water softener, glass, ceramics|
|Glutaraldehyde||Eliminates bacteria in the water||Disinfectant, sterilisation of medical and dental equipment|
|Guar Gum||Thickens the water to suspend the sand||Thickener in cosmetics, baked goods, ice cream, toothpaste, sauces|
|Citric Acid||Prevents precipitation of metal oxides||Food additives, food and beverages, lemon juice|
|Isopropanol||Used to increase the viscosity of the fracture fluid||Glass cleaner, antiperspirant, hair colouring|
State regulations and the industry Code of Practice require monitoring of production areas – particularly the wells and groundwater aquifers to make sure the gas production is functioning according to plan. Water analysis, pressure testing and in some cases, additional seismic measurements are used to make sure the operation is running smoothly and the environment is being protected effectively.
Onshore gas developments are designed to minimise impact on the ground surface and land use.
A typical drilling site would require clearing up to two hectares to allow for well development and stimulation. After the exploration drilling, most of the land is rehabilitated, leaving a small cleared area around each well head.
Some of the fraccing fluid can flow back to the surface where it is stored in ponds which are sealed to high environmental standards. The recovered fluids are recycled, re-injected into deep saline aquifers, sold or disposed of in approved facilities. The rest of the fluid remains locked in the gas-bearing rock formations at least two kilometres beneath the ground surface and well below any freshwater aquifers.
The use of horizontal drilling has helped to reduce the footprint for some potential shale gas and tight gas operations. Sophisticated technology allows the exploration or production companies to drill to the gas formation and then redirect the drill bit through the gas-bearing zone. This means that up to six wells can be operated from one surface drilling pad – significantly reducing the surface footprint.