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In this Feb. 21, 2012, file photo, oil field workers drill into the Gypsum Hills near Medicine Lodge, Kan., using horizontal drilling and a technique known as hydraulic fracturing, or "fracking, " to coax out oil and gas. Illinois legislation is advancing that would regulate decades-old but debated technology used to reach previously inaccessible natural gas reserves deep underground. The Illinois state Senate on Thursday, April 26, 2012, unanimously sent to the House a bill addressing hydraulic fracturing, or fracking. That technology involves using mixtures of water, sand and chemicals to free below-ground energy reserves. (Orlin Wagner/AP Photo)

In this Feb. 21, 2012, file photo, oil field workers drill into the Gypsum Hills near Medicine Lodge, Kan., using horizontal drilling and a technique known as hydraulic fracturing, or "fracking, " to coax out oil and gas. Illinois legislation is advancing that would regulate decades-old but debated technology used to reach previously inaccessible natural gas reserves deep underground. The Illinois state Senate on Thursday, April 26, 2012, unanimously sent to the House a bill addressing hydraulic fracturing, or fracking. That technology involves using mixtures of water, sand and chemicals to free below-ground energy reserves.

(Orlin Wagner/AP Photo)

Explainer: Four big questions about fracking Add to ...

Within Canada, comfort levels with the oil and gas industry vary widely by region, but even in Western Canada, where shale gas development has proceeded under the umbrella of existing regulations, changes may be needed to encompass ways in which hydraulic fracturing is different from conventional drilling.

 

 

WHAT IS FRACKING?

Hydraulic fracturing, or fracking, is a way of liberating reserves of natural gas that are locked within shale formations deep below the surface. Because shale is not very porous, gas does not travel through the rock easily. Unlike conventional gas wells, merely drilling down is not enough to get the shale gas out.

A shale gas well begins vertically but then bends once it reaches the shale layer and continues horizontally to maximize access to the gas-bearing rock.

After the drilling, a series of explosive charges followed by the injection of a fluid under high pressure is used to fracture the rock. This opens up cracks in the rock. Sand grains in the fluid get  into the cracks and keep them open, allowing the gas to seep into the well and travel up to the surface. 

WHAT'S IN THE FRACKING FLUID?

Most of the fluid injected into shale gas wells is simply water and fine particles of sand or clay, but an array of chemical additives are used to improve fluid flow and inhibit the buildup of minerals and bacteria. The precise mix may vary from well to well depending on geology and other factors. British Columbia and Alberta require operators to disclose the chemicals they use, although there is some leeway in the rules to allow for protection of  trade secrets.

WHAT ARE THE CONCERNS?

A new report from the Council of Canadian Academies looks closely at what is known about the possible environmental impacts of shale gas extraction in Canada. Although the technology is evolving rapidly and data is gradually emerging from the United States where the industry has expanded rapidly, the report finds a number of areas where uncertainties remain. 

Well casing

Improperly formed or deteriorating cement around the upper sections of a well bore can allow gas to leak and potentially reach groundwater. Well integrity is a persistent challenge in the gas industry but the risk of poor well construction is amplified when it comes to hydraulic fracturing because of the pressures and wear and tear associated with the process and because many more wells are needed per unit of gas extracted relative to conventional drilling.

Gas leaks and climate change

Natural gas burns more cleanly than coal and puts less carbon in the atmosphere. It has been touted as a bridge to a low carbon energy future and a way to help slow the warming of the Earth’s climate.  However, methane, the primary constituent in natural gas is also a greenhouse gas. Research is currently divided over how much methane is leaking from shale gas operations and to what extent those leaks reduce the potential benefits of natural gas for climate change.

Industrial activity and pollution

The industrial activity associated with hydraulic fracturing can have bigger and more obvious impacts on the environment than the process itself. A large increase in emissions related to high truck traffic, drilling rig operations, gas compressors and other industrial effects generates air pollution, noise and other social impacts in areas that are not accustomed to resource extraction.

Flowback

Some of the fluid used in hydraulic fracturing returns to the surface and must be disposed of. This flowback water carries material from deep below that may pose a health risk, from radioactive minerals to compounds such as benzene that are associated with gas deposits. In regions where reinjection into the ground is not an option, the holding, shipping and disposal of large quantities of flowback water has the potential to create a significant environmental hazard.

Seismic activity

Both hydraulic fracturing and wastewater reinjection have been known to trigger minor earthquakes. The threat of harm from such events is generally considered to be low but seismic events can be minimized with more detailed information on geological conditions in areas where shale gas extraction is proposed.

HOW MUCH SHALE GAS DOES CANADA HAVE?

Estimates suggest there could be more than 3,000 trillion cubic feet of shale gas in Canada -- more than 50 times the country’s remaining conventional gas reserves. However, current techniques are typically not able to recover more than about 30 per cent of the gas in shale formations.

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