Natural gas 101

Article

Natural gas is a fossil fuel. This means that, like oil and coal, it was formed from the remains of plants and animals buried under many layers of sediment millions of years ago. Heat and pressure created chemical changes over time, transforming the material into hydrocarbons such as natural gas. Today this important energy source is found in sedimentary rock throughout the world.

What are the properties of natural gas?

The main ingredient of natural gas is methane, but it may have small amounts of other gases (including ethane, propane and butane). Natural gas is colourless and odourless in its pure form. The distinctive "rotten egg" smell we often associate with natural gas is actually an odour-causing substance, called mercaptan, added to gas for safety reasons. When burned, natural gas gives off a great deal of energy while producing few emissions.

How is natural gas used?

Natural gas is abundant, safe, reliable, efficient and a cleaner-burning option than other fossil fuels. Because of these properties, natural gas is a popular fuel for heating our homes, cooking our food, fueling transportation, generating electricity, running industrial plants and providing raw material for a range of products.

Where is natural gas found in Canada?

Natural gas is found in several regions across Canada. British Columbia, Alberta, Quebec, Nova Scotia and the Northwest Territories all have significant natural gas resources.

How is water protected during natural gas production?

Water is used at different stages of natural gas operations. During drilling, water cools and lubricates the drill bit and carries rock cuttings to the subsurface. To complete shale gas wells, we use water to fracture the rock and recover the gas. We adhere to strict regulatory frameworks and sound practices concerning well design and construction to prevent accidental releases and reduce risk to ground water.

Drinking water aquifers are usually located less than 300 metres underground, while shale gas reservoirs are often found at depths of 2,000 to 3,000 metres. When drilling through aquifers, we install an engineered steel casing system around the wellbore and cement it in place. This provides an impermeable protective layer between the well and the surrounding environment, including any water sources.

Hydraulic fracturing uses water during the initial fracturing stage for each well. To minimize the amount of water used, we seek to recycle water recovered from our fracturing operations, wherever possible. In those cases where reuse is not possible, water is safely injected and stored in deep underground control wells according to government regulations.

Natural gas and technology

Our industry has been aware for decades that natural gas has been locked in shale and tight gas formations. The key has been finding and developing the advanced technologies to unlock these resources so they can be commercially viable.

Hydraulic fracturing

Unconventional gas resources such as shale are now being accessed using a process called hydraulic fracturing. This technique involves injecting a mixture of water, sand and a small amount of other additives into the well. The pressurized hydraulic fluid does the hard work of creating hairline cracks in the shale. These cracks, held open by the sand particles, allow the gas to flow up through the wellbore to the surface.

Hydraulic fracturing is not new. It was first used in conventional oil and gas extraction in the late 1940s in North America. Since then, more than one million wells around the world have been drilled using hydraulic fracturing. In Alberta, it has been used for more than 60 years to safely and reliably fracture over 167,000 wells.

What is new, however, is the use of multiple technologies in conjunction with one another to make accessing unconventional gas more feasible. By combining hydraulic fracturing with horizontal drilling, operators can safely produce affordable, reliable quantities of natural gas from shale and other unconventional sources.

Hydraulic fracturing fluids

Fracturing fluids are used to help create the tiny cracks in the rock to allow the gas to flow. These fluids typically consist of about 90 percent water and 9.5 percent sand. Many of the ingredients in the remaining 0.5 percent of the mixture have common consumer applications in household products, detergents and cosmetics. These chemicals are used to reduce friction, prevent bacteria growth and protect the rock formation, making the hydraulic fracturing safer and more efficient.

Additive	Chemical Ingredient	Purpose	Common use of chemical ingredient
Acid	Hydrochloric acid or muriatic Acid	Helps dissolve minerals and initiate cracks in rocks	Swimming pool chemical and cleaner
Antibacterial agent	Glutaralhehyde	Eliminates bacteria in water that produces corrosive by-products	Disinfectant; sterilizer for medical and dental equipment
Breaker	Ammonium persulfate	Allows a delayed breakdown of the gel	Used in hair colouring, as a disinfectant, and in the manufacturing of common household plastics
Corrosion inhibitor	Formamide	Prevents corrosion of the well casing	Used in pharmaceuticals, acrylic fibres and plastics
Crosslinker	Borate salts	Maintains fluid viscosity as temperatures increase	Used in laundry detergents, hand soaps and cosmetics
Friction reducer	Petroleum distillate	“Slicks” the water to minimize friction	Used in cosmetics including hair, make-up, nail and skin products
Gel	Guar gum or hydroxyethyl cellulose	Thickens the water in order to suspend the sand	Thickener used in cosmetics, baked goods, ice cream, toothpaste, sauces and salad dressings
Iron Control	Citric acid	Prevents precipitation of metal oxides	Food additive; food and beverages; lemon juice ~ 7% citric acid
Clay stabilizer	Potassium chloride	Creates a brine carrier fluid that prohibits fluid interaction with formation clays	Used in low-sodium table salt substitutes, medicines and IV fluids
pH adjusting agent	Sodium or potassium carbonate	Maintains the effectiveness of other components, such as crosslinkers	Used in laundry detergents, soap, water softener and dishwasher detergents
Proppant	Silica, quartz sand	Allows fractures to remain open so the gas can escape	Drinking water filtration, play sand, concrete and brick mortar
Scale inhibitor	Ethylene glycol	Prevents scale deposits in pipe	Used in household cleansers, de-icer, paints and caulk
Surfactant	Isopropanol	Used to reduce the surface tension of the fracturing fluids, to improve liquid recovery from the well after the frac	Used in glass cleaner, multi-surface cleansers, anti-perspirant, deodorants and hair colour
Water	Water	Used to expand the fracture and deliver proppant (sand)	Landscaping, manufacturing

XTO Energy Canada

Imperial is a 50-50 partner with ExxonMobil Canada in XTO Energy Canada (formerly Celtic Exploration). This asset includes 545,000 net acres in the liquids-rich Montney shale, 75,000 net acres in the Duvernay shale, and additional acreage in other areas of Alberta. XTO holdings provide Imperial with flexible options and potential diluent supply.

Visit the XTO Energy website at xtoenergy.com.