Canadian Natural Gas Natural Gas and Water
Natural Gas and Water n
Water is used in the production, processing and transmission of natural gas, and in natural gas power generation. Water use, recovery, recycling and disposal is regulated by government and Canadian natural gas companies meet or exceed all regulations. Regulations are in place to address both water use and water quality, with particular attention to ensuring that drinking water is protected. The Canadian natural gas industry is committed to providing the best available information about all aspects of natural gas production and use, to identifying potential areas of concern, and to continuing to adopt new technology and best practices to improve performance. Over its full lifecycle, natural gas uses less water per unit of energy produced than many other sources of energy.
The use of natural gas as a key energy source offers Canadians opportunities for reduced water intensity as compared to other forms of thermal power.
Summary To some extent, water is impacted by all components of the natural gas value chain. In terms of water use, the greatest quantities of water are used in natural gas production – particularly during the initial drilling of unconventional natural gas wells - and in electrical power generation. According to the Natural Resources Canada report Water Use by the Natural Resources Sectors: Facts (March 2009), 1 per cent of all industrial water use in Canada can be attributed to oil, natural gas and coal production combined. In Alberta, which currently leads other Canadian provinces in oil and natural gas production, 8.5% of the province’s water resources are licensed for use by the oil and natural gas industry. The oil and natural gas production industry does not currently use its full license entitlement in Alberta, although increases in natural gas production will require additional water resources. Meanwhile, the natural gas production industry continues to seek ways to reduce water consumption through water recycling, new technology, and the use of non-drinkable water. 2
Canadian regulators and the natural gas industry are focused on the protection of surface and groundwater and the mitigation of risk. Environmental assessments and permits issued for natural gas exploration and production govern how the industry conducts its work. All Canadian jurisdictions regulate the interface between water and the natural gas industry. These regulations are set and administered by a number of Ministries, including environment, natural resources, sustainable development, energy, and others. In addition, major producing jurisdictions have oil and gas regulatory entities â€“ either provincial boards or the federal National Energy Board. International cooperation by industry and regulators also protects water,
through the development of international standards and risk assessments, for example, and international research initiatives. The natural gas industry recognizes the importance of water to its work and is engaged in ongoing research and the adoption of new processes and technologies to reduce water use and prevent any releases of impure water. On a full cycle, production-tocombustion basis, the use of natural gas as a key energy source offers Canadians opportunities for reduced water intensity as compared to other forms of thermal power. The natural gas industry is focused on continuing to seek ways to reduce water use throughout the natural gas value chain and to ensuring that water quality is maintained so as to protect the environment and human health.
A Water Glossary Potable or drinking water is suitable for drinking, which in Canada means that the quality of the water falls within the standards set in Guidelines for Canadian Drinking Water Quality. Drinking water in Canada typically comes from a municipal water system or a private well. Raw water is fresh water in its natural state. It may require treatment before it is suitable for use as drinking water. An aquifer is an underground geological formation in permeable rock that feeds fresh groundwater to springs and wells. The water table is the area located near the top of an aquifer. Groundwater is located in underground aquifers. Surface water is open to the air, as in a lake, pond or river. A watershed is an area where various bodies of water naturally ďŹ‚ow into a main body of water. Brackish water is naturally occurring salty groundwater, with total dissolved salts (TDS) occurring between 1,000 mg/L and 35,000 mg/L (the salinity of seawater). Brackish water is too salty to drink or to use for irrigation. Saline water can occur deep underground, well below drinking water aquifers. It contains TDS between 35,000 and 100,000 mg/L. Brine is even more salty, with TDS of more than 100,000 mg/L.
Water and Natural Gas Production Water is relevant to natural gas production in the following respects, each of which is addressed in this section: n
it is used in drilling and well stimulation activities;
it forms part of the ďŹ‚uids which are recovered from drilling and fracturing activities; and,
it may be produced from the natural gas-bearing formation along with natural gas.
Developing natural gas resources requires water for drilling, and can also require the use of water for hydraulic fracturing before the well can produce natural gas. Fracturing is the most water-intense 4
activity associated with natural gas production. A typical fracturing operation in a deep horizontal well might use between 3500 m3 to 15000 m3 of water to enhance the recovery of the gas. However, this operation typically takes place only once per fractured well, at the beginning of the well operation. Most wells then produce for 20 to 30 years without requiring any further fracturing and related water use.
to reduce impacts on surface water and aquifers. The water used for oil and gas production is consumed water, since it comes into contact with hydrocarbons and other contaminants and cannot be returned to the environment without additional treatment. Increasingly, companies are treating the ďŹ‚uids used for fracturing and recycling them. If the ďŹ‚uid is not recycled, it is recovered and disposed of as required by regulations. When drilling and fracturing take Not all the water used in place offshore, rules based drilling or fracturing activity on international standards is withdrawn from fresh are applied to prevent the water sources. Natural gas use of any chemicals that are producers use methods such considered to be toxic or to as water recycling techniques, bioaccumulate (meaning the or fracturing with non-potable chemicals concentrate in living brackish water, to offset organisms in greater quantities increased demand for water and as one moves up the food
chain). Surface gas-well lease
Regulations governing the disposal of drilling ﬂuids vary between jurisdictions. However, all regions require actions to mitigate any environmental risks associated with disposal of drilling ﬂuid. These actions vary, depending on the composition of the ﬂuid. In some parts of western Canada, for example, nitrates are the main additive in the water used for drilling. Since this is effectively a low grade fertilizer, regulators, operators and landowners all prefer disposal of this drilling ﬂuid by spraying it on the land surface (as long as other additives meet speciﬁed chemical constraints). The water is therefore completely recycled back into the environment. Natural gas wells can also produce water. This produced water exists naturally, deep below ground, within raw (unprocessed) natural gas. Due to the salinity and the presence of various other components in this water, it has no other use. According to regulation, after the produced water is separated from the methane it must be placed into disposal wells at depths considerably below the water table or otherwise disposed of according to local regulations. Some Canadian coalbed methane operations
Private water well
Municipal water well Shallow groundwater aquifer Deep groundwater aquifer Protective steel casing: Steel casing and cement provide well control and isolate groundwater zones
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Induced shale fractures
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also result in non-potable water production. The water is produced so as to reduce the pressure in the coal seam to allow natural gas to be released and ﬂow to the well. The same produced-water regulations apply, as described above. In fact, in western Canada, all ﬂuids which do not meet speciﬁed criteria are transported to disposal wells and injected deep underground. Water disposal wells have been used for decades, and are well
Note: Buildings and well depth not to scale
understood and stringently regulated. In provinces without deep disposal well capability, drilling ﬂuids are disposed according to the environmental regulations in those jurisdictions, ensuring integrity of existing land use and protection of surface and groundwater resources. Drinking water – referred to as potable water – is an abundant resource in Canada, but not an inﬁnite one. Protection of drinking water is a key priority 5
for both regulators and the natural gas industry. Canadian natural gas production takes place in a way that isolates the natural gas production area from drinking water resources, including wells, groundwater and waterways. All drilling and well construction operations adhere to rigorous regulations to isolate and protect potable groundwater from natural gas operations through installing, and cementing in place, steel surface casing before proceeding to drill to greater depths. In some areas, mandatory pre-drill testing of local water wells provides additional assurance of drinking water protection. Pre-testing of water wells has the added beneﬁt of discovering contamination that predates any oil and gas industry activity, which might have not been previously known to exist.
Natural gas wells can also produce water.
Shale gas resources typically occur several thousand feet below potable aquifers. Rock mechanics characteristics and the extremely low permeability of shale make contamination 6
of drinking water supplies by hydraulic fracturing processes very improbable (U.S. Department of Energy, Ofﬁce of Fossil Energy, National Energy Technology Laboratory, Modern Shale Gas Development in the United States: A Primer, April 2009). In response to continuing public interest, more study is underway by the U.S. Environmental Protection Agency, the U.S. Congress and some state regulators to better understand hydraulic fracturing operations. Industry welcomes the opportunity to participate in scientiﬁc and engineering studies on hydraulic fracturing and groundwater. The Canadian natural gas industry has a very lengthy and successful track record in applying hydraulic fracturing techniques. Notwithstanding these results, the Canadian industry continues to seek improvements in technology and operating practices and will also consider any ﬁndings and recommendations arising from studies in the U.S.. There have been reports from some areas of shale gas operations in the United States that water wells have been contaminated by chemicals related to hydraulic fracturing. However, investigations by governments and regulatory bodies of these incidents
have consistently found that hydraulic fracturing for shale gas production was not the cause, although in some cases the determination has been made that the incident was caused by failures in the natural gas well construction or by accidental leaks that occurred during the transportation or storage of materials. As is the case with any industrial operation, the storage, use and disposal of all chemicals and wastes needs to be managed responsibly and in accordance with appropriate lease construction and environmental protocols to ensure that contamination does not occur through runoff, seepage, or breach of containment. The upstream industry is very cognizant of its responsibility to protect both groundwater and the environment for the use of landowners, members of the public, and future generations. Research and development efforts today continue to focus on developing new and better fracturing ﬂuids that reduce or eliminate chemicals that could impact the environment or human health.
Water and Natural Gas Processing Water is used for industrial processes in natural gas processing plants (such as emissions controls or chemical production), as well as for regular maintenance and cleaning. This water comes into contact with various substances, including hydrocarbons, heavy metals, biocides and other chemicals. Like other industrial water users, the natural gas processing industry carefully applies best practices, and adheres to all regulations, to prevent environmental damage from any contaminants. Natural gas processing plants incorporate water treatment facilities to enable water recirculation or puriďŹ cation before any discharges are made to the environment. Water that cannot be treated is properly contained. Storm water barriers provide further protection in the event of accidental spills.
Water and Natural Gas Transmission The main use of water in the pipeline system is for pressuretesting the pipelines, typically when they are ďŹ rst built. Hydrostatic pressure testing uses a quantity of ďŹ ltered water, which often contains anti7
consume 9 per cent of water, while 58% is consumed by agriculture (Water Use by the Natural Resource Sectors â€“ Facts, March 2009)
corrosives or other additives appropriate for the protection, testing, and maintenance of the pipeline, such as dye. Best practices for the water recovered from hydrostatic pressure testing include re-use of the water, the prevention of environmental harm through use of benign or reduced concentrations of additives, and treatment of the recovered water to ensure it is safe before being discharged.
Water and Natural Gas Uses In comparison with other major water uses, all forms of thermal power generation combined (nuclear, coal, oil 8
and natural gas) comprise the largest portion of gross surface and groundwater use. However, almost all of the water used by thermal power generation is for cooling and it is either returned to source (the only difference being that it is usually a slightly higher temperature) or it is cooled and re-circulated through the power system. Of the fresh water that is consumed, or considered used, in Canada by major water using sectors, Natural Resources Canada reports that 15 per cent of all surface and groundwater consumption goes to thermal-electric power generation, while 0.7 per cent is taken for producing oil, gas and coal products. Municipalities
Using natural gas in combined cycle generation plants to produce electricity reduces the amount of water required for thermal generation by one-half as compared to other forms of thermal generation. In a comparison of full-lifecycle water withdrawal impacts by various energy sources conducted by the U.S. Department of Energy, natural gas power generation using gas from both from conventional and unconventional sources was found to use a smaller quantity of water overall than most other forms of generation (Energy Demands on Water Resources, December 2006). A 2008 EPRI study estimated a 50% improvement in water use (over other forms of thermal generation) when combined-cycle natural gas electricity generation is used. Smaller, distributed generation applications can be operated with natural gas using no water.
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Water is used in the production, processing and transmission of natural gas, and in natural gas power generation. Water use, recovery, recyc...
Published on May 27, 2011
Water is used in the production, processing and transmission of natural gas, and in natural gas power generation. Water use, recovery, recyc...