Natural gas is an abundant domestic energy resource that emits the lowest amount of carbon dioxide per calorie of any fossil fuel. Natural gas resources in the United States are components of a national energy program that seeks both greater energy independence and greener energy sources. Many state agencies have been cautious in granting permits because of concerns related to water supply and wastewater disposal. Gas companies, drillers and landowners are eager to move forward to develop the resource, but some states have placed moratoriums on drilling until these issues are resolved. The technology of drilling directional bore holes and the use of sophisticated hydraulic fracturing processes to extract gas resources from tight rock have improved over the past few decades. Yet it is still unclear how this extraction might affect water resources.
Oil shale does not actually contain oil, but rather a type of organic matter called kerogen, a precursor of oil that is converted to a type of crude oil when heated to about 450 to 500 degrees Celsius. Oil shale deposits occur in three structural and sedimentary basins:
- the Piceance Basin in western Colorado
- the Uinta Basin in eastern Utah and western Colorado
- the Greater Green River Basin in southwestern Wyoming and northwestern Colorado
Liquid natural gas facilities use a liquidification process which involves the removal of natural gas components by condensing natural gas into a liquid form. Liquid natural gas takes up one six-hundredths of the volume of gaseous natural gas and allows the transport of natural gas by sea vessels and tankers into areas that are not accessible by pipeline. Like other oil and gas processing plants, liquid natural gas facilities are often several hundred acres and are typically sited in coastal areas with access to deep sea vessels.
Fish and Wildlife Considerations
Oil and gas extraction activities may adversely affect fish and wildlife and their habitats by exposure to containment ponds or spills. Extraction activities use a variety of chemicals to retrieve the resources. Drilling muds contain additives to reduce friction and control temperature and may be contaminated by sub-surface hydrocarbons. These or other chemicals may seep from leaks in bore holes, spill from tanks and trucks, or be placed into containment ponds along with other fluids.
Hydraulic fracturing fluids contain chemicals such as acids, salts, surfactants, biocides and corrosion inhibitors. Fracking also involves the use of large amounts of water, usually 3 to 5 million gallons per well for hydraulic fracturing alone. It takes 200 tanker trucks to haul 1 million gallons of water, resulting in 600 to 1,000 tanker trucks per well. Water withdrawals can change the character of a stream, possibly de-watering it entirely. Water withdrawal may result in streams warming, changing mussel, fish and macroinvertebrate habitats. Stream warming may also change species diversity and populations over time. For example, several sport fisheries that breed in cool water may leave or fail to reproduce if the water warms. Another issue is potential contamination of a stream by spills. Oil and gas extraction activities involve flowback of fluids used to fracture the rock to extract the resources. The fluid may contain a variety of chemicals, many of which can be hazardous. Evaporation pits or ponds are required to contain the adulterated water that flows back from the well. These pits or ponds may attract birds and other wildlife or they may leak, causing the fluid to flow into a nearby stream. Flowback fluid may contaminate the stream, resulting in fish kills and changes in species diversity and populations. Using fully enclosed containment systems and re-using flowback water (after treatment) helps to avoid these impacts. Spills and leaks still may occur due to truck accidents, mechanical failures, corrosion of the tanks or human error. Using enclosed containment systems, together with best management practices may decrease the severity and number of spill incidents.
Operation and maintenance of oil and gas equipment and facilities, may also impact wildlife. Equipment generates noise that may disturb wildlife, for example, nesting sage grouse and prairie chickens. Human movement and noise near wildlife can also cause abandonment of breeding areas. Construction of access roads, transmission lines and other infrastructure may fragment the habitat and interfere with migration corridors. Wells may also leak dangerous gases such as hydrogen sulfide, which is toxic to both humans and wildlife.
Common best management practices include: reducing the size of roads, utilities, and well pads; placing pipes and powerlines in corridors along the road; drilling multiple wells from a single well pad; eliminating hazards to wildlife; reducing noise; centralizing production facilities; and remote production monitoring.
Access technical information and best management practices for oil and gas extraction from the Bureau of Land Management.
Learn more about the transportation and distribution of oil and gas.
