![Deep injection well](https://upload.wikimedia.org/wikipedia/commons/3/38/Deep_injection_well.jpg)
An injection well is a device that places fluid deep underground into
porous rock
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...
formations, such as sandstone or limestone, or into or below the shallow
soil
Soil, also commonly referred to as earth or dirt
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
layer. The fluid may be
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
,
wastewater
Wastewater is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industrial ...
,
brine (salt water), or water mixed with industrial chemical waste.
Definition
The
U.S. Environmental Protection Agency
The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
(EPA) defines an injection well as "a bored, drilled, or driven shaft, or a dug hole that is deeper than it is wide, or an improved sinkhole, or a subsurface fluid distribution system". Well construction depends on the injection fluid injected and depth of the injection zone. Deep wells that are designed to inject
hazardous wastes
Hazardous waste is waste that has substantial or potential threats to public health or the environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits: ignitability, reactivity, cor ...
or carbon dioxide deep below the Earth's surface have multiple layers of protective casing and cement, whereas shallow wells injecting non-hazardous fluids into or above drinking water sources are more simply constructed.
Applications
Injection wells are used for many purposes.
Waste disposal
Treated wastewater can be injected into the ground between impermeable layers of rocks to avoid polluting surface waters. Injection wells are usually constructed of solid walled pipe to a deep elevation in order to prevent injectate from mixing with the surrounding environment.
Injection wells utilize the earth as a filter to treat the wastewater before it reaches the aquifer. This method of wastewater disposal also serves to spread the injectate over a wide area, further decreasing environmental impacts.
In the United States, there are about 800 deep injection waste disposal wells used by industries such as chemical manufacturers, petroleum refineries, food producers and municipal wastewater plants. Most produced water generated by oil and gas extraction wells in the US is also disposed in deep injection wells.
Critics of wastewater injection wells cite concerns about potential groundwater contamination. It is argued that the impacts of some injected wastes in groundwater is not fully understood, and that the science and regulatory agencies have not kept up with the rapid expansion of disposal practices in US, where there are over 680,000 wells as of 2012.
Alternatives to injection wells include direct discharge of treated wastewater to receiving waters, conditioning of oil drilling and fracking
produced water
Produced water is a term used in the oil industry or geothermal industry to describe water that is produced as a byproduct during the extraction of oil and natural gas, or used as a medium for heat extraction. Produced water is the kind of brackis ...
for reuse, utilization of treated water for irrigation or livestock watering, or processing of water at
industrial wastewater treatment plants.
Direct discharge does not disperse the water over a wide area; the environmental impact is focused on a particular segment of a river and its downstream reaches or on a coastal water body. Extensive irrigation is not typical in areas where the produced water tends to be salty,
and this practice is often prohibitively expensive and requires ongoing maintenance and large electricity usage.
Since the early 1990s,
Maui County
Maui County, officially the County of Maui, is a county in the U.S. state of Hawaii. It consists of the islands of Maui, Lānai, Molokai (except for a portion of Molokai that comprises Kalawao County), Kahoolawe, and Molokini. The latter two a ...
, Hawaii has been engaged in a struggle over the 3 to 5 million gallons per day of wastewater that it injects below the
Lahaina
Lahaina ( haw, Lāhainā) is the largest census-designated place (CDP) in West Maui, Maui County, Hawaii, United States and includes the Kaanapali and Kapalua beach resorts. As of the 2020 census, the CDP had a resident population of 12,702. Lah ...
Wastewater Reclamation Facility, over the claim that the water was emerging in seeps that were causing
algae bloom
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompasse ...
s and other environmental damage. After some twenty years, it was sued by environmental groups after multiple studies showed that more than half the injectate was appearing in nearby coastal waters. The judge in the suit rejected the County's arguments, potentially subjecting it to millions of dollars in federal fines. A 2001 consent decree required the county to obtain a water quality certification from the
Hawaii Department of Health The Hawaii State Department of Health (DOH) is a state agency of Hawaiʻi, with its headquarters in Honolulu CDP, Honolulu County on the island of Oʻahu.
The Hawai'i Department of Health is organized into three administrations: Health Resources, ...
, which it failed to do until 2010, after the suit was filed. The case proceeded through the
United States Court of Appeals for the Ninth Circuit
The United States Court of Appeals for the Ninth Circuit (in case citations, 9th Cir.) is the U.S. federal court of appeals that has appellate jurisdiction over the U.S. district courts in the following federal judicial districts:
* District ...
and subsequently to the
Supreme Court of the United States. In 2020 the Court ruled in ''
County of Maui v. Hawaii Wildlife Fund
''County of Maui v. Hawaii Wildlife Fund'', No. 18-260, 590 U.S. ___ (2020), was a United States Supreme Court case involving pollution discharges under the Clean Water Act (CWA). The case asked whether the Clean Water Act requires a permit when ...
'' that injection wells may be the "functional equivalent of a direct discharge" under the Clean Water Act, and instructed the EPA to work with the courts to establish regulations when these types of wells should require permits.
Oil and gas production
Another use of injection wells is in
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
and
petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
production
Production may refer to:
Economics and business
* Production (economics)
* Production, the act of manufacturing goods
* Production, in the outline of industrial organization, the act of making products (goods and services)
* Production as a stati ...
. Steam,
carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
, water, and other substances can be
injected into an oil-producing unit in order to maintain
reservoir
A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation.
Reservoirs can be created in a number of ways, including contro ...
pressure, heat the oil or lower its viscosity, allowing it to flow to a producing well nearby.
[EPA]
"Class II Oil and Gas Related Injection Wells."
Updated 2015-10-08.
Waste site remediation
Yet another use for injection wells is in
environmental remediation, for cleanup of either
soil
Soil, also commonly referred to as earth or dirt
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
or
groundwater contamination. Injection wells can insert clean water into an
aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteris ...
, thereby changing the direction and speed of groundwater flow, perhaps towards
extraction well Extraction may refer to:
Science and technology
Biology and medicine
* Comedo extraction, a method of acne treatment
* Dental extraction, the surgical removal of a tooth from the mouth
Computing and information science
* Data extraction, the pr ...
s downgradient, which could then more speedily and efficiently remove the contaminated groundwater. Injection wells can also be used in cleanup of soil contamination, for example by use of an ozonation system. Complex
hydrocarbons
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or e ...
and other contaminants trapped in soil and otherwise inaccessible can be broken down by
ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
, a highly reactive gas, often with greater cost-effectiveness than could be had by digging out the affected area. Such systems are particularly useful in built-up urban environments where digging may be impractical due to overlying buildings.
Aquifer recharge
Recently the option of
refilling natural aquifers with injection or percolation has become more important, particularly in the driest region of the world, the
MENA
MENA, an acronym in the English language, refers to a grouping of countries situated in and around the Middle East and North Africa. It is also known as WANA, SWANA, or NAWA, which alternatively refers to the Middle East as Western Asia (or a ...
region (Middle East and North Africa).
Surface runoff can also be recharged into
dry well
A dry well or drywell is an underground structure that disposes of unwanted water, most commonly surface runoff and stormwater and in some cases greywater. It is a gravity-fed, vertical underground system that captures surface water from imper ...
s, or simply barren wells that have been modified to functions as cisterns. These hybrid
stormwater management systems, called
recharge wells, have the advantage of aquifer recharge and instantaneous supply of potable water at the same time. They can utilize existing infrastructure and require very little effort for the modification and operation. The activation can be as simple as inserting a polymer cover (foil) into the well shaft. Vertical pipes for conduction of the overflow to the bottom can enhance performance. The area around the well acts as funnel. If this area is maintained well the water will require little purification before it enters the cistern.
Geothermal energy
Injection wells are used to tap
geothermal energy in hot, porous rock formations below the surface by injecting fluids into the ground, which is heated in the ground, then extracted from adjacent wells as fluid, steam, or a combination of both. The heated steam and fluid can then be utilized
to generate electricity or directly for
geothermal heating
Geothermal heating is the direct use of geothermal energy for some heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of ...
.
Regulatory requirements
In the United States, injection well activity is regulated by EPA and state governments under the
Safe Drinking Water Act
The Safe Drinking Water Act (SDWA) is the principal federal law in the United States intended to ensure safe drinking water for the public. Pursuant to the act, the Environmental Protection Agency (EPA) is required to set standards for drinking wa ...
(SDWA).
The “State primary enforcement responsibility” section of the SDWA provides for States to submit their proposed UIC program to the EPA to request State assumption of primary enforcement responsibility. Thirty-four states have been granted UIC primacy enforcement authority for Class I, II, III, IV and V wells.
For states without an approved UIC program, the EPA administrator prescribes a program to apply. EPA has issued Underground Injection Control (UIC) regulations in order to protect drinking water sources.
[EPA]
"Underground Injection Control Regulations."
Updated 2015-10-05.
EPA regulations define six classes of injection wells. Class I wells are used for the injection of municipal and industrial wastes beneath underground sources of drinking water. Class II wells are used for the injection of fluids associated with oil and gas production, including waste from hydraulic fracturing. Class III wells are used for the injection of fluids used in mineral
solution mining
In-situ leaching (ISL), also called in-situ recovery (ISR) or solution mining, is a mining process used to recover minerals such as copper and uranium through boreholes drilled into a deposit, ''in situ''. In situ leach works by artificially disso ...
beneath underground sources of drinking water. Class IV wells, like Class I wells, were used for the injection of hazardous wastes but inject waste into or above underground sources of drinking water instead of below. EPA banned the use of Class IV wells in 1984. Class V wells are those used for all non-hazardous injections that are not covered by Classes I through IV. Examples of Class V wells include stormwater drainage wells and
septic system leach fields. Finally, Class VI wells are used for the injection of carbon dioxide for
sequestration, or long term storage.
Currently, there are no Class VI wells in operation, but 6 to 10 wells are expected to be in use by 2016.
Injection-induced earthquakes
![Cumulative induced seismicity](https://upload.wikimedia.org/wikipedia/commons/7/79/Cumulative_induced_seismicity.png)
A July 2013 study by US Geological Survey scientist William Ellsworth links earthquakes to wastewater injection sites. In the four years from 2010-2013 the number of earthquakes of magnitude 3.0 or greater in the central and eastern United States increased dramatically. After decades of a steady earthquake rate (average of 21 events/year), activity increased starting in 2001 and peaked at 188 earthquakes in 2011, including
a record-breaking 5.7-magnitude earthquake near
Prague, Oklahoma
Prague () is a city in Lincoln County, Oklahoma, United States. The population was 2,346 at the 2020 census, an 1.76 percent decrease from the figure of 2,388 in 2010. Czech immigrants founded the city, and named it after the capital of the pres ...
which was the strongest earthquake ever recorded in Oklahoma. USGS scientists have found that at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells. Injection-induced earthquakes are thought to be caused by pressure changes due to excess fluid injected deep below the surface and are being dubbed “man-made” earthquakes.
[USGS]
"Man-Made Earthquakes Update"
Updated January 17, 2014. On September 3, 2016,
a 5.8-magnitude earthquake occurred near
Pawnee, Oklahoma
Pawnee ( Pawnee: Paári, iow, Páñi Chína) is a city and county seat of Pawnee County, Oklahoma, United States. The town is northeast of Stillwater at the junction of U.S. Route 64 and State Highway 18.
It was named for the Pawnee tribe, ...
, followed by nine aftershocks between magnitudes 2.6 and 3.6 within three and one-half hours. The earthquake broke the previous record set five years earlier. Tremors were felt as far away as
Memphis, Tennessee
Memphis is a city in the U.S. state of Tennessee. It is the seat of Shelby County in the southwest part of the state; it is situated along the Mississippi River. With a population of 633,104 at the 2020 U.S. census, Memphis is the second-mos ...
, and
Gilbert, Arizona.
Mary Fallin
Mary Fallin (; née Copeland; born December 9, 1954) is an American politician who served as the 27th governor of Oklahoma from 2011 to 2019. A member of the Republican Party, she was elected in 2010 and reelected in 2014. She was the first and s ...
, the Oklahoma governor, declared a local emergency and shutdown orders for local disposal wells were ordered by the Oklahoma Corporation Commission.
USGS calls for shut down of wells, governor declares emergency in wake of 5.6 quake in Oklahoma
''Enid News & Eagle
The ''Enid News & Eagle'' is a daily newspaper published Tuesday through Sunday in Enid, Oklahoma, United States. The publication covers several counties in northwest Oklahoma and is owned by Community Newspaper Holdings Inc. The newspaper also ...
'', Sally Asher & Violet Hassler, September 3, 2016. Retrieved 4 September 2016. Results of ongoing multi-year research on induced earthquakes by the United States Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...
(USGS) published in 2015 suggested that most of the significant earthquakes in Oklahoma, such as the 1952 magnitude 5.5 El Reno earthquake may have been induced by deep injection of waste water by the oil industry.
Notes
References
* US Army Environmental Center. Aberdeen Proving Ground, MD (2002)
"Deep Well Injection."
''Remediation Technologies Screening Matrix and Reference Guide.'' 4th ed. Report no. SFIM-AEC-ET-CR-97053.
External links
EPA - Underground Injection Control Program
{{DEFAULTSORT:Injection Well
Drinking water
Hydrology
Water pollution
Petroleum technology
Natural gas technology