Injection well
Encyclopedia
An injection well is a vertical pipe in the ground into which water, other liquids, or gases are pumped or allowed to flow.
supplies or adversely affecting quality of receiving 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 are widely considered to be the best method for disposal of treated waste water. Unlike outfalls or other direct disposal techniques, injection wells utilize the earth as a filter to further clean the treated wastewater before it reaches the receiving water. This method of waste water disposal also serves to spread the injectate over a wide area, further decreasing environmental impacts.
Critics of waste water injection wells cite concerns relating to the injectate polluting receiving waters. Most environmental engineering
professionals, however, consider waste water treatment followed by disposal through injection wells to be the most cost effective and environmentally responsible method of waste water treatment. The only known alternatives to injection wells are direct discharge of treated waste water to receiving waters or utilization of the treated water for irrigation. 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 waterbody. Extensive irrigation is often prohibitively expensive and requires ongoing maintenance and large electricity usage.
production
. Steam, carbon dioxide
, water, and other substances can be injected into an oil-producing unit
in order to maintain reservoir pressure, heat the oil or lower its viscosity, allowing it to flow to a producing well nearby. See also Enhanced oil recovery
.
contamination. Injection wells can insert clean water into an aquifer
, thereby changing the direction and speed of groundwater flow, perhaps towards extraction wells 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 and other contaminants trapped in soil and otherwise inaccessible can be broken down by ozone
, 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.
region.
Surface runoff can also be recharged into dry well
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.
(EPA) and state governments under the Safe Drinking Water Act
. EPA has issued Underground Injection Control (UIC) regulations in order to protect drinking water sources.
Waste disposal
One application is waste water disposal, in which treated waste water is injected into the ground between impermeable layers of rocks to avoid polluting fresh waterFresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
supplies or adversely affecting quality of receiving 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 are widely considered to be the best method for disposal of treated waste water. Unlike outfalls or other direct disposal techniques, injection wells utilize the earth as a filter to further clean the treated wastewater before it reaches the receiving water. This method of waste water disposal also serves to spread the injectate over a wide area, further decreasing environmental impacts.
Critics of waste water injection wells cite concerns relating to the injectate polluting receiving waters. Most environmental engineering
Environmental engineering
Environmental engineering is the application of science and engineering principles to improve the natural environment , to provide healthy water, air, and land for human habitation and for other organisms, and to remediate polluted sites...
professionals, however, consider waste water treatment followed by disposal through injection wells to be the most cost effective and environmentally responsible method of waste water treatment. The only known alternatives to injection wells are direct discharge of treated waste water to receiving waters or utilization of the treated water for irrigation. 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 waterbody. Extensive irrigation is often prohibitively expensive and requires ongoing maintenance and large electricity usage.
Oil and gas production
Another use of injection wells is in petroleumPetroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
production
Extraction of petroleum
The extraction of petroleum is the process by which usable petroleum is extracted and removed from the earth.-Locating the oil field:Geologists use seismic surveys to search for geological structures that may form oil reservoirs...
. Steam, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
, water, and other substances can be injected into an oil-producing unit
Water injection (oil production)
Water injection refers to the method in oil industry where water is injected back into the reservoir, usually to increase pressure and thereby stimulate production. Water injection wells can be found both on- and offshore, to increase oil recovery from an existing reservoir...
in order to maintain reservoir pressure, heat the oil or lower its viscosity, allowing it to flow to a producing well nearby. See also Enhanced oil recovery
Enhanced oil recovery
Enhanced Oil Recovery is a generic term for techniques for increasing the amount of crude oil that can be extracted from an oil field...
.
Waste site remediation
Yet another use for injection wells is in environmental remediation, for cleanup of either soil or groundwaterGroundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
contamination. Injection wells can insert clean water into an aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
, thereby changing the direction and speed of groundwater flow, perhaps towards extraction wells 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 and other contaminants trapped in soil and otherwise inaccessible can be broken down by ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
, 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 MENAMENA
The term MENA, for "Middle East and North Africa", is an acronym often used in academic, military planning and business writing.The term covers an extensive region, extending from Morocco to Iran, including the majority of both the Middle Eastern and Maghreb countries...
region.
Surface runoff can also be recharged into dry well
Dry well
A dry well is an underground structure that disposes of unwanted water, most commonly stormwater runoff, by dissipating it into the ground, where it merges with the local groundwater. Often called a soakaway in the UK....
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.
Regulatory requirements
In the United States, injection well activity is regulated by the United States Environmental Protection AgencyUnited States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
(EPA) and state governments under the Safe Drinking Water Act
Safe Drinking Water Act
The Safe Drinking Water Act is the principle federal law in the United States intended to ensure safe drinking water for the public. Pursuant to the act, the Environmental Protection Agency is required to set standards for drinking water quality and oversee all states, localities, and water...
. EPA has issued Underground Injection Control (UIC) regulations in order to protect drinking water sources.