Hydraulic Fracturing
Hydraulic fracturing produces fractures in the rock formation that stimulate the flow of natural gas or oil, increasing the volumes that can be recovered. Wells may be drilled vertically hundreds to thousands of feet below the land surface and may include horizontal or directional sections extending thousands of feet.
Fractures are created by pumping large quantities of fluids at high pressure down a wellbore and into the target rock formation. Hydraulic fracturing fluid commonly consists of water, proppant and chemical additives that open and enlarge fractures within the rock formation. These fractures can extend several hundred feet away from the wellbore. The proppants - sand, ceramic pellets or other small incompressible particles - hold open the newly created fractures.
Once the injection process is completed, the internal pressure of the rock formation causes fluid to return to the surface through the wellbore. This fluid is known as both "flowback" and "produced water" and may contain the injected chemicals plus naturally occurring materials such as brines, metals, radionuclides, and hydrocarbons. The flowback and produced water is typically stored on site in tanks or pits before treatment, disposal or recycling. In many cases, it is injected underground for disposal. In areas where that is not an option, it may be treated and reused or processed by a wastewater treatment facility and then discharged to surface water.
"Unconventional" Natural Gas Production, Shale Gas Extraction and Hydraulic Fracturing
Hydraulic fracturing is a technique used in "unconventional" gas production. "Unconventional" reservoirs can cost-effectively produce gas only by using a special stimulation technique, like hydraulic fracturing, or other special recovery process and technology. This is often because the gas is highly dispersed in the rock, rather than occurring in a concentrated underground location.
Extracting unconventional gas is relatively new. Coalbed methane production began in the 1980s; shale gas extraction is even more recent. The main enabling technologies, hydraulic fracturing and horizontal drilling, have opened up new areas for oil and gas development, with particular focus on natural gas reservoirs such as shale, coalbed and tight sands.
Shale Gas Extraction
Shale rock formations have become an important source of natural gas in the United States. Shale gas is present in many locations in the contiguous United States, including some areas where oil or gas production has never occurred before.
Production of Coalbed Methane
Coalbed methane (CBM) was first extracted from coal mines as a safety measure to reduce the explosion hazard posed by methane gas in the mines. Today the methane is captured and used as a source of energy. Deeper coal formations might require hydraulic fracturing to release the natural gas.
Tight Sands
Tight sands are gas-bearing, fine-grained sandstones or carbonates with a low permeability. Unless natural fractures are present, almost all tight sand reservoirs require hydraulic fracturing to release gas.
FAQs
Hydraulic fracturing produces fractures in the rock formation that stimulate the flow of natural gas or oil, increasing the volumes that can be recovered. Wells may be drilled vertically hundreds to thousands of feet below the land surface and may include horizontal or directional sections extending thousands of feet.
What is an unconventional form of natural gas? ›
Unconventional gas refers to natural gas that requires advanced production methods. Main types include gas within tight pore spaces – shale gas and coal bed methane – and gas that is trapped in ice on the sea floor – gas hydrates.
What are three sources of unconventional natural gas? ›
Unconventional natural gas (UG) comes primarily from three sources: shale gas in low-permeability shale formations; tight gas in low-permeability sandstone and carbonate reservoirs; and coalbed methane (CBM) in coal seams.
What has allowed unconventional oil and gas plays to be economically * developed in the US? ›
The U.S. has vast reserves of such resources that are commercially viable as a result of advances in horizontal drilling and hydraulic fracturing technologies. These technologies enable greater access to oil and natural gas in shale formations.
Does EPA regulate fracking? ›
Environmental Concerns Related to Fracking
Fracking is regulated under the Clean Air Act, the Clean Water Act, the Resources Conservation and Recovery Act and the Comprehensive Environmental Response, Compensation, and Liability Act.
What is the process of unconventional natural gas production EPA? ›
Hydraulic fracturing produces fractures in the rock formation that stimulate the flow of natural gas or oil, increasing the volumes that can be recovered. Wells may be drilled vertically hundreds to thousands of feet below the land surface and may include horizontal or directional sections extending thousands of feet.
What is an example of an unconventional gas? ›
There are several types of unconventional gas, including shale gas and tight gas, which occur in reservoirs with very low permeability compared to conventional reservoirs. In these geological formations, horizontal drilling and hydraulic fracturing are often necessary for economic gas extraction.
What is unconventional oil and gas production? ›
In the oil and gas industry, the term “unconventional oil” refers to crude oil that is obtained through methods other than traditional vertical well extraction. Examples of such methods include developing oil sands, directional drilling, and hydraulic fracturing (colloquially known as “fracking”), among others.
What are the methods of unconventional gas extraction? ›
Shale gas or unconventional gas is extracted from the impermeable shale through a process called hydraulic fracturing (also known as hydrofracking or fracking). A crude form of this technique, involving nitroglycerine, was used for the first time around the 1860s to explore for oil and gas.
What is the difference between conventional and unconventional oil production in the US? ›
Conventional gas and oil production follows well-established techniques involving standard drilling methods. As long as pressure remains adequate, these resources can flow naturally to the surface. On the other hand, unconventional resources require advanced technologies to extract trapped energy reserves.
By the turn of the millennium, a new kind of energy resource was required, particularly by the USA, who were driven to achieve energy independence. The USA turned to unconventional reservoirs to achieve their goals, which had been known about for decades but had previously been too costly to be economically attractive.
What does EPA not regulate? ›
Indoor Air Quality: EPA does not regulate indoor air, but we do offer assistance in protecting your indoor air quality. Find information about mold, radon, formaldehyde and other indoor air quality issues.
What is the difference between conventional and unconventional natural gas? ›
Conventional gas and oil production follows well-established techniques involving standard drilling methods. As long as pressure remains adequate, these resources can flow naturally to the surface. On the other hand, unconventional resources require advanced technologies to extract trapped energy reserves.
What are the 4 types of natural gas? ›
They are known as the four natural gases and include the first four alkanes — methane, ethane, butane, and propane.
What are the unconventional natural gas reserves? ›
Today, unconventional reservoirs include basin-centered gas, shale gas, coalbed methane (CBM), gas hydrates, tar sands, light tight oil and oil shale, mostly from North America.
What are 3 unconventional fossil fuels? ›
At the same time, attention is turning towards what are called 'unconventional fossil fuels'. There are four: tar sands, oil shale, shale gas and deepwater oil.
