The Barnett Shale is more than 7,000 feet below the surface and is comprised of dense non-permeable rock. According to Dr. Ken Morgan, a geologist at Texas Christian University, “Solid hard rocks that are 7000 feet down don’t subside. You have more than a mile of solid rock that holds it all up. Subsidence occurs when you have loose, soft materials like in Houston (sands, clays, etc.) but not in cemented hard rocks like the Barnett Shale.”
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This is a common question that is usually accompanied with the misconceived notion that hundreds of chemicals are used. As is often the case, a quick Google search on the topic produces a wide variety of answers, many of which are not factual.
Shale development could ultimately be extremely beneficial for American manufacturing. In fact, America’s natural gas could save U.S. manufacturers a lot of money in different areas.
In short, yes. The term “fracking,” which is (supposedly) shorthand for the well completion process of hydraulic fracturing, is actually correctly spelled “frac’ing.”
The Energy Institute at The University of Texas at Austin recently conducted a study entitled "Fact-Based Regulation for Environmental Protection in Shale Gas Development.
Facts About Drilling & Fracturing
There are two kinds of oil and gas deposits: conventional and unconventional. The Barnett Shale is considered an unconventional deposit by geologists because the methane gas is not located in highly porous rock formations which create easy-to-access pockets of gas (known as “conventional” deposits).
In the Barnett Shale, the source rock in the shale has to be fractured to release the gas. Two methods are used:
- Larger hydraulic fracturing methods use water and sand under high force to break the rock and release the gas.
- Horizontal drilling techniques.
This unique combination of new technology and techniques was first used in the late 1990s and made drilling for natural gas in the Barnett Shale a reality on a large scale.
With the advent of directional and horizontal drilling technology, natural gas wells have a much smaller impact on land than drilling vertical wells because multiple wells can be drilled off of one well site. These new drilling techniques are also quieter and more energy efficient.
Life Cycle of a Gas Well
With so many wells appearing on the North Texas landscape, how are well sites chosen? And once sites are selected, what is the process?
There are five stages of a gas well:
1. Staking the well
Engineers, geologists and land negotiators work with landowners and other interested parties to determine the best location for the well. This is the part of the process when you, your neighbors or neighborhood association could be approached to lease the mineral rights under your land should your mineral rights be established.
Refer to the Leasing Page on this site for further information about this process. Because of horizontal drilling, the actual gas well site may or may not be near your land, but permission must be granted to drill under someone’s property.
Once the site has been selected, the drilling stage begins.
What can I expect when a company is going to drill in my area?
A sign is usually placed near the proposed well site advising that a permit application has been submitted. In cities such as Fort Worth, notices will be sent to residents/property owners within 1,000 feet of the well site.
How far must a well be from my residence or public structures/areas?
Most municipalities have drilling ordinances that require a minimum distance from existing structures. In cities such as Fort Worth, no well may be drilled closer than 600 feet from any protected use, such as a residence, religious institution, public building, hospital, school or public park, without a waiver from the protected-use owners or City Council approval. The ordinance in other cities may specify other distances.
Refer to the City Ordinances page for future information.
Will drilling affect the foundation of my house?
Gas wells are drilled approximately one mile below the surface into the Barnett Shale, way beyond a house’s foundation.
Most foundation problems occurring in the North Texas area are a result of ground swell and contraction during alternating periods of wet and dry weather.
If I live near a potential site, how will my neighborhood be affected?
City regulations and ordinances are intended to minimize the impact of natural gas drilling to the quality of life in neighborhoods. However, you should expect some increase in traffic as a rig is erected and drilling operations are conducted. When the well is completed, additional truck traffic will be required for the fracturing operation. In the city of Fort Worth, traffic associated with drilling operations, and sound is constantly monitored to ensure compliance. Once a gas well is drilled, completed and production begins, the gas well has little visual impact on the environment. Most city regulations require that fencing, landscaping and proper signage are in place.
2. Drilling
There are four primary steps in the drilling phase before completion:
Preparation
A level pad site, generally 300 feet by 300 feet, will be prepared in approximately one week, and a drilling rig will then be moved onto the location.
Located under the rig floor is a blowout preventer, a series of hydraulic valves that secure the wellbore (the hole in the ground created by the drill) in the event an over-pressure formation is encountered during the drilling operations.
Surface Casing/Cementing
The first hole to be drilled is known as the surface hole, which typically reaches a depth of 800 feet to 1,300 feet.
After the surface hole is drilled, the drillstring is removed and surface casing is lowered into the hole.
The Railroad Commission of Texas requires operators to set surface casing through the deepest potable water aquifer in the area.
Cement is then pumped down the entire length of the casing, and through the bottom, so the cement circulates back up and around the outside of the casing, all the way to the surface. This seals the space between the casing string and the wellbore.
Data Logging
In the logging process, engineers and geologists use sensitive instruments to measure various properties of the rocks and determine where the hydrocarbons are located in the wellbore. Smaller bit drills are used at this point.
Production Casing/Cementing
Next, production casing is run into the hole and the drilling stage is nearly complete.
One of the final steps is to cement the production casing into place. Cement is pumped down through the inside of the casing, up around the outside between the wellbore and casing.
Cementing the production casing ensures that gas inside the wellbore will not be allowed to escape. As a result, operators can direct the flow of gas through the production casing and the tubing until it reaches the surface.
How long will the drilling take?
A well in the Barnett Shale typically takes 20 to 30 days to drill. However, depending on the area, multiple wells may be drilled consecutively on one site. When drilling is completed, the drilling rig is removed and a smaller completion rig is put into place. After the completion rig is finished, frac trucks arrive for the fracturing process which takes an additional 4 to 5 days. Finally, a wellhead (or “Christmas tree”) is installed along with a few storage tanks. A Barnett Shale well is expected to produce for 20 to 30 years or more.
Is drilling a 24/7 operation?
Yes, but only for about a month per well. You can expect some sound while the drilling rig is in place, but today’s drilling rigs are much quieter than older rigs. Most drillers use sound abatement equipment, such as sound barriers and sound blankets, to reduce the temporary disturbance. All drilling operators must comply with local ordinances that specify the decibel levels allowed.
Will someone be on the drilling site at all times?
During drilling operations personnel are on site 24 hours. Completion operations are usually conducted during the day, but personnel may be on site 24 hours during a short flow-back period.
Is gas drilling really safe?
Gas well drilling is highly regulated to ensure both health and safety. The Texas Railroad Commission (RRC) and Texas Commission on Environmental Quality (TCEQ) have rules and regulations in place to ensure that safety features are operational. Sites are inspected regularly by local and state authorities. There are around 14,000 producing wells in the Barnett Shale, most of those drilled since 2001.
3. Drilling Completed
Following the drilling process and after the drilling rig is moved off location, completion activity begins.
There are three steps in the completion process, which typically lasts 10 to 15 days:
Perforating the casing
To perforate the casing, a cylindrical perforating tool containing high-energy jet charges is lowered to a desired depth and detonated using electrical signals.
These jet charges penetrate the steel casing and cement sheath surrounding the casing, which in turn penetrates the very dense hard rock formations several inches.
This creates a pathway for the gas to flow from the reservoir to the well’s production casing.
Fracturing (known as Fracing) the well
Hydraulic fracturing, or fracing (rhymes with “cracking”), is the process of creating fissures in underground formations to allow natural gas to flow.
Fracing involves pumping a mixture of water, sand and other additives at high pressure into the shale formation to create fractures. During this process, long, narrow cracks are created to serve as a flow channel for gas trapped in the shale below. Frac fluid is approximately 99.5 percent water and sand, with a small amount of special-purpose additives. The sand is used to "prop" open newly created fractures to allow the natural gas to flow into the well bore and up to the surface. Each hydraulically fractured well uses an estimated two- to five-million gallons of water for drilling and fracturing. Water comes from either groundwater or surface sources, depending upon the location of the well.
Drilling out plugs/allowing natural flow back
Prior to fracing, the temporary bridge plugs are placed in the wellbore between each "frac" stage. Once the fracing process is complete, a smaller rig drills through the plugs and allows gas to flow through the perforations and up the steel casing.
After the plugs have been drilled out, the well is allowed to flow naturally. Initially, water plug material and trace amounts of sand flow with the gas to the surface. Some of the water is collected and may be recycled; the remainder is disposed of and /or hauled off site.
4. Production
The production stage consists of separating the gas from the liquids that are retrieved from the well.
Natural gas is not usually commercial quality when it comes from the wellhead. The gas often contains a mix of shale, sand, water and other components besides methane, that are removed as the natural gas goes through various stages of processing before becoming marketable.
Once the gas has been separated from the produced water and any hydrocarbon liquids, it is metered and sent though a gathering line to a compressor facility, treatment plant or hauled by truck to a disposal site.
5. Reclamation
Before, during and after the drilling process, producers are diligent about minimizing their environmental footprint.
Once the drilling and completion processes are completed, all fluids are removed and either reused, or disposed of, and the drill site is fenced. If the well site is located in an urban area, landscaping is added around the site.
Other questions associated with the life cycle of a gas well:
Why must wells be fractured?
The Barnett Shale is known as a "tight gas" reservoir, indicating that the gas is not easily extracted. The shale is very hard, and it was virtually impossible to produce gas in commercial quantities from this formation until recent improvements were made in hydraulic fracturing technology and horizontal drilling. The “fracing” process produces “cracks” in the shale where the gas can be extracted and produced by an operator.
What will the drill site look like when the well is completed?
After an operator completes a well, the size of the padsite may be reduced, fenced and lanscaped per local ordinances. Local ordinances dictate the type of landscaping that must be used. It is important to remember that if an operator plans to drill multiple wells from one location, landscaping may not be completed until the final well has been drilled.
How long will this well be here?
Barnett Shale wells are expected to produce gas for 20 to 30 years or longer.
Will they ever bring back the drilling rig? Or fracture the well again?
Additional use of a drilling rig on an existing wellbore is an infrequent occurrence. Other types of equipment may be needed, such as a wire line unit for maintenance of the well. Typically, hydraulic fracturing is performed only once in the life of a well.
Although re-fracing has been conducted selectively, most operators are awaiting additional production history and advances in methodologies or technology before embracing this concept. However, one must consider that the exploration company may drill more than one well to a lease from a common pad, which may require moving a rig back on location numerous times.
How is the natural gas transported away from the well?
Natural gas from the Barnett Shale is transported from the well site through a network of underground pipelines where it can be sold to market.
Will pipelines run under my house?
No, pipelines cannot be installed under permanent structures, nor can permanent structures be built over pipelines.
Are pipelines safe?
Natural gas pipelines are regulated by the United States Department of Transportation and usually have Class III or Class IV compliance. Natural gas pipelines pose no more risk than utility pipelines that currently deliver gas to your home or office.
Why are big trucks needed for gas wells?
Trucks are used to bring in the rig and other machinery used to drill the well, and the supplies that are used during drilling. “Frac” trucks will be on a pad site for a few days after the drilling rig is removed. After the well is in production, there will be some truck traffic that collects and removes the produced water from the battery tanks located on the site.
Is a company going to pay for the repair of roads caused by truck traffic?
Municipalities require a bond from drilling companies before they will issue a permit to drill.
When will the roads be repaired?
Roads are repaired after the well is completed and is in production.
Where do you take all of the water that flows back out of the well?
Flowback or produced water from the well is either transported through a system of pipes or removed from the well site by trucks for disposal into a saltwater disposal well. Some companies reuse flowback to hydraulically fracture more than one well as a way to conserve water.
Can wastewater wells pollute drinking water?
Wastewater wells are highly regulated by the Railroad Commission of Texas and the Texas Water Commission. These wells are classified as Type II wells and are drilled to depths, much deeper than drinking water tables. The wells are lined with steel pipe and cemented in place in accordance with stringent requirements.
Regulatory Issues
Who regulates the gas industry?
The regulation of exploration and production of oil and gas in Texas is the responsibility of the Railroad Commission of Texas. Additionally, numerous federal regulations govern the fracturing process. The primary responsibilities of the Railroad Commission include preventing waste of oil and gas resources, protection of surface and subsurface water, and helping ensure interests of mineral owners. The Railroad Commission does not oversee or have jurisdiction for issues related to oil and gas exploration and production such as roads, traffic, aesthetics and sound, which are regulated locally, as are odors, leases, pipeline easements and royalty payments.
Who regulates roads?
Texas Department of Transportation. However, most municipalities require road use agreements with additional stipulations, and counties may exert influence on the points of entry into a location affecting how roads are used.
