Barnett Shale
As of 2007, some experts suggested that the Barnett Shale might have the largest producible reserves of any onshore natural gas field in the United States.
[2] Some local governments are researching means by which they can drill on existing public land (e.g., parks) without disrupting other activities so they may obtain royalties on any minerals found, whereas others are seeking compensation from drilling companies for damage to roads caused by overweight vehicles (many of the roads are rural and not designed for use by heavy equipment).
In addition, drilling and exploration have generated significant controversy because of environmental damage including contamination to the ground water sources.
In the early 20th century during a geological mapping expedition, scientists noted a thick black organic-rich shale in an outcrop close to the stream.
[3] The Barnett shale has acted as a source and sealing cap rock for more conventional oil and gas reservoirs in the area.
[4] The field was discovered in 1981 when Mitchell Energy drilled and completed the C. W. Slay #1 near Newark, Texas, in Wise County.
[8] In 1991, Mitchell Energy, with a subsidy from the federal government, drilled the first horizontal well in the Barnett, but the experiment was not considered a success.
[8][10] By going against conventional wisdom and switching to the slickwater frac, Mitchell Energy not only lowered the cost of completing wells by $75,000 to $100,000, but also dramatically increased the recovery of gas.
Techniques such as fracturing, or "fracking", wells, used by Mitchell Energy, opened the possibility of more large scale production.
[5] Proved reserves as of the end of 2011 were 32.6 trillion cubic feet of gas and 118 million barrels of oil or condensate.
In 2005–2007 horizontal drilling in the Barnett Shale extended south into Johnson, Hill, and Bosque counties, with a 100% success rate on completed wells.
[14] Hydraulic fracturing carried out in the Barnett Shale is done by pumping a mixture of water, sand, and various chemical additives (to affect viscosity, flow rates, etc.)
into the well bore at a sufficient pressure to create and propagate a fracture in the surrounding rock formation down hole.
This is crucial in low permeability rock as it exposes more of the formation to the well bore and greater volumes of gas can be produced by the increased surface area.
[22] Critics say that tax revenues may be offset by cleanup costs for toxic byproducts of gas drilling, such as benzene and naturally occurring radioactive material (NORM).
Ed Ireland, of the Barnett Shale Energy Council (an industry advocacy group) has said that he believes regulation will increase under the Obama administration; as of 2012, this has not been the case.
Faults may divert hydraulic fracturing, reducing its effectiveness, and karst features may contain abundant water that limits the production of gas.
[29] Some environmental groups and north Texas residents have expressed concern about the effects of drilling on air and water quality in the areas surrounding the wells and pipelines.
[30] In 2010, the Environmental Protection Agency (EPA) issued an emergency order against Range Resources, stating that the company's drilling activities in Parker County, Texas had contaminated at least two residential drinking water wells.
[34] The mayor of DISH, Texas complained that air pollution from a natural gas compressor station was sickening his family.
The agency concluded: “The information obtained from this investigation did not indicate that community-wide exposures from gas wells or compressor stations were occurring in the sample population.
Other sources of exposure such as cigarette smoking, the presence of disinfectant by-products in drinking water, and consumer or occupational/hobby related products could explain many of the findings.”[35] Texas environmental regulators and the EPA have ordered the Texas Commission on Environmental Quality to begin investigating drilling complaints on-site within 12 hours of reception.
