What is benzene?
Benzene is an organic chemical compound widely used in the United States. It ranks in the top 20 chemicals for production volume, and is used to make some types of lubricants, dyes, detergents and pesticides.
Volcanoes and forest fires are natural sources of benzene. Low levels of benzene can usually be found outdoors from tobacco smoke, gas stations, and motor vehicle exhaust. Indoor air usually contains higher levels of benzene from glues, paints, furniture wax and detergents. You can learn more about benzene on the Centers for Disease Control website.
Are there elevated benzene levels in North Texas?
The Texas Commission on Environmental Quality (TCEQ) conducted three days of air quality sampling at 126 natural gas wells in Fort Worth in December 2009. The agency said these preliminary tests showed no evidence that the wells released benzene and other hazardous chemicals. Samples were tested for 22 chemicals, including benzene and other carcinogens. Other tests done by TCEQ have shown evidence of chemicals being released at rural well sites where there are storage tanks for condensate. Such "wet" wells are primarily in the far northwestern part of Tarrant County; Denton, Wise and Parker counties and further north and west. Tanks that emit high levels of chemical compounds are required to have vapor recovery units that reduce emissions.
Do natural gas wells produce benzene?
Benzene levels in dry gas wells (gas wells that do not produce oil or condensate) are extremely minute, comprising less than .001% (one one-thousand of one percent) of the compounds that make up methane. Natural gas wells are closed systems with the natural gas going straight into pipelines.
Benzene is one of the chemical compounds found in condensate storage tanks. All of the natural gas wells in Tarrant County are dry gas wells except for a few wells in the far northwestern part of the county. In the nine counties that the EPA has designated a non-attainment area for ozone levels, only 19% of the wells produce condensate and thus have condensate storage tanks on site. Condensate production in the Barnett Shale is primarily to the north (Denton and Wise counties and north) and west (Parker county and west). Oil and condensate storage tanks that emit high levels of chemical compounds including benzene are required to have vapor recovery units that reduce emissions.
What is being done about it?
BSEEC members are making sure that they are in compliance with TCEQ regulations regarding air emissions at natural gas facilities. Several members of the BSEEC are also partners with the EPA Natural Gas STAR Program, a voluntary partnership dedicated to improving operational efficiency and reducing emissions. Read more about the program here.