When natural gas is produced, some of the gas and other volatile substances present in the wells escapes. EPA released the first federal air rules for natural gaswells that are hydraulically fractured, specifically requiring operators of newfractured natural gas wells to use “green completion,” which is a series of technologies and practices to capture natural gas and other volatile substance that might otherwise escape the well during the completion period when the well transitioned from drilling through the completion string and fractured.
Much of the air pollution from fracked gas wells is vented when the well transitions from drilling to actual production, a multi-day process that involves running a pipe casing or a liner down the well to the production zone, and cementing it in place leaving perforations for flow. Once the completion string is in place, the final step is to fracture the well. Drilling requires large amounts of water to create a circulating mud that cools the bit and carries the rock cuttings out of the borehole. After drilling, the shale formation is then stimulated by hydro fracking, using 2-5 million gallons of water. For gas to flow out of the shale, all of the water not absorbed by the formation during fracking must be recovered and disposed of. Though less than 0.5% by volume, the proprietary chemicals represent 15,000 gallons in the waste water recovered from the typical hydro fracking job. The chemicals serve to increases the viscosity of the water to a gel-like consistency so that it can carry the propping agent (typically sand) into the fractures to hold them open so that the gas can flow.
The flowback fluid carries residual drilling muds, fracking fluid and gas. In many instances it is allowed to flow our of an open well and the fluid is placed in open ponds. The new rules will require this fluid to be captured by 2015, and flared before that. Open ponding of fracking fluids is eliminated. An earlier version of the rule limiting air pollution from gas wells would have required companies to install pollution-reducing equipment immediately after the rule was finalized, but in the final version there is a phase in period. Besides the new air pollution standards for oil and gas wells, the EPA also updated existing rules for natural gas processing plants, storage tanks and transmission lines.
According to the EPA , these new rules have received inter-agency feedback and provide industry flexibility as required under the recently signed Executive Order on Natural Gas Development. Agencies involved include the departments of Defense, Interior, Agriculture, Commerce, Health and Human Services, Transportation, Energy and Homeland Security, as well as the EPA, Council on Environmental Quality, Office of Science and Technology Policy, Office of Management and Budget, and National Economic Council.