At the state level, two agencies—the Colorado Oil and Gas Conservation Commission (COGCC) and the Colorado Department of Public Health and Environment (CDPHE) —regulate air emissions from oil and gas operations.  

 By Cindy Allen

The COGCC regulates air emissions through operational mandates. Specifically, it requires “green completion” technology in all but a few instances.  Green completions require oil and gas operators to capture the methane released by a well when it’s initially brought onto production.  Previously, companies allowed this methane to dissipate into the air or burned (flared) it off until the well was connected to a gathering line. 

Because methane is a powerful greenhouse gas, this initial capture is important. Utilizing equipment such as flowback separators, operators can now capture and separate the gas from water and hydrocarbon liquids flowing back from the well after it’s completed.  This is a win for operators from a financial standpoint; capturing this gas means selling it rather than letting it go to waste. 

FEW EMISSION POINTS

Once the well is producing, there are very few emission points.  The wellhead is just piping.  The gas from the well typically goes to a separator where the gas will be separated and sent to the sales line; any liquids produced are typically sent to storage tanks. The storage tanks are the only significant source of emissions. The CDPHE sets limits on emissions from individual tanks, as well on system-wide operations. 

On Colorado’s Front Range, those limits include a 90 percent control of system-wide emissions during the ozone season (May through September). On an individual basis, tanks are required to have emission control equipment that attains an efficiency of 95 percent. Typically, this equipment includes combustors that incinerate emissions in a closed chamber and Vapor Recovery Units that capture and retain emissions rather than releasing them into the atmosphere.

On the Front Range, the CDPHE requires an air permit for every source with actual annual emissions above a minimum threshold. For most pollutants the threshold is 2 tons per year.

In addition to state regulation, the Environmental Protection Agency mandates the emission standards for engines used in drilling. Recently, EPA also weighed in with rules related to operations. These rules are largely modeled on the state regulations already in place in Colorado and Wyoming.  For this reason, these rules aren’t expected to have much impact in terms of further emission reduction. They will, however, require greater record-keeping by operators.

OZONE LEVELS DOWN

Colorado has led the way on control of air emissions from oil and gas operations. In fact, while the level of activity on the Front Range has increased, state monitoring data indicates ozone levels have dropped.   This is good news for those who live in communities where drilling occurs.  At the same time, it’s important to remember that oil and gas operations are but one of many sources that contribute to air pollution. In fact, the Volatile Organic Compounds (VOCs) that are a pre-cursor of ozone formation, from one controlled gas well equal the equivalent of VOC emissions from 66 cars.

As drilling activity continues to grow in the Niobrara play of Colorado’s Front Range, it’s important that further air emission data is gathered.  Through applying sound science, operators, regulators and communities can work together to better understand and mitigate air impacts.

About the Author: Cindy Allen is team lead for Environment, Health and Safety for Encana Oil & Gas (USA)’s South Rockies (Colorado) business unit. Prior to joining Encana, she worked for the Colorado Department of Public Health and Environment as an air quality control specialist.