Gas Flares from Shale Wells
07-22-2014
Congratulations to Dana (first author), Dr. Shepson, Obie, whose paper "Methane Destruction Efficiency of Natural Gas Flares Associated with Shale Formation Wells" was published in Environmental Science and Technology today! Way to go! Click here to read it. Abstract below:
Flaring to dispose of natural gas has increased in the United States and is typically assumed to be 98% efficient, accounting for both incomplete combustion and venting during unintentional flame termination. However, no in-situ measurements of flare emissions have been reported. We used an aircraft platform to sample 10 flares in North Dakota and 1 flare in Pennsylvania, measuring CO2, CH4 and meteorological data. Destruction Removal Efficiency (DRE) was calculated by assuming a flare natural gas input composition of 60-100% CH4. In all cases flares were greater than 99.80% efficient at the 25% quartile. Crosswinds up to 15 m/s were observed, but did not significantly adversely affect efficiency. During analysis unidentified peaks of CH4, most likely from unknown venting practices, appeared much larger in magnitude than emissions from flaring practices. Our analysis suggests 98% efficiency for non-sputtering flares is a conservative estimate for incomplete combustion and that the unidentified venting is a greater contributor to CH4 emissions.