Mobile Measurement of Methane and Hydrogen Sulfide at Natural Gas Production Site Fence Lines in the Texas Barnett Shale

摘要

Production of natural gas from shale formations is bringing drilling and production operations to regions of the U.S. that have seen little or no similar activity in the past. This has generated considerable interest in potential environmental impacts. This study focused on the Barnett Shale Fort Worth Basin in Texas, which saw the number of gas-producing wells grow from 726 in 2001 to 15,870 in 2011. This study aimed to measure fence line concentrations of methane and hydrogen sulfide at natural gas production sites (wells, liquid storage tanks, and associated equipment) in the Barnett Shale. This study included coverage of the 4 core counties of the Barnett Shale (Denton, Johnson, Tarrant and Wise). A mobile measurement survey was conducted of 4,788 wells at 401 lease sites, representing 35% of gas production volume, 31% of wells, and 38% of condensate production volume in the 4-county core area. Methane and hydrogen sulfide concentrations were measured using a Picarro G2204 Cavity Ring-Down Spectrometer (CRDS). Since the research team did not have access to lease site interiors, measurements were made by driving by roads on the exterior of the lease sites. Over 150 hours of data were collected from March - July 2012. It was found that 22 lease sites (5.5%) had hydrogen sulfide concentrations ＞ 4.7 parts per billion (ppb) (odor recognition threshold) just beyond the fence line. 58 sites (14.4%) had methane concentrations ＞ 3 parts per million (ppm) just beyond the fence line, and 29 lease sites (7%) produced methane concentrations ＞ 5 ppm just beyond the fence line.