Kang Mary, Kanno Cynthia M, Reid Matthew C, Zhang Xin, Mauzerall Denise L, Celia Michael A, Chen Yuheng, Onstott Tullis C
Civil and Environmental Engineering Department,
Civil and Environmental Engineering Department.
Proc Natl Acad Sci U S A. 2014 Dec 23;111(51):18173-7. doi: 10.1073/pnas.1408315111. Epub 2014 Dec 8.
Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells ("controls") in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10(-6) kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10(-3) kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4-7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories.
废弃的油气井为甲烷和其他流体向大气的地下迁移和排放提供了一条潜在途径。对于美国存在的数百万口废弃油井的甲烷通量，人们了解甚少。在此，我们报告了使用静态通量室对宾夕法尼亚州废弃油气井甲烷通量的直接测量结果。2013年7月、8月、10月以及2014年1月，分别在森林、湿地、草地和河流区域的油井及其附近地点（“对照点”）进行了总共42次和52次直接测量。这些油井位置的平均甲烷流速为0.27千克/天/口油井，对照点的平均甲烷流速为4.5×10⁻⁶千克/天/个位置。在19口被测油井中，有3口是高排放井，其甲烷流速比中位数流速1.3×10⁻³千克/天/口油井大三个数量级。假设此处发现的平均流速代表宾夕法尼亚州所有废弃油井的情况，我们将甲烷排放量按比例推算为宾夕法尼亚州估计的人为甲烷排放总量的4 - 7%。乙烷、丙烷和正丁烷的存在以及甲烷的同位素组成表明，排放的甲烷主要来源于热成因。这些测量结果表明，废弃油气井的甲烷排放可能相当可观。应该开展在全国范围内量化这些排放所需的研究，以便能够准确描述它们并将其纳入温室气体排放清单。
