Department of Earth System Science, Stanford University, Stanford 94305, California, United States.
Civil Engineering and Applied Mechanics, McGill University, Montreal H3A 0G4, Quebec, Canada.
Environ Sci Technol. 2020 Nov 17;54(22):14617-14626. doi: 10.1021/acs.est.0c05279. Epub 2020 Oct 30.
California hosts ∼124,000 abandoned and plugged (AP) oil and gas wells, ∼38,000 idle wells, and ∼63,000 active wells, whose methane (CH) emissions remain largely unquantified at levels below ∼2 kg CH h. We sampled 121 wells using two methods: a rapid mobile plume integration method (detection ∼0.5 g CH h) and a more sensitive static flux chamber (detection ∼1 × 10 g CH h). We measured small but detectable methane emissions from 34 of 97 AP wells (mean emission: 0.286 g CH h). In contrast, we found emissions from 11 of 17 idle wells-which are not currently producing (mean: 35.4 g CH h)-4 of 6 active wells (mean: 189.7 g CH h), and one unplugged well-an open casing with no infrastructure present (10.9 g CH h). Our results support previous findings that emissions from plugged wells are low but are more substantial from idle wells. In addition, our smaller sample of active wells suggests that their reported emissions are consistent with previous studies and deserve further attention. Due to limited access, we could not measure wells in most major active oil and gas fields in California; therefore, we recommend additional data collection from all types of wells but especially active and idle wells.
加利福尼亚州拥有约 124000 口废弃和封堵（AP）油井和天然气井、约 38000 口闲置油井和约 63000 口活跃油井，这些油井的甲烷（CH）排放量在低于约 2kgCH h 的水平下基本上没有被量化。我们使用两种方法对 121 口油井进行了采样：一种是快速移动羽流积分法（检测下限约为 0.5gCH h），另一种是更敏感的静态通量室法（检测下限约为 1×10 gCH h）。我们从 97 口 AP 井中的 34 口（平均排放量：0.286gCH h）中测量到了虽小但可检测到的甲烷排放量。相比之下，我们在 17 口闲置油井中的 11 口（目前不生产，平均排放量为 35.4gCH h）、6 口活跃油井中的 4 口（平均排放量为 189.7gCH h）以及一口未封堵的油井（无基础设施的开式套管，排放量为 10.9gCH h）中发现了排放物。我们的研究结果支持了先前的发现，即封堵油井的排放量较低，但闲置油井的排放量则更高。此外，我们对少量活跃油井的采样表明，它们报告的排放量与先前的研究一致，值得进一步关注。由于进入受限，我们无法对加利福尼亚州大多数主要活跃的油气田中的油井进行测量；因此，我们建议从所有类型的油井中收集更多数据，特别是活跃和闲置油井。
