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温室气体排放是全球气候变化的重要诱因[1]。甲烷是仅次于二氧化碳的温室气体,具有远高于二氧化碳的升温潜势和较短的大气寿命。甲烷减排对缓解气候变化和全球变暖具有重要意义[2]。国际能源署 (International Energy Agency, IEA) 相关数据显示,自工业革命以来,甲烷对全球温升的贡献已达到30%,故甲烷减排被认为是实现巴黎协定目标的关键举措[3]。油气行业是大气环境中甲烷的重要排放源[3-17]。IEA发布的报告显示,能源行业对全球甲烷排放量的贡献比例接近40%,其中油气行业甲烷排放量达到约7.900×107 t[3]。油气生产井、收集与增压站、处理场站等设施均会向大气环境排放大量甲烷,设备组件与管线泄漏、储罐、装卸及有组织排放等为主要排放源[5-17]。
CHEADL等[5]对油气生产设备泄漏导致的甲烷排放及减排潜力进行了分析。BRANTLEY等[9]、ALLEN等[10,12-13]和JOHNSON等[7]分别对油气生产井场、气动设备、储罐及返排过程甲烷排放情况进行了系统监测。MITCHELL等[11]对油气收集和处理环节甲烷排放进行研究。结果表明,页岩气生产井场平均甲烷排放为9.5 kg·d−1,而天然气处理场站甲烷排放速率为3~600 kg·h−1[6,11]。储罐和气动阀对甲烷排放总量贡献比例较高[7]。美国油气开发过程实测甲烷排放量要高于温室气体排放清单数据[9-10];超级排放源对油气生产过程甲烷排放影响显著[15]。
与美国页岩气开发过程相比,我国油气主要源于常规油气田,油气开发与处理过程与页岩气差异较大,相关环节甲烷排放研究较少,处理场站等设施甲烷排放特征不明确,难以支撑油气行业开展温室气体减排工作[18-19]。针对上述问题,本研究以西北地区大型油气田典型油气处理场站为样本,开展油气处理过程甲烷排放特征研究,以明确生产设备设施的泄漏率,量化重点源项甲烷排放速率、设备与设施排放因子及年度排放量,并针对排放特征给出治理建议,以期对完善我国油气开发过程甲烷排放基数,指导国内油气行业绿色低碳发展,开展温室气体减排工作提供参考。
油气处理场站温室气体甲烷排放特征与量化
Characteristics and quantification of greenhouse gas methane emission from oil and gas processing plant
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摘要: 油气生产过程是甲烷重点排放源,对气候变化产生显著影响。采用便携式火焰离子检测器 (FID) 和Hi-Flow大流量仪等设备,对我国某油田3座油气处理场站甲烷泄漏排放特征进行了研究,明确了组件泄漏率,量化了重点源项甲烷排放速率,构建了设备设施甲烷排放因子,开展了甲烷排放量核算并提出了管控建议。结果表明,该油田油气处理场站设备组件与管线的甲烷泄漏率为0.7%~1.2%,压力表、阀门和储罐等在泄漏源项中占比较高。不同类型泄漏组件甲烷排放速率具有显著差异,处理场站的甲烷排放速率为111.66~274.63 L·min−1。单个储罐和场站的甲烷排放因子分别为989.9 L·h−1和0.19 L·m−3。3座场站年度甲烷排放量为303 783.40 m3,储罐是首要排放源,对总排放量贡献占比为94.1%。组件泄漏导致的甲烷排放主要源于高强度排放源,15%的泄漏点贡献了排放量的88.4%。该研究结果可为油田油气处理场站泄漏防控和温室气体排放控制提供参考。Abstract: Oil and gas (OG) production processes are key methane emissions sources, having prominent climate implications. Three OG processing plant located in a typical oil field in China were measured using portable FID and Hi-Flow Sampler in this work. The component based leakage characteristics and emission rates were studied and quantified, and corresponding abatement and management suggestions were proposed. The leak detection and repair results suggested that 0.7%~1.2% component and lines have leak problem, with pressure gauge, valve and tank having the largest contribution. There are distinct differences among emission rates for OG processing related components, and 111.66~274.63 L·min−1 methane released from OG plant. The established methane emission factor was 989.9 L·h−1 and 0.19 cubic meter per 1000 meters gas processed. In summary, almost 303 783.4 cubic meters methane were emitted from the measured sources annually, with tank contributing 94.1% total emission. As to component leak-related methane, most fraction derived from high emission source and 15% leaking point contributes more than 88.4% of leak-related methane.The research findings can provide reference for leak prevention and control and Greenhouse gas emission control in oil and gas processing plants.
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Key words:
- oil and gas /
- methane /
- emission source /
- leak /
- emission rate
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表 1 Hi-Flow 大流量仪技术参数
Table 1. Technical specification for Hi-Flow sampler
序号 技术参数 基本情况 1 流量范围 0.01~300 L·min−1 2 体积分数范围 0~100% 3 检测方法 催化氧化 4 精度 甲烷体积分数0.02% 5 稳定工况抽气速率 200 L×min−1 6 电池类型 镍氢充电包 7 电压 5.5 V 8 工作时长 4.5 h 9 安全等级 本质安全 表 2 油气处理场站泄漏情况
Table 2. Leakage information on oil and gas processing plant
场站及项目名称 密封点数/处 泄漏点数/处 泄漏率 DN 3 083 34 1.1% YM 10 282 73 0.7% DH 1 258 15 1.2% 合计 14 623 121 0.8% 表 3 油气处理场站泄漏组件甲烷排放速率
Table 3. Emission rate of methane for leaking component in oil and gas processing plant
泄漏组件 排放速率/(L·min−1) 泄漏组件 排放速率/(L·min−1) 泄漏组件 排放速率/(L·min−1) 泄漏组件 排放速率/(L·min−1) P-1# 0.013 P-11# 0.18 P-21 13.107 V-9# 0.074 P-2# 0.176 P-12# 0.357 P-22 5.682 V-10# 0.002 P-3# 0.080 P-13# 0.016 V-1# 0.924 V-11# 0.019 P-4# 0.013 P-14# 2.186 V-2# 0.041 V-12# 0.135 P-5# 0.006 P-15# 0.004 V-3# 0.103 V-13# 0.069 P-6# 0.014 P-16# 4.624 V-4# 0.004 V-14# 0.013 P-7# 0.090 P-17# 0.014 V-4# 1.922 V-15# 0.132 P-8# 0.043 P-18# 0.088 V-6# 0.019 V-16# 0.031 P-9# 0.006 P-19# 0.626 V-7# 0.176 F-1# 0.006 P-10# 0.090 P-20# 0.012 V-8# 2.365 F-2# 0.180 表 4 生产设施甲烷排放速率
Table 4. Emission rate of methane for production facility
设施 L×min−1 设施 L×min−1 YM-T-1#(凝析油,小呼吸,拱顶) 0.68 DH-T-4#(处理后污水,大呼吸,拱顶) 2.94 YM-T-2#(凝析油,大呼吸,拱顶) 71.25 DN-T-1#(含油污水,大呼吸,拱顶) 104.43 YM-T-3#(轻烃,大呼吸,内浮顶) 5.91 DN-T-2#(含油污水,大呼吸,拱顶) 71.76 YM-T-4#(轻烃,小呼吸,内浮顶) 0.25 DN-T-3#(处理后污水,大呼吸,拱顶) 2.07 DH-T-1#(凝析油,小呼吸,拱顶) 33.80 DN-T-4#(凝析油,小呼吸,拱顶) 2.60 DH-T-2#(凝析油,大呼吸,拱顶) 104.35 DN-T-5#(轻烃,大呼吸,内浮顶) 10.80 DH-T-3#(凝析油,大呼吸,拱顶) 133.30 Y-1# 0.96 表 5 各油气场站的甲烷排放速率
Table 5. Emission rate of methane for oil and gas processing plant
L·min−1 YM DH DN 均值 111.66 274.63 191.68 192.66 表 6 甲烷排放因子对比
Table 6. Comparison of methane emission factor
源项 本研究 文献[25] 文献[24] 储罐 989.9 L·h−1 (均值) — 950.9 L·h−1 场站 0.19 L·m−3 0.74 L·m−3 1.34 L·m−3 -
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