中国油气行业甲烷逃逸排放核算与时空特征研究

Accounting and spatial-temporal characteristics of fugitive methane emissions from the oil and natural gas industry in China

甲烷是仅次于二氧化碳的第二大温室气体,油气开发利用的全产业链均会产生甲烷逃逸排放。在2060年前实现碳中和的愿景下,我国油气行业的甲烷减排需求迫切,而准确地核算与评估甲烷逃逸排放是油气行业开展甲烷排放控制工作的前提。本文采用《IPCC2006年国家温室气体清单指南(2019修订版)》推荐的排放因子,核算了2000-2017年我国油气行业甲烷逃逸排放,并分析了具体的时空演变特征。结果表明,2000-2017年我国油气行业的甲烷逃逸排放持续增长,2000年所估算的区间范围为703.6 Gg(低排放情景)~970.4 Gg(高排放情景),到2017年增长为1697.3~3288.3 Gg;其中石油系统的甲烷排放先增加后下降,从2000年的561.9~648.0 Gg增长到2017年的696.6~783.0 Gg;天然气系统的甲烷排放保持持续增长,从2000年的141.7~322.5 Gg增长到2017年的1000.7~2505.3 Gg。天然气系统相比于石油系统,其甲烷逃逸排放增长更快。从具体的排放源类别来看,在以排放更低的技术和实践为主的低排放情景,油气行业的生产环节为关键排放源,而在排放更高的技术和实践为主的高排放情景下,天然气系统的运输环节也成为关键的排放源,表明这些排放源具有较大的减排潜力。从空间特征来看,伴随油气资源勘探开发布局的变化,我国油气行业甲烷逃逸排放的分布总体呈现出由东北、华北地区向西北、西南地区转移的趋势;对比现有的清单研究结果发现,由于排放源完整性、核算方法和数据精度方面的差异,关于我国油气系统甲烷逃逸排放的估算研究仍存在较大的不确定性。最后,从国家清单编制常态化、清单编制方法学完善、高分辨率排放源识别等方面,对促进我国油气行业甲烷排放清单的编制提出了相应建议。

Methane is the second largest greenhouse gas after carbon dioxide.The emissions of methane inevitably occur along the entire oil&natural gas supply chains.Under the vision of being carbon neutral by 2060,China's oil&gas industry has an urgent need to reduce methane emissions.Accurate accounting and evaluation of fugitive methane emissions is a prerequisite for the oil and gas industry to carry out methane emissions control.Based on the emission factors recommended by 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventory,we estimate the fugitive methane emissions from China’s oil&natural gas systems from 2000 to 2017,identify the main features of temporal and spatial inventory changes,and compare the inventory data with those adopted from existing studies.The results show that methane emissions from China’s oil&natural gas systems increased continuously,from 703.6 Gg(low emission scenarios)~970.4 Gg(high emission scenarios)in 2000 to 1697.3~3288.3 Gg in 2017.The methane emissions of the oil system increased from 561.9~648.0 Gg in 2000 to 696.6~783.0 Gg in 2017;methane emissions from the natural gas system continued to grow,from 141.7~322.5 Gg in 2000 to 1000.7~2505.3 Gg in 2017.The natural gas system had a much larger growth rate of fugitive methane emissions than the oil system.Considering most activities occurring with lower-emitting-technologies and practices,the production segment of the oil&natural gas industry is the key emission source.The transportation segment of the natural gas system is an important emission source under the condition of most activities occurring with higher-emitting-technologies and practices,suggesting large mitigation potentials in different fields.From the point of view of spatial characteristics,the distribution of methane emissions in China’s oil&natural gas industries of China shows the trend of shifting from Northeast and North China to Northwest and Southwest China,along with the layout change of oil&natural gas resources exploration and development.Comparing with the results of the existing inventory research,it is found that there is still a great uncertainty in the estimation of methane emission from oil&natural gas systems in China,owing to the differences on the completeness of emission sources,accounting methods and data accuracy.Finally,this study provides some suggestions to develop the inventories of methane emissions in China’s oil&natural gas industries,such as the normalization of national inventory compilation,the improvement of accounting methodology and the implementation of high-resolution source monitoring.