An improved method for estimating GHG emissions from onshore oil and gas exploration and development in China

•Present a first effort to systematically measure GHG emissions from ONG exploration and development in China;•An improved method is proposed to estimate GHG emissions from ONG systems;•The GHG emissions of ONG systems in China were seriously overrated by IPCC method.

Greenhouse gas (GHG) emissions from oil and gas exploration and development are major contributors to emission inventories in oil and natural gas (ONG) systems. For the developing countries, including China, studies of this aspect of the industry, being at an early stage, lack a unified method of calculation, and this leads to varied projections of national emissions. In this paper, progress is reported on direct measurement of CH4 and CO2 emissions along the oil and gas value chain, for four oil and gas fields. An improved calculation method (classification calculation method), which considers the production status of each type of oil and gas field in China, is proposed for the first time in this study. Based on in situ measurement, it is used to estimate the national CH4 and CO2 emissions from the process of petroleum exploration and development. The results showed that CH4 and CO2 emissions in 2013 were 73.29 × 104 and 20.32 × 104 tonnes, respectively (in CO2 equivalent: 1559.36 × 104 tonnes). Compared with the results (731.52 × 104 tonnes of CH4, 1031.55 × 104 tonnes of CO2, 16,393.48 × 104 tonnes of CO2 equivalent) in 2013 determined by the Tier 1 method of the Intergovernmental Panel on Climate Change (IPCC), the carbon emissions from field measurement method were much lower than that of IPCC method, which indicated that carbon emissions of ONG systems in China were severely overrated by IPCC. Hence, the GHG emission results reported herein could fundamentally improve the knowledge and understanding of GHG emissions from ONG exploration and development in China.

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