中国晚古生代煤系相关的气田及其在天然气工业上的重要意义

The Late Paleozoic gasfields related to coal measure in China and their significances on natural gas industry

中国晚古生代煤系气源岩为下石炭统滴水泉组、上石炭统巴塔玛依内山组、本溪组、下二叠统太原组和山西组以及上二叠统龙潭组,形成煤成气在奥陶系、石炭系、二叠系和古新系成藏,并分布在鄂尔多斯盆地、渤海湾盆地、准噶尔盆地和四川盆地,共发现16个气田,其中12个为大气田,如中国储量最大、年产量最高的苏里格大气田。根据99个气样的组分和烷烃气碳同位素资料,以δ^(13)C_2值>-28.5‰为煤成气以及应用δ^(13)C_1—δ^(13)C_2—δ^(13)C_3鉴别图判别了上述气田均为煤成气。晚古生代煤系形成相关气田对中国天然气工业有重要意义:一是中国探明天然气总地质储量和年产量,其占1/3;二是支持中国成为产气大国5个关键大气田中3个(苏里格、靖边和大牛地)气源为该类气;三是晚古生代煤系形成各气田和各大气田平均储量分别是全国各气田和各大气田的5.3倍和1.7倍。

The coal measuregas sources of coal-derived gas fields in the Late Paleozoic,China,are the Lower Carboniferous Dishuiquan Formation,the Upper Carboniferous Batamayineishan and Benxi formations,the Lower Permian Taiyuan and Shanxi Formations,and the Upper Permian Longtan Formation.The coal-derived gas accumulates in Ordovician,Carboniferous,Permian,and Paleocene reservoirs,and distribute in the Ordos,Bohai Bay,Junggar and Sichuan Basins.There are 16 gas fields,and 12 of them are large gas fields,such as Sulige large gas field with the largest reserves and highest annual output in China.According to component and alkane carbon isotopic data of 99 gas samples,they are distinguished to be coal-derived gas by the criterion of δ13C2〉-28.5‰ and the δ13C1-δ13C2-δ13C3 identification chart.The Late Paleozoic gas fields related to coal measureare significant for Chinese natural gas industry：their proven natural gas geological reserves and annual gas output account for 1/3in China of the total,and the three out of five significant large gasfields which supports China to be a great gas producing country are sourced from coal measure;the average reserves of the gasfields and the large gasfields formed from the Late Paleozoic coal measure are 5.3and 1.7times that of the gasfields and the large gasfields in China.