中国天然气田的时空分布

SPACE-TIME DISTRIBUTION OF GAS FIELD IN CHINA

截止 1998年底 ,中国陆上及近海海域气田总数为 32 1个 ,其中小型 2 5 2个 ,中型 5 4个 ,大型 15个。小型气田数量虽占气田总数的 79% ,其探明地质储量仅占中国天然气总探明地质储量的 16 % ;大中型气田个数虽占气田总数的 2 1% ,但却构成了中国气田总探明地质储量的 84% ,仅大型气田探明地质储量占天然气总探明储量的 5 0 %。这表明 ,大中型气田构成中国已探明地质储量的主体。该主体中天然气的成因类型有煤成气、生物气、湖相泥岩气和碳酸盐岩气 ,其中煤成气的探明地质储量已占大中型气田探明地质储量的 5 7%。在层位上 ,已发现气田主要分布在新生界、上古生界和下古生界。新生界、中生界、上古生界、下古生界和元古界分别占总探明地质储量的 38%、17%、30 %、13%和 2 %。按地质层系探明地质储量自大而小的顺序依次为第三系、石炭系、奥陶系、三叠系、第四系、白垩系、二叠系、侏罗系和震旦系。在泥盆系、志留系和寒武系三个层位目前尚未获得天然气探明地质储量。在中国已发现大中型气田中 ,气藏内分布的天然气类型普遍具有混源的特点 ,煤成气在中国大中型气田占有重要地位 ,过成熟的裂解气主要分布在四川、塔里木和鄂尔多斯盆地 ,油田伴生气集中分布在松辽、渤海湾和准噶尔盆地中 ,幔源无机成因CO2 ?

There are 321 gas fields in total in the continent and offshore areas in China, among which there are 252 small fields, 54 middle ones, 15 large ones. Although the number of small fields is 79% in total, their proved reserves is only 16% in the total proved geologic reserves in China; while the number of middle and large fields are 21% in total, but their proved reserves are 84 % in total. Only in the large fields does the proved reserves occupy one half of the total ones of natural gas. All the data from statistics show that middle and large gas fields have been the essential parts of the proved reserves in China. In the middle and large gas fields, there appears many kinds of gases, like coal-formed gas, shale gas and carbonate gas. The proved reserves of coal-formed gas occupies 57% in total proved reserves of large and middle gas fields. Gas fields have been found to be distributed mainly in Cenozoic, Upper Palaeozoic and Lower Palaeozoic. The proved reserves in Cenozoic, Mesozoic, Upper Palaeozoic, Lower Palaeozoic, Proterozoic respectively are 38%, 17%, 30%, 13% and 2% in total. The proved reserves from the most to the least were found in successive geologic formations as follows: Tertiary, Carboniferous, Ordovician, Triassic, Quaternary, Crataceous, Permian, Jurassic and Sinian. But till now the proved reserves of gas have not been found in Devonian, Silurian and Cambrian. Among those discovered large and middle gas fields in China, gases in reservoirs were found from various gas sources. There are a large number of coal-formed gas there. Most post-matured cracking gas is distributed in Sichuan, Talimu and E' erduosi Basins. Most associated gas is gathered in Songliao Basin, Bohai Bay and Zhunge'er Basin. Mantle source inorganic gas of carbon dioxide is distributed in the eastern heat basins with the thinner crust thickness.