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至2010年底中国共发现15个致密砂岩大气田,分布在鄂尔多斯盆地、四川盆地和塔里木盆地.这些气田2010年气产量和总储量分别为222.5×108和28657×108 m3,分别占全国的23.5%和37.3%,是中国产量和储量的主要组成部分.根据81个气样分析,中国致密砂岩大气田稳定碳氢同位素组成主要特征为:(1)综合δ13C1-δ13C2-δ13C3图版,δ13C1-C1/C2+3图版和δ13C1-δ13C2回归线分析,中国致密砂岩大气田的天然气为来自含煤岩系的煤成气;(2)原生烷烃气随分子中碳数顺增,碳氢同位素值随之变重,即δ13C1<δ13C2<δ13C3<δ13C4和δ2H1<δ2H2<δ2H3;(3)δ13C2-δ13C1,δ13C3-δ13C1和δ2H2-δ2H1,δ2H3-δ2H1随Ro(%)和C1/C1~4值渐增而减小;(4)碳氢同位素倒转成因有7种,中国致密砂岩大气田碳氢同位素倒转主要是多期成藏充注所致.
15 tight sandstone gas fields were discovered in China by the end of 2010 and distributed in Erdos Basin, Sichuan Basin and Tarim Basin.The gas production and total reserves in these fields in 2010 were 222.5 × 108 and 28657 × 108 m3, accounting for 23.5% And 37.3%, respectively, are the major components of China’s production and reserves.According to the analysis of 81 gas samples, the main features of the stable hydrocarbon isotope composition of the tight sandstone gas field in China are as follows: (1) Comprehensive δ13C1-δ13C2-δ13C3 plate, δ13C1-C1 / C2 +3 plate and δ13C1-δ13C2 regression line, the natural gas in the tight sandstone gas field of China is coal-derived gas from the coal-bearing rock series. (2) With the increase of the carbon number in the molecule, the hydrocarbon isotope value Heavy, that is, δ13C1 <δ13C2 <δ13C3 <δ13C4 and δ2H1 <δ2H2 <δ2H3; (3) δ13C2-δ13C1, δ13C3-δ13C1 and δ2H2-δ2H1, δ2H3-δ2H1 increase with Ro (%) and C1 / C1-4 values (4) There are seven genesis causes of hydrocarbon isotope inversion. The hydrocarbon isotope inversion in the tight gas field of the tight sandstone in China is mainly caused by multi-phase accumulation.