苏里格气田天然气运移和气源分析

通过分析鄂尔多斯盆地苏里格气田天然气组分、稳定同位素和稀有气体同位素组成指出，该气田天然气以烃类气体为主，气体碳同位素组成偏重；天然气源岩形成于淡水一半咸水沉积环境；天然气主要来源于石炭二叠系煤系烃源岩；天然气碳同位素（δ^13C1，δ^13C2）具有从西南向东北方向变重和^3He／^4He值呈略增加的趋势；反映了天然气具有从东北向西南运移的趋势。根据天然气中^40Ar／^36Ar值，计算了石炭一二叠系源岩中K含量的变化范围，初步确定了煤岩生成天然气的贡献率在65％以上，为主要生气源岩。

GEOCHEMISTRY OF NATURAL GAS AND CRUDE COMPUTATION OF GAS-GENERATED CONTRIBUTION FOR VARIOUS SOURCE ROCKS IN SULIGE GAS FIELD, ORDOS BASIN

According to measuring chemical composition, stable isotope and noble gas isotope in natural gas from Sulige gas field, Ordos basin, that natural gas is characterized as the higher concentration of hydrocarbon gases enriching in ^13C, suggests the gaseous alkanes were derived from humic matter, in combination with the hydrogen isotopes referring the source rocks of natural gas would be deposited in flesh-brackish water. The pathway of natural gas migration in Sulige gas field is principally directed from northeast to southwest, based on the tendency of enrichment in ^13C of hydrocarbon gases from southwest to northeast and slight increase of ^3He/^4He ratios. Based on the ^40Ar/^36Ar ratios in natural gas, the K concentration in the source rocks in C-P was calculated, and then the more 65 % contributing proportion of coal to gas generation as a source rock was determined.