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吐哈盆地台北凹陷天然气以湿气为主,具有原油伴生气的特征。烃类气体以CH_4为主,主要分布在60%~80%之间,重烃气(C_2)含量较高,集中在20%~40%,天然气干燥系数(C_1/C_(1-5))变化较大,集中在60%~80%,为典型的湿气;非烃气体主要为N_2和CO_2,总体含量较低,其中雁木西地区含量较高的N_2主要来源于大气氮。天然气δ~(13)C_1偏轻,集中在-41‰~-39‰,δ~(13)C_2值大于-29‰,主频率为-28‰~-26‰,δ~(13)C_3值集中在-26‰~-24‰,δ~(13)nC_4值集中在-26‰~-24‰,表明台北凹陷天然气主要为煤成气。雁木西油田部分样品天然气湿度较大且碳、氢同位素发生倒转,主要是细菌降解作用影响所致。天然气主要处于成熟的热演化阶段(R_o=0.8%~1.0%),主要来源于下侏罗统八道湾组成熟烃源岩,其次为中侏罗统西山窑组未熟—低熟烃源岩。台北凹陷天然气具有较好的成藏条件,烃源岩主要发育于中下侏罗统煤系地层,储盖组合好,孔隙型的储集层利于天然气富集,盖层主要为中侏罗统七克台组上段泥岩、齐古组湖相泥岩以及白垩系吐谷鲁群中上部胜金口组和连木沁组湖湘泥岩,输导体系主要由断层、不整合面和砂体组成,圈闭类型主要以构造固闭、岩性圈闭以及复合类型圈闭为主,发育自生自储、下生上储2种生储盖组合。
The natural gas in the Turpan-Hami basin in the Turpan-Hami basin is dominated by moisture and has the characteristics of associated gas with crude oil. Hydrocarbon gases are dominated by CH 4, mainly distributed between 60% and 80%, with high content of heavy hydrocarbon (C 2), concentrated in 20% -40%, natural gas drying coefficient (C 1 / C 1-5) The variation is large, concentrated in 60% -80%, which is typical moisture. The main non-hydrocarbon gases are N 2 and CO 2, and the overall content is relatively low. The N 2 with high content in the Nanshi West region mainly comes from atmospheric nitrogen. The δ 13 C 2 value of natural gas is light, concentrated in the range of -41 ‰ to -39 ‰, δ 13 C 2 value is greater than -29 ‰, and the dominant frequency is -28 ‰ -26 ‰, and δ 13 C 3 Concentrations ranged from -26 ‰ to -24 ‰, and δ ~ (13) nC_4 values ranged from -26 ‰ to -24 ‰, indicating that the natural gas in the Taipei depression is mainly coal-derived gas. Some samples from the Yanmuxi Oilfield show high humidity and reversed carbon and hydrogen isotopes, mainly due to bacterial degradation. Natural gas is mainly in the mature thermal evolution stage (R_o = 0.8% -1.0%), mainly from the mature source rocks of the Lower Jurassic Badaowan Formation, followed by the immature-low maturity source rocks of the Xishayao Formation in the Middle Jurassic. The natural gas in the depression in the Taipei depression has good reservoir forming conditions. The source rocks mainly develop in the Lower-Middle Jurassic coal measures strata, with good reservoir-cap assemblage. The pore-type reservoirs are conducive to the enrichment of natural gas. The cap rocks are mainly of Middle Jurassic The mudstones in the upper reaches of the Qijia Formation and the lacustrine mudstones in the Qigu Formation and the upper Shengjinkou Formation in the Cretaceous Tuugu Group and the Hu Xiang mudstone in the Lianmuqin Formation. The transport systems are mainly composed of faults, unconformities and sand bodies. Traps The types are mainly composed of solid and closed structures, lithologic traps and composite types of traps.