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中坝气田位于川西气区北部,主要产层为上三叠统须家河组二段和中三叠统雷口坡组三段,但其雷口坡组三段气藏的气源目前还没有定论。基于此,全面分析了中坝气田雷口坡组天然气组分和碳、氢同位素组成,并选取中坝气田须家河组煤成气、河湾场气田二叠系茅口组和长兴组以及三叠系飞仙关组油型气、川东北飞仙关组油型气与之进行对比。中坝气田雷口坡组天然气总体显示干气特征,干燥系数大都在0.97附近,H2S和CO2含量较高。中坝气田雷口坡组天然气中烷烃气碳、氢同位素组成与中坝须家河组、河湾场气田及川东北飞仙关组天然气的同位素组成都有明显差异,乙烷碳同位素组成较河湾场气田、川东北飞仙关组天然气重,而甲烷碳同位素组成较川东北飞仙关组天然气轻。甲烷氢同位素值在-140‰左右,比川东北飞仙关组油型气普遍低约20‰,而高于中坝须家河组煤成气约30‰。综合天然气组分,碳、氢同位素及轻烃和汞的特征分析认为中坝气田雷口坡组天然气以二叠系油型气为主,混有部分须家河组煤成气,且受TSR作用改造。
The Zhongba gas field is located in the northern part of Sichuan West Gas District. The main pay zone is the third member of the Upper Triassic Xujiahe Formation and the Middle Triassic Leikoupo Formation. However, the gas source of the third member of the Leikoupo Formation is still No conclusion. Based on this, a comprehensive analysis of the gas composition and carbon and hydrogen isotopic compositions of the natural gas in the Leikoupo Formation in the Zhongba gas field was made. The coal gas of the Xujiahe Formation in the Zhongba gas field, the Maokou Formation and the Changxing Formation in the Permian of the Hewanchang Gas Field Triassic Feixianguan Formation oil-type gas, northeastern Feixianguan formation oil-gas contrast. The natural gas of the Leikoupo Formation in the Zhongba gas field shows dry gas characteristics generally with the drying coefficients mostly around 0.97 and higher H2S and CO2 contents. The gas and carbon isotope compositions of alkanes in the natural gas of the Leikoupo Formation in the Zhongba gas field are significantly different from those of the Xujiaxuhe Formation, the Hewanchang Gas Field and the Feixianguan Formation in the northeastern Sichuan Basin. The carbon isotope composition of ethane Bay Field gas field, northeastern Feixianguan group heavy natural gas, and carbon isotope composition of methane northeastern Feixianguan natural gas lighter. The hydrogen isotope value of methane is about -140 ‰, which is about 20 ‰ lower than that of Feixianguan Formation in northeastern Sichuan, and about 30 ‰ higher than that of Xujiahe Formation in Zhongba. Based on the characterization of natural gas components, carbon and hydrogen isotopes and light hydrocarbons and mercury, the natural gas of Leikoupo Formation in the Zhongba gas field is dominated by Permian oil-gas, with part of the Xujiahe Formation coal-forming gas mixed with TSR The role of transformation.