新疆准噶尔盆地独山子泥火山天然气地球化学特征  

Geochemical Characteristics of Natural Gas from Dushanzi Mud Volcano in Junggar Basin,Xinjiang

作　　者：高苑[1,2] 王永莉[1] 郑国东[1] 孟培[1,2] 吴应琴[1] 杨辉[1] 张虹[1] 王有孝[1] 

机构地区：[1]中国科学院油气资源研究重点实验室,甘肃兰州730000 [2]中国科学院研究生院,北京100049

出　　处：《地球学报》2012年第6期989-994,共6页Acta Geoscientica Sinica

基　　金：国家973计划项目(编号:2012CB214701-05);中国科学院战略性先导科技专项(编号:XDA05120204);国家自然科学基金项目(编号:41172169);中国科学院知识创新工程重要方向项目(编号:KZCX2-EW-104)联合资助

摘　　要：独山子泥火山位于新疆准噶尔盆地南缘,地处北天山山前坳陷带的独山子背斜轴部。本文通过分析独山子泥火山喷出天然气组分及其碳同位素研究,对天然气的来源进行了判识。3个天然气样中δ13C1值均在-41‰左右,C1/(C2+C3)<20,为热成因气;δ13C(C2-C1)在15‰左右,iC4/nC4和C2/C3值均较高,说明天然气曾遭受了厌氧微生物降解作用;其中两个喷口的天然气δ13CCO2值超过+10‰,说明天然气在受微生物降解后发生CO2还原作用二次生成甲烷,而另外一个喷口δ13CCO2值无正异常,未发生CO2还原作用。不同喷口相同成因天然气在储藏或运移过程中发生不同的改造作用,说明泥火山不同喷口对应不同的天然气运移通道或储藏条件。Dushanzi mud volcano is located on the axis of the Dushanzi anticline in northern Tianshan piedmont depression, which lies in the southern margin of the Junggar Basin, northwestern China. This study aims to identify the origin of the natural gases released by Dushanzi mud volcano by analyzing their geochemical characteristics, and the result shows that the gases should be attributed to a thermogenic source with δ^13C1 higher than -50% and C1/（C2＋C3） lower than 20, and that oil or heavier hydrocarbon anaerobic biodegradation occurs along the seepage system of the mud volcano indicated by higher iC4/nC4 and C2/C3 values. The high δ^13CCCO2 values of two gas samples from two different vents suggest secondary methanogenesis with CO2 reduction after oil biodegradation, while isotopically enriched COn is absent in the third vent. The variability of the δ^13CCO2 value might mean that the different vents of Dushanzi mud volcano might correspond to different circulation systems and different reservoirs.

关 键 词：准噶尔盆地 泥火山 天然气 碳同位素 厌氧微生物降解 

分 类 号：TE121.1[石油与天然气工程—油气勘探] P597.2[天文地球—地球化学]