| 准噶尔盆地浅层天然气多种成因地球化学研究 |
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| 引用本文： | 孙平安,王绪龙,唐勇,万敏,曹剑.准噶尔盆地浅层天然气多种成因地球化学研究[J].地球化学,2012(2):109-121. |
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| 作者姓名： | 孙平安 王绪龙 唐勇 万敏 曹剑 |
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| 作者单位： | 1. 南京大学地球科学与工程学院,江苏南京210093
2. 中国石油天然气股份有限公司新疆油田公司,新疆克拉玛依834000 |
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| 基金项目： | 国家自然科学基金(41072090,40872086) |
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| 摘 要： | 浅层天然气是当前国内外天然气勘探和基础研究的一个热点,在准噶尔盆地是油气勘探的一个重要新领域,但研究程度较低.为给区域勘探和成藏研究提供信息,并为国内外同类研究对比参考,主要以盆地腹部地区为例,着重从地球化学角度,包括系统的天然气组分、烷烃系列碳同位素组成、轻烃等,结合与天然气共生凝析油和储层沥青的研究,揭示了浅层天然气具有多种成因.研究区浅层天然气主要分布在陆梁、滴西、滴北和白家海4个地区.其中,陆梁地区浅层天然气成因为原油次生生物降解气,典型地球化学特征是气组分很干,几乎全为甲烷组成,甲烷碳同位素特别轻(–55‰~–45‰).滴西地区浅层天然气以石炭系来源煤型气为主,兼有二叠系来源煤型气和油型气,典型特征是乙烷碳同位素值变化大(–30.67‰~–22.20‰).滴北地区浅层天然气为石炭系来源煤型气,典型特征是乙烷碳同位素重(–24.54‰~–23.72‰).白家海地区浅层天然气为二叠系来源高成熟煤型气,典型特征是干燥系数大(0.97),甲烷碳同位素重(–30.15‰~–29.45‰),乙烷碳同位素较重(–25.83‰~–25.81‰).因此,研究区浅层天然气具有多种成因,主要包括来自不同烃源的原油次生生物降解气、油型气和煤型气,这预示着成藏的复杂性,需在下一步的勘探中给予充分重视
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| 关 键 词： | 浅层天然气 成因 地球化学 油型气 煤型气 原油次生生物降解气 准噶尔盆地 |
Geochemical constraints on the multiple origins of shallow-buried natural gases in the Junggar Basin |
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| SUN Ping-an,WANG Xu-long,TANG Yong,WAN Min,and CAO Jian.Geochemical constraints on the multiple origins of shallow-buried natural gases in the Junggar Basin[J].Geochimica,2012(2):109-121. |
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| Authors: | SUN Ping-an WANG Xu-long TANG Yong WAN Min and CAO Jian |
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| Institution: | 1.School of Earth Sciences and Engineering,Nanjing University,Nanjing 210093,China;2.PetroChina Xinjiang Oilfield Company,Karamay 834000,China |
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| Abstract: | The shallow-buried natural gas is a hot topic in the exploration and basic study of natural gas,and has become a new important petroleum-exploration field in the Junggar Basin.It,however,has not been well studied.Based on a case study of the central Junggar Basin,multiple origins of the gas are revealed in this study by relatively comprehensive geochemical analyses including gas components,carbon isotope and light hydrocarbon,as well as biomarker analyses of associated condensates and reservoir bitumens.This provides more information for understanding gas accumulation and exploration of the area,and may also have wide implications for analogue elsewhere.The shallow-buried natural gases in the central Junggar Basin are mainly found in the Luliang,Dixi,Dibei and Baijiahai areas.Gases in the Luliang area are attributed to the origin of oil biodegradation.Their representative features include extremely high dryness(consisting almost entirely of methane) and light δ13C1 values(ranging from –55‰ to –45‰).Gases in the Dixi area are mainly the coal-type gas sourced from the Carboniferous,and partly coal-type and oil-type gases sourced from the Permian.The gases have a relatively large variation in δ13C2 values,ranging from –30.67‰ to –22.20‰.Gases in the Dibei area are the coal-type gas generated from the Carboniferous,with heavy δ13C2 values varying from –24.54‰ to –23.72‰.Gases in the Baijiahai area are highly mature coal-type gases sourced from the Permian.The gases are characterized by high dryness up to 0.97 and heavy δ13C2 values ranging from –30.15‰ to –29.45‰.Therefore,the shallow-buried gases in the study area have multiple origins,mainly including oil degradation gas,oil-type gas and coal-type gas with different sources.This indicates that gas accumulation of the area is complex,which should be laid enough emphasis in the future petroleum exploration. |
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| Keywords: | shallow-buried natural gas origin geochemistry oil-type gas coal-type gas oil degradation gas Junggar Basin |
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