| 中国最古老的气藏--四川威远震旦纪气藏 |
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| 引用本文： | 徐永昌,沈平.中国最古老的气藏--四川威远震旦纪气藏[J].沉积学报,1989,7(4):3-13. |
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| 作者姓名： | 徐永昌 沈平 |
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| 作者单位： | 中国科学院生物、气体地球化学开放研究实验室·兰州 |
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| 摘 要： | 本文研究了中国最大的气田--四川威远气田的气体组分和碳、氢、硫、氩、氦同位素组成。其特征如下:（1）震旦纪气藏相对于其它气藏具有高氮（9％），高CO2+H2S（5％）和高氦（0.18％），高氩（0.05％）的特征；（2）震旦纪气藏的氩同位素组成为4400-9255，平均7000，显示了很高的年代积累效应。3He/4He比值低为n×10-8，这意味着威远气藏中的氦主要来自壳源物质；（3）He/Ar丰度为5.39-6.14，是笔者研究过的天然气中的最低值；（4）N2/Ar,N2/He浓度具有较好线性关系；（5）碳、氢、硫、氩同位素丰度比可将三叠纪、二叠纪、寒武纪、震旦纪气藏明显加以区分，证明各自属不同气源。（6）震旦系岩石吸咐烃和储气层气体的C2/C3有良好的对比性。因此，笔者认为:震旦系气藏为自生自储。稀有气体不具地幔物质特征，但不排斥有幔源物质加入的可能。
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| 关 键 词： | 震旦纪 古老气藏 同位素 稀有气体 年代积累效应 |
| 收稿时间： | 1989-05-16 |
THE OLDEST GAS POOL OF CHINA-- WEIYUAN SINIAN GAS POOL ， SICHUAN PROVINCE |
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| Institution: | Laboratory of Biogeochemistry and Gasgeochemistry, Lanzhou Institute of Geology, Academia Sinica |
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| Abstract: | This paper studies the largest gas field-Weiyuan gas field in Sichuan ? basin . There are four gas-bearing layers in the gas pool, i.e. Triassic, Permian, Cambrian and Sinian. The main industry reservoir in the dolomite of the Siniansy stsyem. The oldest layer is about 700~800 x 106years. It is the largest and oldest gas field which has been found in China so far. It is significant for the study of early organic matter evolution, mineral and energy resources to study out the genesis ofgaspool, especially, to decide whether the source of Sinian gas pool may be relative to Precambrian layers.The characteristics of the gas constituent and the i so topic composition of C， H， S， Ar，He from this gas field are the following: 1. Compared with the other gas pools, Sinian gas pool gas high content of N2(9%), C02+H2S (5%), He (0.18) and Ar (0.05%)； 2.The value of 40Ar/36Ar in Sinian gas pool is very high, from 4400 to 9255, the average is 7000, showing high age-accumulating effect. The value of 3He/4He is low. only n x 10-8. This means that the He in the Wciyuan gas pool is mainly from the crustal matter; 3. He /Ar is from 5.39 to 6.14, the lowest value which has been found by us; 4. The values of N2/Ar and N2/He have better linear relativity; S.Triassic, Permian, Cambrian and Sinian gas pools can be classified with the isotopic composition of C, H, S， Ar, which shows the gas in these gas pools is from different gas sources; 6. The components of absorbed hydrocarbon from Sinian source rock are diiTcrent from other source rocks, and the value of C2/C3from the source rock can be well compared with that from gases.To sum up, we think that the Sinian gas pool is of autochthonous origin. It was formed by organic matter at the early stage of earth f s evolution. The CH4 and rare gas are not characteristics of mantle mater; but we cannot rule out a possibility that there may be some mantle matter being pux in this gas pool. |
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