The Cretaceous Austin Chalk of South Texas--A Petroleum Source Rock
The Cretaceous Austin Chalk of South Texas--A Petroleum Source Rock
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发表时间：
1984
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通讯作者：
J. Hunt;A. McNichol
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作者：
J. Hunt;A. McNichol
碳酸盐岩通常被认为是重要的烃源岩，因为与页岩相比，碳酸盐岩的有机碳含量较低，催化活性较低。然而，碳酸盐烃源岩主要含有腐泥型有机质，其比页岩的更多腐殖型有机质更早地产生更高百分比的油。此外，碳酸盐岩生储层序列在许多地方在石油生成和聚集期间被完美的盖层蒸发岩覆盖。相反，许多砂泥岩序列在聚集期间和之后倾向于漏失石油。世界上最丰富的烃源岩是犹他州的绿色河、委内瑞拉的拉卢纳和加拿大西部盆地的诺德格等地层中的泥质和硅质碳酸盐。碳酸盐岩，如德克萨斯州南部的白垩纪奥斯汀白垩，含有60-90%的CaCO 3，既是源岩也是储集岩。轻烃分析和热解数据都支持的概念，大部分的石油在奥斯汀粉笔是土生土长的。
Carbonate rocks commonly have been discounted as important source rocks because of their lower organic-carbon content and lower catalytic activity in comparison to shales. However, carbonate source rocks contain mostly sapropelic organic matter, which yields a higher percentage of oil earlier than the more humic organic matter of shales. Furthermore, carbonate source-reservoir sequences are at many places overlain by the perfect seal, evaporite, during the time of oil generation and accumulation. In contrast, many sandstone-shale sequences tend to leak petroleum during and after accumulation. The richest source rocks in the world are the argillaceous and siliceous carbonates in formations such as the Green River of Utah, the La Luna of Venezuela, and the Nordegg of the Western Canada basin. Carbonate rocks like the Cretaceous Austin Chalk of south Texas, which contains 60-90% CaCO3, act as both source and reservoir rock. Light-hydrocarbon analyses and pyrolysis data both support the concept that most of the oil in the Austin Chalk is autochthonous.