柴达木盆地英西地区渐新统热液改造型白云岩的发现及意义

发布时间：2018-02-12 07:13

  本文关键词： 热液白云岩 晶间孔 碳氧同位素 英西地区 柴达木盆地　出处：《地质科技情报》2017年01期 　论文类型：期刊论文

【摘要】：通过岩心及微观岩石学特征、结构特征、微量元素和碳氧同位素地球化学特征的综合研究,首次在柴达木盆地英西地区发现了一种罕见的热液改造型白云岩储集层,但热液改造程度不强,主要包括以下几个方面:1主要储集层较为致密,主要发育泥晶结构的铁白云石和方解石,偶见钠长石、黄铁矿、重晶石和天青石等热液矿物;2碳酸盐矿物中富含FeO、MnO等,其平均质量分数分别为4.112%和0.186%,显著高于本区准同生交代成因白云石中铁锰含量,且钙、镁含量也有所升高,反映了热液流体为富含Ca~(2+),Fe~(2+),Sr~(2+),Mn~(2+)和少量Mg~(2+)等多种离子的碱性热卤水;3ΣREE具有较大的变化范围且总量较高,稀土元素配分模式具有明显的Eu负异常,代表了湖泊环境特有的热流体稀土元素组成特征,形成于偏碱性的深湖热卤水还原环境;4δ18OPDB变化范围为-6.8‰~-3.6‰,平均值为-5.2‰,介于热液白云岩和准同生交代成因白云岩之间,显示了英西地区渐新统白云岩在准同生交代成因基础上受到了一定程度的热液改造。裂缝的发育程度和与热液通道的距离远近不同而使得样品的改造程度存在一定的差异性。综上所述,热液改造型白云岩储集层的首次发现开拓了柴达木盆地英西地区深层致密油气勘探的新视野,这一研究成果对英西深层寻找优质"甜点"储层具有重要指导意义。
[Abstract]:A rare hydrothermal reformed dolomite reservoir was first discovered in Yingxi area of Qaidam Basin through a comprehensive study of core and microscopic petrological characteristics, structural characteristics, trace elements and carbon and oxygen isotopic geochemistry. However, the degree of hydrothermal transformation is not strong, mainly including the following aspects: the main reservoir of 1: 1 is relatively compact, the main mud-crystal structure of iron dolomite and calcite, occasionally albite, pyrite, The carbonate minerals such as barite and celadite are rich in Feo _ (2) mn _ O, the average mass fraction of which is 4.112% and 0.186, respectively, which is significantly higher than the iron and manganese content in the pseudo-synmetasomatic dolomite, and the contents of calcium and magnesium are also increased. The results show that the alkaline hot brine 3 危 REE, which is rich in Ca~(2 and Mg~(2, has a larger range of variation and higher total amount, and the REE partition model has obvious negative EU anomaly. It represents the characteristic of REE composition in the lake environment and is formed in the alkaline deep lake hot brine reduction environment with a range of -6.8 鈥，

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