徐家围子断陷营城组火山岩岩石学及地球化学特征

徐家围子断陷位于松辽盆地北部,断陷发育期火山活动强烈,早白垩世营城组火山岩分布最为广泛,是松辽盆地北部深层天然气的重要储层类型.综合应用岩心观察、薄片鉴定、荧光元素分析以及X衍射等手段,对该区营城组火山岩化学特征和岩石矿物学特征进行了细致研究,指出化学成分类型主要为酸性,火山岩系列属于亚碱性中的钙碱性系列.划分为熔岩和火山碎屑岩2大类8个亚类的火山岩类型.同时探讨了该类气藏岩性的特殊性以及由此导致的储集空间和演化的特殊性,普遍发育的碱交代作用揭示深层火山岩的储层演化具有深部热流体参与的新机制.

Petrologic and geochemical characteristics of volcanic rock of Yingcheng Formation in Xujiaweizi Fault Depression

Xujiaweizi Fault Depression is located in the northern part of Songliao Basin, during the developmental phases of which, volcanic activities were very extensive. Volcanic of Yingcheng Formation during Early Cretaceous period has the largest widespread distribution and is an important reservoir type for deep zone gas in the northern part of Songliao Basin. In this article, the following methods such as core observation, thin-section analysis, fluorescent elemental analysis and X diffraction are applied synthetically to the intensive study of the mineralogy of the volcanic rocks in Yingcheng Formation. The study indicates that the main type of chemical composition is acidity, and the volcanic sequence belongs to the calc-alkalic series of subalkalic. Two main types of lava and volcaniclastic rock, as well as eight subtypes of volcanic rocks are classified in the study. Meanwhile, the specialty of the lithology in this kind of gas reservoir is discussed and thus the associated specialty of accumulative space and evolution, the widespread alkaline metasomatism shows new mechanism that the volcanic rock changed by the deep fluid during reservoir evolution.