查干凹陷火山岩发育特征及其对碎屑岩储层的影响

The characteristics of volcanic rock development and its influence on clastic rock reservoir in chagan depression

查干凹陷主要的储集层为火山岩,其特点为期次多,厚度十分大,凹陷内广泛分布。岩性以玄武岩为主,其次为安山岩、火山角砾岩和凝灰岩等。钻井揭示火山岩岩相以溢流相为主,深大断裂是这一时期查干凹陷火山岩发育的主要构造部位。碱性岩系火山岩水岩作用产生的碱性流体使本区火山岩下碎屑砂岩长期处于碱性成岩环境。常见石英颗粒的溶解和长石的次生加大现象,是碎屑岩储层异常致密的主要原因之一。

volcanic rocks in chagan depression a re characterized by many stages of development,large thickness and wide distribution area.The lithology is mainly basalt,andesite,volcanic breccia and tuff,and basalt is the most developed.Volcanic rocks developed during the sedimentary period of the suhongtu formation.The alkaline fluid produced by the hydrolithogenesis of volcanic rocks in the alkaline rock series has kept the volcanic sub-clastic sandstone in the alkaline diagenetic environment for a long time.In this diagenetic environment,the obvious dissolution of quartz particles and the large scale secondary growth of feldspar are the most characteristic diagenetic phenomena in alkaline diagenesis.This alkaline diagenetic environment is one of the main reasons for the abnormal density of volcanic subclastic reservoirs in the study area.