摘要
通过岩心分析、显微镜下观察(常规、铸体薄片和扫描电镜)、岩石地球化学分析测试等技术手段,以准噶尔盆地西北缘下二叠统油气储层为实例,研究了火山岩、火山碎屑岩和火山岩屑质砂砾岩中的火山玻璃、火山碎屑、长石以及辉石、角闪石等火山物质的低温-埋藏蚀变作用。镜下观察发现,在含火山物质油气储层中,常见对储集空间具有重要影响的自生矿物主要有绿泥石、沸石(包括方沸石、片沸石和浊沸石)、方解石、钠长石和自生的石英。结合共生关系、元素组成和元素迁移,分析了自生矿物的微观特征和成因,建立了火山物质蚀变的成岩演化序列,可以概括为:①火山玻璃水化—蒙脱石化—沸石化及各种沸石的转化——钠长石化;②铁镁矿物影响的绿泥石化;③长石蚀变向绿泥石和方解石转化,后期发生钠长石化。在研究区,火山物质的蚀变和自生矿物的析出与中-基性的母岩物质组成密切相关,并受地层温度、压力、孔隙水的化学性质控制。研究火山物质蚀变的产物、蚀变过程及控制因素,能够明确含火山物质的油气储层质量差异机理,为优质储层预测提供科学的依据。
Based on observations of available cores ,thin-sections and SEM and analysis of rock geochemistry ,we studied low-temperature-burial metamorphism （ alteration ） of volcanics in the Lower Permian at northwestern margin of Junggar Basin .These volcanics include volcanic glass , volcanic clasts , feldspar , and mafic minerals such as pyroxene and horn-blende,etc.,which originate from lavas,pyroclastic rocks,and volcaniclastic sandstones or conglomerates .In oil/gas reservoirs containing volcanics ,the authigenic minerals that are common but important to pore spaces include chlorite ,ze-olites（like analcime,heulandite,and laumontite）,calcite,albite,and authigenic quartz.Based on the paragenetic relation-ship of minerals and the composition and migration of elements ,we analyzed the microscopic characteristics and origins of authigenic minerals ,and established diagenetic evolution models during volcanic alteration .The alteration can be summa-rized as follows：①volcanic glasses hydrolysis-montmorillization-zeolitization-albitization;②chloritization related to mafic minerals and smectites;③transformation of feldspar to chlorite,calcite,and finally to albite.The alteration of volcanics and the formation of authigenic minerals in the study area were controlled by various factors such as the precipitation of authigenic minerals ,composition of neutral-basic host rocks ,temperature and pressure ,and the chemical behaviors of pore water.The study on alteration process,alteration products,and control factors is helpful to understand the mechanisms that cause the differences of volcanics-bearing reservoir qualities , so as to provide a scientific geological foundation for the predication of high-quality reservoirs .
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2014年第1期77-85,共9页
Oil & Gas Geology
基金
国家自然科学基金青年科学基金项目(41202107)
教育部高等学校博士学科点专项科研基金(新教师类)项目(20120007120004)
中国石油大学(北京)科研基金项目(KYJJ2012-01-20)
国家重大油气专项(2011ZX05009-002
2011ZX05001-002)
关键词
自生矿物
蚀变作用
成岩序列
火山物质
油气储层
准噶尔盆地
authigenic mineral
alteration
diagenetic evolution
volcanics
hydrocarbon reservoir
Junggar Basin
