鄂尔多斯盆地周缘晚古生代火山活动对盆内砂岩储层的影响  

Influence of the Late Paleozoic Volcanic Activity on the Sandstone Reservoir in the Interior of Ordos Basin

作　　者：杨华[1] 杨奕华[2] 石小虎[2] 尹鹏[2] 

机构地区：[1]中国石油长庆油田分公司,西安710021 [2]中国石油长庆油田分公司勘探开发研究院,西安710021

出　　处：《沉积学报》2007年第4期526-534,共9页Acta Sedimentologica Sinica

基　　金：国家"十五"科技攻关项目(项目编号2004BA616A-03)资助

摘　　要：鄂尔多斯盆地上古生界天然气储集体是一套以次生孔隙为主的低渗透砂岩。通过次生孔隙成因研究发现,各种溶蚀孔隙的形成与砂岩中火山物质和硅酸盐碎屑颗粒的溶蚀、蚀变关系密切。通过储层岩石学研究,对火山物质成分、结构构造、物态、次生变化等特征精细观察表明,这些火山物质具有同沉积的特点,即来源于盆地周缘同期的火山喷发。这些同沉积火山物质不仅改变了储层砂岩的物质成分,而且为储层次生孔隙的形成提供了溶蚀母质,形成了晶屑溶孔、岩屑溶孔、灰屑溶孔以及蚀变高岭石、绿泥石晶间孔,在原生孔隙基本消失的砂岩中形成了以次生孔隙为主的砂岩储层。同时,火山物质的残存、蚀变和溶蚀的差异使储层表现出强烈非均质性。Upper Paleozoic natural gas reservoir of Ordos Basin consists of low-permeability sandstone which bears typical secondary porosity. After studying secondary porosity forming cause, it is turned out that there is some direct relation between formation of all kinds of dissolution porosity and dissolution and erosion of volcanic material. Based on the study of petrology, the observation of volcanic material composition, construction and structure, the state and secondary change, we can reach the conclusion that these volcanic materials has the characteristics of simultaneous sedimentation. Combing the formal achievements about simultaneous volcano eruptive-rock on basin edge, there is cause-effect relation, which showing volcanic material of the sandstone comes from the simultaneous sedimentary volcanic eruption, which confirms that important geological events in Basin-orogen coupling period have great influence on inter-basin sedimentation. Not only the simultaneous volcanic material changes the composition of the sandstone, but also offers the dissolution matter for the formation of secondary porosity in these sandstones. The dissolution of volcanic material, with largely unsteady physical and chemical characteristics, led to the formation of dissolution porosity in crystal-fragment, in rock-fragment, and in ash-fragment, as well as eroded kaolinite and chlorite inter-crystal porosity in diagenetic period. Meanwhile, remnant, erosion of volcanic material and dissolution differences lead to the heterogeneous reservoir.

关 键 词：鄂尔多斯盆地 晚古生代 火山活动 火山物质 砂岩储层 

分 类 号：TE122.2[石油与天然气工程—油气勘探]