松辽盆地北部中——深层砂岩的次生孔隙研究

松辽盆地北部中——深层砂岩的次生孔隙主要是由不稳定的骨架颗粒组分溶解而成,按结构系列,次生孔隙可划分为八种类型。斜长石的溶解是造成次生孔隙的主要原因,它可以在埋藏浅处开始溶解,在1000-1500m 深处溶解变得集中和剧烈。钾长石的溶解一般发生在埋藏较深处。钾长石溶解和浊沸石溶解大大丰富了深层砂岩的孔、渗条件。次生孔隙的形成不仅取决于酸性介质环境,而偏碱性的孔隙溶液对长石的溶解亦具有重要意义。

A STUDY ON SECONDARY POROSITY OF THE MIDDLE-DEEP SANDSTONE IN THE NORTHERN SONGLIAO BASIN

The secondary porosity of middle-deep sandstone in northern Songliao Basin was formed mainly by the dissolution of unstable framework components (feldspars, rock fragments) According to pore texture, the secondary porosity is distinguished to be of eight types.It is known that the secondary porosity is produced by the dissolution of plagioclases, which may be dissolved commonly at shallow burial depth and the process is concentrated and intensified at 1,000-1,500 m depth, but k-feldspar is dissolved usually at a greater burial depth. The dissolution of k-feldsppars and lomonites provides the condition for formation of porosity and permeability of sandstone.The formation of secondary porosity depends not only on acid medium, but also on meta-alkaline environment which may be more significant.