砂岩中石英胶结物的成因及其研究意义

Genesis and Significance of Quartz Cement in Sandstones

次生加大石英胶结物是砂岩中最丰富的胶结物之一。石英胶结物的时空分布表现在越年轻的地层石英胶结物的含量越少 ,随埋深增加石英胶结物的含量增加 ,而且盆地类型也是控制石英胶结物含量的一个不可忽视的因素。石英胶结物的硅质来源有很多种说法 ,但是区域上可能以某一种或某几种来源为主。影响石英胶结物沉淀的主要因素有温度、流体的 pH值等 ;而关于孔隙流动与硅质搬运和沉淀有三种假说 ,即 :浅部地下水循环说、压实驱动流体高度集中说、扩散和局部流体再循环说。石英胶结物的研究对古温度的定时、了解储层非均质性的成因及储层物性有着重要的意义。

Quartz cement as syntaxial overgrowths is one of the most abundant cements in sandstones. The distribution of quartz cement in time and space indicates that the more younger the stratigraphy is, the more less the quantity of quartz cement is, and the amount of quartz cement increases with increasing of depth, and basin types also is a factor which controls the amount of quartz cement. The sources of silica for quartz cement have many opinions, but there is one or more important sources. Temperature and pH of fluid are major factors which influence the precipitation of quartz cement. There exist three hypotheses on the flow of pore fluid and transport and precipitation of silica, that is, the hypothesis of cycle of shallow underground water, the hypothesis of high concentration of fluid driven by compaction and the hypothesis of diffusion and recycle of local fluid. The research of quartz cement is significant for the timing of paleotemperature , heterogeneity of reservoir, physical property of reservoir and the timing of oil immersion,and so on.