含片钠铝石砂岩的基本特征及地质意义

含片钠铝石砂岩是一种含片钠铝石自生矿物的砂岩，一般为富含长石的砂岩，与片钠铝石稳定共生的自生矿物主要为铁白云石、菱铁矿等碳酸盐矿物。砂岩中片钠铝石的含量变化较大，其存在与否不受砂岩结构的制约。含片钠铝石砂岩往往分布在断裂和岩浆岩体附近，既可以作为CO2气储层，又可以作为油气储层。含片钠铝石砂岩是一种具有特殊地质意义的砂岩，表现为：①含片钠铝石砂岩记录了深、浅部层圈之间及烃源岩—储层之间的物质转移；②在含油CO2气藏和油藏中，含片钠铝石砂岩记录了CO2与油气双重充注，其中含油CO2气藏中的含片钠铝石砂岩记录了CO2充注驱油现象；③含片钠铝石砂岩是进行CO2地下储存研究的理想的天然实验室。

Basic Characteristics of Dawsonite-bearing Sandstone and Its Geologic Significance

Dawsonite-bearing sandstone, a type of authigenic mineral, commonly riching in feldspar, is the sandstone containing dawsonite. The paragenetic minerals with dawsonite mostly are carbonate ones, such as ankerite, siderite etc.. Percentage composition of dawsonite in sandstone varies within great range. The presence of dawsonite is not restricted by sandstone structure. Dawsonite-bearing sandstone always distributes near fault and magmatic sys-tern and acts as both CO2 gas reservoir and petroleum reservoir. Dawsonite-bearing sandstone is the sandstone with special geologic significance because of the reasons in the folllowing. Firstly, dawsonite-bearing sandstone records mass transfer between deep lithosphere and shallow lithosphere or between source rock and reservoir. Secondly, dawsonite-bearing sandstone records dual infilling by CO2 and petroleum in CO2 gas petroleum-bearing reservoir and petroleum reservoir. In CO2 gas petroleum-bearing reservoir, dawsonite-bearing sandstone records the phenomena of petroleum replaced by CO2 infilling. Finally, dawsonite-bearing sandstone is ideal natural laboratory for researching on CO2 sequestration.