鄂尔多斯盆地东部奥陶系马家沟组盐下具有马五7、马五9、马四、马二1和马二2等5个储集层，储层的孔隙度普遍较低，而渗透率相对较好。根据盐下探井观察，盐间白云岩不仅有明显的烃类生成和聚集现象，而且在溶孔型储层中已见碳质沥青充填，并且生储盖配置良好，圈闭类型多样，具有形成盐间、盐下气藏的地质条件，是值得开拓的天然气勘探新领域。

O1m75,O1m95,the upper O1m4 member, O1m12 and O1m22 are the five reservoirs located below the salt of the Ordovician Majiagou formation in eastern Ordos basin. The porosity o2f these reservoirsis generally low, but they have a relatively high permeability. Observation from the under-salt exploration wells demonstrates that the under-salt dolomite take on an obvious phenomenon of hydrocarbon generation and accumulation. Carbonaceous asphalt fills the dissolved reservoirs, and there are excellent source-reservoir-seal association and various types of traps. Having these geologic conditions of forming under-salt gas pools, the under-salt dolomite is a new favorable gas exploration area.