关键词: 呼和坳陷, 第四系, 上新统, 生物气, 气源, 储层, 盖层, 圈闭, 勘探前景

Abstract: The depth of Quaternary and Pliocene source rocks deposited in Huhe depression, Hetao Basin, ismore than 1200m, in which the content of organic carbon (OC) averages 0.59%,and organicmatter includes mixing and humic types, source rocks are immaturity and have the ability to generate much gas. The air bubbles emitted from many hydrologic shallow wells can confirm the existence of biogenic gas.The reservoir rocks consist of shallow-and half-deep lacustrine facies silty-fine sandstones, argrillaceous silty sandstone, with low diagenesis and relatively loosen rocks, so the porosity of reservoir is usually more than 20%, reulting in high-quality reservoirs. Mudstone, mirabilite and humic soil developed on the Quaternary section of 150-300m, which has relatively high sealling feature and it can become ideal cap rock.The concentration of biogenic gas ismainly controlled the trap. By contrasting, it is found that the accumulation condition of biogenic gas in Hetao Basin is same as that in Qaidamu Basin, it has a potential of gas resources and promising prospects of exploration.