Abstract: Deeply buried source rocks in Qingshui Subsag of Liaohe Depression feature in well development, huge thickness, wide distribution, high abundance and good types of organic matter. Es3 source rock is mainly lacustrine mudstone and has favorable conditions for oil generation, laying a solid basis for forming large-and medium-sized lithologic oil and gas reservoirs. Reservoir sandstones developed in Dongying Formation and they are mainly floodplain fluvial deposits. Channel sandbodies developed in Ed3 with largermonolayer thickness and good reservoiring performance, providing favorable conditions of the development of lithologic oil and gas reservoirs. Favorable regional caps developed in each segment of Dongying Formation, forming good reservoir-cap assemblages combined with sandstone rocks developed in each segment in the area. Two types of oil and gas transportation systems developed in the Formation, i.e., the fault transportation system determined by structural effect and the sandstone transportation system determined by sedimentary effect, providing channels for oil and gas migration and accumulation. Research shows that the lithologic reservoir of Qingshui Subsag could be the target for next exploration.

Key words: Liaohe Depression, Qingshui Subsag, Dongying Formation, lithologic oil and gas reservoir, channel sand