The lower Youshashan formation of Wunan Oilfield had mainly developed flood-lake facies, shallow lake-deltaic facies, and tempestite sedimentary facies.

• 确定乌南油田下油砂山组主要发育洪水-漫湖相、浅水湖泊型三角洲相及风暴岩沉积相，并总结了其沉积相模式。