Crude oil is discovered in fractures and miarolities of calcite vein in wellNan-11 of the Niqiuji sag in the Ruanghe-Huaihe Basin. The Pr/Ph-value ofthe crude oil is 2.28-2.60. the C

27

/C

29

-value of ααα20R sterane is 0.37-0.31

the major peak carbon of saturated hydrocarbon is C

27

and the δ

13

C-values ofaromatic hydrocarbon range from -27.56 to -28.14%. It is inferred that thecrude oil may come from the coal measure of the Carboniferous-Permian but notLower Cretaceous mudstone.