Abstract: Free hydrocarbon content(S₁)is a frequently-used pyrolytic parameter in assessment of shale oil resource.However,light and heavy hydrocarbon losing during the process often yields result on the low side.For heavy hydrocarbon loss,we compared pyrolysed hydrocarbon content(S₂)obtained through pyrolytic experiment before and after extraction of samples to estimate the lost heavy hydrocarbon of S₁.For light hydrocarbon loss,we carried out Rock-Eval and PY-GC experiments on immature shale samples and gold tube experiment on crude samples to calculate the ratio of C_6-13/C₁₃₊ in different stages of maturity according to chemical dynamic theory and Easy R_o model,then took this ratio as the ratio of residual C_6-13/C₁₃₊ in shale,and finally performed correction of light hydrocarbon lose based on S1 obtained after heavy hydrocarbon correction.Using the corrected parameter in assessment of shale oil resource made a great difference.Taking the E₂s⁴⁽²⁾ member in Damintun Sag,Bohai Bay Basin as an example,the result is only 22.6 billion tons without correction but 2.86 times higher (64.7 billion tons) after the corrected parameter was used.It is therefore suggested that correction of light and heavy hydrocarbon loss for residual hydrocarbon S₁ during assessment of shale oil resources is necessary.

Key words: free hydrocarbon content(S₁), light and heavy hydrocarbon correction, shale oil, resource assessment, Damintun Sag, Bohai Bay Basin