Keywords: 
• reservoir fluid types(oil and g as) identifying /
• saturated hydrocarbon mass-chromatography /
• totalion chart /
• n-alkanes /
• distribution /
• oil reservoir

Abstract: Reservoir fluid ty pes are usually identified by logging well technology, repeat fo rmation test or geology ang geochemistry logg ing during drilling, and logging well interpreting is based on the physical property of reservoir fluids, there will be difficult in interpreting some low resistance oil intervals o r volcannic rock oil reservoirs.However reservoir geochemistry technology can be remedial for those defects, which can directly i- dentify reservoir fluid types(oil and g as)based on the fluid chemical character. authors use m ass-chormatography total ion chart of saturated hy drocarbon extracted from reservoir sand- stones to indentify reservoir fluid ty pes(oil and gas)).Fingerprints of oil saturated sandstones o r oil intervals show w ide n-alkane distribution, which ranges from C₁₅ to C₃₈, and is similar to those of oil sample; finger- prints from condensate sandstone show lig htly abbreviated n-alkane distribution, which ranges from C₁₅ to C₃₅, but the content of hig h hydrocarbon com pounds( C₂₁) is apparently lower than that of oil sandstone; finger- prints from dry g as sandstone show a further abbreviated n-alkane distribution, which ranges from C₁₅ to C₂₈, the co ntent of high carbon compounds is very low, but the content of low carbon compounds is abundant, so this technology can be used to identify the types of reservoir fluid(oil and gas), reevaluate oil and g as intervals in old well whose log data is incomplete, and provide scientific evidence for optimizing acid treatment intervals.