The writers

applied the method of chromatographic analysis of hydrocar-bon group in crude oil

here determined the content of pristane and phytanein crude oil from 20 distincts or oil fields in our country

and a preliminary study of the character of isoprenoid alkane assemblages and the influence of the secondary alteration of crude oil to the character have been carriedout.The total content of pristane and phytane ranges generally from 0.38-1.53%

and very few up to 4.78% by weight. According to assemblage patterns

the relative peak values of is oprenoid alkanes can be classified into 5 types:firstly

the ratio of pristane to phy-tane is very high(2.64-6.35)

the distribution curves of is oprenoid alkanes vary greatly;the second

the ratio(0.55-1.42)and the ralative contents of pristane and phytane are still rather high;the third

the phytane is predo-minant

and the ratio of pristene to phytane is less than 0.50;the fourth

the crude oil with low maturity or subjected to the secondary alteration with degraded characteristics displays mainly the chromatographic peaks of pri-stane and phytane on the chromatogram;and the fifth

with the conbination characteristics of light crude oil and condensate

the peak value of isotride-cane and isotetradecane are apparrently increased.Finally

the influence of the secondary alteration of oil to the relative peak value of isoprenoid alkanes have also been discussed by the authors.