Thermal evolution of Fushun and Maoming oil shales is studied by Fischer Assay and Rock-Eval

and aromaticities of pyrolysis products are measured by nuclear magnetic resonance and fixed carbon ratio.In respect to the behavior of aromatic carbon and aliphatic carbon during thermal evolution

the authors found that the aromatic carbon pyrolysis residue remains unchanged

and the carbon contained in oil and gas are primarily originated from aliphatic car-bon.Thus an evolution model of organic carbon fractions of kerogen is sug-gested.In consideration of the mass balance of aromatic carbon and aliphatic carbon during evolution

an equation relating oil and gas yield P

to the orga-nic carbon content C

org

and the“quality parameter”of organic carbon K

c

isderived as follows:P=1.2 C

org

K

c

Where K

c

is equal to(f

a

i

/f

a

o

)-1

f

a

i

and f

a

o

are the aromaticities of samples after and before the evolution respectively.The calculated values are checked by Rock-Eval experimental results

the average error is less than 10%.