Eight lacustrine Type I kerogen samples from the Songliao Basin were pyrolyzed using the Rock-Eval
equipment, and parallel first-order reaction models including the model with a single frequency factor
and a discrete distribution of activation energies (SFF model) and the model with multiple frequency
factors and a discrete distribution of activation energies (MFF model) were adopted to analyze kinetic
characteristics of hydrocarbon generation of the Type I kerogen samples. The results show that the MFF
and SFF models can satisfactory simulate hydrocarbon generation under laboratory conditions and the
Type I kerogen shows relatively concentrated activation energy distributions (activation energies of MFF
model range from 190 kJ/mol to 250 kJ/mol, activation energies of SFF model range from 220 kJ/mol to
240 kJ/mol), which indicates a homogeneous chemical bond structure of the Type I kerogen. The
hydrocarbon generated curves from Type I kerogen were calculated by using the two models with
a linear heating rate (3.3 K/Ma). It indicates that the hydrocarbon generation potentials (reaction fractions)
are underestimated by using the SFF model during the kerogen thermal degradation for the
components with chemical bond of lower and higher activation energies, while this problem can be
avoided by using the MFF model. The calculated temperatures for 50% transformation ratio (TR) of all
samples differ by as much as 20 C. For the SFF model, the hydrocarbon generation curve obtained by
using the weighted averaged kinetic parameters and the SFF model almost includes every curve calculated
by using its own kinetic parameters. While the curve obtained by using the weighted averaged
kinetic parameters and the MFF model cannot include every curve for all samples, it lies at the position of
the averaged curve of all samples. The application of the MFF model in Songliao Basin shows that if TR
10% is taken as the onset of hydrocarbon generation, the threshold depth of hydrocarbon generation is
about 1700 m, which is consistent with other geochemical parameters, such as S1/TOC, S1/(S1 þ S2) and
HC/TOC.