Different viewpoints on the oil-source correlation of
the Angdarco
paleo-reservoir in the Qiangtang Basin, northern Tibet, China, have
seriously affected oil and gas exploration in this area. In this work,
based on the results of biomarker analysis on six oil seepage samples
and 11 potential source rock samples, the oil source of the oil seepages
in the Angdarco area was examined by correlating the composition characteristics
of
n
-alkanes, multiple factors of biomarkers, correlograms
of biomarker parameters, and δ
13
C values of individual
n
-alkanes between oil seepages and potential source rocks.
In addition, the sedimentary environment and thermal maturity characteristics
of the potential source rocks were also discussed. The biomarkers
indicated that the potential source rocks of the Lower Jurassic Quse
Formation (J
1
q) presented characteristics of littoral sediments,
deposited under suboxic conditions, while the potential source rocks
of the Middle Jurassic Buqu Formation (J
2
b) were deposited
in a marine sedimentary environment and presented characteristics
of a low mature to mature stage. The potential source rocks of the
Middle Jurassic Xiali Formation (J
2
x) were deposited in
a low-salinity environment and presented characteristics of low-mature
source rocks. Finally, the oil seepages of the Buqu Formation were
deposited in a suboxic littoral environment and presented characteristics
of a low mature to mature stage. It is concluded that the oil seepages
in the Angdarco paleo-reservoir were mainly sourced from the Lower-Jurassic
Quse oil shales. This work provides a scientific basis for the exploration
of paleo-reservoirs in the southern Qiangtang Basin.
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