25th International Meeting on Organic Geochemistry IMOG 2011

P-316
The occurrence of crude oil in the coal-bearing strata of Hulin
Basin and its hydrocarbon potential analysis, north-eastern
China
Xue Wang, Bo Chi, Wei Fang, Huasen Zeng, Zhongliang Dong, Xiaochang Zhang
Exploration and Development Research Institute, PetroChina Daqing Oilfield Company, Da qing, China
(corresponding author:xuewang@petrochina.com.cn)
Oil contribution from coal and coaly shale is still
controversial. Gippsland oilfield in Australia and
Mahakam oilfield in Indonesia are the earlier places to
find oil from coaly strata; and oil in Turpan basin that
is in western China is thought to have been generated
from lower Jurassic coal-bearing formations. In 2009,
Paleocene coal-bearing strata in Hulin Basin that is in
north-eastern China was first to produce oil. Multiple
geochemical indices were integrated by this study to
characterize the crude oil from Hulin Basin and to
estimate the hydrocarbon potential.
Hulin Basin with an area of 9150km 2 lies in
Heilongjiang province, north-eastern China and to the
east of Songliao Basin. Hulin Basin was over upon
Paleozoic metamorphic rock and Precambrian
crystalline basement. Hulin basin is widely covered by
Mesozoic-Cenozoic strata, including upper Jurassic
Peide formation, Paleogene Hulin formation, Neogene
Fujin and Daotai formations, and of which Hulin
formation spreads widely in the basin and is the main
exploration target. At the base of Hulin formation,
rocks are sandstones, siltstones, and grey-dark
mudstones with tens of coal interbeds which contain
plenty of plant fossils. In the mid of Hulin formation
are thick dark mudstones and in the top are
interbeded grey-green mudstones and argillaceous
siltstones with some coal beds. Hulin basin has
experienced early extension and then depression
expansion followed by contraction phase and the
distribution of Mesozoic-Cenozoic strata is controlled
by those extensional faults. Hulin Basin has been
explored since 1980s and well Hu-1 as the only oilproducing
well of all the six drilled wells was
completed early in 2009. Hulin formation in well Hu-1
produces 0.058 tons of oil daily and is considered to
be the breakpoint in its exploration history.
Crude oil in Hu-1 is black solid at atmospheric
temperature with density of 0.85g/cm 3 , wax content of
34.6%, viscosity of 44.4mPa.s, and molecular weight
of 330. As shown in figure 1, the crude oil of Hu-1 is
characterized by (1) high saturate content at 74%, (2)
high Pr (pristane) content with Pr/Ph ratio (pristane
vs. phytane) at 11.39 and Pr/nC17 at 4.6, (3) low
content of Gammacerane, (4) low content of tricyclic
terpanes with the presence of tetracyclic terpanes, (5)
prevailing content of C29 hopanes with low content of
Ts and high content of C29 steranes with abundant C29
diasteranes, (6) content of 1-methylphenanthrene is
twice that of other methylphenanthrenes, (7)
abundant retene, and (8) stable carbon isotope of
single compound in saturated hydrocarbons ranges -
27.6% ~ -30.14% and decreases with carbon number
while δ 13 C29 is the lightest. These geochemical
characteristics indicate that the source rock of crude
oil was deposited in fresh water and the crude oil is
characterized Prby
higher-plant input.
TIC
m/z191
m/z217
C 30 hopane
C 29 sterane
Fig.1 mass fragmentograms for oil sample
of Well Hu-1
The source rock of Hulin Basin is thought to be
Paleogene Hulin formation, which contains thick
mudstones and coal beds. Take well Hu-1 as
example, the thickness of mudstone is 729.7 meters
while that of coal is 184.8 meters. The source rock is
organic-rich with TOC (total organic carbon) of 68% of
samples higher than 2%. The kerogen type is
dominated by II2-III while hydrogen-rich macerals
mainly contain sporinite, cutinite, suberinite, and
resinite. The distribution of biomarker and componentspecific
stable carbon isotope is close to that of crude
oil. Based on the source rock distribution and thermal
history, the oil potential is assessed to be 0.84×10 8
tons and the gas is about 60 ×10 8 cubic meters.
The discovery of crude oil in Hulin Basin adds
another proof that coaly formation can generate liquid
petroleum. The area of Hulin Basin is small while the
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