А. Feyzullayev / Natural Science 3 (2011) 359-364
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363
statement is confirmed by spatial change of the devel-
opment density of mud volcanoes. The more density of
their development is noted in overpressured zone (zone
III) in comparison with the zones of moderate and nor-
mal pressures (zone I and II, accordingly) (Figure 7).
The migration of HCs will then have an explosive
character, which can also be promoted by earthquakes
occurring in the SCB, the hypocenters of which are
mostly at shallow depths [25].
3. CONCLUSIONS
The results of investigations indicate that the SCB is
characterized by the following features:
unequal conditions of generations and expulsion of
HCs from source rocks;
the processes of HCs generation (mainly in
deep-buried part of SCB) are shifted to relatively
deeper depths, from where the expulsion of HCs
from source rocks is complicated. As a result in
this zone, characterizing as a relatively closed sys-
tem, overpressures and mud volcanoes are widely
developed;
there is retardation of thermal transformation of
OM and clay minerals, generation of oil and
cracking it into gas in overpressured source rocks;
mud volcanoes are focal centers of periodic explo-
sive unloading of HCs from overpressured source
rocks.
Results of investigations have both scientific and ap-
plied significance.
The scientific significance is that the classical scheme
of the vertical zonality of HC generation [2,3] should be
improved with reference to the overpressured basins.
According to the latest discoveries of large accumula-
tions of oil at depths of 8.5 - 10.5 km in the Gulf of
Mexico [34], the “oil window” in basins with overpres-
sure where the retardation of OM transformation is ob-
served, have to be shifted in the classical scheme of the
vertical zonality of HC generation to greater depths in
comparison with the basins without overpressure.
This indicates an increase in liquid HC resources for
the deep-water parts of basins like the South Caspian,
which in turn challenges the necessity to increase explo-
rations in overpressured zones.
REFERENCES
[1] Lopatin, N.V. (1971) Temperature and time as factors of
coalification. Izvestiya Akademii Nauk SSSR, Seriya ge-
logicheskaya (in Russian), 3, 95-106.
[2] Tissot, B.P. and Welte, D.H. (1984) Petroleum formation
and occurrence. Springer-Verlag, Berlin.
[3] Vassoevich, N.B. (1974) Principal scheme of a vertical
zoning and oil and gas generation. Proceedings of the
Academy of Sciences of USSR. Geological Series (in
Russian), 5, 17-29.
[4] Waples, D.W. (1980) Time and temperature in petroleum
formation: Application of Lopatin’s method to petroleum
exploration. AAPG Bulletin, 64, 916-926.
[5] Allen, E.B. and Allen, M.F. (1990) The mediation of
competition by mycorrhizae in successional and patchy
environments. In: Grace, J.B. and Tilman, D. Eds., Per-
spectives on Plant Competition, Academic Press, Cam-
bridge, 367-389.
[6] Khorasani, G.K. and Michelsen, J.K. (1994) Four-dimen-
sional fluorescence imaging of oil generation: Develop-
ment of a new fluorescence imaging technique. Organic
Geochemistry, 22, 211-223.
doi:10.1016/0146-6380(95)90018-7
[7] Hao, F., Li, S., Sun, Y. and Zhang, Q. (1996) Organic
matter maturation and petroleum generation model in the
Yinggehai and Qiongdongnan basins. Science in China.
Series D, 39, 650-658
[8] Helgeson, H.C. (1985) Adjective-diffusive/dispersive
transport of chemically reacting species in hydrothermal
system. Grant US Department of Energy: DE-FG03-
-85ER13419.
[9] Osborne, M.J. and Swarbrick, R.E. (1997) Mechanisms
for generating overpressure in sedimentary basins: A re-
evaluation. AAPG Bulletin, 81, 1023-1041.
[10] Barker, C. (1990) Calculated volume and pressure changes
during the thermal cracking of oil to gas in reservoirs.
AAPG Bulletin, 74, 1254-1261.
[11] Duppenbecker, S.J., Riley, G.W., Abdullayev, N.R.,
Green, T.J. and Doran, H. (2009) Petroleum systems dy-
namics of the south caspian basin. AAPG Hedberg Re-
search Conference, Napa, 3-7 May 2009, 13.
[12] Luo, X. and Vasseur, G. (1996) Geopressuring mecha-
nism of organic matter cracking: numerical modeling.
AAPG Bulletin, 80, 856-874.
[13] Momper, J.A. (1980) Generation of abnormal pressure
through organic matter transformation. AAPG Bulletin,
64,753-761.
[14] Xie, X., Bethke, C.M., Lii, S., Liu, X. and Zheng, H.
(2001) Overpressure and petroleum generation and ac-
cumulation in the Dongying Depression of the Bohaiwan
Basin, China. Geofluids, 1, 257-271.
doi:10.1046/j.1468-8123.2001.00017.x
[15] Hao, F., Zou, H., Gong, Z., Yang, S. and Zeng, Z. (2007)
Hierarchies of overpressure retardation of organic matter
maturation: Case studies from petroleum basins in China.
AAPG Bulletin, 91, 1467-1498.
doi:10.1306/05210705161
[16] He, S., Middleton, M., Kaiko, A., Jiang, C. and Li, M.
(2002) Two case studies of thermal maturity and thermal
modelling within the overpressured Jurassic rocks of the
Barrow Sub-basin, north west shelf of Australia. Marine
and Petroleum Geology, 19, 143-159.
doi:10.1016/S0264-8172(02)00006-5
[17] Huijun, L., Tairan, W., Zongjin, M. and Wencai, Z. (2004)
Pressure retardation of organic maturation in clastic res-
ervoirs: A case study from the Banqiao Sag, Eastern
China. Marine and Petroleum Geology, 21, 1083-1093.
doi:10.1016/j.marpetgeo.2004.07.005
[18] Wang, C.Y. and Du, J.G. (2007) Experimental study on
existence of hydrocarbon under high pressure and tem-