Geology Reference
In-Depth Information
7.2
Role of Ground Water Discharge Zones and Foci
in the Formation and Placement of Regional and
Local Oil and Gas Occurrences
The following was shown based on the analysis of lateral and vertical (by
the stratigraphic intervals and depth) oil and gas occurrence distribution:
in most of the world regions the positions and formation times of hydro-
carbon accumulations correspond with the areals, zones, local areas (foci)
and periods of paleo- and present-day discharge of regional geo-fluid-
dynamic systems.
The association between hydrocarbon saturation and zones and areas of
the ancient and present-day discharge of underground reservoirs is recorded
in almost all oil and gas basins regardless of their geostructural belong-
ing (platforms, platform orogens, aulacogens or mobile belts). It is found
whether it is on the surface or at depth, and whether it is open through
tectonic and lithological unconformities or hidden (dispersed) through the
water barriers. It is identified through a number of factors, which include:
t
The omnipresent, invariable and mandatory spatial associa-
tion of commercial oil- and gas-saturation with deep-feed
saline lakes.
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The ascending thermal source.
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Onland and offshore hydrocarbon and ground water shows.
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Hydrochemical, hydrodynamical, geothermal and other
anomalies of the cross-flow/injection origin.
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Hydrothermal development (travertine, sodium-dominated
formations, secondary quartzites, etc.) zones.
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Mud volcanoes.
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Solid bitumen accumulations.
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Oil and asphalt lakes.
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Low topographic points, erosion cuts, present-day and
paleo-river valleys.
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Regional zones and isolated areas of diapirism, faulting and
salt-dome tectonics, fracturing, etc.
The data were abundantly studied by Krotova (1975), Kartsev (1972,
1978), Kudryakov (1976), Gurevich (1969, 1980), Rachinsky (1969, 1970,
1971, 1973, 1981, 1982, 1983, 1987, 1989), Levorsen (1970), Hubbert
(1958), Russell (1958), Ver-Wiebe (1957, 1959) and others.
Following are contrasting manifestations of spatial interrelation between
the fields and natural fluidal systems' drainage zones and foci (Aliyev and
