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1968). This results in leveling of of the formation temperature in their
sections and decline of average gradients.
The actual data show that the association between hydrocarbon satura-
tion and thermal regime of the subsurface is observed not only on the indi-
vidual structures with different temperature conditions. It is also noted for
the entire west flank of the South Caspian Depression. Table 8.11 shows
that in all areas at the same depths, higher formation temperatures cor-
respond with greater hydrocarbon reserves. This correlation is especially
clear in the depth interval 500-1,500 m where the bulk of the region's
Pliocene reserves (over 40%) is concentrated.
In light of the aforementioned, the temperature jump from unsaturated
to productive intervals of the section noted in most fields of South Caspian
areas is symptomatic. For instance, in the Eastern Apsheron the transi-
tion from unproductive interval 0-500 m to the oil-saturated one shows
temperature increase of 12°С, whereas in the next interval, with about the
same amount of hydrocarbons, the increment is 9.3°С (Table 8.11). This
affects also the values of geothermal gradients.
The described correlation between quantitative parameters of hydrocar-
bon saturation and baric regime of natural reservoirs (functionally associ-
ated with the nature of water-exchange) is typical for not only individual
areas and regions (Figures 8.9, 8.10). It is of a wider scope and is recorded
within the entire Alpine folding zone. The correlations in Figure 8.11 of
proved hydrocarbon reserves per unit area ( Q S , MT/km 2 ) and the sediment
cover volume ( Q V , MT/km 3 ) in the regions with average for the entire terri-
tory intensity parameter of geo-fluid-dynamic systems ( К ан ) shows a clear
increase in oil and gas occurrences with the optimizing of their discharge.
See Figure 8.9.
Thus, based on the analysis of all quoted material, the major pattern
appears to be the consistent spatial conjunction within the Alpine mobile
belts of all large fields with positive geothermal and hydrodynamic anoma-
lies. The anomalies are caused in turn by the drainage of intensely faulted
local structural forms.
The reviewed correlations together with the materials in Chapters 2, 3
and 4 establish in some cases the correspondence of both positive and neg-
ative concentration anomalies with local piezo-minimum zones and the
associated areas of low geothermal gradients (i.e., thermobarically-open
traps). They establish in some other cases the correspondence with piezo-
maximums of high thermal gradient values, i.e., thermobarically-closed
reservoirs.
The associations of the first type correspond with the fields' largest in
reserve density and even partially deformed due to intense drainage of
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