Geology Reference
In-Depth Information
The PT-KT sediments over most of their development area had not yet
entered the final stage of oil-generation and almost entirely preserved their
initial insignificant hydrocarbon-generating potential.
Obviously, as the region is differentiated in heat regime intensity within
individual areas and zones, different stages, substages and grades of
organic matter thermal metamorphism may be realized in each of them.
For this reason, total picture of the source organic transformation is a
mosaic (“patchy”) one. A liquid hydrocarbon phase may be generated in
one fault-block. The gas phase may be generated at the same depth in
another one whereas in the third one the generation may not be occur-
ring at all (due to the complete realization of the HC resource at previous
stages of the geologic evolution and/or due to the placement of oil-gas-
generating intervals under geothermal insufficient for the organic matter
transformation). The quoted data support a secondary nature of hydro-
carbon saturation in the PT-KT of the region and the dominant role in the
formation of accumulations and fields of the subvertical interformational
fluid migration.
his issue is reviewed in more detail in Chapter 6 of this topic.
4.3
Geothermal Field of Local Structures
Conductive heat transfer creates a general geothermal background for the
formation of temperature fields in local structures of the Alpine folding.
A significant role is also played by the convective component of heat flow
(heat transfer by migrating fluids). The effect of this factor is particularly
contrasting due to geothermal regime association with structural and
hydrogeological conditions of individual structures.
Local temperature maxima are associated with the crestal, tectonically
most stressed zones of individual highs, with areas modified by mud volca-
noes and faults, with parts of structures with elevated fracturing of carbon-
ate reservoirs, etc. Typical examples follow.
In the South Caspian Depression:
t Balakhany-Sabunchi-Ramany field (at the same depth the
temperature difference in the Bog-Boga mud volcano area
(structural crest) and over the flank is 4-5°С).
t Lokbatan, Zykh, Peschany Isl. and Bibieybat fields (tem-
perature in the areas of the same-name mud volcanoes is by
5-10°С higher than on the flanks and plunges.
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