Geology Reference
In-Depth Information
The data on the other Alpine folding regions show qualitatively similar
relationships between genetic types, ground water dynamics and oil and
gas occurrences. This objectively confirms the dominant significance of
the stated mechanism in those regions. The legitimacy of this conclusion
is supported by the association in all Alpine mobile belt regions of main
commercial hydrocarbon reserves with areas and intervals of contrasting
positive and negative deep generation hydrochemical anomalies and their
areal conjunction with zones of intense fault tectonics, reservoir fractur-
ing, mud volcanism, diapirism, etc.
The clearest spatial interconnection between hydrocarbons and ground
waters may be the Viennese Depression. There, up the section, its oil-
saturation significantly declines and maximum reserves densities in the
Neogene are associated with zones and areas of high-salinity low hard-
ness “transitional” and least alkaline waters against the general field of low-
salinity hydrocarbonate-sodium water medium. This fact combines with
the presence in the said interval of clearly filtered oil genetically associated
with underlying deposits (Vysotsky and Faingersh, 1969; Kalinin, 1961),
in which chlorine-calcium brines are common (Chapter 2). Altogether,
these describe the secondary nature of the hydrocarbons in the reservoirs
of the Neogene series. This conjunction is further illustrated by the group
of fields Matzen-Bokflies - Bokflies-Tief - Schonkirchen-Schonkirchen-
Tief-Schonkirchen-Ubertief with largest in the region reserves densities
and absolute values. There, in the Neogene deposits, as opposed to most of
the other less oil-saturated fields with dominant alkaline waters, are com-
mon relatively high-salinity chlorine-calcium and chlorine-magnesium
formation solutions (Koelbl, 1958; Schrocfcenfuchs, 1975). Their depen-
dence on a mechanism of mixing of different-type waters clearly shows in
their composition (secondary salinity factor of 0.2-4.7%-equiv) and salin-
ity. Modeling indicates that the content of the chlorine-calcium ingredient
in the formation water mixes fringing the Neogene accumulation in the
said fields is up to 25%.
The Maracaibo Depression presents a similar picture. There, in the
oil-saturated areas (fault-blocks) of individual fields are common most
alkaline water mixes, drastically different from the waters of the regional
hydrochemical background. At the same time for the fields as a whole is
clearly recorded the direct correlation between the reserves density in the
Cenozoic reservoirs and the invasion height in their sections of Mesozoic
generation hard saline chlorine-calcium waters. The prospects with maxi-
mum reserves density (Lama, Lamar and La Paz) have substantial injection
of the lower waters (Borger, 1952; Smith, 1931; Suter, 1947).
