Geology Reference
In-Depth Information
1960; Kartsev, Vagin, Baskov, 1969; Kartsev, 1972; Sukharev,
1979): One view contradicts the duration of their presence
within the enclosing reservoirs. This would have undoubt-
edly resulted in higher than currently observed salinity due
to the normal leaching.
t
Another view contradicts a mostly fracture permeably
nature of the Mesozoic compact reservoirs with the fractur-
ing developed mostly over the crests of local structures; this
could not have provided for the lateral transit of the mete-
oric agents in sufficient amounts for any substantial distance
from paleo-charge areas.
t
A third view contradicts the regional occurrence of such
waters within the entire trough even at maximum distances
from the mountains.
The syndepositional nature of the chlorine-calcium ground waters in
Cenozoic intervals and post-depositional nature of the low-salinity alkaline
waters most logically explains the aforementioned zoning of the water dis-
tribution by the salinity and hydrochemical types in the Paleogene-Lower
Eocene and Upper Eocene on the different flanks of structures. Based on
this, the hard brines on the southern flanks of local structures may be due
to the effect of their hydrodynamic isolation. This isolation causes lim-
ited penetration through the faults of the alkaline waters. It also causes
the preservation in the environment of a practically nonexistent water-
exchange of the background chlorine-calcium varieties not replaced by the
migrated alkaline waters. The southern flanks of local structures (closest to
the surface exposure of the complexes) preserve for a long time the satura-
tion with hard formation waters. This indicates a minuscule effect from the
paleo- and present-day infiltration by fresh sulphate- and hydrocarbonate-
sodium surface waters onto the formation of hydrochemical environment
in Paleocene-Lower Eocene and Upper Eocene reservoirs.
The regional background of most clayey Upper Pliocene and Oligocene-
Lower Miocene complexes in the subsided axial zone of the Indolo-Kuban
trough is formed by the medium-salinity (17-26 g/l) hydrocarbonate-
sodium
(primary alkalinity factor 10-12%-equiv.) waters. These writers
believe that these waters are a result of several superposed mechanisms:
microbial desulphatization of ground waters in a reducing environment;
ion-exchange adsorption; water generation during catagenic transforma-
tion of clay minerals and thermochemical effects (Kissin and Pakhomov,
1967; Kononov, 1965; Krasintseva, 1968) under the environment of ele-
vated formation temperature. The former two mechanisms predetermined
