Geology Reference
In-Depth Information
Limited and to a certain extent desultory field data for the Mesozoic of
the Indolo-Kuban Foredeep currently prevent the creation of a complete
concept of the ground water spatial zoning in terms of their salinity and
composition. For this reason the quoted information, although defining
general trends, remains preliminary.
The waterhead complex of the
Paleocene-Lower EoceneŠ°
clastic flysh
(the Tsitse, Goryachiy Klyuch, Ilsk and Zybza formations) is composed of
rhythmically alternating compact sandstones, siltstones, gravelites, marls
and clays turning down the regional dip into a clayey facies. This complex
is saturated in the Akhtyrsko-Bugundyrsk, Zybza-Gluboky Yar, Abino-
Ukrainskoye, Kholmskoye, Kaluga and some other fields with hydrocar-
bonate-sodium and chlorine-calcium-type waters. The former have the
salinity of about 30-50 mg-equiv. (9-14.3 g/l) and primary alkalinity factor
20-49.5%-equiv. They are mostly localized on the intensely faulted near-
crestal areas and on partially eroded northern flanks of the structures. The
latter have the salinity of up to 247.2 mg-equiv. (70.7 g/l) and secondary
salinity factor 15-20.5%-equiv. They are mostly found on the southern
downthrown, often recumbent and underthrust flanks of the same struc-
tures and form the regional background complex.
Ground water flows from the
Upper Eocene
complex flyshoid sand-
siltstone reservoirs (the lower part of the Kuma Fm. in the West Kuban
trough) were produced in the Kaluga, Novo-Dmitriyev, North Novo-
Dmitriyev, East Seversk, Zybza-Gluboky Yar, Chernomor, Abino-
Ukrainsk, Akhtyr-Bugundyr, Levkin, North West-Afip and other fields.
Low-porosity lens-shaped low-permeability sand reservoirs both up and
down the regional dip are replaced by clays and are overlain and underlain
by thick marly-clayey rocks thus forming isolated reservoirs. The com-
plex two major ground water types: high-salinity (212-229.4 mg-equiv. -
60.6-62.9 g/l) chlorine-calcium (secondary salinity factor 13.4-15.2%-
equiv.) and much lower salinity (39.1-90.6 mg-equiv. - 11.2-25.9 g/l)
hydrocarbonate-sodium (primary alkalinity factor 12.1-49.5%-equiv.).
Hard waters form regional hydrochemical background and are found in
the pinch-out portions of the reservoir members, outside the accumula-
tion outlines and over the southern flanks of local highs on the depres-
sion's southern flank. The alkaline varieties on the southern flank of the
depression are usually present in the most faulted blocks of the northern
flanks in the local structures. They form contrasting negative hydrochem-
ical anomalies (in the crestal zones of the Zybza-Gluboky Yar, Akhtyrsk-
Bugundyr, Abino-Ukrainskoye fields). Over the trough's axial area (the
Anastasyev-Krasnodar anticlinal belt) the hard waters are more common
and cover significant areas.
