Geology Reference
In-Depth Information
he
Oligocene-Lower Miocene
complex (the Maikopian formation)
is formed by lens-shaped sand reservoirs within a thick clay sequence
in the mid-portion of the interval. Ground waters were produced in
the Anastasyev-Troitsk, Fedorov, Kaluga, Novo-Dmitriyev fields and
Moshkarev, Fontanov, Vladislavov, Kuybyshev, etc., prospects. The sec-
tion includes both high-salinity and low-salinity waters. The high-salinity
(220-231.2 mg-equiv. - 62.8-66.1 g/l) chlorine-calcium (secondary salin-
ity factor 12.2-14.1%-equiv.) varieties are found only at the edges of the
trough's flanks and reservoir pinch-out zones (the relics of the ancient
background). The low-salinity
(44.7-70 mg-equiv. - 12.8-20 g/l) hydro-
carbonate-sodium waters
(primary alkalinity factor 10.6-38.1%-equiv.)
form at maximum total salinity values (60-70 mg-equiv.) and minimum
primary alkalinity factor values (10-22%-equiv.) the present-day hydro-
chemical background. At minimum salinity (40-50 mg-equiv.) and
maximum alkalinity (25-40%-equiv.) they form negative hydrochemical
anomalies spatially associated with intensely faulted crestal areas of the
local highs, sometimes with diapirism and mud volcanism (Anastasyevsko-
Troitskoye, Novo-Dmitriyevskoye fields and a number of prospects in the
Kerch-Taman area).
he
Middle-Upper Miocene
complex includes waterhead intervals in
the Chokrackian, Karaganian, Sarmatian and Meothic rocks. The complex
comprises sandstone and fractured dolomitic reservoirs in the subsided
zones. They are replaced over the flank portions of the trough by a clay
facies and are saturated by waters of all hydrochemical types with substan-
tially variable salinity. The complex is tested in most fields and at most
prospects in the region.
Saline (25-33 g/l) alkaline and «transitional» sulphate-sodium and chlo-
rine-magnesium waters are mostly typical of the negative hydrochemical
anomalies in the faulted parts of structures. High-salinity (43.5-62.4 g/l)
chlorine-calcium waters in all intervals of the complex form the regional
background.
For the complex as a whole the range of total salinity is 56.1-218.3 mg-
equiv. (16-62.4 g/l), of the secondary salinity factor 0.8-13.3%-equiv.,
primary alkalinity 0.9-28%-equiv. and the sodium/chlorine ratio = ratio
0.87-1.50. In some intervals the same parameters are respectively: for the
Chokrackian and Karaganian horizons 56.1-218.3 mg-equiv. (16-62.4 g/l),
12.5-13.3%-equiv., 1.2-28%-equiv., 0.87-1.50; for the Sarmatian Stage
70.3-186.8 mg-equiv. (20.1-53.2 g/l), 5-7%-equiv., 0.9-22%-equiv., 0.94-
1.30; for the Meothic Stage 65-152.2 mg-equiv. (18.6-43.5 g/l), 2.4-5%-
equiv., 0.9-30%-equiv., 0.93-1.10.
