Geology Reference
In-Depth Information
Table 10.3
Ground water salinity vs. type of basic saturation on local structures
(West Apsheron, Dzheyranchekmes Depression, Baku Archipelago, NE part of
Low
er Kura Depression).
Accumulation
type
Salinity, mg-equiv.
V
Horizon
VII
Horizon
VIII
Horizon
(NKP)
PK
Fm.
Oil
35.8
35.3
-
-
Gas-condensate
60.3
73.0
52.4
51.4
Nonproductive
65.0
83.2
68.9
-
In the Apsheron Archipelago (Yuzhnaya Field), salinity of the contact
water in gas-condensate accumulations of the PK Formation averages 48.8
mg-equiv. and its primary alkalinity is 17%-equiv. The adjacent Neftyanyye
Kamni Field has an oil accumulation within the same PK Formation; with
about the same formation water salinity (50.0 mg-equiv.), its primary alka-
linity is already 32%-equiv.
Data for the fields in the West Apsheron, SE Kobystan (Djeiranchekmes
Depression), Baku Archipelago and northeastern part of the Lower Kura
Depression indicate that the formation waters of gas-condensate accumu-
lations in these areas have the same specific features (Table 10.3).
Table 10.3 lists the data on the formation water salinity (average values)
as a function of the type of phase saturation in traps of these areas. The
Table shows that in all stratigraphic intervals of the section, the formation
waters coming with gas and condensate aggregations are of higher salinity
compared with waters in contact with oil accumulations of the equivalent
intervals, and waters from unproductive traps, in turn, in their total salin-
ity exceed the waters of gas-condensate accumulations.
The waters in unproductive traps, compared with waters of gas-conden-
sate accumulations, are less alkaline, and in some cases even hard (V hori-
zon in the Duvanny-More, VII horizon in the Alyaty-More Fields) and of
higher salinity (Table 10.4).
The fact of a drastic decrease in the formation water alkalinity and
increase in salinity in conditions of zero hydrocarbon saturation is impor-
tant because it confirms the described mechanism of a connection between
oil and gas occurrences and ground water dynamics.
As concerns distinctions in the hydrochemical attributes of the forecast
hydrocarbon aggregation types, an important role, along with formation
