Geology Reference
In-Depth Information
separating hard and alkaline waters in their sections and their reserve den-
sity. In areas where this boundary is shallowest (i.e., alkaline waters are
present in the most of the section), the hydrocarbon reserve density is at its
maximum (Figure 8.4-
d
,
e
,
h
).
Within an individual formation or horizon, the most saturated areas
correspond with higher alkalinity water among the alkaline water
1
(or
water with lower secondary salinity factor among the hard water) of low-
est salinity in this particular stratigraphic interval. In the Apsheron oil-gas
area, this is observed in several fields. In the Balakhany-Sabunchi-Ramany
Field, the main saturation is found on the northern flank of the structure.
In Surakhany and Karachukhur, the reserves in the Productive Sequence's
Lower Group are concentrated mostly of the eastern flanks. In Lokbatan,
Binagady and Buzovny-Mashtagi,
the
saturation is encountered mostly on
the southern flanks. In the Lower Kura oil and gas area in Kyurovdag Field
only the southwestern flank is productive, and in Kalmas, the northwest-
ern fault-block. In the Sangachaly-More-Bulla Isl. anticlinal zone (Baku
Archipelago), the penetrated accumulations are located on the northeast-
ern flanks of all anticlines in the zone, etc.
A demonstrative illustration
of this association is found in the Apsheron Archipelago. There, on spo-
radically-saturated structures Grigorenko Stone and Apsheron Bank
in the basal PK and KaS formations are recorded “transitional” waters
with primary alkalinity factor (or secondary salinity) 3-5%-equiv. This
is at least three times lower than in the equivalent productive intervals
on the adjacent structures of the Zhiloy Isl, Neftyanyye Kamni, Darwin
Bank and Artem Isl., which contain larger oil aggregations.
Water distribution in nonproductive and weakly saturated intervals is
the opposite. These intervals, regardless of their stratigraphy, usually con-
tain high salinity chlorine-calcium type hard brines. Examples of this kind
are such fields as Zyrya (the entire section of the Productive Sequence up
to the Kirmaki Fm.), Yuzhnaya (the Surakhany and Sabunchi formations),
Peschany Isl. (Surakhany and Sabunchi formations), Binagady (the Upper
Group of the Productive Sequence), Karachukhur and Kala (Surakhany
Formation), etc. (Akhundov, Mekhtiyev and Rachinsky, 1976; Minsky,
1975).
Thus, the quoted data identify a definite connection between the extent
of the hydrocarbon saturation on individual structures and chemical out-
look of the water medium. A broad regional nature of this relationship is
1
In some cases (see below), a similar situation may occur in accumulations
destroyed by hydrodynamical factor.
