Geology Reference
In-Depth Information
indeed the mixtures of the source ingredients and they are all positioned
in the area bounded by two extreme components of the mix. On the other
hand, the conversion of hard waters into alkaline ones always occurs at
70
80% content of hydrocarbonate-sodium component in the formation
mix (Akhundov, Mekhtiyev and Rachinsky, 1976; Rachinsky, 1970).
Statistical processing was conducted of the modeling data about the
content in formation mixes of the foreign alkaline component as a function
of the distance from base of the Productive Sequence (see Figure 2.17).
It showed that in all reviewed fields and intervals the amount of alkaline
water in the mix regularly declines with the increase in this distance. The
derived statistical parameters for the entire reviewed sediments complex
(correlation coefficient 0.87, correlation ratio 0.91 and three-sigma inter-
val
−
0.061) indicate rather close correlation between the variables.
It is important to recognize that the mathematical form of generalized
curves describing the ground water salinity and alkaline component con-
tent change in the mixes as a function of the distance from base of the
Productive Sequence was identical (see Figure 2.17). The correlations, as
the Figure shows, differ only in their sign.
The conclusion was made that the objective correlation exists between
the formation water salinity in the Pliocene and the content in them of a
foreign alkaline ingredient. It is an inverse change of the formation water
concentration with the increase in the alkaline component. Similar results
were obtained at experimental modeling of mixing performed with dual
mixtures of natural formation waters from the Kala Field (Akhundov,
Mekhtiyev and Rachinsky, 1976). The following waters were used for mix-
ing: the chlorine-calcium water of Horizon С (Surakhany Fm.) with salin-
ity 567 mg.-equiv. (162 g/l), secondary salinity factor 22.7%-equiv. and
alkaline water from the PK Fm. with salinity 47 mg.-equiv. (13.4 g/l) and
primary alkalinity factor 32.9%-equiv. (Figure 2.21). The Figure shows that
the chlorine-calcium type is stable and converts into the chlorine-magne-
sium and hydrocarbonate-sodium at the respective ratios of the chlorine-
calcium and alkaline ingredients of 25/75 and 15/85. Both mathematical
and experimental modeling showed that water distribution in the field
section totally complies with the law of water mixing process; and that its
hydrochemical outlook in specific intervals is a result of different partici-
pation of the source components in the formation mixes.
Qualitatively identical results were obtained by the similar treatment
of the Hauterivian-Danian and Paleogene-Miocene intervals wherever
they were drilled (SE plunge of the Caucasus Major Meganticlinorium,
Kobystan, western part of the Apsheron Peninsula (Akhundov, Mekhtiyev
and Rachinsky, 1976).
±
