Geology Reference
In-Depth Information
lengthwise faults and smaller radial faults within the blocks. For instance, at
Neftechala Field ground water salinity in the upper part of the Productive
Sequence of the northeastern wet flank is 2-3 times greater than on the
southwestern oil-saturated flank. A similar water distribution picture in
terms of its salinity is observed at Khilly, Kyurovdag, Karabagly, Mishovdag
and Kalmas.
Hydrodynamic isolation of different flanks is supported also by a dras-
tic difference in the static waterhead. Most reliable data of this kind are
available for the Neftechala, Khilly, Mishovdag and Kalmas fields where the
ground water head on the southwestern flanks is several times that of the
northeastern flanks (Ginis, 1966).
This is a typical feature in all Lower Kura Depression fields. The water
static level vs. time curves in wells producing from the equivalent intervals
of different fault-blocks differ greater than the same curves in wells pro-
ducing from different intervals within the same block. And in the course of
the development, despite the differences in liquids production from wells,
the head decline in different intervals of the same fault-block in most cases
occurs simultaneously.
The above examples of the barrier effect from regional faults running
along the anticlinal zone axes support the stagnant hydrodynamic regime
within specific structures, i.e., locally. The same activity of these faults is
maintained in the areas between the structures. The latter circumstance
determines the role of regional axial faults as reliable spatially consistent
hydrodynamic boundaries separating adjacent tectonic blocks and steps
and controlling the nature and extent of ground water mobility from
the regional viewpoint. Thus, each step is to a significant degree a closed
hydrodynamic subsystem with certain specifics of ground water behavior
within it and with its own energy resources.
When estimating the areal scale of lateral migration, it is important to
account for mutual spatial position of large isolating faults and their posi-
tion in relation to the charge and discharge areas of the South Caspian
elision system hypothesized by some writers. Figures 1.1 and 1.2 sche-
matically display major regional faults on the west flank of the depression.
The data show that the region has a complex structure and is separated
by a fault system into a number of large tectonic steps. It was established,
when analyzing spatial relationships between oil and gas fields and faults,
that practically all areas of potential and actual oil and gas accumulation
in the region (Gorin and Buniat-Zadeh, 1971; Durmishyan, Muradian
and Rachinsky, 1972; Rachinsky, 1982; Rachinsky and Muradian, 1983;
Rachinsky, 1989) are separated by faults from one another and from the
center of the South Caspian deep area.
