Geology Reference
In-Depth Information
(see Figures 1.1, 1.2, 1.3), which is believed to be the internal source area of
the elision hydrodynamic system (14. Bagir-Zadeh, Kerimov and Salayev,
1988). Low permeability and lithological variability of the reservoirs indi-
cate limited possibility for the formation and active functioning in these
deposits of the elision-type waterhead system.
The combination of these geologic factors and the aforementioned
(see Chapter 2) patterns in spatial distribution of ground waters in terms
of their chemical composition and salinity determine the existence in
the Paleogene-Miocene complex of a stagnant hydrogeological environ-
ment excluding (substantially restricting) long-distance lateral flow of the
ground water.
At the same time there are indications of substantial vertical discharge
of ground waters in the Paleogene-Miocene complex and the definitive
role of this particular mechanism in its hydrodynamic regime. These indi-
cations are:
t
Vertical hydrochemical zoning.
t
Consistent localization of hydrocarbon manifestations
and alkaline waters genetically associated with them
around faults (Durmishyan, Rachinsky and Malysheva,
1971; Durmishyan and Rachinsky,1972; Durmishyan and
Rachinsky,1973; Rachinsky,1989).
t
Large amplitude of faults facilitating the communication
between different stratigraphic intervals.
t
Intense gas-mud volcanism.
t
Numerous surface oil and gas shows spatially associated
with faults, etc.
The issue of the
Pliocene
complex's regional dynamics is not satisfactorily
solved until now. Its many facets are controversial. Various scientists accept
the functioning in the complex of infiltration (Ignatovich, Sulin, Ushakov,
and Krotova), elision (Kartsev, Sultanov, Bars, Viskovsky, Buryakovsky,
and Kolody) and cross-flow/injection (Anikeyev, Mekhtiyev, Rachinsky,
and Gorin) water-exchange mechanisms.
The available data show that the first mechanism is untenable. The
obstacles are:
t
Numerous lithological and tectonic barriers in the way of
the infiltrating water.
t
Shaling-out of the Pliocene section down the regional dip.
