Geology Reference
In-Depth Information
zone of highs.
К
AHPP
is similarly correlated with clay content of the section,
thickness and depth to the PT-KT surface. Depths to the tops of AHPP
zones correlate satisfactorily with the other parameters (see Table 3.3.).
The other geobaric pore parameters range over the region as follows.
Depth to the AHPP zone surface (
D
APP
) 0.59-1.58 km, the thicknesses
ratio of AHPP zone and of the PT-KT (
M
APP
) 30-90.5%, pore pressure
gradient at the PT-KT surface (G
APP
) 0.010-0.021 MPa/m. All AHPP and
AHFP parameters are in a direct correlation. The correlation between
AHPP parameters and structural-tectonic, geotemperature and hydrody-
namic parameters of the local structures is similar to those for AHFP (see
Table 11.3).
Table 3.3 shows that there no clear quantitative correlation in the basin
between
К
AHFP
and
К
AHPP
values, clay content, thickness of the section and
depth to the PT-KT surface. This is a natural situation caused by drastic
differences in the geologic, lithofacies and hydrodynamic environments in
each of the zones, in the AHFP generation mechanisms and their inter-
relations. This is a reason why a reliable quantitative correlation between
these parameters exists only within individual areas. The consideration of
specificities in each area will enable the basin subdivision into individual
geobaric zones and the identification of: zonal formation pressure close to
the hydrostatic (
К
AHFP
<1.25); zones of moderate AHFP (
К
AHFP
=1.25-1.45);
zones of intense manifestation (
К
AHFP
=1.45-1.55); zones of e xtreme mani-
festation (
К
AHFP
>1.65) (see Figure 3.2).
Figure 3.2 showing AHFP zones in the South Caspian Basin and Table
3.3 indicate that pressure close to the hydrostatic covers the following areas:
the northern and central Apsheron Peninsula, Apsheron Archipelago,
Priallahi-Kelkor trough, individual structures in the northern Baku
Archipelago, a number of highs in the North-Apsheron zone, extreme west-
ern portion of the Apsheron-Balkhan Sill and the Turkmen shelf terrace.
The zone of extreme AHFP is recorded on the individual anticlines in the
south part of the Alyat Ridge (Koturdagh and Dashgil prospects); on the
most subsided structures in the northern, central and southern anticlinal
zones of the Baku Archipelago (Bulla-More-2, Umid, Dashly (formerly
Ignaty Rock), Sabail (formerly Kornilov-Pavlov), Byandovan-More, Inam,
etc.; on the structures in the southern part of the Gograndagh-Chikishlyar
zone (Okarem, Chikishlyar, Miaser, Ak-Patlavuk, Gasan-Gulu, etc.); at the
Elbrus trough prospects (Enzeli-Deniz and Gozel Tepeh). They are also
forecast for all structures in the South Caspian deep water depression. The
remaining territory of the South Caspian Basin (Lower Kura Depression,
Kobystan, South-Apsheron and Kyzylkum troughs, central portion of the
Apsheron-Balkhan Sill) is the zone of moderate and intense AHFP.
