Geology Reference
In-Depth Information
of Chilov prospect (Zhiloy Isl.). The data in effect describe a distant water-
saturated PT area. As opposed to the Chilov prospect where
К
AHFP
reaches
1.34, formation pressure in all horizons at Janub is close to the hydrostatic.
The same is observed on the eastern flank of the basin. Formation pressure
at the offshore prospect West Erdekli (positioned over the regional sub-
sidence of КТ) corresponds with the hydrostatic, whereas in the adjacent
Erdekli field (positioned up the regional dip)
К
AHFP
is 1.72.
Other most important parameters of the PT-KT geobaric field are depth
to the surface of AHFP zones (
D
ADP
) and the AHFP fraction of the PT-KT
zone thickness (
M
ADP
). For the region as a whole they are 640-2,100 m and
31-98 %. The first parameter sets minimum depth (distance from the sur-
face) for individual structures of the AHFP manifestation zones. The sec-
ond parameter sets the PT-KT trap volume affected by formation pressure
abnormality. All geobaric parameters strongly correlate with structural-
tectonic parameters of local structures. These latter parameters include:
t
Depth to the PT-KT surface, its thickness, extent of per-unit
area faulting and steepness of the structures.
t
Parameters of their geotemperature fields.
t
Ground water dynamics.
t
Reservoir properties of rocks in the section.
In particular,
D
ADP
directly correlates with the structures' per-unit area
faulting and intensity (steepness), whereas
M
ADP
displays inverse correla-
tion (Table 11.3).
A number of factors support in such geologic environment the mostly
epigenetic nature of AHFP. These factors include:
t
Dominating effect of the powerful subvertical inter-forma-
tional fluid-mass transfer.
t
The nature of AHFP manifestations in the areas and on the
structures with the lowermost clay content of the PT-KT sec-
tion (North Apsheron zone of highs, Apsheron Peninsula,
western and eastern plunges of the Apsheron-Balkhan Sill:
clay content is 30-55 %).
t
Their permanent association with local high-pressure
allochtonous ground water discharge areas and geotempera-
ture anomalies associated with most faulted crestal portions
of structures.
t
Decrease in intensity of their manifestations toward periph-
eral parts of structures.
