Geology Reference
In-Depth Information
t
Elastic compression of reservoir beds as a result of recent
and present-day tectonic motions.
The epigenetic component is due to the injection of ground water and
hydrocarbons from the underlying complexes through faults in the areas
of decreased thickness (or absence) of the regional Upper Eocene water
barrier (Beloglin Formation).
he
Middle-Upper Miocene
complex (the Chokrackian, Karaganian,
Sarmatian and Meotian waterhead horizons) has practically ubiquitous
AHFP development on the local structures except for the latest interval.
Abnormality factors 1.35-2.17 (Borzov and Priozernaya prospects)
recorded only in the Middle Miocene accumulations of the southeast-
ern Kerch Peninsula at depths of 430-861 m against the general back-
ground of much lower values in the rest of the area (1.08-1.10 at the South
Sivash, North-Kerch and other prospects) (Durmishyan, Muradian and
Rachinsky, 1976; Kucheruk and Ozerny, 1987; Novosiletsky, 1975; Orlov,
1980) are believed to be the result of fluid penetration from the underlying
complexes.
Formation pressure excess over the hydrostatic in the Chokrackian
sediments of the West Kuban Trough is 0.1-27.2 MPa with abnormality
factor of 1.0-1.93. The highest values of these parameters (9.1-27.2 MPa,
1.30-1.93) are recorded on the structures in the central part of the trough
(Kurchansky, Anastasyev-Troitsky, Fedorov and South-Andreyev pros-
pects). In the southern flank zone local structures are more complex and
more intensely faulted (the Abin, Adagum, Djigin, Blagoveshchen and
other prospects). Excess pressure there is no greater than 5.0 MPa with an
abnormality factor of 1.00-1.27.
The areal AHFP in the Karaganian and Sarmatian intervals is similar. In
the former case the excessй pressure and abnormality factor values are 15.8
MPa and 1.84, and in the latter, 5.8 MPa and 1.55, with maximum values
recorded on local structures in the central part of the trough (Anastasyev-
Troitsk, Kurchansk and other prospects).
Following are specifics in the AHFP manifestations in the Middle-
Upper Miocene complex:
t
Association of their maximum values with insignificantly
faulted structures.
t
Decrease in excess pressure and abnormality factor values
up the section (up to equaling the hydrostatic pressure in
the Meotian).
