Geology Reference
In-Depth Information
Deniz, Garasu fields in the Baku Archipelago) at a depth of 5 km are at the
PC-B
stage (Dmitriyeva
et al
., 1981).
Our calculations indicate that the following scenarios exist in differ-
ent complexes of the South-Caspian Basin at the present-day evolutionary
stage:
a. The Mesozoic Complex, having thickness of 4.5 to 11 km
and the top/base temperatures of 167/424
C, generates
mostly the high-temperature methane, CO
2
and N
2
.
b. The Paleogene-Miocene Complex, having thickness of 2.5
to 5 km and the top/base temperatures of 76/237
°
C, gener-
ates oil, wet gas, condensate and, partly, the late-catagenetic
methane.
c. The Pliocene-Quaternary Complex generates mostly the
early-catagenetic methane and small amounts of the oil of
the early-generation.
°
The following stratigraphic position and depth of hydrocarbon-gener-
ating zones may be characteristic of individual regions depending on their
temperature regime:
a. Early-catagenetic methane generation (substage
PC
, tem-
perature of 20-60
°
C): Quaternary - PS/RBS at depths of 0.06
to 2.6 km.
b. Oil generation (grade
MC
1
-MC
3
; temperature of 60-135
°
C;
the oil window is at
MC
2
at temperature of 80-115
°
C): PS/
RBS - Miocene at depths of 2.6 to 5.5 km.
c. Wet gas and condensate generation (grade
MC
4
-AC
2
; tem-
perature of 135-210
C): Oligocene - Upper Cretaceous at
depths of 5.3 to 10.9 km.
d. Late-catagenetic methane generation (grade
AC
3
-AC
4
; tem-
perature of 210-300
°
°
C): Eocene - Middle Jurassic at depths
of 8 to 17 km.
e. Dry and sour gas generation (stage
MG
; temperature
>300oC): Lower Cretaceous-Middle Jurassic at depths of
13.4 to 21.5 km.
Consideration of the basin's subsidence rate requires significant cor-
rections to the estimates of the hydrocarbon generation potential of
rocks. This will modify the existing estimate of hydrocarbon-generating
potential.
