Geology Reference
In-Depth Information
Table 6.4
Hydrocarbon generation temperature and depth in the South-Caspian
Basin after catagenic scales by Kartsev
et al
. (first lines of cells) and Waples
(second lines of c
ells).
Sratigraphic
complex
Catagenic grades and stages
MC
1
-MC
3
MC
4
-AC
2
AC
2
-AC
4
MG
Oil generation
zone
Condensate
and wet gas
generation
zone
Late-
catagenic
methane
generation
zone
Dry and
sour gases
generation
zone
Mesozoic
2.40 (60
°
)
-
5.79
5.79 (135
°
)
-
9.90 (210
°
)
-
15.0 (300
°
)
-
(135
°
)
9.90 (210
°
)
15.0 (300
°
)
17.0 (332
°
)
3.64 (92
°
)
-
6.13
6.13 (141
°
)
-
9.90 (210
°
)
-
12.0 (247
°
)
-
(145
°
)
9.90 (210
°
)
12.0 (240
°
)
17.0 (332
°
)
Paleogene-
Miocene
2.40 (60
°
)
-
5.79
5.79 (135
°
)
-
)
3. 64 (90
(135
°
7.70 (170
°
)
°
)
-
6.61 (150
°
)
-
6.61 (150
°
)
7.70 (170
°
)
Pliocene-
Quaternary
2.40 (60
)
-
4.0
(101°)
-
MC
1
°
occurrence of oil shales in this section (Ali-Zadeh
et al
., 1975; Salayev
et al
., 1988).
These observations indicate the absence in the complex of favorable
conditions for unencumbered outflow of catagenic transformation prod-
ucts of dispersed organic matter. The above data indicate that the present-
day depth of the oil and gas-generation zone in the South-Caspian Basin
ranges from 8 to 10 km, whereas the condensate and wet gas generation
zone occurs down to 12 to 14 km. Therefore, these processes occur mainly
within the section underlying the PS/RBS. This conclusion supports an
important theoretical position that
the PS/RBS hydrocarbons are mostly
of secondary origin, i.e., the oil, gas and condensate in these reservoirs
are allochtonous
.
The aforementioned conclusions are supported by the results obtained
using Waples' scale of catagenic transformations. The latter scale is based
on the correlation of vitrinite reflectance with the degree of dispersed
