Geology Reference
In-Depth Information
deposited under drastically different geotectonic environments. Therefore,
they have drastically differing thermophysical parameters up the region's
(area's) section. The utilization of the
“temperature vs. depth”
function per-
taining to the uppermost stratigraphic unit for the entire underlying sec-
tion is absolutely unacceptable.
These writers proposed for the geologic environment of the South
Caspian Basin a cardinally new technique for the estimation of geotemper-
ature at great depths not covered by the well thermometry. The technique
eliminates the identified errors. This is how geotemperature is forecast for
deep stratigraphic and physical levels.
The actual temperature at the base of the PT-KT is built-up using the
temperature gradients of the standard correlation
t
=
f
(
H
) for the Miocene-
Paleogene within the depth range of its actual presence in the section of a
local structure. Then so derived temperature at its base is built-up using the
temperature gradients of the standard correlation for the Mesozoic in its
entire range down to the surface of the crystalline basement (Kerimov and
Rachinsky, 1989).
This temperature estimation technique indirectly takes
into account real variations of the thermophysical parameters of the entire
forecast sedimentary section. The reason is that the temperature gradient
(the rate of geotemperature change with depth) is included in latent form
and determines specific parameter values of the correlations
“temperature
vs. depth”
and
“geothermal gradient vs. depth”.
As the calibrating correlation of temperature gradients vs. depth for
the Mesozoic interval in the Azerbaijan portion of the South Caspian
Basin are taken the data for prospects over the SE plunge in the central
zone of the Caucasus Major meganticlinorium (Keshchay, Begimdagh,
Sovetabad, Sitalchay and Gyadysu prospects) and in the North-Apsheron
offshore zone of highs (Dva Brata Rocks, Tsuryupa Bank, Apsheron Bank,
Gilavar, Khazri and Nakhichevansky prospects). The penetrated thick-
ness of the complex reaches there in some cases 5.5 km (Sovetabad pros-
pect). he
G
t
mz
=
f
(
H
) correlation is actually
G
t
mz
= 5.5522
H
−
0.13375
. For the
Turkmenistan part of the basin the data for the complex are available at the
Karadepe, Kumdagh and Boyadagh prospects; and the actual correlation is
G
t
mz
=
6.2111
⋅
H
−
0.1494
.
The Paleogene-Miocene interval in the Azerbaijan portion is collected
at the Kobystan prospects (Umbaki and Adjiveli), Apsheron Peninsula
prospects (Shorbulag and Zigilpiri) and prospects in the North-Apsheron
zone of highs (Tsyurupa Bank, Dva Brata Rocks, Apsheron Bank, Gilavar,
Khazri and Nakhichevansky). The correlation is
G
pg-mi
= 6.1678
⋅
H
−
0.1542
; for
the Turkmenistan portion (Karadepe, Kumdagh and Boyadagh) the same
correlation is
G
pg-mi
= 32.3725
⋅
⋅
H
−
0.398
.
