Geology Reference
In-Depth Information
0
10
20
30
40
50
60
70
80
90
100
110
120
P
II.I
, MPa
500
Miocene
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
6500
Oligocene
Eocene
Paleocene
Up. Cretaceous
H
,
M
Figure 3.9
Initial formation pressure in waterhead complexes, internal zone of
Carpathian Foredeep. Fields:
1.
Staro-Sambor,
2.
Borislav (I structural stage),
3.
Borislav
(II structural stage);
4.
Ivanikov,
5.
Orov-Ulichnyansk,
6.
Stynyav,
7.
Strutyn,
8.
Vygo d a-
Vitvitskoye,
9.
North Dolinskoye,
10.
Dolinskoye,
11.
Spasskoye,
12.
Kosmachskoye,
13.
Rosilnyanskoye,
14.
Gvizdetskoye,
15.
Pnivskoye,
16.
Bitkovskoye,
17.
Sloboda
Rungurskaya,
18.
Urozhskoye,
19.
Luga,
20.
Dobrogostovskoye,
21.
Starunskoye.
Important for the interpretation of the nature of high ground-water
head in the trough's internal zone is the occurrence of AHFP not only in
the productive but also water-bearing intervals. In the water-bearing inter-
vals, the abnormality factors are usually the greatest (Novosiletsky, 1975).
Kolody (1983) determined that anomalies of the formation pressure go
together with anomalies in ground water salinity.
The aforementioned indicate that AHFP formation occurred due to
ground water vertical migration from deep zones of the sedimentary sec-
tion and to hydraulic communication between the upper water horizons
and the lower ones in the environment of a reliable isolation underneath
the clay-salt sequence. A precondition for AHFP generation under such
model is overhydrostatic pressure at depth. Kolody believes that the ele-
vated formation pressure foci have been ubiquitous in the Borislav-Pokut
Subzone in the process of folding.
They were, however, preserved until now only within isolated fault-
blocks at great depth. The fact is supported by a common association of
AHFP with the anticlines in the II and III structural stages. High-pressure
ground water cross-flows into the upper horizons during tectonic motions.
At that time, faults and fractures providing for a hydraulic communication
