reservoir geomecanics

37 Pore pressure at depth in sedimentary basins
a.
6000
psi
OVERBURDEN
SAND 1
5000
4000
INITIAL
CONDITIONS
A-7
3000
Pp
Hydrostat.
B-4
A-8
2000
A-10 A-12
A-6
1000
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
Production year
b.
6000
psi
5000
OVERBURDEN
INITIAL
CONDITIONS
A-1
A-4
SAND 2
A-8
A-1ST
4000
A-10
3000
Pp Hydrostat.
2000
1984
1986
1988
1990
1992
1994
Production year
Figure 2.9. Production-induced pore pressure variations within two reservoirs in the South Eugene
Island field, Gulf of Mexico (modified after Finkbeiner 1998). (a) Sand 1 appears to behave as a
fully interconnected reservoir. Production from the first wells in the field causes pressure to drop
from moderately overpressure values to sub-hydrostatic. (b) Production from Sand 2 demonstrates
that this reservoir appears to be compartmentalized. The pressure decline associated with
production from well A-1 was not sensed in the sections of the reservoir penetrated by the other
wells. Instead, A-4, A-8 and A-1ST appear to have penetrated essentially undepleted sections of the
reservoir.