reservoir geomecanics

3 o W
64 o N
Stress trajectories
a. b.
3 o W
2 o W
1 o W
1 o E
2 o E
3 o E
4 o E
5 o E
6 o E
7 o E
8 o E
9 o E
10 o E
11 o E
64 o N
64 o N
3 o W
2 o W
1 o W
1 o E
2 o E
3 o E
4 o E
5 o E
6 o E
7 o E
8 o E
9 o E
10 o E
11 o E
64 o N
1
0.95
64 o N
3 oW 2 o W
c.
2 o W
1 o W
1 o E
2 o E
3 o E
4 o E
5 o E
6 o E
7 o E
8 o E
9 o E
10 o E
64 o N
1
0.95
63 o N
63 o N
63 o N
63 o N
0.9
63 o N
63 o N
0.9
62 o N
62 o N
62 o N
Modeled S hmin /S v
0.75
62 o N
0.85
62 o N
Observed S hmin /S v
0.75
62 o N
0.85
0.8
61 o N
61 o N
61 o N
6 1 o N
61 o N
61 o N
0.8
60 o N
60 o N
60 o N
60 o N
60 o N
60 o N
59 o N
59 o N
59 o N
59 o N
95 oN
59 o N
58 o N
58 o N
58 o N
58 o N
58 oN
58 o N
57 o N
2 o W
1 o W
0 o
0 o 1 o E
km
0 50 100
2 o E
3 o E
4 o E
5 o E
6 o E
7 o E
8 o E
9 o E
10 o E
11 o E
57 o N
57 o N
3 o W
2 o W
1 o W
km
0 o
0 o 1 o E
0 5 0 100
2 o E
3 o E
4 o E
5 o E
6 o E
7 o E
8 o E
9 o E
10 o E
11 o E
57 o N
57 o N
3 o W
1 o W
0 o
0 o 1 o E
km
0 5 0 100
2 o E
3 o E
4 o E
5 o E
6 o E
7 o E
8 o E
9 o E
10 o E
57 o N
Figure 9.3. Comparison between observed directions of maximum horizontal stress in the northern North Sea
and calculated stress directions incorporating the effects of lithospheric flexure due to removal of the
Fennoscandian ice sheet (Grollimund and Zoback 2003). (a) The model accurately reproduces stress
orientations in the northern North Sea. (b) The calculated stress magnitudes are shown as the ratio of the
minimum horizontal stress to the overburden. (c) The magnitude of the minimum horizontal stress as
determined from leak-off tests in wells is quite similar to that predicted by the model. AAPG C○ 2003 reprinted
by permission of the AAPG whose permission is required for futher use.
a. b.
c.
31 31.5 32
32 34 36 38 40 44 46 48 50 52
Required P m Required P m
Required P m
Figure 10.4. The effects of wellbore trajectory and stress state on wellbore stability. The parameters used in
this figure are the same as those used for the calculations shown in Figure 8.2. The figure shows the mud
pressure (in ppg) required to drill a stable well (maximum breakout width 30 ◦ for a relatively strong rock
(UCS ∼50 MPa) as a function of well orientation at a depth of 3 km for hydrostatic pore pressure: (a) normal
faulting, (b) strike-slip faulting and (c) reverse faulting.