Page 67 - Reservoir Geomechanics

51 Pore pressure at depth in sedimentary basins

a. 0 0

500 5

Vertical Effective Stress (psi) 1000 f = 0.386e − (3.13 × 10 −2 s v ) 10 Vertical Effective Stress (MPa)

1500

2000
15

2500
0.1 0.2 0.3 0.4

b.

ISSLER (1922)
-0.14
f
t

log (1 - porosity) -0.16

-0.18 T77 (A-20ST2) T96 (A-12)
f
t f f = 2.19
t

-0.2
-2.25 -2.2 -2.15 -2.1
log (1/DT)
Figure 2.16. (a) Decrease in porosity of shale in the SEI-330 field with effective stress based on
geophysical logs at depths characterized by hydrostratic pressures (Finkbeiner, Zoback et al. 2001;
Flemings, Stump et al. 2002). Such measurements are used to determine the compaction parameter,
β c , described in the text. (b) Laboratory measurements of the variation of porosity with P-wave
transit time (V p −1 )to determine the acoustic formation factor, f,as described in the text. Reprinted
with permission from American Journal Science.