Page 152 - Origin and Prediction of Abnormal Formation Pressures
P. 152
128 G.V. CHILINGAR, V.A. SEREBRYAKOV, S.A. KATZ AND J.O. ROBERTSON JR.
10.0
8.0
5.0
~ 3.0
<~ 1.0
~ 0.8
II O.5
~ 0.3
0
121
0.1
1000 3000 i
Depth (h), m
'1 * 121 *1 31 ~ I
41,151-!
Fig. 5-1. Relationship between the sealing potential of shales, characterized by the factor k~ and depth (h)
of the seal (caprock) in m. Age of the deposit at the base of the seal being studied: 1 = Miocene; 2 -
Oligocene; 3 = Eocene; 4 -- Upper Cretaceous; and 5 = Lower Cretaceous. (Modified after Dobrynin and
Serebryakov, 1989, fig. 41, p. 93.)
The term
Ah~
I -- (5-2)
(kw/~Z,)
in Eq. 5-1 is related to the isolating ability of the seal and depends on its thickness and
permeability (Fig. 5-1).
The next part of Eq. 5-1"
zcq~
L -- (5-3)
gpwh
mostly reflects the lithology of the geological section and the depth of burial.
The last part of Eq. 5-1"
S- R- Rcr (5-4)
