Page 128 - Origin and Prediction of Abnormal Formation Pressures

TRANSFORMATIONS
SMECTITE-ILLITE
Pore size
and pore size; average values
Permeability
permeability (k\h)
Porosity
(&,),
Contents of various clay minerals in the Apsheron Archipelago oilfields, variation with depth of porosity
Kaolinite (wm) mD) Mixed-layer Chlorite 5-10 1.7-3.9 Traces 15-20 (1 7.5) (6.5) (2.7) 0-10 0-15 1.3-3.1 Traces (13.0) (2.1) (7.0) 5-20 1.0-2.5 5-15 (7.0) (7.0) (1.6) 0.7-2.0 0-10 0-20 (12.5) (5.5) (1.3) 0-15 0-30 0.5-1.5 (15.5) (5.0) (0.8) 0-10 10-25 (15.5
are shown in parentheses (after Buryakovsky et al., 1995, table 2, p. 208)
Hydromica 35-65 (43.5) 20-40 (35.0) 30-60 (42.0) 10-60 (38.0) 20-65 (39.0) 20-60 (37.5)
Clay-mineral content (%) Montmorillonite 10-45 (32.5) 35-70 (45.0) 15-50 (36.0) 15-70 (40.0) 5-65 (39.0) 5-70 (36.0)

TABLE 4-3 Depth range (m) 1000-2000 2000-3000 30004000 4000-5000 5000-6000 More than 6000 m