Page 29 - Reservoir Formation Damage

Mineralogy and Mineral Sensitivity of Petroleum-Bearing Formations 13

Table 2-1
Description of the Authigenic Clay Minerals*

Mineral Chemical Elements* f Morphology
Kaolinite Al 4[Si 40 10](OH) 8 Stacked plate or sheets.
Chlorite (Mg,Al,Fe) 12[(Si,Al) 80 20](OH) 16 Plates, honeycomb,
cabbagehead rosette or fan.
Illite Irregular with elongated
spines or granules.
Smectite (|Ca, NA) 07(A1, Mg, Fe) 4[(Si, Al) g Irregular, wavy, wrinkled
0 20] • nH 20 sheets, webby or honeycomb.
Mixed Illite-Smectite Ribbons substantiated by
Layer Chlorite-Smectite filamentous morphology.
* After Ezzat, ©1990 SPE; reprinted by permission of the Society of Petroleum Engineers.
t After J. E. Welton (1984).

SAND-SIZE
RITAL GRAIN
ISOPACHOUS
RIM CEMENT
PORE THROAT
CEMENT
INTERGRANULAR
PORES

DEFORMED _
MUD FRAGMENT
INTERGRANULAR
PRESSURE - MICROPOROSITY
SOLUTION IN CLAY

INTERGRANULAR
PORE
BODY
Figure 2-2. Description of the constituents in typical sandstone (after Mancini,
1991; reprinted by permission of the U.S. Department of Energy).