Role of pressure in smectite dehydration - effects on geopressure and smectite-to-illite transformation

Journal Article · Sun Nov 01 04:00:00 EST 1987 · AAPG Bull.; (United States)

OSTI ID:6633576

Colten-Bradley, V A

Evaluation of the effect of pressure on the temperature of interlayer water loss (dehydration) by smectites under diagenetic conditions indicates that smectites are stable as hydrated phases in the deep subsurface. Hydraulic and differential pressure conditions affect dehydration differently. The temperatures of dehydration under differential-pressure conditions are inversely related to pressure and interlayer water density. The temperature range for interlayer water loss by smectite under differential-pressure conditions is approximately coincident with the beginning of the smectite-to-illite transformation and hydrocarbon generation. The model presented assumes the effects of pore fluid composition and 2:1 layer with decreasing interlayer water content, increasing pressure and temperature, and changing pore-fluid chemistry may be important in initiating clay and organic matter transformations. Changes in clay stability with interlayer water loss may also be responsible for the different rates of smectite-to-illite transformation observed in interbedded sandstones and shales. 8 figures, 3 tables.

• Research Organization: Geological Survey, Denver, CO (USA)
• OSTI ID: 6633576
• Journal Information: AAPG Bull.; (United States), Journal Name: AAPG Bull.; (United States) Vol. 71:11; ISSN AABUD
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
CLAYS
DIAGENESIS
GEOLOGIC DEPOSITS
MATURATION
MINERAL RESOURCES
PETROLEUM DEPOSITS
POROSITY
PRESSURE DEPENDENCE
RESERVOIR ROCK
RESOURCES