An experimental study of the physical and chemical property changes occurring during the smectite to illite reaction

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:425446

Brown, K M; Fitts, T; Tryon, M; Ransom, B ^[1]

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1. Scripps Institution of Oceanography, La Jolla, CA (United States)

Smectite dehydration and the formation of illite releases significant amounts of fluid deep within sedimentary basins. The release of water from smectite and the resulting physical property changes have been linked to the generation of significant overpressures and may also assist in the primary migration of hydrocarbons. Little quantitative data exists, however, as to how chemical and physical property changes may be coupled under in situ stress conditions. Presented here are the initial results from a one dimensional consolidometer system in which a K-smectite was reacted under differential stress conditions at temperatures up to 250{degrees}C. Sample volume, permeability and effluent fluid compositions are monitored through out the experiments. Partial collapse of the K-smectites occurred in all runs, with rapid dehydration apparently taking place at T close to 100{degrees}C. Initial samples were bilayer hydrates in the 0.5M KCI pore fluids used in the experiments. Dilution of the output fluid suggests the loss of two layers of water. Samples heated to <115{degrees}C and were still subsequently expandable, while the samples run at 250{degrees}C showed some irreversible collapse (illitization) after glycolation. Accelerated volumetric creep and permeability reductions occurred during heating increments, with over an order of magnitude reduction in permeability occurring during some runs.

• OSTI ID: 425446
• Report Number(s): CONF-960527--
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
CHEMICAL REACTIONS
DIAGENESIS
FLUID FLOW
HYDROCARBONS
MIGRATION
RESERVOIR ROCK
SEDIMENTARY BASINS
SMECTITE