Smectite dehydration-its relation to structural development and hydrocarbon accumulation in northern Gulf of Mexico basin
A comparison of clay diagenesis data obtained from a study of Tertiary shales from the Brazos-Colorado River system of Texas, the Mississippi River system of Louisiana, and the Niger River system of Nigeria illustrates significant differences in temperature intervals over which smectite diagenesis occurs. The threshold temperature required to initiate diagenesis ranges from about 160/sup 0/F (71/sup 0/C) in Mississippi River sediments to more than 300/sup 0/F (150/sup 0/C) in the Niger delta. Water expelled from smectite into the pore system of the host shale during the process of diagenesis may migrate out of the shale early or may be totally or partially trapped and released slowly through time. In either situation, the water can act as a vehicle for hydrocarbon migration provided hydrocarbons are present in a form and in sufficient quantities to be transported. Observations from the northern Gulf of Mexico basin indicate a close relation between buildup of high fluid pressure and the smectite-illite transformation process. Abnormal pressures exert partial control on the type and quantity of hydrocarbons accumulated because pressure potential determines the direction of fluid flow, and overpressuring partly controls the geometry of growth faults and related folds in basins where shale structures are the dominant type formed. The depths to which growth faults can penetrate and the angle of dip that these faults assume at depth are largely dependent on fluid pressure in the sedimentary section at the time of faulting.
- Research Organization:
- Mobil Research and Development, Dallas, TX
- OSTI ID:
- 6006003
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 68:6; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
ATLANTIC OCEAN
CARIBBEAN SEA
CENOZOIC ERA
CLAYS
DEHYDRATION
DIAGENESIS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GEOLOGY
GULF OF MEXICO
MINERAL RESOURCES
MINERALS
NATURAL GAS DEPOSITS
OXYGEN COMPOUNDS
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
RESOURCES
ROCK-FLUID INTERACTIONS
ROCKS
SANDSTONES
SEAS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SMECTITE
SURFACE WATERS
TECTONICS
TEMPERATURE EFFECTS
TERTIARY PERIOD