Effects of provenance on clay diagenesis and porosity in upper Wilcox Formation

Conference · Wed Mar 01 04:00:00 EST 1989 · AAPG Bull.; (United States)

OSTI ID:5798925

Strickler, M E; Ferrell, Jr, R E

The provenance of sediments in the lower Eocene upper Wilcox Group in southeastern Louisiana was studied in 16 conventional cores from the Lockhart Crossing field by using optical, x-ray diffraction, and electron microprobe methods. Detrital clays were a mixture of highly illitic degraded micas, degraded chlorites, and minor kaolinite derived from the weathered metamorphic, plutonic, and sedimentary rocks of the region. The abundance of gneissic, granitic, and metasedimentary rock fragments, detrital IIb chlorites, 1M and 2M micas, and the iron, magnesium, and aluminum ratios of chlorites and muscovites also support the provenance interpretation. Clay diagenesis in the southeast Louisiana Wilcox differs from the typical smectite-illite sequence reported from the western Gulf of Mexico. The montmorillonite (derived from volcanics) deposited in the Wilcox of southwestern Texas was very unstable at greater burial depths and temperatures and reacted to form illite. This reaction in turn provided cations for cements and authigenic clays that usually have detrimental effects on permeability. Early carbonate cementation and later dissolution of these cements are the most important events affecting porosity and permeability in the Wilcox of the Lockhart Crossing field. Diagenetic kaolinite, which formed at the expense of feldspars, rock fragments, and detrital clays, has had little effect on permeability unless redistributed. Iron-rich glauconites and chlorites could potentially be detrimental to porosity and permeability during acidization. In general, clay diagenesis has had only minor harmful effects on the porosity and permeabilities of the Wilcox in the eastern Gulf of Mexico basin, and provenance rather than diagenesis has been more important in determining the present clay mineral assemblage.

• Research Organization: Texaco U.S.A., New Orleans, LA
• OSTI ID: 5798925
• Report Number(s): CONF-890404-
• Conference Information: Journal Name: AAPG Bull.; (United States) Journal Volume: 73:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CENOZOIC ERA
CLAYS
DIAGENESIS
DRILL CORES
EOCENE EPOCH
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
ILLITE
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KAOLINITE
LOUISIANA
MATERIALS
MINERAL RESOURCES
MINERALS
MONTMORILLONITE
NORTH AMERICA
OXYGEN COMPOUNDS
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
TERTIARY PERIOD
USA