Burial diagenesis of lower Ismay limestones: Paradox basin

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

OSTI ID:6148437

Dawson, W C

Ismay phylloid algal limestones (upper Paradox formation, Desmoinesian) are major hydrocarbon reservoirs in the Paradox basin. Lower Ismay carbonates have undergone a complex diagenetic history during progressive burial. All porosity (average 15%) is secondary; mesogenetic dissolution is mainly responsible for porosity distribution. Permeability is enhanced by open stylolites and microfractures. Petrographic (polarized, cathodoluminescence, and fluorescence) and carbon/oxygen isotopic data were used to resolve lower Ismay paragenesis: (1) marine (cementation and micritization); (2) meteoric (neomorphism; precipitation of equant, bladed, and syntaxial zoned nonferroan calcites; and dissolution I); (3) mixing-zone/shallow burial (silicification and mechanical compaction); (4) mesogenetic (stylolitization, dissolution II; ferroan calcite and anhydrite cementation, dissolution III; saddle dolomite and fluorite cementation); and (5) oil migration. Post-stylolitization porosity (dissolution II) occurs adjacent to stylolites, indicating that stylolites served as conduits for fluid migration. Post-stylolitization mesogenetic dissolution in phylloid algal limestones has been duplicated experimentally at confining pressures simulating up to 15,000 ft of burial. Optimum reservoir conditions exist where mesogenetic cements (especially anhydrite) have been removed by dissolution III from stylolitized Ismay carbonates. Because phylloid algal carbonates typically have their porosity occluded during early diagenesis, mesogenetic dissolution is essential to reservoir development therein.

• Research Organization: Texaco Exploration and Production Technology Div., Houston, TX (USA)
• OSTI ID: 6148437
• Report Number(s): CONF-890404-
• Conference Information: Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 73:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
DIAGENESIS
DOLOMITE
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
LIMESTONE
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERAL RESOURCES
MINERALS
OXYGEN COMPOUNDS
PARADOX BASIN
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY ROCKS