Development of a predictive model for corosity distribution in the Smackover Formation of southwest Alabama. Final report, project year 1984-1985

Technical Report · Fri Mar 07 04:00:00 EST 1986

OSTI ID:5401369

Benson, D J

Analyses of samples from 108 cores indicate that the Smackover in southwest Alabama was comprised of seven different depositional lithofacies. Appreciable amounts of depositional porosity were associated only with the oolitic grainstone (30 to 40% porosity), skeletal-peloidal grainstone/packstone (10 to 20% porosity), and algal boundstone (10 to 20% porosity) lithofacies. Depositional porosity was significantly modified by post-depositional diagenesis. Primary porosity was occluded by eogenetic and mesogenetic cementation and significant amounts of mechanical and chemical compaction. Secondary porosity was created by fabric selective eogenetic dissolution, brine reflux dolomitization, and nonfabric selective mesogenetic dissolution. Ultimate porosity is one or a combination of four types: interparticulate, moldic, vuggy, and intercrystalline. Dolomitic intercrystalline porosity, which includes both simple intercrystalline porosity and oversized intercrystalline porosity formed through dissolution of included anhydrite, is the most common pore type in the Smackover of southwest Alabama. Porosity ranges from less than 5 to 22% with permeabilities of less than .1 md to 100 md. Porosity vs depth crossplots show that while porosity does decrease with increased depth, the Smackover in southwest Alabama possesses significant amounts of reservoir grade porosity (>5%) at depths as great as 18,500 feet. In general, porosity in the Smackover of southwest Alabama is most common along the updip margin of the unit and across the paleohighs. The crests and flanks of the paleohighs offer the most promise for future hydrocarbon exploration since intercrystalline, vuggy, and moldic porosity are all common across the paleohighs. 27 refs., 20 figs., 1 tab.

• Research Organization: Alabama Univ., University (USA). Dept. of Geology
• OSTI ID: 5401369
• Report Number(s): NP-6901586; ON: TI86901586
• Country of Publication: United States
• Language: English

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