Petrophysical characteristics of the Jurassic Smackover formation, Jay field, Conecuh embayment, Alabama and Florida

Journal Article · Wed Jan 01 04:00:00 EST 1992 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5425307

Melas, F F ^[1]; Friedman, G M ^[2]

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1. City Univ. of New York, NY (United States)
2. Brooklyn Coll., NY (United States)

Detailed petrophysical studies of the Smackover carbonates in the Conecuh embayment, Alabama and Florida, indicate that petrophysical parameters, such as porosity, effective porosity, recovery efficiency, irreducible water saturation, critical pore-throat sizes, pore-throat size distributions, and displacement pressure, reflect the shape of the mercury capillary-pressure curves to which they correspond. The Smackover carbonates of the Conecuh embayment are classified in terms of their capillary-pressure curves into reservoir and nonreservoir petrofacies. The reservoir petrofacies are former moderate-energy to high-energy grainstones, now composed almost exclusively of medium-crystalline sucrosic dolomite. Steeply sloping capillary-pressure curves with flat plateaus correspond to reservoir samples. Porosity consists of diagenetic intercrystalline pores (averaging 15%) exhibiting low irreducible water-saturation values that never exceed 40%. Narrow throat-size distributions (1.1-2.7), large critical throat sizes (2-9 {mu}m), and very low displacement pressures indicate that the pores are homogeneous in size and well interconnected by numerous large pore throats. The nonreservoir petrofacies are former low-energy mudstones and wackestones, now partly composed of finely crystalline dolomite, with small intercrystalline pores and larger moldic, vuggy, and some fracture pores. Gently sloping capillary-pressure curves with steep plateaus or no plateau characterize nonreservoir samples. In general, irreducible water-saturation values for the nonreservoir samples are highly variable (10-90%), as are throat-size distributions (1.2-10) and values of displacement pressure, indicating variable critical throat sizes.

• DOE Contract Number: FG02-85ER13322
• OSTI ID: 5425307
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 76:1; ISSN AABUD; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

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CRYSTAL STRUCTURE
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GEOLOGIC AGES
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WATER SATURATION