Styles of deposition and diagenesis in the Monahans Clear Fork reservoir: Implications for improved characterization of Leonard reservoirs on the Central basin platform

Conference · Wed Apr 01 00:00:00 EST 1992 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6969503

Ruppel, S C ^[1]

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1. Univ. of Texas, Austin (United States)

The Leonard Series (Lower Permian) of west Texas contains a substantial hydrocarbon resource; the original oil in place in these predominantly carbonate rocks totaled about 14.5 billion bbl. Recovery of this resource has proven difficult, however. Current recovery efficiencies average about 20%, far below the 35% average for other Permian basin carbonate reservoirs. Detailed characterization of the Leonard in the Monahans field (Ward and Winkler counties, Texas) illustrates that poor reservoir performance in these reservoirs is the result of extreme lithologic heterogeniety resulting from cyclic rise and fall of relative sea level. Patterns of both depositional and diagenetic facies are a function of this cyclicity. Three orders of cyclicity are apparent in the Leonard: high-frequency, fifth-order cycles averaging 1-2 m in thickness, fourth-order cycles averaging 15-20 m in thickness, and third-order cycles averaging 200 m in thickness. Diagenetic patterns reflect control by fourth-order and third-order cyclicity. Both depositional and diagenetic trends are modified by local topography. Porosity and permeability also manifest cycle-related trends. Porosity and permeability exhibit opposite relationships to paleotopography. Porosity, which is encountered in tidal-flat and subtidal facies, is greatest on paleotopographic highs, whereas permeability, which is most commonly developed in subtidal facies, is most common on paleotopographic lows. Preliminary investigation of Leonard carbonate sequences elsewhere in the Permian basin reveals analogous styles and patterns of facies development. The concepts and models developed in the Monahans field should help improve characterization of these sequences as well.

• OSTI ID: 6969503
• Report Number(s): CONF-9204139-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 76:4; Conference: American Association of Petroleum Geologists (AAPG) Southwest section meeting, Midland, TX (United States), 21-24 Apr 1992; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
PETROLEUM DEPOSITS
DIAGENESIS
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TEXAS
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GEOLOGIC FORMATIONS
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PERMIAN BASIN
PERMIAN PERIOD
POROSITY
RESERVOIR ROCK
DEVELOPED COUNTRIES
FEDERAL REGION VI
GEOLOGIC AGES
GEOLOGIC DEPOSITS
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NORTH AMERICA
PALEOZOIC ERA
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020200* - Petroleum- Reserves
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