Diagenetic heterogeneity and reservoir quality: Fluvial, deltaic, and turbiditic sandstone reservoirs, Potiguar and Reconcavo rift basins, Brazil
- Cidade Universitaria, Rio de Janeiro (Brazil)
- Univ. of Wyoming, Laramie (United States)
Fluvial and lacustrine (deltaic and turbiditic) sandstones are major hydrocarbon reservoirs in the onshore Potiguar and Reconcavo rift basins in northeastern Brazil. Diagenetic elements including mechanically infiltrated (MI) clay, calcite, dolomite, and chlorite show distinct distribution patterns at interwell and field-wide reservoir scales. At the interwell scale, relationships between sandstone body geometry and the distribution of diagenetic elements are a critical aspect of reservoir heterogeneity. At this level, (1) MI clay concentrations occur in fluvial reservoirs following the orientation of paleochannels, generating strong compartmentalization of the reservoirs, (2) calcite cement appears either concentrated near sand-shale contacts (peripheral distribution) or dispersed in the interior of the sandstone layers (scattered distribution), (3) dolomite cement may appear concentrated along laminations in cross-stratified sandstones, causing a decrease in the effective horizontal permeability, and (4) authigenic chlorite is observed to reduce the permeability in fine-grained sandstones than in coarse-grained sandstones. An effect that may cause important modifications in the permeability structure of the reservoirs. Diagenetic heterogeneity includes (1) stratigraphic zonation of diagenetic properties in fluvial reservoirs, (2) increasing carbonate cementation toward the border of the hydrocarbon accumulations in deltaic reservoirs, and (3) distinct patterns of carbonate cementation observed in channel fills and lobes in turbiditic reservoirs. Incorporating the distribution and effects of diagenetic elements into the interwell and field-wide geological modeling is essential to achieve a realistic reservoir representation. Such incorporation is performed by the integration of diagenetic properties with other geological attributes improving reservoir quality evaluation and leading to more precise prediction of reservoir performance. 32 refs., 15 figs., 1 tab.
- OSTI ID:
- 6103835
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:7; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
BRAZIL
CALCITE
CARBONATE MINERALS
COASTAL REGIONS
CRETACEOUS PERIOD
CURRENTS
DEVELOPING COUNTRIES
DIAGENESIS
DISTRIBUTION
DOLOMITE
FRESH WATER
GEOLOGIC AGES
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
HYDROCARBONS
HYDROGEN COMPOUNDS
LATIN AMERICA
MESOZOIC ERA
MINERALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PERMEABILITY
RESERVOIR ROCK
RIFT ZONES
RIVER DELTAS
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SOUTH AMERICA
WATER
WATER CURRENTS