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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 996

Last Page: 996

Title: Geology and Reservoir Distribution, Pinda Formation, Offshore Zaire and Southern Offshore Cabinda: ABSTRACT

Author(s): Richard H. Spaw, Robert P. Koehler

Article Type: Meeting abstract


The Albian-Cenomanian Pinda Formation of offshore Zaire and Cabinda is composed of mixed carbonates and siliciclastics deposited in a transgressive sequence of supratidal, intertidal, and subtidal facies. The Pinda overlies Aptian salts of the Loeme Formation and is unconformably overlain by calcareous shales of the Iabe Formation.

The supratidal sediments were probably deposited on sabkhas, in coastal playas, and by intermittent streams. Intertidal environments included offshore bars, tidal flats, tidal channels, and restricted lagoons. Shallow-water subtidal sediments accumulated on a broad, gently sloping ramp on which a few isolated shoals developed.

A series of north-northwest-trending growth faults, active during and after Pinda deposition, have affected the thickness and attitude of Pinda rocks, influenced the distribution of secondary dolomite, and created both productive and prospective structures.

Pinda reservoirs are primarily dolomites with intercrystalline, moldic and vug porosity, and sandstones with intergranular porosity. Less important are lime packstones and grainstones with interparticle porosity. Facies, dolomitization, distance from source area, and growth faulting control the occurrence and quality of Pinda reservoirs. Thicker, more prospective reservoirs exist on the eastern part of the shelf, where coarser siliciclastics accumulated closer to their source and secondary dolomitization occurred. Production rates in Pinda fields of offshore Zaire reflect the differences between reservoir characteristics in the eastern and western shelf areas.

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