Print this pageSedimentological Study of Cores and Correlation with Well -Logs, "O" Limestone, Barinas Basin, Venezuela
AQUINO, ROSA, JULIE KUPECZ, LUISA FIGUEROA, MARIA PRIETO, ELIZABETH HERNANDEZ, RODOLFO SALAZAR, and EDUARDO GARCIA
The "O" member of the Upper Cretaceous Escandalosa Formation in the Barinas sub-basin is a predominantly carbonate interval that has been drilled in the majority of the wells in the area, and produces a considerable volume of petroleum. The "O" member is 70 to 80 feet thick and is composed of limestone, dolostone, arenitic dolostone, and calcareous sandstone, intercalated with shales and calcareous shales. Hydrocarbons are produced predominantly from the dolomitized facies.
The depositional setting is interpreted to be a shallow carbonate platform with periods of exposure. Significant surfaces have been identified and are interpreted as sequence boundaries that separate the basal "O" member from the underlying "P" member, and the upper "O" member from the overlying La Morita member of the Navay Formation. Internal surfaces within the low member subdivide it into two depositional cycles or parasequences.
On the basis of core and thin section analyses, sedimentary, lithologic and mineralogical characteristics have been integrated with well logs and extrapolated to wells having logs but no cores. Facies within the "O" Limestone have also been subdivided according to predominant pore types and correlated with production data. Regional mapping provides information on distribution of productive horizons.