Abstract: Reservoir Connectivity in the Carina Field, Tierra Del Fuego, Argentina Appraised Using lsotope Geochemical Analyses of Formation Waters and Calcite Cements

Sommer, Frederic - Total; John J. McBride* - Isotopic Analytical Services Ltd.,UK

The Carina Field is located 80km offshore Tierra Del Fuego, Argentina. Oil and gas is reservoired in the Cretaceous, Springhill/Carina and Paloma Formations which comprise good reservoir quality shallow marine shelf sandstones with localized pervasive calcite cement layers, and interbedded marine mudstones.

Strontium Isotope Residual Salt Analyses (SrRSA) have been performed in 5 wells to investigate vertical and lateral connectivity of the reservoir sequences with particular reference to the barrier potential of the localized calcite cement layers. 87Sr/86Sr, d180 and d13C analyses of the calcite cements have also been performed to investigate the paragenesis of the cements.

The conclusion from the combined SrRSA and Sr-O-C isotope results is that the low permeability argillaceous and carbonate cemented layers present in these wells are likely to be baffles with only localized effect on vertical connectivity at any well location, rather than laterally extensive, sealed barrier features. The SrRSA results are consistent with sedimentological modeling suggesting that lateral facies variations across the field may cause restrictions to lateral connectivity. The SrRSA data suggest that three separate flow units may exist: in the Southwest, North and East of the Carina Field area.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil