Julie Kupecz¹, Jehovah Sorondo¹, Leonardo Rojas², Miguel Petito², Rosa Chang¹, Pedro Calderon², Euridice Solorzano¹, Elizabeth Hernandez¹
(1) PDVSA Intevep (EPCT), Los Teques, Venezuela
(2) PDVSA Exploración y Producción, Caracas, Venezuela

Abstract: Quantitative characterization of a mixed carbonate-siliciclastic interval for reservoir simulation: Escandalosa Formation, "O" Member, Barinas-Apure Basin, Venezuela

The "O" Member of the Cenomanian-Turonian Escandalosa Formation (Barinas-Apure Basin, Venezuela) is considered to be a triple-porosity system for dynamic reservoir simulation, with intercrystalline porosity ( ± connected vugs); non-connected vuggy porosity in tight matrix; and fractures.

The "O" member can be subdivided into nine 4-5th order parasequences, from 2-15' thick. Due to the depositional and diagenetic complexity, there is a wide range of pore types. However, by integrating petrographic and mercury injection capillary pressure data, these pore types can be grouped into three families having similar flow characteristics, allowing "flow units" to be interpreted and correlated.

Because of the lithological and diagenetic complexity of these thin parasequences, matrix permeability can vary up to five orders of magnitude, thus having significant implications in well completion and well design. Extreme variation of permeability for a given value of porosity makes prediction of permeability in non-cored wells difficult. However, cross-plots of porosity and permeability by pore type 'family' yield significantly improved correlations. Two benefits arise from the improved correlation: 1) equations from regression analysis for each 'family' allows more accurate prediction of permeability; 2) appropriate porosity-permeability cutoffs for each pore type 'family' allow for more realistic reserves calculations.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana