Chemostratigraphic, Sedimentologic, and Biostratigraphic Characterization of Carito and Furrial Fields, Northern Monagas, Venezuela

Disnahir Pinto¹ and Carrillo Marta^2
1 PDVSA División Oriente, Puerto La Cruz, Venezuela
² PDVSA-INTEVEP, Los Teques, Venezuela

The Stratigraphic framework of Carito and Furrial fields is uncertain because of its high structural complexity. In consequence, a stratigraphic correlation of high resolution with conventional tools has not been possible. The aim of this work is to enhance the stratigraphic resolution of the Cretaceous-Tertiary sequence of these fields by combining Chemostratigraphy, Biostratigraphy, and Sedimentology.

The mineralogy was determined from 4 wells by the use of X-ray diffraction, the main chemical elements were defined by ICP-AES, while the minor and the trace elements were both determined by ICP-MS. Three major Chemostratigraphic units and 9 minor sequences were defined by Cluster analysis and cumulative frequency curves. A detailed biostratigraphic and sedimentological characterisation was possible from cutting and core analysis.

Three major changes were determined from deflections trends observed in the cumulative frequency curves of the minor, trace, and major elements. In a stratigraphic sense, the first deflection of Cretaceous age, corresponds to the mineralogical change of the argillaceous cement from illite to kaolinite. The second deflection is interpreted as the K/T boundary, and corresponds to a barren biostratigraphic interval, located between Tertiary and Cretaceous sediments. The third major deflection and the 9 minor sequences correspond to paleoclimate changes during the Cretaceous extending into the Tertiary period.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005