--> Abstract: Lithostratigraphic Characterization and Hydrocarbons Distribution in the Oligocene-Miocene Sequence of the Northern Monagas Area, EVB, by A. Gomez, P. Lopez, and B. Ascanio; #91012 (1992).

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ABSTRACT: Lithostratigraphic Characterization and Hydrocarbons Distribution in the Oligocene-Miocene Sequence of the Northern Monagas Area, EVB

GOMEZ, A., P. LOPEZ, and B. ASCANIO,* Corpoven S.A., Puerto La Cruz, Venezuela

Since the discoveries of El Furrial-Musipan and Carito fields in 1985 and 1988, respectively, an important activity in exploration and exploitation has been developed in the new oil province of the Eastern Venezuelan basin, known as Northern Monagas.

Eighty exploratory and outpost wells have been drilled in the area in which the main target is the Naricual Formation, a lower Oligocene-Miocene clastic sequence.

The purpose of this study was to identify and characterize lithostratigraphically the productive sequence as well as to analyze the hydrocarbons distribution in terms of API gravity.

The integration of several disciplines such as biostratigraphy, sedimentology, electrofacies, X-ray diffractometry, petrophysics, and the information of 62 wells allowed us to clearly identify three lithostratigraphics units, as well as to place the pre-Tertiary unconformity, which represents the base of the Oligocene-Miocene sequence.

The characterization of these units was possible using thickness maps, structural maps, net pay sand, total gross sand, sand percentage maps, isoporosity, iso-gas-oil ration, and iso-API gravity maps. Some relevant conclusions can be pointed out from this study: The structural configuration is maintained through the whole sequence, the hydrocarbons accumulations are due to a structural control, the net pay sand/total gross sand ratio is 0.75, the porosity decreases toward the north, the API gravity decreases with depth and increases toward the west, the analysis of the electrofacies and the petrophysics data suggests that there is a vertical communication between the identified units which has been corroborated by later reservoir pressure behavior studies, and there is an inversion of the direction of the clastic source between the identified units.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)