ABSTRACT: Geological and Geophysical Evaluation of the Naricual Formation, Musipan-El Carito Area, Eastern Venezuela Basin

Juan Abud, Pablo Oviedo, Jose Hernandex, Eduardo Garcia, Nicolas Escalona

The recent giant oil discoveries in the lower Tertiary sedimentary sequence of the Monagas overthrust belt, Eastern Venezuela basin, require short- and medium-term development plans based on technical production geological studies and models.

The present study consists of a detailed geological and geophysical evaluation to define the reservoir in the producing Naricual Formation in the Musipan-El Carito areas, located west of El Furrial oil field.

Due to its geological and reservoir characteristics, the northern Monagas area is considered as the top priority production alternative for the Venezuelan oil industry for the next 20 yr. The structural pattern of the area is related to major compressional stress applied northwest and from the northeast. Two fault systems are associated with this compression: (1) first-order, east-west-trending reverse faults dipping to the north, and (2) second-order, north-south-trending right-lateral strike-slip faults.

The proposed sedimentological model is that of a paleodelta prograding from north to south. The depositional environment ranges from internal to continental shelf (barrier bars, tidal and distributary channels, lagoonal and associated facies).

The STOIP in the Naricual Formation is 4.8 billion bbls, 52% of which is light-grade oil and 48% is medium-grade oil.

The results of reservoir pressure analyses suggest lateral communication within the Naricual Formation between the Furrial and Musipan areas and give evidence of a permeability barrier between the Furrial-Musipan and El Carito areas. Depth vs. API gravity plots indicate a direct relationship between crude oil type and depth. The production drive for both Musipan and El Carito areas is fluid expansion with average reservoir pressure of 11,200 psi.

The application of the results of the integrated reservoir studies gives precise answers to the production behavior of wells. An adjusted development plan is now under way to guarantee a rational, optimum recovery of the oil reserves.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990