No abstract

This paper Summarizes an interdisciplinary study performed to plan final Reservoir Development and Secondary Recovery Strategies for The Carito Field discovered in late 1987. Carito is a very large oil Field located in Northeastern Venezuela, with an estimated Volumetric Oil in Place of 1.8 Billion Stb. Production is mainly from Naricual Formation with a thickness of about 1300 feet in a faulted anticline. At the time of this Study, 25 wells had been drilled below 12200 ft ss. These wells were producing about 90000 Stb/D through 39 completions. Original reservoir pressure was abnormally high (11300 psig at 14040 ft SS) and the Temperature averages 300 degrees Fahrenheit. The field shows a graded fluid system that varies from a gas condensate to a medium oil. Gas cap to oil zone ratio is about 1.2 and crude oil gravity varies with depth from 36 to 21 API degrees. The simulation study, conducted to establish the optimum exploitation strategy, incorporated a detailed geologic model based on seismic, sedimentary environment, and production geologic concepts. The data from the geologic model, routine and special test data from conventional cores, and the data from 58 fluid analysis were consolidated in a numerical reservoir simulator model, which predicted the potential reservoir performance under various Development, Production and Secondary Recovery Planning. The results of this study led us to design a Gas Injection Secondary Recovery Process encompassing a rate injection of 600 MMScf/D through 10 injector wells and the perforation of an additional 16 producer wells. We expect to double the natural depletion oil Recovery as a consequence of the Pressure Maintenance Program. Introduction The Carito Field was discovered in September of 1987 and is located in the State of Monagas, 40 Kms. to the west of its capital Maturin and 500 kIns. to the east of Caracas (fig. 1). The discovery well (MUC-1E) which penetrated Oligocene Naricual formation and reached Cretaceous formation at a depth of 15000 feet, showed an initial production rate of 4000 Stb/D through a completion from the upper part of the Naricual formation. The field has been producing an average of 90000 Stb/D of oil, with a GOR of 1400 Scf/Stb. As of March 1995 the field has accumulated 200 MMStb of oil (11% of IOIP) through 39 completions. This study was performed using a 3D-three phase Black Oil Simulator with the "Volatile Oil" option to represent de gas condensate behavior. P. 587