The Appraisal and Development Plan for the Heavy Oil Jubarte Field, Deepwater Campos Basin, Brazil

Abstract

Abstract Heavy oil production from the deepwater Campos Basin, southeastern Brazil, has comprised a new challenge for Petrobras (Pedroso et al., 2003; Pinto et al., 2003a, 2003b; Bruhn et al., 2003). One of the most recent discoveries in the Campos Basin is the Jubarte oilfield, located off the Espirito Santo State, under water depths between 1,000 and 1,500 m, and containing reserves of about 600 million bbl of 17.1° API oil. Jubarte field was discovered in January 2001, when a vertical well found 40 m of oil-saturated, Maastrichtian turbidite reservoirs underlain by a thick aquifer. The well was cased and tested, but the recorded PI showed to be insufficient to guarantee commercial oil production. In order to investigate the actual production potential, the drilling and testing of a 1,076 m-long horizontal well was approved, based on the "Value of Information" approach. The horizontal well recorded a PI 12 times the PI of the vertical well; this proved that it would be possible to produce the Jubarte field heavy oil at commercial flow rates. The appraisal of the area was completed with the additional drilling of two wells. With the same approach, an Extended Well Test, with the horizontal well flowing to an FPSO, was proposed and started operation in October 2002. Again, the obtained production rate was better than the predicted, and the commerciality of the field was declared in December 2002. Based on well log data, core samples, seismic data and interpretation of the extended well test data, stratigraphic and structural analysis were performed, resulting in a complete 3D geological model. Multiphase flow studies and a full field flow model were built, which allowed the forecasting of the field behavior. With a reliable flow model, supported by a complete uncertainty analysis, the development plan for the whole field was defined. To mitigate the production uncertainties, the first phase will consist of 4 wells only, with different lift systems, connected to a FPSO with a processing capacity of 60,000 bopd. In this paper we describe the whole process of the discovery, test, appraisal and definition of the strategy to develop the Jubarte Field. Special emphasis is given on the technological challenges that must be overcome to make possible the development of the oil field containing the heaviest oil ever produced from the deepwater Campos Basin. Introduction Jubarte Field, discovered in January 2001, is located 77 km off the Espirito Santo State coast, southeastern Brazil, under water depths between 1,000 and 1,500 m (Fig. 1). It contains 17.1°API oil, with viscosity of 14.5 cP at the saturation pressure of 183.5 kgf/cm2. The dead oil viscosity at 20 °C is about 3,000 cP, being the most viscous oil at surface conditions ever produced in Brazil through a wet completion system.