TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Furrial field is the most important oil field in the East of Venezuela, with 6880 Millions Barrels of oil initial in place. The initial pressure is 11.000 psi at a depth of 13.800 ft and it has an average temperature of 298°F. To prevent the pressure decline in the reservoir and avoid asphaltene precipitation problems, flank water injection (450 Mbwpd) project was implemented in 1992 and a miscible gas injection scheme initiated in 1998, in the crest of the Naricual Superior reservoir with seven wells injecting a total of 400 MMscfpd. The goal of these projects is to increase the final recovery from the field. Due to the large thickness of the oil column (800 feet), considerable heterogeneity of the reservoir properties and large damage zones (high skin) observed in the producers and injectors wells, the gas-injectors exhibit channeling problems and decrease in injectivity. As a results premature breakthrough of gas in the producing wells is observed through sands of high permeability. This put risks to the oil production and the pressure maintenance program and limits the sweep efficiency of the displacement process. In this paper, techniques and tools used to monitor and control the gas injection are presented. They are used to diagnostic and to correct the problems of injectivity losses and gas channeling problems. The techniques are:1.Control and monitoring at real time of main injection parameters such as heavy component (C3+) and water (H2O) content in the gas injection stream, pressure and temperature of injection stream, injection rates and opening size (%) of flow valve.2. Diagnostic: Flow logging tests, saturation logging tests, chromatographic analysis of produced gas and injection of chemical tracers.3. Preventive measures to eliminate channeling and low injectivity problems such as stepwise perforation, steam tube stimulation, improving gas conformance by applying Multigel, use of sand plugs, etc. Finally, we will present the learned lessons and best practices of the miscible gas injection project in the hope it will serve as a world reference for similar projects.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe Furrial field is the most important oil field in the East of Venezuela, with 6880 Millions Barrels of oil initial in place. The initial pressure is 11.000 psi at a depth of 13.800 ft and it has an average temperature of 298°F. To prevent the pressure decline in the reservoir and avoid asphaltene precipitation problems, flank water injection (450 Mbwpd) project was implemented in 1992 and a miscible gas injection scheme initiated in 1998, in the crest of the Naricual Superior reservoir with seven wells injecting a total of 400 MMscfpd. The goal of these projects is to increase the final recovery from the field. Due to the large thickness of the oil column (800 feet), considerable heterogeneity of the reservoir properties and large damage zones (high skin) observed in the producers and injectors wells, the gas-injectors exhibit channeling problems and decrease in injectivity. As a results premature breakthrough of gas in the producing wells is observed through sands of high permeability. This put risks to the oil production and the pressure maintenance program and limits the sweep efficiency of the displacement process. In this paper, techniques and tools used to monitor and control the gas injection are presented. They are used to diagnostic and to correct the problems of injectivity losses and gas channeling problems. The techniques are:1.Control and monitoring at real time of main injection parameters such as heavy component (C3+) and water (H2O) content in the gas injection stream, pressure and temperature of injection stream, injection rates and opening size (%) of flow valve.2. Diagnostic: Flow logging tests, saturation logging tests, chromatographic analysis of produced gas and injection of chemical tracers.3. Preventive measures to eliminate channeling and low injectivity problems such as stepwise perforation, steam tube stimulation, improving gas conformance by applying Multigel, use of sand plugs, etc. Finally, we will present the learned lessons and best practices of the miscible gas injection project in the hope it will serve as a world reference for similar projects.