A Comparative Study of Emulsion Flooding and other IOR Methods for Heavy Oil Fields
- Manoel Leopoldino Rocha De Farias (Petrobras) | Marcio da Silveira Carvalho (PUC-Rio) | Antonio Serra de Souza (Petrobras) | George J. Hirasaki (Rice University) | Clarence A. Miller (Rice U.)
- Document ID
- Society of Petroleum Engineers
- SPE Latin America and Caribbean Petroleum Engineering Conference, 16-18 April, Mexico City, Mexico
- Publication Date
- Document Type
- Conference Paper
- 2012. Society of Petroleum Engineers
- 2.4.3 Sand/Solids Control, 5.4.5 Conformance Improvement, 5.7.2 Recovery Factors, 4.1.2 Separation and Treating, 5.3.2 Multiphase Flow, 5.6.5 Tracers, 5.2.1 Phase Behavior and PVT Measurements, 4.3.4 Scale, 5.4.1 Waterflooding, 2.5.2 Fracturing Materials (Fluids, Proppant), 6.5.2 Water use, produced water discharge and disposal, 5.3.4 Reduction of Residual Oil Saturation, 5.4.7 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex), 5.3.1 Flow in Porous Media, 5.2 Reservoir Fluid Dynamics
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Flooding experiments in sandpacks were performed to investigate the potential use of diluted oil-water macro-emulsions as an EOR agent for viscous oils. The emulsion dispersed phase was the oil in place in the sandpack. Oil recovery factors obtained with emulsion flooding were compared to synthetic sea water injection and surfactant solution injection. Results have indicated a reduction in cumulative water-oil ratio and an increase in oil production after a bank of emulsion was injected. At the appropriate conditions, emulsion oil drops block pores already swept by water flooding, changing the residual oil saturation and mobility of the water phase, and therefore mobilizing oil. The increased volume of oil produced was a function of the drop size of the emulsion. Produced water can be considered as a diluted oil-in-water emulsion. The results presented here suggest the possibility of using an effluent as a resource, after appropriate treatment, in IOR projects.
A Waterflood typically displaces from 50% to 80% of contacted oil. Taking into account the volumetric reservoir sweep efficiency, the average oil recovery is 30% for conventional oils . For heavy oilfields, the unfavorable mobility ratio reduces the range to even lower values. A possible solution is the addition of a thickener to the water phase, such as polymer or any other additives , . This does not mobilize residual oil phase.
On the other hand, emulsion flooding may offer recovery mechanisms based on capillary-driven mobility control that lead to both a reduction in residual oil saturation as well as macroscopic sweep improvement. This, in principle, could be combined with surfactants to further increase recovery, as discussed by Guillen et al. . Emulsions have also been recognized to play an important role in improved oil recovery in steam and ASP projects . Oil-water emulsion can be injected directly into the reservoir. McAuliffe has performed experiments using Berea, Alhambra and Boise sandstones plugs to evaluate the potential use of emulsions as a viscous fingering control method in heavy oilfields . The oil concentrations in these emulsions have varied from 0.5% to 3% (1 µm < oil droplet size < 12 µm). His main conclusions were: a) for the same permeability level, small droplets caused less impairment than large ones; b) Small oil droplets were predominant in the effluent; c) the permeability reduction caused by emulsion was irreversible even after injection of several pore volumes of distilled water. McAuliffe's results motivated an emulsion injection project at Midway-Sunset Oilfield in USA . It was injected 33,000 bbl of oil-in-water emulsion (oil concentration = 14%). The results were monitored through radioactive tracer injection and produced water salinity analysis. These analyses indicated an oil mobilization from unswept reservoir regions, producing an estimated additional oil of 55,000 bbl. Despite the good results, the pilot wasn't expanded.
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