A Novel and Successful MEOR Pilot Project in a Strong Water-Drive Reservoir Vizcacheras Field, Argentina

Abstract

Abstract The synergy between a novel biotechnological design, streamlines simulation and field-monitoring practices produced successful results in Papagayos formation, a strong water-drive reservoir of Vizcacheras field (Attachment A, Figures 25, 26, 27). Vizcacheras field (8,636 BOPD, 162 producers) located in Cuyo Basin (Mendoza province, Argentine) started producing in 1965, involving two main reservoirs (Papagayos and Barrancas). The 60% of total Vizcacheras production is coming from Papagayos formation, which has a temperature of 198 °F, an average permeability of 1000 mDarcy, an effective porosity of 25% and residual oil saturations of 25%. The Microbial Program started in September 1999 by a systematic inoculation in VI-286 injector using hydrocarbon degrading anaerobic-facultative microorganisms. The project was developed for along 19 months of uninterrupted treatment. The MEOR methodology used a novel approach based on low-rate injector wells serving only as a surface-to-reservoir transport link to introduce periodic batches of nutrients, biocatalyzers and microorganisms into the reservoir to colonize the contacted pore volume. Pre- and Post-MEOR geochemical and rheological evaluations contributed to a better understanding of underlying fluid-rock-biological interactions. Fractional flow alteration in produced fluids has shown a clear improvement: oil increased and water retracted in neighbor producers of treated injector. Three dominant combined mechanisms explain this behavior: 1) further reduction of residual oil saturation by in-situ biosurfactants with low interfacial tension, 2) improved oil mobility from short-chain solvents originated by microbial alteration of heavy paraffinic ends and 3) Conformance efficiency improvement created by the colonizing biomass in active streamtubes that diverts fluids to unflooded zones. MEOR in Papagayos formation increased the oil production rate 20% in average over baselines and the incremental reserves are estimated in 176 MBO. The development cost of the pilot reached 2.87 $/BO and is expected to be lower than this value during future scaled stages. The present work includes an overview of the proposed expansion project, which involves two additional patterns and the current pilot injector.