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

摘要

The synergy between a novel biotechnological design,streamlines simulation and field-monitoring practicesproduced successful results in Papagayos formation, a strongwater-drive reservoir of Vizcacheras field (Attachment A,Figures 25, 26, 27).Vizcacheras field (8,636 BOPD, 162 producers) located inCuyo Basin (Mendoza province, Argentine) started producingin 1965, involving two main reservoirs (Papagayos andBarrancas). The 60% of total Vizcacheras production iscoming from Papagayos formation, which has a temperatureof 198 °F, an average permeability of 1000 mDarcy, aneffective porosity of 25% and residual oil saturations of 25%.The Microbial Program started in September 1999 by asystematic inoculation in VI-286 injector using hydrocarbondegrading anaerobic-facultative microorganisms. The projectwas developed for along 19 months of uninterruptedtreatment. The MEOR methodology used a novel approachbased on low-rate injector wells serving only as a surface-toreservoirtransport link to introduce periodic batches ofnutrients, biocatalyzers and microorganisms into the reservoirto colonize the contacted pore volume.Pre- and Post-MEOR geochemical and rheological evaluationscontributed to a better understanding of underlying fluid-rockbiologicalinteractions. Fractional flow alteration in producedfluids has shown a clear improvement: oil increased and waterretracted in neighbor producers of treated injector. Threedominant combined mechanisms explain this behavior: 1)further reduction of residual oil saturation by in-situbiosurfactants with low interfacial tension, 2) improved oilmobility from short-chain solvents originated by microbialalteration of heavy paraffinic ends and 3) Conformanceefficiency improvement created by the colonizing biomass inactive streamtubes that diverts fluids to unflooded zones.MEOR in Papagayos formation increased the oil productionrate 20% in average over baselines and the incrementalreserves are estimated in 176 MBO.The development cost of the pilot reached 2.87 $/BO and isexpected to be lower than this value during future scaledstages. The present work includes an overview of the proposedexpansion project, which involves two additional patterns andthe current pilot injector.