Аннотация:Summary Micro- and macroevaluations were conducted to understand modified-enzyme enhanced-oil-recovery (EOR) mechanisms using various fluids. Huff'n'puff and flooding tests were carried out with variable modified-enzymes concentrations in several reservoirs. The resulting production performances were improved considerably. At reservoir temperature 50 to 80°C, laboratory experiments indicated that the modified enzyme solution was adaptable to both light and heavy oil and was not sensitive to minerals, water with bivalent cation (1000 mg/L), or high salinity (10%). The enzyme working performances were enhanced further with microorganism occurrence in the solution. The micromodeling experiment reveals that spontaneous emulsification and solubilization can take place between the modified enzyme and crude with emulsion particles of 2–6 μm in diameter, which are produced through stripping as a result of solubilization. Core desorption and flooding experiments suggest that desorbed crude volume and displacement efficiency are related to modified-enzyme concentrations that usually ranged from 5 to 10%, with the optimum being 8%. In optimal conditions, recovery can, on average, be increased by 16.9%. Experiments also proved that the modified enzyme and crude oil could form an emulsion, but the emulsion was not stable. One specific pilot test with modified enzyme had achieved additional oil production of 22,869 bbl.
