Visualisation of water flooding and subsequent supercritical CO_2 flooding in fractured porous media with permeability heterogeneity using MRI

摘要

Fractured reservoirs form a large percentage of the world’s hydrocarbon reserves. However, in spite of their wide occurrence and huge reserves, the oil recovery from most of these reservoirs is extremely low. CO_2 flooding has proven to be an efficient Enhanced Oil Recovery (EOR) method. This article addresses the use of MRI technique to follow the removal process of oil, water, supercritical CO_2 multiphase flow in fractured artificial consolidated sandstone core with permeability heterogeneity at a typical reservoir temperature and pressure condition. Fluid saturation development was monitored both in the matrix and in the fractures. 2D images at various times and quantitative saturation curves were obtained during all stages of the flooding process. The fronts and interfaces between displaced and displacing fluids were also dynamics monitored in situ during water and subsequent supercritical CO_2 flooding process. The results showed that the oil recovery rate can be determined by porosity, permeability and structure of the core, supercritical CO_2 flooding can enhance oil recovery evidently after the water flooding.