Characterization of pore structures after ASP flooding for post-EOR

With the global assistance of oil fields entering the stage of improving oil recovery, diversified composite flooding technology has become one of the key research targets. This article takes composite flooding to improve oil recovery as the research object, explores the differential mechanism of crude oil displacement efficiency under water flooding and composite flooding conditions, and elucidates the dynamic evolution characteristics of pore structure before and after composite flooding. Results show that: (a) The permeability and porosity of Daqing oilfield cores have a good correlation. The porosity of cores after water driving and ternary composite driving mainly ranged from 23.6% to 27.4% and 22.8% to 26.8%. The water- driving permeability mainly ranged from 168×10-3 μm2 to 2162×10-3 μm2. Ternary composite driving permeability mainly ranges from 302×10-3 μm2 to 2307×10-3 μm2. (b) Compared with water driving, quartz and clay minerals are corroded by alkali during ternary composite driving. (c) Under the condition of similar permeability, the average pore size of the core after ternary composite driving is smaller than the average pore size after water driving.