Displacement efficiency in the water flooding process in fracture–vuggy reservoirs

To determine how fracture–vuggy structure, pressure, and injection–production mode influence displacement efficiency in the water flooding process in fracture–vuggy reservoirs, two types of models were built based on the characteristic of such reservoir: two fracture models with different fracture apertures and two fracture– vuggy models with different sizes of vugs. A series of twophase fluid flow experiments was conducted to study oil and water distribution as well as flow pattern in the water flooding process. Results show that displacement efficiency is significantly influenced by injection–production mode and injection pressure. By contrast, its relationship with the size of vugs is insignificant. Under the same injection– production mode, high-to-low recovery that corresponds to model type includes the small fracture, large fracture, small vug, and large vug models. Under the same pore volume multiple, high-to-low recovery that corresponds to model includes the small fracture, small vug, large fracture, and large vug models.