Experimental Study of Water Flooding in Low Permeability Reservoirs Considering Longitudinal Heterogeneity

The vertical heterogeneity of oil reservoirs with low permeability is the most important reason that restricts the water-drive development effect, which seriously affects the recovery of oil. In order to study the impact of vertical heterogeneity on water-drive development effect of low permeability reservoirs, indoor displacement experiments were carried out by using sand-filled tubes for simulating cores with the permeability in the range of the oil reservoir with low permeability. The experiments were closely focused on the impact of vertical heterogeneity on water-drive development effect of low permeability reservoirs. By using the recovery rate evaluation device, experiments were conducted under different conditions to investigate water-drive development effect of low permeability reservoirs. The influencing laws of permeability ratio, displacement velocity, injection-production pattern on water-drive development were revealed. Experimental results indicate that the larger the permeability ratio, the earlier the water breakthrough. As the displacement velocity increases, the water breakthrough later; the recovery curve increases linearly in the initial stage, then increases slowly, and finally remains stable; as the displacement velocity increases, the recovery decreases; the recovery rate of separate injection and production is the largest, followed by combined injection and production, while the combined injection and separate production has the worst effect.