Study On Measures To Improve Development Effect Of Water-flooded Sandstone Reservoir In Middle And Late Stage

This article mainly studies the distribution and extraction of remaining oil in sandstone reservoirs in the middle and late stages of water flooding.With the development of water flooding,the physical properties of reservoirs change,and the location and mechanism of remaining oil also change.By comparing the displacement effects of water drive and gas drive through long core displacement experiments,the effects of different development methods on recovery were studied.A numerical model was established to study the distribution of residual oil in long core displacement,and the effect of different displacement pressure gradients on residual oil was studied.A nine-point well pattern model is established to study the macroscopic distribution of residual oil in reservoirs with different permeability.Finally,the best measures are selected by comparing and analyzing different measures to improve water flooding effect.The results show that the effect of gas drive is better than that of water drive by comparing the recovery degree of water drive with that of gas drive.The heterogeneity of interlayer permeability and the different production conditions of wells in different positions of well pattern lead to the uneven distribution of remaining oil.Compared with the water flooding effect,gas water alternate flooding improves the displacement efficiency 17.76%,nitrogen foam flooding enhanced oil recovery 10.38%,gas water alternate flooding effect is better.