Evaluation method of steam override between injector and producer in steam flooding

Steam flooding shows obvious phased feature.Evaluation of steam override is conducted usually for the whole process of steam flooding without considering the differences in override degree at different steam flooding stages and steam fronts.Based on analysis of the force and velocity of injected steam,an evaluation method of steam override degree at different steam fronts has been obtained by using vertical flow ratio and iterative algorithm.Vertical flow ratio characterizes the ability of regional steam override between injector and producer.The greater the flow ratio is,the stronger the override ability is.Steam override in the middle of injector and producer is much greater than in the regions 20m around injector and producer.The degree of steam override becomes severe with the propagation of steam front.Sensitivity analysis on the factors affecting steam override degree has concluded that the greater the ratio of radial to vertical permeabilities,the smaller the well spacing,the stronger the injection-production intensity,and the higher the pressure gradient is,the lower the degree of steam override would be.The result of numerical simulation on steam chamber geometry and remaining oil distribution is consistent with the theoretical analysis in the paper.