Numerical Simulation Studyon The Factors Of Affecting Oil-water Displacement Efficiencyin Mid-low Permeability Rocks

Oil-water displacement efficiency is one of the main indexes of oilfield development,thus the key to improve it is to study of the factors of it.In the existing literature,the study of water displacement efficiency,are mostly based on the experimental study to qualitatively describe and explain the experimental phenomena and results on different emphasis.But some experimental phenomena haven't been well explained.For example,experiments found that cores of different lengths have some difference in displacement efficiency.Therefore,in this paper,through numerical simulation software the displacement model on core scalesare established.The model is used to conduct a comprehensive research and analysis of the factors.Combined with the methods of laboratory experiment,the method of setting the core interface,the number of grid,basic parameters of the model,relative permeability and capillary pressure and other parametersare determinedrespectively,and then the numerical simulation model on core scalesare established.In the study of water displacement efficiency factors,the effects of core length,displacement pressure gradient and capillary pressure,heterogeneity and perforation operationare studied respectively.The following research methods are used respectively to analysis the influence factors of the oil-water displacement efficiency.Five different lengthsof core are chosen to analyze the influence on the oil-water displacement efficiency.As for the displacement pressure gradient,we choose four displacement pressure gradients to do numerical simulation.In the study of the capillary pressure,the method is todecrease and increase the capillary pressure for ten times.Simulate fracturewith four different locations in the coreare usedto analyze the effect of heterogeneity on displacementefficiency.Two types of perforation are conducted to study the effect of completion method on the displacementefficiency.The results of numerical simulation with different conditions described above areanalyzed and studied systematically,and mechanisms of some experimental phenomena areexplained,which were not very clearly explained in the past.