The Characteristics And Displacement Efficiency Of Chemical Flooding

The theory of 1-D waterflooding performance prediction is mature, however the saturation distribution and displacement efficiency of waterflooding in low permeability reservoir, waterflooding in multilayered reservoirs, polymerflooding and ASPflooding which includes the effect of capillary force are still untouched. Here, we focused on these four types of flooding, analysis their saturation distribution, water cut and displacement efficiency.Firstly, the method to calculate water cut, saturation distribution and displacement efficiency of waterflooding in low permeability reservoir is presented by taking start pressure gradient in to consideration. The case study shows the larger start pressure gradient assumes lower displacement efficiency.Secondly, the model to calculate the displacement efficiency of waterflooding in multilayered reservoirs has been derivate and the case study shows that the factors affect the performance are permeability and height of different layers. The layer with higher permeability assumes better displacement effect. The displacement efficiency of other layers increase lineally before the water breakthrough, which however increase gently after the water breakthrough. The impression of height is not as significant as that of permeability.Thirdly, a novel method was deployed to calculate the displacement efficiency for polymerflooding. This method was based on the improved Blake-Kozeny equation and Buckley-Leverett equation which consider the Non-Newtonian fluid displacement Newtonian fluid. The rheological property of the polymer solution, displacement velocity and the characters of reservoir will dictate the performance of polymerflooding. The case study shows that compared to waterflooding, the water cut slow down and breakthrough recovery improve significantly. Firstly, as consistency coefficient and power law index increases, water cut increasing will be prolonged and breakthrough displacement efficiency improved, however the limited displacement efficiency improved not significant as breakthrough displacement efficiency. Further more, a small velocity always supposes high breakthrough displacement efficiency and slow water cut increasing. And finally polymer flooding is not suitable to improve oil recovery in low permeability reservoirs.Finally, Foaks model is used to establish the displacement equation of waterflooding which includes the effect of capillary force. We conclude that the ration of water viscosity to oil viscosity and no dimensionless capillary force are the key factors that affect the process of ASP flooding. The case study shows the best displacement effect appears when the viscosity equal one. The saturation distribution appears continuity after taking capillary force into consideration. The affect of capillary force appears lower and lower in the process of water injection.The achievement described above can be used to predict the performance of different types of flooding.