Profile Control Agent On The Wettability And Fluid Distribution

Profile control is a method that reduces water cutting and enhances oil recovery. Besides good plugging agents ,the reservoir and the processing technology must be researched further in order to make success and get benefit in oil-field application .The three of them should match for each other and shouldn't do one thing and neglect another .This paper studies the gel and sealing characteristics of two different types of profile control agents on condition of the simulated formation, and also studies their adsorption and retention characteristics in the formation and evaluates them . The research demonstrates that the two selected profile control agents can form gel under certain conditions and have very good plugging effect .The plugging ratio is normally above 90% ,and can last for a long time .It still can achieve above 80% when water injection is above 20PV .The profile control agents have absorbability on the surface of rock before they gel .The adsorption power is related to the concentration of profile control agents ,injection rate ,pH value and salinity. Apart from these ,profile control and oil displacement experiment has been done .The oil displacement parameters ,adsorption power ,the variable regularity of wettability and distribution regularity of saturation have also been measured and analyzed .These parameters include recovery efficiency ,residual oil saturation ,water cutting ,injection pressure and so on .The research result demonstrates that the oil displacement effect will improve distinctly ,water cutting ,residual oil saturation and the water phase end-point permeability will reduce ,recovery efficiency and injection pressure will increase after profile control .The higher concentration of the two types of profile control agents ,the bigger margin of water cutting reducing and recovery efficiency enhancing on condition that the injection volumes of profile control agents are the same .The reducing margin of water cutting ,residual oil saturation and water phase end-point permeability before forming gel is bigger than that while forming gel .The higher injection pressure after profile control ,the higher injection pressure and reducing margin of water phase end-point permeability after forming gel than that before forming gel .The increasing margin of recovery efficiency about profile control agent Ⅰbefore forming gel is bigger than that after forming gel ,on the contrary ,the increasing margin of recovery efficiency about profile control agentⅡ before forming gel is smaller than that after forming gel .The rock wettability will change after injecting profile control agents, the rock water-wet exponent will increase, and the hydrophilicity will heighten because the profile control agents adsorb in the rock .The more injection volume and concentration of the profile control agents, the stronger rock hydrophilicity .The changes of rock wettability lead to the changes of water saturation, but the distribution regularity of saturation is consistent with that of waterflood. Compared with the saturation of waterflood, the higher concentration and injection volume of profile control ,the higher water saturation .Under the same conditions ,the water saturation before forming gel is bigger than that after forming gel .With the increasing of distance from the injection side of profile control agents ,water saturation increases .It will decrease when the distance achieves a certain value ,and will approach the saturation of waterflood near the delivery end .