The Characteristic Research Of Water Flooding In Extra-high Water Cut Stage

At present, most of the oil fields in our country have entered into the extra-high watercut stage, which is an endless development process. The oil recovery can be improved continuously in this stage, but the exploitation difficulty is greater. In this stage, the distribution of remaining oil is more scattered, the distribution condition of oil and water in the porous media is more complicated, and the flow patterns are also more diversified. It is significant for this special development period of water flooding characteristic to carry out further research.Begin from microcosmic physical simulation experiment, the remaining oil microscopic seepage modes and the dominant modes in different watercut stage are summarized. The migration mechanism of every remaining oil microscopic seepage mode is analyzed, and the remaining oil microscopic seepage modes in extra-high watercut stage are emphasized.Using reservoir engineering methods, combining with the oil and water two phase seepage theory and the boundary layer theory, each of flow model of the remaining oil seepage mode is established, the respective microscopic migration equation is deduced. On the basis of capillary seepage model, the unequal radius capillary bundle model is established, each kind of oil and water relative permeability of seepage mode is derived separately, and the relative permeability curve is portrayed. Meanwhile, the factors that influence relative permeability curve are analyzed such as capillary radii, displacement pressure et al.On the basis of the relative permeability formulas, integrating with the remaining oil distribution feature in extra-high watercut stage, a series of combination of different proportion of each remaining oil seepage model is installed, the relative permeability curve when different kinds of residual oil are coexistence is portrayed, and its characteristic is analyzed comparatively.