The Effect Of Interlayer Heterogeneity On Enhanced Oil Recovery In Mid-low Permeability Reservoir

For the contradictions and problems such as interlayer interference, monolayer breakthrough, injection-production imbalance and so on which caused by the heterogeneity of the oilfield during its development and oil recovery processes, the status of the impact of reservoir's heterogeneity on the recovery were studied, and the methods of heterogeneity's classification and discrimination were definited. On the basis of the previous research of reservoir's heterogeneity which was absorbed critically, the reservoir heterogeneity was defined as the heterogeneity of the field which controls and influents the fluid flow and distribution in the reservoir. The heterogeneity of the field was divided into two major categories: macro-heterogeneity and micro-heterogeneity, and macro-heterogeneity was divided into inner-heterogeneity, inter-layer heterogeneity and plain-heterogeneity, the research contents and methods of each heterogeneity were analysed respectivly. Three single man-made cores were connected parallelly to simulate two-dimension vertical heterogeneous reservoir, their water flooding recovery were predicted by the classical theory of non-piston-like displacement(Buckley-levererett equation), and 75 experiments whose average permeability is 100×10^-3μm² have been calculated, the results show that: along withthe increase of variation coefficient, there are different trends of enhanced oil recovery: when the variation coefficient is between 0 and 0.4, the extent of enhanced oil recovery is diminishing, while it is between 0.4 and 0.85 the trend is irregular, and when it is larger than 0.85, the trend is not pronounced and the extent of enhanced oil recovery is almost one indefinite number. 15 experiments whose average permeability is 100×10^-3μm² have beenconducted and the results show that: the water flooding recovery is almost the same as the prediction, the extent of enhanced oil recovery by binary flooding is 8-10 percent and the extent of enhanced oil recovery by the low permeable layer is highest among three layers.