Abstract:

The commonly used water flooding characteristic curves are suitable in describing the water flooding laws in the middle-high water cut periods. However, these curves can hardly describe the water flooding characteristics of low and high water cut periods because of their theoretical basis of exponential expression of relative permeability curves and approximation during the derivation process. The applications showed that, for different reservoir characteristics and the water cut rising features, the conventional water flooding curves mighe shew as no straight line in the low water cut period and raise in the high water cut period, which resulted in poor fitting effect. So we proposed a new type of water flooding characteristic curve based on a new kind of widely applicable expression of relative permeability curve. This new curve could accurately describe the production dynamic rules under different water cut stages and directly calculate the recoverable reserves by fitting parameters. Applications showed that, by this method, the fitting straight line appeard earlier, the correlation coefficient was high, and the fitting effect was good. It had good applicability in different water cut stages, could describe the characteristics of water flooding more accurately and could easily predict the recoverable reserves. There was good application value in the dynamic analysis and making the production strategy of oil fields.

Key words: relative permeability, water flooding characteristic curve, low water cut stage, high water cut stage, recoverable reserve