The transient pressure analysis of well test with water-oil two-phase fluid flow

Based on the principle of water-oil phase flow, an integral model is developed for well test with water-oil phase flow. Numerical result of bottom hole pressure is derived from numerical methods. New typical curve on well test analysis of homogeneous reservoirs and fracturing well is developed under water cut influence. The reasons why the pressure derivative curves chang are analyzed. Late pressure derivative curves go down then go up, even though no water is produced from the oil wells when water displaces oil, because the pressure wave reaches the boundary with constant pressure effect initially, then water-oil two-phase flow for the oil reservoir appears when the aquifer moves forward to the oil well. For the well test of oilfield displaced by water, changing pattern of pressure derivative curves determines the movement of aquifer at early stage. When water cut of the fracturing wells is high, even though the pressure derivative curve shows horizontal line, the feature of fracturing crack still exists. There are great difference between two-phase flow model and conventional single-phase flow model for well test curves of the fracturing well in reservoirs.