Method for calculating production indices of multilayer water drive reservoirs

Based on the dual-phase unstable flow theory of oil and water, the production indices calculating method of multilayer water drive reservoirs are established, which takes the changes of rock permeability and oil viscosity into consideration. The flowing resistance and production pressure drop of every sublayer is taken as the weighting coefficient in the allocation of well productivity. The solution of pressure equation is obtained by the implicit difference equation. And the water saturation is calculated by the streamline model, which enhanced the stability of solution. Using this model the production indices such as water cut and the degree of reserve recovery can be calculated for the development unit of multilayer reservoir at different development stage. The calculation method is applied into field example and the result shows the good agreement with the actual case. This research provides an important measure for the optimization of layers recombination modes.