Development prediction and the theoretical analysis in the ultra-high water cut stage for water-flooding sandstone reservoirs

A new relationship between the ratio of water and oil relative permeability, and the water saturation is proposed based on the flow characteristic in porous media in the ultra-high water cut stage which results in a new water flooding characteristic curve with reservoir engineering method. Then a new algorithm to forecast development indexes is derived on the basis of the new relationship above, the new water flooding characteristic curve and the production decline law using Welge equation in which there are many parameters including time, water cut, the average water saturation and the oil recovery that can be used to evaluate the recoverable reserve. Through the examinations with the numerical simulation method and the on-site application, it shows that the new algorithm can give an accurate prediction with an relative error less than 6 %, which is instructive for the oil field development.