Abstract: The geological conditions of Sichuan gas field are complicated, including obvious low porosity and permeability, a strong heterogeneity, and the fractures having different fracture growing degrees.Because of locally active edge or bottom water, it breaks through into the gas reservoir along larger fractures, making the production of gas wells greatly reduced and the gas wells waterflooded. It also damages gas reservoirs and decreases the recovery factor. It is very important for early water control in aquifer gas reservoirs to use the early production testing data for studying the aquifer behavior and water invasion performance. Based on material balance equations, a new method for prediction of water invasion performance of fractured gas reservoirs is presented in the paper. By this method calculation of water invasion rate by introducing the water invasion factor is avoided. A nonlinear optimization solution procedure is employed and the proposed solution has more improvement than traditional method. A field example is presented that illustrates the capabilities of this water invasion prediction method for the analysis of past performance of fractured and watered reservoirs. Real case study indicates that the method can acquire the aquifer behavior and water invasion performance exactly and the results are useful to the measures for water invasion

Key words: gas reservoir, fracture, water invasion, prediction, material balance equation