Interference test analysis method using the Kalman filtering and its application to the takigami geothermal field, Japan

A method to analyze multi-well variable-flowrate interference test data using the line source solution based on an infinite reservoir is described. This presented method employs the Kalman filter technique which provides the best estimates of the reservoir parameters, transmissivity(T) and storativity(S), at every moment when the new pressure value becomes available. Measured pressure data of two observation wells from the interference test conducted for nine months at the Takigami geothermal field, Japan, have been analyzed. The results indicate that the poor initial guesses of parameters will not lead to the divergence of calculations if the ratio of the guesses(S/T) is given to be one or less. The parameter estimation behavior seems to reflect the effects of the faulty pressure data caused by malfunctioning of measurement apparatus and by the fluid flow which dose not satisfy the infinite reservoir model.