Inverse Modeling of Pressure Interference Test Data

a Case Study at the Mori Geothermal Field

Abstract

Injection tests were carried out in 2000 by NEDO (New Energy and Industrial Technology Development Organization) using Well KS-6 at the Mori Geothermal field in Hokkaido, Japan. The pressure interference response at Well NT-303, 460-m apart from the injection well KS-6, was observed. We have conducted inversion analyses of the data using inversion program “DIAGNS”. In addition to conventional line-source models, we assumed point-source models with and without impermeable boundaries. Inversion analysis has been conducted both on the preprocessed interference signals and on the unit response function obtained by the “deconvolution” analysis of the data. As a result, the point-source model with upper and lower impermeable boundaries gives a slightly better estimate than the line-source model. On the basis of the conceptual models, the point source model is preferable, which provides the estimate of the vertical permeability. It is also shown that the quantitative estimation of pressure drift in the data is essential to obtain reliable estimates.