[SVC44-P05] Estimation of Temperature and Permeability Distribution in Kakkonda Geothemal Field, Iwate Prefecture, Japan, Using Neural Network
Since permeability along a well is not generally measured, we created a training data of permeability from existing resistivity data, we first estimated permeability along a well based on porosity deduced from resistivity log using the Archie’s law. The temperature dependence of the resistivity of water was corrected at the processing. In addition, we assumed that the salt concentration at each depth was equal to the salt concentration of the collected fluid inclusion. Subsequently, the porosity was converted into the permeability by the Kozeny-Carman equation. Data about D 95 and mineral isograds were also added to the training data to further improve the estimation.
We then estimated temperature and permeability distribution around the target area. For training data, we used temperature logs and the estimated permeability logs using resistivity profiles at the 20 wells. To estimate temperature distribution, we used the 3D resistivity structure made by the MT survey (Yamaya et al., 2017).
The result exhibited that both temperature and permeability show a distribution according to the physical law. As for the temperature, the high temperature part assumed to be a heat source was estimated in the deep part, and the permeability showed high values in the low specific resistance part. With the increase in the types of input data, our method enables to estimate more accurate distribution.