Abstract
Vapor-dominated geothermal resources were first exploited for commercial power generation, because of the easiness for utilization, i.e. wells in vapor-dominated geothermal fields produce dry steam alone. Understanding of the resource was improved first by accumulation of field experience, examples and data. Then, several different conceptual models were developed based on interpretations of the data. These conceptual models were tested and validated by numerical modeling, and then evolved into the current form. These processes led to the current understanding of the vapor-dominated geothermal resources. Thus, the key factors which contributed for the improvement are the increase of field data and experiences both in quantity and quality, and the advancement of numerical techniques. Among many vapor-dominated geothermal fields, real natural state of a reservoir has only been confirmed at Matsukawa, to date.
