抄録
Well head pressure in geothermal field generally increases to its maximum after shut-in valve. The maximum well head pressure, which is controlled by fluid temperature of the after flow from reservoir to well bore, is mathematically estimated based on energy balance and mass balance equations for well volume. Well head pressures measured in the Sumikawa geothermal field quite match to the vapor phase pressure simulated in upper part of well bore. Pressure fluctuation after shut-in valve is also explained by difference of fluid temperature and density between the bore hole and the reservoir in case of multiple feed point exist. This simulator is effective to design the flow casing and the well head equipments.
