A Numerical Model of Magmatic Hydrothermal System and Its Application to Kuju Volcano, Central Kyushu, Japan

摘要

The objective of this study is to develop a new numerical simulator for the investigation of thermal processes in the high temperature reservoir, which is part of the magmatic hydrothermal system. In this study, the finite difference method (FDM) based on the mass and heat balance equations is used to obtain the pressure and the enthalpy distribution in the reservoir. The derived pressure and enthalpy are used to calculate the other parameters (thermodynamic properties of fluid). These parameters represent the thermal state of the fluid in the reservoir (liquid phase, two phase and superheated steam conditions). The development of the magmatic hydrothermal system is calculated by using the transient flow rate of magmatic water discharged from a magma chamber as a boundary condition at the bottom of the reservoir. This concept is applied to simulate the thermal processes beneath Kuju volcano, central Kyushu, Japan. In the numerical simulation, the initial condition of the reservoir is a liquid phase. Accompanying the development of the reservoir supplied by magmatic water, the fluid phase in the reservoir changes with time from liquid to two phase and superheated state. These processes interpret the development of magmatic hydrothermal system beneath Kuju volcano.