Modeling the Deep Roots of Geothermal Systems

Abstract

This paper discusses the challenges associated with modeling high enthalpy geothermal systems and magmatic intrusions. In reservoir modeling, the heat sources are commonly assumed to be below the model’s depth range and only incorporated into the model by choosing appropriate boundary conditions. However, the heat sources extend up to shallower depths in high enthalpy geothermal systems as indicated by wells that have been drilled into magma or very hot formations. Thus, it is of interest to improve current field scale numerical models by incorporating magmatic intrusions and the entire water circulation into the modeling scheme. A discussion of the difficulties related to modeling high enthalpy systems is provided in this paper. Various flow simulators were studied to find a simulator that could model supercritical conditions caused by the high pressures and temperatures at the deep roots of geothermal systems. A magma chamber was modeled and the thermal transfer between the magma chamber and the hydrostatic reservoir was investigated. The flow simulator cannot describe the system in full detail but the goal is for the model to capture the essence of the system. That way, the ability to answer questions relevant to the field management of magmatic geothermal systems can be improved.