3D Conceptual Modeling Based on Geophysical and Geological Information for Targeting Geothermal Prospect Area in Hidden Geothermal System

Abstract

Hidden geothermal system is defined as a geothermal system with lack of surface manifestations. While surface manifestation gives a lot of information about the underlying geothermal system and could assist area targeting during exploration, a lack of such surface indication may complicate the delineation of geothermal system components, such as heat source, cap rock, and reservoir position. Thus area targeting would rely heavily on the interpretation of subsurface survey result, as well as to certain degree on surface data. Area targeting in geothermal is crucial since it is related to risk and financial issues for the next subsequent stages of geothermal project development. Optimum area delineation depends on the availability of data and its quality. All geosciences data need to be combined into one integrated conceptual model for interpretation. A common 2D model limits a complete definition of geothermal body features such as reservoir or clay cap. A 3D model was attempted in this work, based on geological, geophysical and geochemistry information, in order to improve the understanding of geothermal system, hence more guided area targeting process for hidden geothermal prospect. Regional and local geology data, as well as surface structure information, are used to construct the framework of the model. Geophysical data such as gravity, magnetic, and magnetotellurics, as well as surface geochemistry survey was utilized to constrain and infer the position and characteristics of heat source, permeable zone, cap rock, and reservoir body. The result of the 3D model created may improve the conceptual model and understanding of the hidden geothermal system, and make optimum process of area targeting.