Numerical modeling of fluid flow and heat transfer in Kurşunlu geothermal field-KGF (Salihli, Manisa / Turkey)

Authors: ALİ TOYGAR AKAR, ÜNSAL GEMİCİ, ADİLE MELİS SOMAY ALTAŞ, GÜLTEKİN TARCAN

Abstract: Nowadays, the need for energy is increasing more and more. It is more difficult to acquire new resources in various fields than to preserve existing energy resources. Although Turkey is a very rich state in terms of various energy resources, misuse of these resources can even lead to conflicts that may occur between the states in forthcoming years. In today's economic conditions, we can only protect our energy resources with the correct way of management. In this context, it is very important to reveal the mechanisms that make up the geothermal systems, which are very common in Western Anatolia. In this study, how the fluid circulation mechanism in the geothermal system takes place, and under which conditions the infiltrating water is heated in the Kurşunlu geothermal field (KGF) have been examined. FEFLOW software was used in numerical modeling. Fluid flow and heat transfer equations are solved on a twodimensional vertical model using FEFLOW software. A variable-width finite element mesh consisting of 55,590 elements was created in this scope. Since triangular meshes are preferred in vertical models, the mesh produced according to the Delaunay method was used. All lateral boundaries are designed as a no-flow boundary condition. For boundary conditions, hydraulic heads on top of the model and temperature values at both the top and bottom of the model are defined. Additionally, initial values were produced for the entire Kurşunlu geothermal system under steady-state conditions, and a transient model was built to run for 700,000 days. The regional flow direction is towards to the North. The fluids are transmitted deeply and heated through fault zones and transported towards the surface. Convective flows start to form below -1000 m altitudes in the fault zones and in the geothermal aquifer widespread convective flows in deeper regions were formed, while smaller spread convective flows were formed near the surface and shallow depths of the aquifer. In the process of convective flow, heated fluids reach to Kurşunlu region and forms the spring. Finally, two more possible high-temperature areas have been identified, indicating that the flow vectors point to the surface.

Keywords: Geothermal aquifer, groundwater modeling, fluid flow mechanism, Salihli, FEFLOW

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