DataSheet1_Numerical evaluation of thermal and hydrodynamic effects caused by heat production well on geothermal Phlegraean Fields.PDF

This study describes the geothermal response of the Phlegraean Fields as well as the impact of changes in its thermal and hydrodynamic properties brought on by a deep borehole heat exchanger (DBHE). For this purpose, we have developed a specialized model based on the Galerkin Method (GM) and the iterative Newton–Raphson algorithm to perform a transient simulation of heat transfer with fluid flow in porous media by solving the related system of coupled non-linear differential equations. A two-dimensional domain characterized with an anisotropic saturated porous media and a non-uniform grid is simulated. Extreme characteristics, such as non-uniformity in the distribution of the thermal source, are implemented as well as the fluid flow boundary conditions. While simulating the undisturbed geothermal reservoir and reaching the steady temperature, stream function, and velocity components, a DBHE is placed into the domain to evaluate its impact on the thermal and fluid flow fields. This research aims to identify and investigate the variables involved in the Phlegraean Fields and provide a numerical approach to accurately simulate the thermodynamic and hydrodynamic effects induced in a reservoir by a DBHE. The results show a maximum temperature change of 107.3°C in 200 years of service in the study area and a 65-year time limit is set for sustainable geothermal energy production.

本研究阐述了坎皮佛莱格瑞火山区（Phlegraean Fields）的地热响应，以及深部钻孔换热器（deep borehole heat exchanger，DBHE）引发的该区域热学与流体动力学特性变化所带来的影响。为此，本研究基于伽辽金法（Galerkin Method，GM）与迭代牛顿-拉夫逊算法，开发了一款专用模型，通过求解相关耦合非线性微分方程组，实现多孔介质内流体流动与热传递的瞬态模拟。本次模拟采用二维计算域，其特征为各向异性饱和多孔介质与非均匀网格。研究同时设置了极端特征工况，包括热源分布非均匀性以及流体流动边界条件。在模拟未受扰动的地热储层并达成温度、流函数与速度分量的稳态分布后，本研究向计算域中植入DBHE，以评估其对热场与流场的影响。本研究旨在明确并探究坎皮佛莱格瑞火山区涉及的各类变量，并提供一种数值方法，以精准模拟DBHE在储层中引发的热力学与流体动力学效应。研究结果显示，研究区域在200年服役期内的最高温度变化可达107.3℃，且本研究将可持续地热能源生产的时限设定为65年。