Enhanced Geothermal System (EGS) has gained great attention since it delivers a geographically disperse, carbon-free energy without the environmental impact. The thermal fracture network also significantly contributes to the energy extraction of EGS. The objective of our EGS model is to evaluate the temperature behavior of the complex fracture network and producing a temperature profile in a natural fractured EGS. Our model can improve the economical evaluation of the EGS system. In this work, a thermal embedded discrete fracture model (Thermal EDFM) is developed to handle the thermal modeling of complex fracture networks. The thermal non-neighbor connections enable us to efficiently simulate the temperature behavior within a massive complex fracture network. Our EGS analysis with our model provides a high-resolution temperature evaluation since we consider the true flow and temperature behavior in each fracture without any upscaling. The thermal reservoir model delivers an accurate heat loss estimation during injecting, flowing through the fracture network, and producing, which benefits the economical evaluation and decision-making process.

1. Introduction

To mitigate the greenhouse gas emissions from oil and gas combustion, low carbon energy has been most researched in recent years. Geothermal energy resource is one of the major renewable energy. The general method to extract energy from a geothermal reservoir is an enhanced geothermal system (EGS). The pioneering exploration of EGS was conducted by the Los Alamos National Laboratory (Smith 1975). The development of EGS includes early exploration and data collection, drilling injection and production wells, reservoir stimulation with hydraulic fracturing, and circulating fluid to extract heat from the geothermal reservoir. The understanding of the geothermal reservoir is usually limited by the high financial cost. There is a heavy demand for accurate prediction of the energy extraction process in the fractured geothermal reservoir to optimize the EGS design and development.

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