2D modeling of well array operating enhanced geothermal system

Abstract

In this paper, the concept of well array operating enhanced geothermal system (EGS) is proposed in response to the existing challenges in EGS commercialization. A well array operating EGS is characterized by well sharing, which substantially reduces drilling cost and maximizes mass flow rate. Following a thorough discussion of conditions for representing an EGS by a 2D model, the life time performance of a well array operating EGS is investigated based on 2D finite element modeling. The accuracy of the presented numerical results is quantified by systematic tests of mesh, element order and time step dependence, and by direct comparison with an analytical solution for 2D porous flow, which is derived in the paper as well. This paper demonstrates that 2D modeling is not only capable of accurately solving a wide range of EGS problems at low computational cost, but also a powerful tool for quantitatively estimating 3D numerical modeling errors, which are usually not adequately addressed in previous studies. The modeling results of the well array operating EGS presented in this paper may serve as a benchmark for testing future EGS models.