Design and optimization of multiple wells layout for electricity generation in a multi-fracture enhanced geothermal system

Abstract

The major challenge in Enhanced Geothermal System is to circulate the injected fluid in most part of the reservoir. One solution to this problem is to create artificial fractures in the reservoir and optimally position multiple injection wells and multiple production wells. The wells layout plays a crucial role and requires investigation. This is the ultimate goal of this paper in order to extract a sufficient amount of energy and allow the fluid to reach a larger volume in the heterogeneous reservoir. The results show that a combination of three injection wells with two production wells provides the best performance. With this well layout, the output electrical power drops from 10.40 to 9.40 MW to 6.84–4.53 MW increasing the injection fluid flow rate in 0.075–0.125 m3/s range because higher the volume flow rate, greater the water losses. The average production temperature after a 40-year period is 164.8 °C and reduced by 3.1%, which is acceptable. The injected fluid temperature and the hydraulic gradient have a low influence on the production temperature evolution and the heat extraction ratio change. Hydraulic gradient influence on the production temperature is noticeable for a hydraulic gradient value greater than 10 mm/m.