A hybrid optimisation approach to improve long-term performance of enhanced geothermal system (EGS) reservoirs

Abstract

Improving the long-term performance of deep geothermal reservoirs, as an energy source, can lead to a significant increase in efficiency of heat extractions from these assets. This will assist designers, energy firms, managers, and government decision makers to plan and maintain the use of limited available energy resources and hence enhance key sustainable development goals. Enhanced geothermal reservoirs possess a multi-phase behaviour with complex interrelationship between several parameters that makes the analysis and design of these systems challenging. Often, this challenge is increased when taking into consideration the optimum use of the available resources and induced costs during both creation and exploitation phases. This research presents a novel design approach developed to achieve efficiency and improved long-term performance in doublet enhanced geothermal systems (EGS). The proposed approach is based on an optimisation procedure using a numerical hybrid methodology integrating a multi-objective genetic algorithm with finite element analysis of fully coupled thermal hydraulic processes of reservoirs. The results of the optimisation process are discussed in comparison with data available from a benchmark case study. The results demonstrate a significant improvement in the long-term performance of EGS reservoir, both in terms of thermal power and costs when optimised using the proposed methodology.

Large scale simulation of pressure induced phase-field fracture propagation using Utopia

“…Fractures and fracture networks strongly affect the hydraulic and mechanical response of the underground. This is of particular relevance for geothermal technologies, which aim at producing electricity from deep geothermal resources by enhancing the permeability of a geothermal reservoir to obtain a sufficiently large heat flux on interior surfaces (Chen et al 2018;Samin et al 2019). In numerical simulations, realistic fracture networks are usually challenging to represent with a discrete geometry (i.e., a mesh), or even impossible at the macro-scale.…”

Impact of Well Placement in the Fractured Geothermal Reservoirs Based on Available Discrete Fractured System

“…While performing a parametric investigation for a multi-well reservoir, Chen and Jiang [26] found that production well configuration with respect to injection well affects the heat mining potential. Chen et al [27] used a multivariate adaptive regression spline technique coupled with hydrothermal numerical simulation to optimize the well placement under the given fault size, and permeability for a prospective geothermal site near Superstition Mountain in Southern California, USA. They found that for the maximum net profit over a period of fifty years, the optimal well spacing is 473 m at 30.7 kg/s.…”

Multi‐objective Optimization of Geothermal Extraction from the Enhanced Geothermal System in Qiabuqia Geothermal Field, Gonghe Basin

“…However, deep geothermal resources have not been extensively developed due to challenges in technology and economics. An enhanced geothermal system (EGS) has been proposed to extract the heat from the deep earth (Samin, et al, 2019). Previous field experiments and geothermal demonstration projects have proved the concept of EGS but, even so, most EGS projects are abandoned due to inefficient production, huge human input, and uncertain risks (Giardini, 2009).…”

“…Previous field experiments and geothermal demonstration projects have proved the concept of EGS but, even so, most EGS projects are abandoned due to inefficient production, huge human input, and uncertain risks (Giardini, 2009). Rosemanowes geothermal project in the UK was abandoned due to a thermal breakthrough (Samin, et al, 2019). Only one EGS project, the Soultz geothermal field in France, is barely being commercially operated among more than 40 EGS projects so far (Gé rard et al, 2006).…”

“…and major characteristics of the reservoir (average well power, initial resource capacity and recharge). Samin et al (2019) proposed a hybrid optimization approach that integrated finite element and genetic algorithms to improve the longterm performance of EGS reservoirs. The optimal objectives include the thermal power, total cost, and thermal drawdown.…”