Prospects of power generation from an enhanced geothermal system by water circulation through two horizontal wells: A case study in the Gonghe Basin, Qinghai Province, China

Energy Science & Engineering

et al. 2019

Yitong Basin is located in subfrigid zone, and it has a good prospect to use geothermal clean heating. The evaluation of economic efficiency for heating with enhanced geothermal system (EGS) is indispensable. A simplified single‐fracture hydrothermal coupling model with laboratory test is developed in the EGS project to calculate temperature and pressure based on Yitong Basin data. The effects of four factors (K, q, D, and T) on heat production and reservoir characteristics are discussed. The parameters and results of H‐T coupling were applied to economic analysis for heating with EGS from private and social perspectives considering costs and revenues. The results indicate that the combination of laboratory tests (rock physical properties) makes the numerical simulation results more suitable for the study area. The production temperature and heating power will decrease with continuous injection of cold water, and the injection pressure and flow impedance will increase due to the increase in μ/ρ. Four factors (K, q, D, and T) will affect difficulty of fluid injection and reservoir thermal breakthrough, and the high injection rate q may trigger secondary fracturing of reservoir. Heating with EGS in single‐fracture model was uneconomical due to expensive drilling costs. However, heating with EGS can be considered from social perspective based on environment, which can provide advice for decision‐making of the government and business.

Section: Economic Analysis Of Heatingmentioning

confidence: 98%

Economic analysis of heating for an enhanced geothermal system based on a simplified model in Yitong Basin, China

Huang

Energy Science & Engineering

et al. 2019

“…To reduce and eliminate the influence of fossil energy, geothermal power has been considered an aspirational and environmentally safe energy in many countries . According to the literatures, geothermal energy is roughly divided into two categories depending on temperature: high‐temperature geothermal heat resources (>150°C) and low‐medium temperature geothermal heat resources (<150°C). As for low‐medium temperature geothermal heat resources, the combined heat and power (CHP), combined cooling and power (CCP), and combined solar collector and geothermal heat pump systems are the main patterns of geothermal utilization.…”

Section: Introductionmentioning

confidence: 99%

“…The Fenton Hill site was the first tested HDR project in 1974, and the great potential and feasibility of the EGS concept have been heralded to exploit thermal energy after 40 years of engineering testing . Then, the Desert peak and Geysers projects (USA), Rosemanows project (UK), Soultz project (France), Ogachi and Hijiori projects (Japan), Gross Schoenebeck project (Germany), and Cooper Basin project (Australia) were built . It is noteworthy that China occupies 7.9% of the world's geothermal energy reserves, at 3.06 × 10 18 kWh/y, and the HDR resource could reach 2.09 × 10 7 EJ within subsurface 3‐10 km subsurface .…”

Section: Introductionmentioning

confidence: 99%

“…They found that the 2D model is more powerful to solve EGS problems than 3D numerical modeling, and an analytical solution for 2D porous flow was derived. Xu et al performed a numerical model with two horizontal wells for the Gonghe Basin using the local thermal nonequilibrium theory (LTNE) and evaluated the production temperature, energy efficiency, and economic and environmental benefits. The results indicated that the electric power mainly depends on fracture spacing and injection temperature, and the saving in greenhouse gas (GHG) emissions ranged between 0.27 and 0.92 Mt over an operation period of 30 years.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Production capacity and mining plan optimization of fault/fracture‐controlled EGS model in Gonghe Basin

Xie

Energy Science & Engineering

2019

Taking full advantage of geological conditions is beneficial to reduce the development cost and enhance the exploit of geothermal energy in the Gonghe Basin. In this paper, a thermal-hydraulic coupled model is put forward to study the heat extraction for Gonghe Basin based on local thermal nonequilibrium theory considering the natural fault. An excellent heat recovery system and reasonable combination of parameters are the premise of sustainable geothermal development. Two doublet systems are introduced to investigate the efficiency of the fault/fracture-controlled EGS model.A comparative analysis is performed from the aspect of production temperature, heat extraction ratio, flow impedance, injection pressure, thermal power, and electric power. Key parameters (injection rate, injection temperature, production pressure, number of fractures, vertical interval between the two storages, and the storage permeability) are discussed. The results show that the fault-fracture-controlled doublet model is more suitable for EGS to heat transfer than the common doublet model. The doublet model at a depth of 3300-3800 m has a temperature gradient of 0.04°C/m.For fault-fracture-controlled EGS model, the optimal values are 50 kg/s, 15 MPa, 60°C, 310 m, 4 × 10 −14 m 2 , and two for injection rate, production pressure and injection temperature, vertical interval, storage permeability, and fracture number, respectively. The best well pattern layout method for the Gonghe Basin is one injection well and two production wells. The production temperature varies from 196.8°C to 192.7°C when the heat extraction ratio is 0.13 at the end of the operation. Thus, the fault-fracture-controlled EGS model can provide a mining method and advance the development of geothermal energy for the Gonghe Basin in the future. K E Y W O R D Senhanced geothermal system, fault/fracture-controlled model, local thermal nonequilibrium, parameter optimization | 2967 ZHANG et Al.

“…Borgia et al used the MINC method to analyze salt precipitation in the fractures of a CO 2 -EGS [31]. Xu et al used the MINC method to calculate the power generation potential of an EGS by water circulating through two horizontal wells in the Gonghe Basin geothermal field [32]. Zeng et al employed the MINC method to compute the electricity generation potential at the Yangbajing geothermal field [33].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Influence of Reservoir Heterogeneity on Electricity Generation Performance of Enhanced Geothermal System

Zeng

Tang

et al. 2019

Processes

The enhanced geothermal system (EGS) reservoir consists of a heterogeneous fracture network and rock matrix, and the heterogeneity of the reservoir has a significant influence on the system’s electricity generation performance. In this study, we numerically investigated the influence of reservoir heterogeneity on system production performance based on geological data from the Gonghe Basin geothermal field, and analyzed the main factors affecting production performance. The results show that with the increase of reservoir heterogeneity, the water conduction ability of the reservoir gradually reduces, the water production rate slowly decreases, and this causes the electric power to gradually reduce, the reservoir impedance to gradually increase, the pump power to gradually decrease and the energy efficiency to gradually increase. The fracture spacing, well spacing and injection temperature all have a significant influence on electricity generation performance. Increasing the fracture spacing will significantly reduce electric power, while having only a very slight effect on reservoir impedance and pump power, thus significantly decreasing energy efficiency. Increasing the well spacing will significantly increase the electric power, while having only a very slight effect on the reservoir impedance and pump power, thus significantly increasing energy efficiency. Increasing the injection temperature will obviously reduce the electric power, decrease the reservoir impedance and pump power, and thus reduce energy efficiency.