Electricity generation from a three-horizontal-well enhanced geothermal system in the Qiabuqia geothermal field, China: Slickwater fracturing treatments for different reservoir scenarios

China has hundreds of thousands of oil and water wells, about 30% of which have been abandoned currently. If we can convert abandoned wells into geothermal wells, it will save lots of money and reduce drilling and completion time greatly. In this paper, six enhanced geothermal system (EGS) well layout schemes are proposed based on the utilization of abandoned oil–water wells and common oilfield well pattern. Here six common injection-production well patterns in oilfield are combined to hot dry rock (HDR) production and the heat extraction performance is simulated. The results show that the injection well number and the location of injection wells have critical influence on the heat extraction performance. Under the same total injection mass flow rate, the injection well number is the key factor and the fracture area is the secondary factor on heat extraction when the HDR energy is enough. For electricity generation, the life span is 20.2, 19.2, 19.0, 19.2, 18.2 and 13.9 years, and the heat extraction ratio is 65.83, 57.35, 65.96, 62.79, 59.30 and 43.09% from case 1 to case 6, respectively. For heating demand, the life span is 30.0, 30.0, 29.9, 30.0, 29.8, and 27.7 years, the heat extraction ratio is 78.91, 69.63, 77.02, 75.92, 72.27 and 58.94% from case 1 to case 6, respectively. The total injection mass flow rate and injection temperature also have a negative effect on the heat extraction performance. Case 1 (row parallel well layout), Case 3 (four-spot well layout) and Case 4 (five-spot well layout) are a good choice both for electricity generation and heating demand. This study provides good guidance for the selection and optimization of different EGS well layout.

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Analysis of influencing factors of production performance of enhanced geothermal system: A case study at Yangbajing geothermal field

Energy ◽

10.1016/j.energy.2017.03.100 ◽

2017 ◽

Vol 127 ◽

pp. 218-235 ◽

Cited By ~ 21

Author(s):

Yuchao Zeng ◽

Liansheng Tang ◽

Nengyou Wu ◽

Yifei Cao

Keyword(s):

Influencing Factors ◽

Geothermal Field ◽

Production Performance ◽

Geothermal System ◽

Enhanced Geothermal System ◽

System A ◽

Factors Of Production

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Enhanced Geothermal System Model for Flow through a Stimulated Rock Volume

10.2118/205967-ms ◽

2021 ◽

Author(s):

Leila Zeinali ◽

Christine Ehlig-Economides ◽

Michael Nikolaou

Keyword(s):

Heat Transfer ◽

High Temperature ◽

Power Plant ◽

Horizontal Well ◽

Numerical Models ◽

Horizontal Wells ◽

Geothermal System ◽

Enhanced Geothermal System ◽

Well Pattern ◽

Flow Through

Abstract An Enhanced Geothermal System (EGS) uses flow through fractures in an effectively impermeable high-temperature rock formation to provide sustainable and affordable heat extraction that can be employed virtually anywhere with no need for a geothermal reservoir. The problem is that there is no commercial application of this technology. The three-well pattern introduced in this paper employs a multiple transverse fractured horizontal well (MTFHW) drilled and fractured in an effectively impermeable high-temperature formation. Two parallel horizontal wells drilled above and below or on opposing sides of the MTFHW have trajectories that intersect its created fractures. Fluid injected in the MTFHW flows through the fractures and horizontal wells, thus extracting heat from the surrounding high-temperature rock. This study aims to find the most cost-effective well and fracture spacing for this pattern to supply hot fluid to a 20-megawatt power plant. Analytical and numerical models compare heat transfer behavior for a single fracture unit in an MTFHW that is then replicated along with the horizontal well pattern(s). The Computer Modeling Group (CMG) STARS simulator is used to model the circulation of cold water injected into the center of a radial transverse hydraulic fracture and produced from two horizontal wells. Key factors to the design include formation temperature, the flow rate in fractures, the fractured radius, spacing, heat transfer, and pressure loss along the wells. The Aspen HYSYS software is used to model the geothermal power plant, and heat transfer and pressure loss in wells and fractures. The comparison between analytical and numerical models showed the simplified analytical model provides overly optimistic results and indicates the need for a numerical model. Sensitivity studies using the numerical model vary the key design factors and reveal how many fractures the plant requires. The economic performance of several scenarios was investigated to minimize well drilling and completion pattern costs. This study illustrates the viability of applying known and widely used well technologies in an enhanced geothermal system.

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Geothermal exploitation and electricity generation from multibranch U-shaped well–enhanced geothermal system

Renewable Energy ◽

10.1016/j.renene.2020.10.090 ◽

2021 ◽

Vol 163 ◽

pp. 2178-2189

Author(s):

Youqiang Liao ◽

Xiaohui Sun ◽

Baojiang Sun ◽

Zhiyuan Wang ◽

Jintang Wang ◽

...

Keyword(s):

Electricity Generation ◽

Geothermal System ◽

Enhanced Geothermal System

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

Processes ◽

10.3390/pr7040202 ◽

2019 ◽

Vol 7 (4) ◽

pp. 202 ◽

Cited By ~ 1

Author(s):

Yuchao Zeng ◽

Liansheng Tang ◽

Nengyou Wu ◽

Jing Song ◽

Zhanlun Zhao

Keyword(s):

Energy Efficiency ◽

Pump Power ◽

Electric Power ◽

Electricity Generation ◽

Production Performance ◽

Geothermal System ◽

Enhanced Geothermal System ◽

Slight Effect ◽

Reservoir Heterogeneity ◽

Well Spacing

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.

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