scholarly journals Evaluation of CO2-Fluid-Rock Interaction in Enhanced Geothermal Systems: Field-Scale Geochemical Simulations

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Feng Pan ◽  
Brian J. McPherson ◽  
John Kaszuba
Keyword(s):  
High Pressures ◽  
Mineral Dissolution ◽  
Heat Extraction ◽  
Working Fluid ◽  
Enhanced Geothermal Systems ◽  
Geochemical Processes ◽  
Geothermal Systems ◽  
Rock Interaction ◽  
Transmission Fluid ◽  
Dissolution And Precipitation

Recent studies suggest that using supercritical CO2 (scCO2) instead of water as a heat transmission fluid in Enhanced Geothermal Systems (EGS) may improve energy extraction. While CO2-fluid-rock interactions at “typical” temperatures and pressures of subsurface reservoirs are fairly well known, such understanding for the elevated conditions of EGS is relatively unresolved. Geochemical impacts of CO2 as a working fluid (“CO2-EGS”) compared to those for water as a working fluid (H2O-EGS) are needed. The primary objectives of this study are (1) constraining geochemical processes associated with CO2-fluid-rock interactions under the high pressures and temperatures of a typical CO2-EGS site and (2) comparing geochemical impacts of CO2-EGS to geochemical impacts of H2O-EGS. The St. John’s Dome CO2-EGS research site in Arizona was adopted as a case study. A 3D model of the site was developed. Net heat extraction and mass flow production rates for CO2-EGS were larger compared to H2O-EGS, suggesting that using scCO2 as a working fluid may enhance EGS heat extraction. More aqueous CO2 accumulates within upper- and lower-lying layers than in the injection/production layers, reducing pH values and leading to increased dissolution and precipitation of minerals in those upper and lower layers. Dissolution of oligoclase for water as a working fluid shows smaller magnitude in rates and different distributions in profile than those for scCO2 as a working fluid. It indicates that geochemical processes of scCO2-rock interaction have significant effects on mineral dissolution and precipitation in magnitudes and distributions.

scholarly journals Longevity of Enhanced Geothermal Systems with Brine Circulation in Hydraulically Fractured Hydrocarbon Wells

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 63
Author(s):  
Zuo ◽  
Weijermars
Keyword(s):  
Limit State ◽  
Extraction Process ◽  
Heat Extraction ◽  
Working Fluid ◽  
Heat Equations ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Geothermal Heat ◽  
Horizontal Fracture ◽  
Rock Temperature

A simple, semi-analytical heat extraction model is presented for hydraulically fractured dry reservoirs containing two subparallel horizontal wells, connected by a horizontal fracture channel, using injected brine as the working fluid. Heat equations are used to quantify the heat conduction between fracture walls and circulating brine. The brine temperature profiles are calculated for different combinations of fracture widths, working fluid circulation rates, and initial fracture wall temperatures. The longevity of the geothermal heat extraction process is assessed for a range of working fluid injection rates. Importantly, dry geothermal reservoirs will not recharge heat by the geothermal flux on the time scale of any commercial heat extraction project. A production plan is proposed, with periodic brine circulation maintained in a diurnal schedule with 8 h active production alternating with 16 h of pump switched off. A quasi-steady state is achieved after both the brine temperature and rock temperature converge to a limit state allowing fracture-wall reheating by conduction from the rock interior in the diurnal production schedule. The results of this study could serve as a fast tool for assisting the planning phase of geothermal reservoir design as well as for operational monitoring and management.

Enhanced Geothermal Systems Projects and its Potential for Carbon Storage

2013 ◽  
Vol 732-733 ◽  
pp. 109-115 ◽  
Author(s):  
Chao Yin Feng
Keyword(s):  
Carbon Dioxide ◽  
Power Plants ◽  
Subsurface Water ◽  
Working Fluid ◽  
Low Permeability ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Geothermal Fields ◽  
Geological Conditions ◽  
Geothermal Wells

Enhanced Geothermal Systems represent a series of technology, which use engineering methods to improve the performance of geothermal power plant. In some geothermal fields, the rocks are in high temperature but a low permeability, or the subsurface water is scarce. In these geological conditions, cool water was injected into the geothermal wells to fracture the tight rock and create man-made reservoir for thermal exploitation. Furthermore, these engineering methods can be utilized to improve the productivity of pre-existing hydrothermal power plants. To save water and treat the global warming, using carbon dioxide instead of water as working fluid was proposed. Numerical simulation reveals that the carbon dioxide has numerous advantages over water as working fluid in the heat mining process. The precipitation caused by carbon dioxide will restore part of carbon dioxide in the rock and reduce the micro-seismicity risk.

Analysis of influencing factors of heat extraction from enhanced geothermal systems considering water losses

Energy ◽  
2016 ◽  
Vol 115 ◽  
pp. 274-288 ◽  
Author(s):  
Wen-Long Cheng ◽  
Chang-Long Wang ◽  
Yong-Le Nian ◽  
Bing-Bing Han ◽  
Jian Liu
Keyword(s):  
Influencing Factors ◽  
Heat Extraction ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Water Losses

Numerical investigations of CO2 and N2 miscible flow as the working fluid in enhanced geothermal systems

Energy ◽  
2020 ◽  
Vol 206 ◽  
pp. 118062
Author(s):  
Jiawei Li ◽  
Wanju Yuan ◽  
Yin Zhang ◽  
Claudia Cherubini ◽  
Alexander Scheuermann ◽  
...  
Keyword(s):  
Working Fluid ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Numerical Investigations ◽  
Miscible Flow

Simulation of heat extraction from CO2-based enhanced geothermal systems considering CO2 sequestration

Energy ◽  
2018 ◽  
Vol 142 ◽  
pp. 157-167 ◽  
Author(s):  
Chang-Long Wang ◽  
Wen-Long Cheng ◽  
Yong-Le Nian ◽  
Lei Yang ◽  
Bing-Bing Han ◽  
...  
Keyword(s):  
Co2 Sequestration ◽  
Heat Extraction ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems

scholarly journals Design, modeling, and evaluation of a doublet heat extraction model in enhanced geothermal systems

2017 ◽  
Vol 105 ◽  
pp. 232-247 ◽  
Author(s):  
Yidong Xia ◽  
Mitchell Plummer ◽  
Earl Mattson ◽  
Robert Podgorney ◽  
Ahmad Ghassemi
Keyword(s):  
Heat Extraction ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Extraction Model

scholarly journals Thermo-hydro-mechanical modelling study of heat extraction and flow processes in enhanced geothermal systems

2021 ◽  
Vol 54 ◽  
pp. 229-240
Author(s):  
Dejian Zhou ◽  
Alexandru Tatomir ◽  
Martin Sauter
Keyword(s):  
Production Rate ◽  
Flow Rate ◽  
Heat Production ◽  
Analytical Solutions ◽  
Pressure Difference ◽  
Heat Extraction ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Fracture Zones ◽  
Heat Production Rate

Abstract. Enhanced Geothermal Systems (EGS) are widely used in the development and application of geothermal energy production. They usually consist of two deep boreholes (well doublet) circulation systems, with hot water being abstracted, passed through a heat exchanger, and reinjected into the geothermal reservoir. Recently, simple analytical solutions have been proposed to estimate water pressure at the abstraction borehole. Nevertheless, these methods do not consider the influence of complex geometrical fracture patterns and the effects of the coupled thermal and mechanical processes. In this study, we implemented a coupled thermo-hydro-mechanical (THM) model to simulate the processes of heat extraction, reservoir deformation, and groundwater flow in the fractured rock reservoir. The THM model is validated with analytical solutions and existing published results. The results from the systems of single fracture zone and multi-fracture zones are investigated and compared. It shows that the growth of the number and spacing of fracture zones can effectively decrease the pore pressure difference between injection and abstraction wells; it also increases the production temperature at the abstraction, the service life-spans, and heat production rate of the geothermal reservoirs. Furthermore, the sensitivity analysis on the flow rate is also implemented. It is observed that a larger flow rate leads to a higher abstraction temperature and heat production rate at the end of the simulation, but the pressure difference may become lower.

Heat Flux to Fluids Within a Rock Fracture in a Geothermal System

2010 ◽  
Author(s):  
Dustin Crandall ◽  
Goodarz Ahmadi ◽  
Grant Bromhal
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Rate ◽  
Numerical Study ◽  
Rock Fracture ◽  
Working Fluid ◽  
Geothermal System ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Ct Scanner

Fractures in rocks enable the motion of fluids through the large, hot geologic formations of geothermal reservoirs. The heat transfer from the surrounding rock mass to the fluid flowing through a fracture depends on the geometry of the fracture, the fluid/solid properties, and the flow rate through the fracture. A numerical study was conducted to evaluate the changes in heat transfer to the fluid flowing through a rock fracture with changes in the flow rate. The aperture distribution of the rock fracture, originally created within Berea sandstone and imaged using a CT-scanner, is well described by a Gaussian distribution and has a mean aperture of approximately 0.6 mm. Water was used as the working fluid, enabling an evaluation of the efficiency of heat flux to the fluid along the flow path of a hot dry geothermal system. As the flow through the fracture was increased to a Reynolds number greater than 2300 the effect of channeling through large aperture regions within the fracture were observed to become increasingly important. For the fastest flows modeled the heat flux to the working fluids was reduced due to a shorter residence time of the fluid in the fracture. Understanding what conditions can maximize the amount of energy obtained from fractures within a hot dry geologic field can improve the operation and long-term viability of enhanced geothermal systems.

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