Thermal Stress Effect on Fracture Integrity in Enhanced Geothermal Systems

2018 ◽  
pp. 388-396
Author(s):  
Chao Zeng ◽  
Wen Deng ◽  
Chenglin Wu ◽  
Matt Insall
Keyword(s):  
Thermal Stress ◽  
Enhanced Geothermal Systems ◽  
Stress Effect ◽  
Geothermal Systems

scholarly journals Numerical simulation of hydraulic fracturing in enhanced geothermal systems considering thermal stress cracks

2021 ◽  
Author(s):  
Ziyang Zhou ◽  
Hitoshi MIKADA ◽  
Junichi TAKEKAWA ◽  
Shibo Xu
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Hydraulic Fracturing ◽  
Geothermal Energy ◽  
Confining Pressure ◽  
Numerical Results ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Compression Tests ◽  
High Confining Pressure

Abstract With the increasing attention to clean and economical energy resources, geothermal energy and enhanced geothermal systems (EGS) have gained much importance. For the efficient development of deep geothermal reservoirs, it is crucial to understand the mechanical behavior of reservoir rock and its interaction with injected fluid under high temperature and high confining pressure environments. In the present study, we develop a novel numerical scheme based on the distinct element method (DEM) to simulate the failure behavior of rock by considering the influence of thermal stress cracks and high confining pressure for EGS. We validated the proposing method by comparing our numerical results with experimental laboratory results of uniaxial compression tests under various temperatures and biaxial compression tests under different confining pressure regarding failure patterns and stress-strain curves. We then apply the developed scheme to the hydraulic fracturing simulations under various temperatures, confining pressure, and injection fluid conditions. Our numerical results indicate that the number of hydraulic cracks is proportional to the temperature. At a high temperature and low confining pressure environment, a complex crack network with large crack width can be observed, whereas the generation of the micro cracks is suppressed in high confining pressure conditions. In addition, high-viscosity injection fluid tends to induce more hydraulic fractures. Since the fracture network in the geothermal reservoir is an essential factor for the efficient production of geothermal energy, the combination of the above factors should be considered in hydraulic fracturing treatment in EGS.

scholarly journals Environmentally friendly, rheoreversible, hydraulic-fracturing fluids for enhanced geothermal systems

Geothermics ◽  
2015 ◽  
Vol 58 ◽  
pp. 22-31 ◽  
Author(s):  
Hongbo Shao ◽  
Senthil Kabilan ◽  
Sean Stephens ◽  
Niraj Suresh ◽  
Anthon N. Beck ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Environmentally Friendly ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Fracturing Fluids

scholarly journals Thermal Stress Effect on Density Changes of Hemp Hurds Composites

2016 ◽  
Vol 11 (2) ◽  
pp. 67-76
Author(s):  
Ivana Schwarzova ◽  
Julia Cigasova ◽  
Nadezda Stevulova
Keyword(s):  
Thermal Decomposition ◽  
Thermal Stress ◽  
Composite System ◽  
Gradual Increase ◽  
Bound Water ◽  
Stress Effect ◽  
Original Sample ◽  
Density Reduction ◽  
Filling Agent ◽  
Naoh Solution

Abstract The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

scholarly journals Water Use in Enhanced Geothermal Systems (EGS): Geology of U.S. Stimulation Projects, Water Costs, and Alternative Water Source Policies

2014 ◽  
Author(s):  
C. B. Harto ◽  
J. N. Schroeder ◽  
R. M. Horner ◽  
T. L. Patton ◽  
L. A. Durham ◽  
...  
Keyword(s):  
Water Use ◽  
Water Source ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Alternative Water
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