Experimental investigation of thermal cycling effect on physical and mechanical properties of bedrocks in geothermal fields

Guan, Rong; Peng, Jun; Cai, Ming; Yao, Mengdi; Zhou, Chuangbing; Sha, Song

doi:10.1016/j.applthermaleng.2018.05.126

Cited by 116 publications

(25 citation statements)

References 45 publications

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“…According to the study of Ge [24,25] and Wang et al [40], for the upper loads lower than the fatigue threshold, the rock sample tends to harden when the rock is only subjected to cyclic loading. When the rock is subjected to cyclic temperature only, Rong et al [11] and Fang [18] showed that the mechanical properties of the rock samples deteriorate gradually, and the higher the upper temperature limit, the more significant is the deterioration. Zhou et al [6] compared the results of the study of a rock subjected to either cyclic temperature or cyclic loading with that of basalt under cyclic uniaxial stress and temperature.…”

Section: Discussionmentioning

confidence: 99%

“…Many earlier studies focused on the mechanical properties of rock subjected to either cyclic temperature or cyclic loading, but not both. In recent years, a concern regarding the effect of cyclic temperature on deep rock engineering and geotechnical engineering has arisen [11][12][13][14][15][16][17][18][19][20][21][22]. Some studies sample.…”

Section: Introductionmentioning

confidence: 99%

“…This phenomenon requires further research.Energies 2020, 13, 2061 2 of 17 reported the effect of cyclic temperature on the physical and mechanical properties of rocks. Rong et al [11,12] investigated the influence of thermal cycling on the physical and mechanical properties of rock (i.e., marble and granite) through a uniaxial compression test and conducted microscopic observations to investigate the thermal damage of rock sample induced by the treatment of different thermal cycles. Battaglia et al [15] measured the linear thermal expansion of marbles subjected to thermal cycles utilizing a high-sensitivity apparatus.…”

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Exploratory Experimental Study on the Mechanical Properties of Granite Subjected to Cyclic Temperature and Uniaxial Stress

Zhao

Jin

2020

Energies

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This paper investigates the variation of mechanical properties of granite during temperature and stress cycling, which is an important part of evaluating the long-term thermal and mechanical stability of thermal energy storage. Cyclic temperature and loading tests were conducted where the upper limit of cyclic temperature was 100-600 • C, and the upper stress limits were 70% and 85% of the average uniaxial compressive strength (UCS) at the corresponding temperature. The response of stress-strain characteristics of the granite samples to changes in temperature, and cyclic load upper limit, while the number of temperature and loading cycles was comprehensively analyzed. The results show that the temperature and stress cycles have significant effects on the mechanical properties of granite (i.e., stress-strain curve, strength, elastic modulus, and deformation). The elastic modulus of the sample during loading increases gradually. The strain corresponding to the upper loads of the granite samples decreases with an increasing number of cycles. Additionally, the UCS of samples after 10 cycles at 70% loading stress is greater than that at 85% loading stress. The mechanical properties of samples change dramatically during the first and second cycles at 85% loading stress, whereas at 70% loading stress, the mechanical properties change gradually in the first few cycles, and then tend to stabilize. Cyclic hardening is observed at temperatures below 500 • C, where post cyclic UCS is greater than the uncycled average UCS. This phenomenon requires further research.Energies 2020, 13, 2061 2 of 17 reported the effect of cyclic temperature on the physical and mechanical properties of rocks. Rong et al. [11,12] investigated the influence of thermal cycling on the physical and mechanical properties of rock (i.e., marble and granite) through a uniaxial compression test and conducted microscopic observations to investigate the thermal damage of rock sample induced by the treatment of different thermal cycles. Battaglia et al. [15] measured the linear thermal expansion of marbles subjected to thermal cycles utilizing a high-sensitivity apparatus. Lin et al. [16] investigated the variation of residual strain and micro-crack density of granite with cyclic temperature in the range of 600 • C, and explained the mechanism of permanent deformation caused by micro-cracks from the microscopic perspective. Fang [18] analyzed and compared the effects of mechanical properties of marble subjected to thermal treatment and thermal cycling. They showed that the physical and mechanical properties of rock samples deteriorate gradually with an increasing number of temperature cycles. Further, other researchers considered that the deterioration of the mechanical properties of building materials and engineering structures in cold regions with harsh climatic conditions was due to freeze-thaw cycles [19][20][21].Most of the earlier studies on the effect of cyclic loading on the mechanical properties of rocks did not consider the effect of temperature, i....

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Exploratory Experimental Study on the Mechanical Properties of Granite Subjected to Cyclic Temperature and Uniaxial Stress

Zhao

Jin

2020

Energies

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“…The AE technique is a method which has been proven to be useful to investigate the microcracking behavior of rock specimens during loading [4,17,37]. As pointed out by Eberhardt et al [52], the recorded AE activity was mainly associated with grain boundary movement, dislocations, or closure, initiation, propagation, and coalescence of microcracks along or inside mineral grains.…”

Section: Acoustic Emission Characteristicmentioning

confidence: 99%

“…With increasing energy demand, it is urgent in the present world to exploit new energy resources aside from fossil energy. Geothermal energy is a renewable and environment-friendly energy source which has gained much attention in recent years [1][2][3][4]. In order to exploit and use the geothermal energy efficiently, it is important to comprehensively investigate the mechanical characteristics and the associated thermal cracking mechanism of rocks under/after exposure to high temperature.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Peng

Yang

2018

Energies

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High temperature treatment has a significant influence on the mechanical behavior and the associated microcracking characteristic of rocks. A good understanding of the thermal damage effects on rock behavior is helpful for design and stability evaluation of engineering structures in the geothermal field. This paper studies the mechanical behavior and the acoustic emission (AE) characteristic of three typical rocks (i.e., sedimentary, metamorphic, and igneous), with an emphasis on how the difference in rock type (i.e., porosity and mineralogical composition) affects the rock behavior in response to thermal damage. Compression tests are carried out on rock specimens which are thermally damaged and AE monitoring is conducted during the compression tests. The mechanical properties including P-wave velocity, compressive strength, and Young’s modulus for the three rocks are found to generally show a decreasing trend as the temperature applied to the rock increases. However, these mechanical properties for quartz sandstone first increase to a certain extent and then decrease as the treatment temperature increases, which is mainly attributed to the high porosity of quartz sandstone. The results obtained from stress–strain curve, failure mode, and AE characteristic also show that the failure of quartz-rich rock (i.e., quartz sandstone and granite) is more brittle when compared with that of calcite-rich rock (i.e., marble). However, the ductility is enhanced to some extent as the treatment temperature increases for all the three examined rocks. Due to high brittleness of quartz sandstone and granite, more AE activities can be detected during loading and the recorded AE activities mostly accumulate when the stress approaches the peak strength, which is quite different from the results of marble.

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Geothermo‐mechanical alterations due to heat energy extraction in enhanced geothermal systems: Overview and prospective directions

Ngoma,

Kolawole,

Olorode

2024

Deep Underground Science and Engineering

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Geothermal energy from deep underground (or geological) formations, with or without its combination with carbon capture and storage (CCS), can be a key technology to mitigate anthropogenic greenhouse gas emissions and meet the 2050 net‐zero carbon emission target. Geothermal resources in low‐permeability and medium‐ and high‐temperature reservoirs in sedimentary sequence require hydraulic stimulation for enhanced geothermal systems (EGS). However, fluid migration for geothermal energy in EGS or with potential CO2 storage in a CO2‐EGS are both dependent on the in situ flow pathway network created by induced fluid injection. These thermo‐mechanical interactions can be complex and induce varying alterations in the mechanical response when the working fluid is water (in EGS) or supercritical CO2 (in CO2‐EGS), which could impact the geothermal energy recovery from geological formations. Therefore, there is a need for a deeper understanding of the heat extraction process in EGS and CO2‐EGS. This study presents a systematic review of the effects of changes in mechanical properties and behavior of deep underground rocks on the induced flow pathway and heat recovery in EGS reservoirs with or without CO2 storage in CO2‐EGS. Further, we proposed waterless‐stimulated EGS as an alternative approach to improve heat energy extraction in EGS. Lastly, based on the results of our literature review and proposed ideas, we recommend promising areas of investigation that may provide more insights into understanding geothermo‐mechanics to further stimulate new research studies and accelerate the development of geothermal energy as a viable clean energy technology.

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Experimental investigation of thermal cycling effect on physical and mechanical properties of bedrocks in geothermal fields

Cited by 116 publications

References 45 publications

Exploratory Experimental Study on the Mechanical Properties of Granite Subjected to Cyclic Temperature and Uniaxial Stress

Exploratory Experimental Study on the Mechanical Properties of Granite Subjected to Cyclic Temperature and Uniaxial Stress

Comparison of Mechanical Behavior and Acoustic Emission Characteristics of Three Thermally-Damaged Rocks

Geothermo‐mechanical alterations due to heat energy extraction in enhanced geothermal systems: Overview and prospective directions

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