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A simple model to represent damage and fracturing in rock salt caused by heating and subsequent cooling: Understanding brine inflow data from the Brine Availability Test in Salt (BATS)
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-02-07 DOI: 10.1016/j.gete.2025.100646
Claire Watson , Steven Benbow , Alexander Bond , Simon Norris , Sam Parsons
Salt deposits are being considered in several countries as potential host rocks for deep geological disposal facilities (GDFs) for radioactive waste. Although the very low porosity and lack of water content are favorable properties of salt that make it well-suited for this purpose, brine is present in amounts that are not insignificant when considering potential corrosion of waste canisters and pathways for radionuclide migration. It is therefore important to understand the processes and mechanisms that can cause brine to flow into the GDF. In this paper a relatively simple model is described that represents damage and fracturing in rock salt caused by heating and subsequent cooling. The model is used to simulate brine inflow to a heated borehole, using data from the Brine Availability Test in Salt (BATS) which was carried out at the Waste Isolation Pilot Plant (WIPP) in New Mexico, USA. Key characteristics of BATS and other, similar, experiments are increased brine production during periods of elevated temperature and a very large but short-lived increase shortly after the heat source is removed. The latter is not directly relevant to the disposal of heat-generating radioactive waste, where the heat source will gradually diminish over time, but the ability to simulate this phenomenon demonstrates an understanding of the coupled thermo-hydro-mechanical (THM) processes that operate in salt-based systems. The modelling demonstrates that a certain level of complexity is needed (such as the inclusion of viscoplastic effects and damage) to capture the key behaviors, but complexity can be tailored to the purposes of the study. In this case, a 1D model and a simple representation of the damage directly linked to permeability change was sufficient to gain a detailed understanding of the system. This includes the importance of the excavation damage zone (EDZ) in controlling the availability of brine.
{"title":"A simple model to represent damage and fracturing in rock salt caused by heating and subsequent cooling: Understanding brine inflow data from the Brine Availability Test in Salt (BATS)","authors":"Claire Watson ,&nbsp;Steven Benbow ,&nbsp;Alexander Bond ,&nbsp;Simon Norris ,&nbsp;Sam Parsons","doi":"10.1016/j.gete.2025.100646","DOIUrl":"10.1016/j.gete.2025.100646","url":null,"abstract":"<div><div>Salt deposits are being considered in several countries as potential host rocks for deep geological disposal facilities (GDFs) for radioactive waste. Although the very low porosity and lack of water content are favorable properties of salt that make it well-suited for this purpose, brine is present in amounts that are not insignificant when considering potential corrosion of waste canisters and pathways for radionuclide migration. It is therefore important to understand the processes and mechanisms that can cause brine to flow into the GDF. In this paper a relatively simple model is described that represents damage and fracturing in rock salt caused by heating and subsequent cooling. The model is used to simulate brine inflow to a heated borehole, using data from the Brine Availability Test in Salt (BATS) which was carried out at the Waste Isolation Pilot Plant (WIPP) in New Mexico, USA. Key characteristics of BATS and other, similar, experiments are increased brine production during periods of elevated temperature and a very large but short-lived increase shortly after the heat source is removed. The latter is not directly relevant to the disposal of heat-generating radioactive waste, where the heat source will gradually diminish over time, but the ability to simulate this phenomenon demonstrates an understanding of the coupled thermo-hydro-mechanical (THM) processes that operate in salt-based systems. The modelling demonstrates that a certain level of complexity is needed (such as the inclusion of viscoplastic effects and damage) to capture the key behaviors, but complexity can be tailored to the purposes of the study. In this case, a 1D model and a simple representation of the damage directly linked to permeability change was sufficient to gain a detailed understanding of the system. This includes the importance of the excavation damage zone (EDZ) in controlling the availability of brine.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100646"},"PeriodicalIF":3.3,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143396010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Discrete fracture network model benchmarks developed and applied in a DECOVALEX-2023 repository performance assessment study
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-02-05 DOI: 10.1016/j.gete.2025.100647
Paul E. Mariner , Rosie C. Leone , Emily R. Stein , Jeffrey D. Hyman , Jan Thiedau , Zhenze Li , Son Nguyen , Yong-Min Kim , Jung-Woo Kim , Chieh-Chun Chang , Scott A. Briggs , Mark Gobien , Ondrej Mikláš , Nicholas I. Osuji , Auli Niemi
This study presents newly developed benchmarks for modeling flow and transport within discrete fracture networks (DFNs) and useful methods for analyzing the results. The new benchmarks are designed to test modeling approaches for use in probabilistic performance assessment models of deep geologic repositories in fractured rock. The benchmarks simulate flow and transport through a 1 km³ block of fractured rock. The first simulates migration of a short pulse of tracer through a simple network of four intersecting fractures. The second adds 1089 stochastically generated fractures. The third changes the pulse to a continuous point source. Evaluation of model performance relies on moment analysis and comparison of the results of different models. The expected nondimensional first moment of the conservative tracer for each benchmark is 1. The benchmarks were simulated by teams from Canada, Czechia, Germany, Korea, Sweden, Taiwan, and the United States as part of a DECOVALEX-2023 study (decovalex.org). The teams used various approaches, including explicit DFN modeling, DFN upscaling to an equivalent continuous porous medium (ECPM), and a combination of both methods. Transport mechanisms are modeled using either the advection-dispersion equation or particle tracking. Results demonstrate strong agreement among the models in breakthrough behavior up to the 75th percentile. Significant deviations in first moments and well-clustered outputs led to the identification of inaccuracies in several models. Such findings exemplify the benefit of exercising these benchmarks and using the presented methods to test DFN flow and transport models.
{"title":"Discrete fracture network model benchmarks developed and applied in a DECOVALEX-2023 repository performance assessment study","authors":"Paul E. Mariner ,&nbsp;Rosie C. Leone ,&nbsp;Emily R. Stein ,&nbsp;Jeffrey D. Hyman ,&nbsp;Jan Thiedau ,&nbsp;Zhenze Li ,&nbsp;Son Nguyen ,&nbsp;Yong-Min Kim ,&nbsp;Jung-Woo Kim ,&nbsp;Chieh-Chun Chang ,&nbsp;Scott A. Briggs ,&nbsp;Mark Gobien ,&nbsp;Ondrej Mikláš ,&nbsp;Nicholas I. Osuji ,&nbsp;Auli Niemi","doi":"10.1016/j.gete.2025.100647","DOIUrl":"10.1016/j.gete.2025.100647","url":null,"abstract":"<div><div>This study presents newly developed benchmarks for modeling flow and transport within discrete fracture networks (DFNs) and useful methods for analyzing the results. The new benchmarks are designed to test modeling approaches for use in probabilistic performance assessment models of deep geologic repositories in fractured rock. The benchmarks simulate flow and transport through a 1 km³ block of fractured rock. The first simulates migration of a short pulse of tracer through a simple network of four intersecting fractures. The second adds 1089 stochastically generated fractures. The third changes the pulse to a continuous point source. Evaluation of model performance relies on moment analysis and comparison of the results of different models. The expected nondimensional first moment of the conservative tracer for each benchmark is 1. The benchmarks were simulated by teams from Canada, Czechia, Germany, Korea, Sweden, Taiwan, and the United States as part of a DECOVALEX-2023 study (decovalex.org). The teams used various approaches, including explicit DFN modeling, DFN upscaling to an equivalent continuous porous medium (ECPM), and a combination of both methods. Transport mechanisms are modeled using either the advection-dispersion equation or particle tracking. Results demonstrate strong agreement among the models in breakthrough behavior up to the 75th percentile. Significant deviations in first moments and well-clustered outputs led to the identification of inaccuracies in several models. Such findings exemplify the benefit of exercising these benchmarks and using the presented methods to test DFN flow and transport models.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100647"},"PeriodicalIF":3.3,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Benchmark study of a new simplified DFN model for shearing of intersecting fractures and faults
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-02-03 DOI: 10.1016/j.gete.2025.100644
Mengsu Hu , Jeoung Seok Yoon , Tsubasa Sasaki , Hejuan Liu , Zhaofeng Wang , Jung-Wook Park , Chan-Hee Park , Jonny Rutqvist , Olaf Kolditz , Jens Birkholzer
It is challenging to quantitatively predict shearing of intersecting fractures/faults because of dynamic frictional contacts accompanied by possible nonlinear rock deformation. To address such challenges, a new conceptual model—the simplified DFN model—was proposed and validated by Hu et al.46 to use major paths (MPs) to represent complicated DFNs for calculation of shearing. In this work, we conducted a benchmark study for three examples that involve different levels of complexity of intersecting fractures, and correspondingly different numbers of MPs. The codes and software that were used in the benchmark cover a range of continuum, discontinuum and hybrid numerical methods: NMM (LBNL), FLAC3D (LBNL), GBDEM (KIGAM), FRACOD (DynaFrax), and CASRock (CAS). The general consistency between DFN and MP cases as predicted by all the codes/software demonstrates that major paths can be used to simplify the geometry of DFNs in a wide range of software. Disagreement in results made by some software and potential future improvements are discussed. We show that (1) shearing of one or multiple major fractures can be reduced if there are multiple smaller intersecting fractures in that area, which is a useful basis for understanding and controlling induced seismicity and merits further analysis, and (2) the agreement achieved in the benchmark examples provide confidence that the simplified DFN model is a promising conceptual model that can be used for different types of numerical approaches and software for simplifying the analysis of the shearing of intersecting fractures and faults.
{"title":"Benchmark study of a new simplified DFN model for shearing of intersecting fractures and faults","authors":"Mengsu Hu ,&nbsp;Jeoung Seok Yoon ,&nbsp;Tsubasa Sasaki ,&nbsp;Hejuan Liu ,&nbsp;Zhaofeng Wang ,&nbsp;Jung-Wook Park ,&nbsp;Chan-Hee Park ,&nbsp;Jonny Rutqvist ,&nbsp;Olaf Kolditz ,&nbsp;Jens Birkholzer","doi":"10.1016/j.gete.2025.100644","DOIUrl":"10.1016/j.gete.2025.100644","url":null,"abstract":"<div><div>It is challenging to quantitatively predict shearing of intersecting fractures/faults because of dynamic frictional contacts accompanied by possible nonlinear rock deformation. To address such challenges, a new conceptual model—the simplified DFN model—was proposed and validated by Hu et al.<sup>46</sup> to use major paths (MPs) to represent complicated DFNs for calculation of shearing. In this work, we conducted a benchmark study for three examples that involve different levels of complexity of intersecting fractures, and correspondingly different numbers of MPs. The codes and software that were used in the benchmark cover a range of continuum, discontinuum and hybrid numerical methods: NMM (LBNL), FLAC3D (LBNL), GBDEM (KIGAM), FRACOD (DynaFrax), and CASRock (CAS). The general consistency between DFN and MP cases as predicted by all the codes/software demonstrates that major paths can be used to simplify the geometry of DFNs in a wide range of software. Disagreement in results made by some software and potential future improvements are discussed. We show that (1) shearing of one or multiple major fractures can be reduced if there are multiple smaller intersecting fractures in that area, which is a useful basis for understanding and controlling induced seismicity and merits further analysis, and (2) the agreement achieved in the benchmark examples provide confidence that the simplified DFN model is a promising conceptual model that can be used for different types of numerical approaches and software for simplifying the analysis of the shearing of intersecting fractures and faults.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100644"},"PeriodicalIF":3.3,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Numerical simulation study of proppant transport within fractures under the influence of interlayers and weak planes
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-18 DOI: 10.1016/j.gete.2025.100642
Dan Zhang , Liangping Yi , Zhaozhong Yang , Jiangang He , Jingyi Zhu , Xiaogang Li , Hongqiang Zhang
A sophisticated three-dimensional multi-cluster fracturing model is developed using a block-based discrete element method, incorporating the spatial distribution of interlayers and weak planes. This innovative model establishes uniform metrics for evaluating the propagation of fracturing fissures in multi-cluster formations and the efficacy of proppant deployment. The model facilitates an in-depth investigation into the dynamics of proppant transport within fractures, which are influenced by the presence of interlayers and weak planes. Key findings from the analysis include a negative correlation between fracturing fluid viscosity and the extent of total fissure and proppant placement areas. Larger proppant particle sizes are associated with reduced proppant placement areas, diminished placement efficiency, and heightened settling phenomena. An approach involving stepwise proppant injection enhances structural support proximal to the wellbore, leading to expanded total fissure areas, improved proppant placement, and enhanced efficiency, thereby contributing to more effective reservoir modification. Additionally, the model identifies that the presence of interlayers and the intersections between hydraulic fractures and weak planes tend to result in narrower fracturing fissures, increasing their vulnerability to proppant blockages.
{"title":"Numerical simulation study of proppant transport within fractures under the influence of interlayers and weak planes","authors":"Dan Zhang ,&nbsp;Liangping Yi ,&nbsp;Zhaozhong Yang ,&nbsp;Jiangang He ,&nbsp;Jingyi Zhu ,&nbsp;Xiaogang Li ,&nbsp;Hongqiang Zhang","doi":"10.1016/j.gete.2025.100642","DOIUrl":"10.1016/j.gete.2025.100642","url":null,"abstract":"<div><div>A sophisticated three-dimensional multi-cluster fracturing model is developed using a block-based discrete element method, incorporating the spatial distribution of interlayers and weak planes. This innovative model establishes uniform metrics for evaluating the propagation of fracturing fissures in multi-cluster formations and the efficacy of proppant deployment. The model facilitates an in-depth investigation into the dynamics of proppant transport within fractures, which are influenced by the presence of interlayers and weak planes. Key findings from the analysis include a negative correlation between fracturing fluid viscosity and the extent of total fissure and proppant placement areas. Larger proppant particle sizes are associated with reduced proppant placement areas, diminished placement efficiency, and heightened settling phenomena. An approach involving stepwise proppant injection enhances structural support proximal to the wellbore, leading to expanded total fissure areas, improved proppant placement, and enhanced efficiency, thereby contributing to more effective reservoir modification. Additionally, the model identifies that the presence of interlayers and the intersections between hydraulic fractures and weak planes tend to result in narrower fracturing fissures, increasing their vulnerability to proppant blockages.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100642"},"PeriodicalIF":3.3,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Centrifuge modeling of temperature effects on the pullout capacity of jacked-in energy piles in saturated soft clay
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-17 DOI: 10.1016/j.gete.2025.100638
Ismaail Ghaaowd , Fernando A. Saboya, jr , John S. McCartney
This study focuses on predicting the impacts of a heating-cooling cycle on the pullout capacity of energy piles installed through a soft clay layer. Geotechnical centrifuge physical modeling was used to evaluate temperature, pore water pressure, volume change, and undrained shear strength profiles in clay layers surrounding energy piles heated to different maximum temperatures to understand their impacts on the pile pullout capacity. During centrifugation at 50 g, piles were jacked-in at a constant rate of penetration into a kaolinite clay layer consolidated from a slurry in a cylindrical aluminum container, heated to a target temperature after stabilization of installation effects, cooled after completion of thermal consolidation requiring up to 30 hours (1250 days in prototype scale), then pulled out at a constant rate. T-bar penetration tests were performed after the heating-cooling cycle to assess differences in clay undrained shear strength from a baseline test. The pullout capacity of an energy pile heated to 80 °C then cooled to ambient temperature was 109 % greater than the capacity in the baseline test at 23 °C, representing a substantial improvement. The average undrained shear strength measured with the T-bar at a distance of 3.5 pile diameters from the pile heated to 80 °C was 60 % greater than at 23 °C but followed the same trend as pile capacity with temperature. An empirical model for the pullout capacity was developed by combining predictions of soil temperature, thermal excess pore water pressure, thermal volumetric strain, and undrained shear strength for different maximum pile temperatures. The empirical model predictions matched well with measured pullout capacities.
{"title":"Centrifuge modeling of temperature effects on the pullout capacity of jacked-in energy piles in saturated soft clay","authors":"Ismaail Ghaaowd ,&nbsp;Fernando A. Saboya, jr ,&nbsp;John S. McCartney","doi":"10.1016/j.gete.2025.100638","DOIUrl":"10.1016/j.gete.2025.100638","url":null,"abstract":"<div><div>This study focuses on predicting the impacts of a heating-cooling cycle on the pullout capacity of energy piles installed through a soft clay layer. Geotechnical centrifuge physical modeling was used to evaluate temperature, pore water pressure, volume change, and undrained shear strength profiles in clay layers surrounding energy piles heated to different maximum temperatures to understand their impacts on the pile pullout capacity. During centrifugation at 50 g, piles were jacked-in at a constant rate of penetration into a kaolinite clay layer consolidated from a slurry in a cylindrical aluminum container, heated to a target temperature after stabilization of installation effects, cooled after completion of thermal consolidation requiring up to 30 hours (1250 days in prototype scale), then pulled out at a constant rate. T-bar penetration tests were performed after the heating-cooling cycle to assess differences in clay undrained shear strength from a baseline test. The pullout capacity of an energy pile heated to 80 °C then cooled to ambient temperature was 109 % greater than the capacity in the baseline test at 23 °C, representing a substantial improvement. The average undrained shear strength measured with the T-bar at a distance of 3.5 pile diameters from the pile heated to 80 °C was 60 % greater than at 23 °C but followed the same trend as pile capacity with temperature. An empirical model for the pullout capacity was developed by combining predictions of soil temperature, thermal excess pore water pressure, thermal volumetric strain, and undrained shear strength for different maximum pile temperatures. The empirical model predictions matched well with measured pullout capacities.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100638"},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An evaluation method of hydraulic fracture propagation behavior in rock containing natural fractures based on fractal dimension
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-17 DOI: 10.1016/j.gete.2025.100640
Yulong Liu , Yanjun Zhang , Yuxiang Cheng , Ziwang Yu , Xuefeng Gao , Lei Liu
This study presents a novel method for quantifying the propagation of hydraulic fractures and their interaction with natural fractures under varying fracturing conditions. We examine the impact of approach angle, fracture aperture, borehole distance, differential stress, and injection rate on hydraulic fracture behaviour using the Particle Flow Code 2D (PFC2D) model. The results reveal two main fracture extension modes: crossing and retained. The approach angle significantly affects the fractal dimension of hydraulic fractures, with peak values of 1.12 at intermediate angles (30°–60°) and lower values (0.96–0.98) at extreme angles (0° and 90°). Increasing fracture aperture accelerates propagation by 13.7 %, while a higher injection rate raises the fractal dimension by 22.6 %. Borehole distance introduces variability, and as differential stress increases, the fractal dimension increases from 0.98 to 1.17, accompanied by a 43.4 % increase in breakdown pressure. To model temporal variations in fractal dimensions, The Logistic method adjusts the fractal dimension amplitude with parameter A2 and controls the growth rate during the acceleration phase with p1. The BiDoseResp method, by contrast, modulates amplitude using A3 and A4, and regulates the entry and exit stages through LoGt1 and LoGt2. Parameters h1, h2, and p2 govern amplitude and growth during the retention and acceleration phases. These models provide a framework for optimising hydraulic fracturing in geothermal development, enhancing fracture dynamics understanding and improving resource extraction efficiency.
{"title":"An evaluation method of hydraulic fracture propagation behavior in rock containing natural fractures based on fractal dimension","authors":"Yulong Liu ,&nbsp;Yanjun Zhang ,&nbsp;Yuxiang Cheng ,&nbsp;Ziwang Yu ,&nbsp;Xuefeng Gao ,&nbsp;Lei Liu","doi":"10.1016/j.gete.2025.100640","DOIUrl":"10.1016/j.gete.2025.100640","url":null,"abstract":"<div><div>This study presents a novel method for quantifying the propagation of hydraulic fractures and their interaction with natural fractures under varying fracturing conditions. We examine the impact of approach angle, fracture aperture, borehole distance, differential stress, and injection rate on hydraulic fracture behaviour using the Particle Flow Code 2D (PFC<sup>2D</sup>) model. The results reveal two main fracture extension modes: crossing and retained. The approach angle significantly affects the fractal dimension of hydraulic fractures, with peak values of 1.12 at intermediate angles (30°–60°) and lower values (0.96–0.98) at extreme angles (0° and 90°). Increasing fracture aperture accelerates propagation by 13.7 %, while a higher injection rate raises the fractal dimension by 22.6 %. Borehole distance introduces variability, and as differential stress increases, the fractal dimension increases from 0.98 to 1.17, accompanied by a 43.4 % increase in breakdown pressure. To model temporal variations in fractal dimensions, The Logistic method adjusts the fractal dimension amplitude with parameter <span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and controls the growth rate during the acceleration phase with <span><math><msub><mrow><mi>p</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>. The BiDoseResp method, by contrast, modulates amplitude using <span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span>, and regulates the entry and exit stages through <span><math><msub><mrow><mi>LoGt</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>LoGt</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. Parameters <span><math><msub><mrow><mi>h</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>, <span><math><msub><mrow><mi>h</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <span><math><msub><mrow><mi>p</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> govern amplitude and growth during the retention and acceleration phases. These models provide a framework for optimising hydraulic fracturing in geothermal development, enhancing fracture dynamics understanding and improving resource extraction efficiency.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100640"},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Cyclic plasticity of hardened oil well cement paste: A nonlinear kinematic hardening perspective
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-17 DOI: 10.1016/j.gete.2025.100641
Linlin Wang , Shuo Chen , Shuitao Zhang , Jiyun Shen , Rongwei Yang
The present work focuses on the deformation of oil well cement subjected to cyclic loading. Different from the conventional models based on damage theory, the strain accumulation in this study is characterized in the framework of nonlinear kinematic hardening plasticity. The main feature of the proposed model is that a recall (nonlinear) term is introduced in the hardening rule so that the back stress hardens nonlinearly with plastic deformation. Accordingly, the back stress varies differently across the unloading and reloading paths, leading to a no-closed hysteresis loop and a ratcheting strain. The proposed model is validated through several experiments conducted on oil well cements cured at different curing temperatures and curing ages. The model results for the ratcheting straining of oil well cement under both uniaxial and triaxial compression agree well with experimental results. In particular, the proposed model well reproduces a much more pronounced residual strain during the first cycle, and a minor as well as constant accumulation rate for the subsequent cycles. For a comparison, such greater residual strain and the following smaller constant residual strain can not be characterized by the conventional damage-based models, which produces an increasing accumulation rates with the cycle numbers.
{"title":"Cyclic plasticity of hardened oil well cement paste: A nonlinear kinematic hardening perspective","authors":"Linlin Wang ,&nbsp;Shuo Chen ,&nbsp;Shuitao Zhang ,&nbsp;Jiyun Shen ,&nbsp;Rongwei Yang","doi":"10.1016/j.gete.2025.100641","DOIUrl":"10.1016/j.gete.2025.100641","url":null,"abstract":"<div><div>The present work focuses on the deformation of oil well cement subjected to cyclic loading. Different from the conventional models based on damage theory, the strain accumulation in this study is characterized in the framework of nonlinear kinematic hardening plasticity. The main feature of the proposed model is that a recall (nonlinear) term is introduced in the hardening rule so that the back stress hardens nonlinearly with plastic deformation. Accordingly, the back stress varies differently across the unloading and reloading paths, leading to a no-closed hysteresis loop and a ratcheting strain. The proposed model is validated through several experiments conducted on oil well cements cured at different curing temperatures and curing ages. The model results for the ratcheting straining of oil well cement under both uniaxial and triaxial compression agree well with experimental results. In particular, the proposed model well reproduces a much more pronounced residual strain during the first cycle, and a minor as well as constant accumulation rate for the subsequent cycles. For a comparison, such greater residual strain and the following smaller constant residual strain can not be characterized by the conventional damage-based models, which produces an increasing accumulation rates with the cycle numbers.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100641"},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143132782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Modeling of coupled processes in full-scale engineered barrier system performance experiment at Horonobe Underground Research Laboratory, Japan
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-15 DOI: 10.1016/j.gete.2025.100636
Hirokazu Ohno , Yusuke Takayama
In the geological disposal of high-level radioactive waste, the overpack lifetime and initial conditions of radionuclide migration are essential considerations along with the assessments of the environmental conditions, including study of the evolution of near-field thermal, hydrological, mechanical, and chemical processes following the emplacement of an engineered barrier system. In this study, experimental data from an in situ full-scale engineered barrier experiment at Horonobe Underground Research Laboratory were used to assess the applicability of a simulation model to evaluate near-field coupled processes. Simulation results indicate that the thermal and hydraulic properties generally explain the temperature and saturation distributions and that it is crucial to capture changes in pore water characteristics as an indicator of changes in saturation. The application of the simplified unsaturated elastoplastic constitutive model improves the reproducibility of the swelling deformation behavior of buffer materials.
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引用次数: 0
The impact of heat exchanger loop configuration on heat transfer in energy piles
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-14 DOI: 10.1016/j.gete.2025.100639
Mohammed Faizal , Abdelmalek Bouazza , John S. McCartney
This paper examines the impact of parallel and series U-loop configurations on heat transfer in energy piles. Heating experiments were conducted on a set of four field-scale energy piles installed under a five-storey building, sharing identical dimensions (diameter = 0.9 m and length = 15 m) but varying numbers of U-loops (loops 1, 2, 3, and 4, in Piles 1, 2, 3, and 4, respectively). The investigation highlights the significance of fluid flow, temperature, U-loop quantity and configuration on heat transfer within solitary and grouped energy piles. In the parallel configuration, heat exchange occurs concurrently across all U-loops, proportional to the flow rate. Conversely, in the series configuration, the initial U-loops dominate heat exchange, with subsequent U-loops showing diminished effectiveness in contributing to the overall heat transfer. For identical flow rates in the individual U-loops of both configurations, the group of energy piles employing parallel U-loops exhibited higher heat exchange. The findings provide practical insights into optimising U-loop configurations to improve heat exchange between the pile and the surrounding soil under the studied boundary conditions.
{"title":"The impact of heat exchanger loop configuration on heat transfer in energy piles","authors":"Mohammed Faizal ,&nbsp;Abdelmalek Bouazza ,&nbsp;John S. McCartney","doi":"10.1016/j.gete.2025.100639","DOIUrl":"10.1016/j.gete.2025.100639","url":null,"abstract":"<div><div>This paper examines the impact of parallel and series U-loop configurations on heat transfer in energy piles. Heating experiments were conducted on a set of four field-scale energy piles installed under a five-storey building, sharing identical dimensions (diameter = 0.9 m and length = 15 m) but varying numbers of U-loops (loops 1, 2, 3, and 4, in Piles 1, 2, 3, and 4, respectively). The investigation highlights the significance of fluid flow, temperature, U-loop quantity and configuration on heat transfer within solitary and grouped energy piles. In the parallel configuration, heat exchange occurs concurrently across all U-loops, proportional to the flow rate. Conversely, in the series configuration, the initial U-loops dominate heat exchange, with subsequent U-loops showing diminished effectiveness in contributing to the overall heat transfer. For identical flow rates in the individual U-loops of both configurations, the group of energy piles employing parallel U-loops exhibited higher heat exchange. The findings provide practical insights into optimising U-loop configurations to improve heat exchange between the pile and the surrounding soil under the studied boundary conditions.</div></div>","PeriodicalId":56008,"journal":{"name":"Geomechanics for Energy and the Environment","volume":"41 ","pages":"Article 100639"},"PeriodicalIF":3.3,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143133433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An international study on THM modelling of the full-scale heater experiment at Mont Terri laboratory
IF 3.3 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2025-01-03 DOI: 10.1016/j.gete.2024.100631
Bastian Johannes Graupner , Kate Thatcher , Larissa Friedenberg , Ruiping Guo , Teklu Hadgu , Wenbo Hou , Sonja Kaiser , Taehyun Kim , Chan-Hee Park , Changsoo Lee , Edward Matteo , Thomas Nagel , Rebecca Newson , Peng-Zhi Pan , Michael Pitz , Jonny Rutqvist , Jan Thiedau , Luca Urpi
We present results from an international model comparison study of the Full-Scale Emplacement (FE) experiment in Opalinus Clay at the Mont Terri Laboratory, Switzerland. Based on a provided parameter set the teams decided which parameters they adopted for their models, whether they considered the excavation and the ventilation phase in addition to the heating phase and if they included technical features like the shotcrete or the EDZ. The teams were able to reproduce the measured parameters temperature, relative humidity and pore pressure. The modelled results for temperature agree very closely between the teams especially in the sensors in Opalinus Clay. All teams were able to reproduce the redistribution of water in the bentonite backfill due to heating. The evolution of the relative humidity showed similar trends with differences in the intensity of the dry out effect. To model the pore pressure evolution is more complex because it comprises the full interaction of the coupled THM processes. The spread between the pore pressure modelled by the teams was larger, with some teams overestimating the pressure increase due to heating and some teams overestimating the extent of drainage. The agreement of modelled results with measurements improves with larger distance to the heater. We conclude that the EDZ and the shotcrete potentially influence the behaviour of the rock causing higher differences closer to the heater. Further research is needed to better implement those influences into the models. Based on the calibrated models, the future evolution of temperature, relative humidity and pore pressure was predicted over the next 10 years following a change of the heat power applied in 2023 and 2024. Again, the predicted temperatures agree very closely between the teams. Most teams do not expect an increase in relative humidity during the next 10 years after the initial dry-out.
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引用次数: 0
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Geomechanics for Energy and the Environment
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