Geothermics最新文献

{"title":"An experimental investigation of hydraulic fracturing mechanisms in menderes metamorphic rocks: Prospects for enhanced geothermal systems","authors":"Hakkı Aydın ,&nbsp;Umutcan Camcı ,&nbsp;Serhat Akın","doi":"10.1016/j.geothermics.2025.103328","DOIUrl":"10.1016/j.geothermics.2025.103328","url":null,"abstract":"<div><div>Hydraulic fracturing is a critical technique for stimulating low-permeability geothermal reservoirs, such as Enhanced Geothermal Systems (EGS) and Hot Dry Rock (HDR). This study investigates the hydraulic fracturing mechanisms in metamorphic rocks such as marble and schist commonly found in western Turkiye, a region with a gross geothermal power capacity exceeding 1,700 MW. For the first time, fracturing experiments using pressurized nitrogen gas and uniaxial compression tests were conducted on both reservoir outcrop and core plug samples of metamorphic reservoir rocks from this region. Vertical and horizontal fractures formed at varying breakout pressures, with the fracture surfaces exhibiting irregular morphologies and apertures facilitating fluid flow. Uniaxial compression tests determined the mechanical properties, including Young's modulus and Poisson's ratio. Vertical crack propagation was observed in outcrop samples, while diagonal fractures appeared in core samples. Mineralogical analysis through thin-section, Scanning Electron Microscopy - Energy Dispersive Spectroscopy (SEM-EDS), and X-Ray-Diffraction (XRD) revealed that the core sample was grayish-green mica schist with muscovite, quartz, garnet, and staurolite, while the outcrop sample was white marble composed primarily of calcite. Results indicate that marble and schist exhibit lower breakdown pressures compared to granite, making them promising candidates for EGS development. This study represents a novel contribution to understanding the interplay between rock type, fracture mechanisms, and experimental findings in Turkiye's metamorphic geothermal systems.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103328"},"PeriodicalIF":3.5,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682385","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}

{"title":"Effects of energy storage body parameters on seasonal energy storage performance of borehole thermal energy storage (BTES) system","authors":"Weibo Yang,&nbsp;Wenxin Xia,&nbsp;Qianyun Sun,&nbsp;Chaoyang Zhang,&nbsp;Feng Wang","doi":"10.1016/j.geothermics.2025.103321","DOIUrl":"10.1016/j.geothermics.2025.103321","url":null,"abstract":"<div><div>Borehole thermal energy storage (BTES) is of great significance for improving energy utilization efficiency and achieving sustainable exploitation of renewable energy. However, the seasonal energy storage performance of BTES are affected by energy storage body parameters and their influence laws are still unclear. In this work, a 3-D numerical model of BTES is developed and validated by the model experiments. Effects of borehole spacing, borehole arrangement, soil stratification and groundwater seepage on the energy storage performance of BTES are numerically investigated. The results show that the energy storage body under different layout forms of borehole exhibits different temperature distributions and thermal diffusion characteristics, and the layout form 2 that the borehole spacing are 4.5, 3.5, and 2.5 m for the interior, middle, and exterior region borehole, respectively has obvious advantages during the energy storage. Compared with the uniform soil and the stratification soil 2 (the geological layers along the depth direction are respectively silty fine sandstone, fine sandstones, mudstone andstone), the stratification soil 1 (the geological layers along the depth direction are respectively sandstone, mudstone, fine sandstone, and silty fine sandstone) not only has larger heat storage and extraction amount, but also has larger energy storage efficiency. Compared to the sequential arrangement form, the staggered arrangement form provides a greater soil volume for energy storage. This leads to lower soil temperatures after heat storage and higher soil temperatures after heat extraction. Moreover, the staggered arrangement form results in larger overall heat storage and extraction capacities, as well as a greater heat storage amount per unit volume. The seepage is unfavorable to the seasonal energy storage of BTES, and the greater the seepage velocity, the more heat is carried to downstream by the seepage, causing heat loss and reduction of energy storage efficiency. Additionally, a small increase in the seepage angle can enhance the heat transfer effect of seepage, and thus the energy storage efficiency can be obviously improved.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103321"},"PeriodicalIF":3.5,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682388","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}

{"title":"Effect of temperature paths on the time-dependent isotropic consolidation behavior of lateritic clay","authors":"Zhifan Xu ,&nbsp;Zhengfa Chen ,&nbsp;Kerui Lang ,&nbsp;Youzhong Zhang ,&nbsp;Jiahua Dou","doi":"10.1016/j.geothermics.2025.103329","DOIUrl":"10.1016/j.geothermics.2025.103329","url":null,"abstract":"<div><div>The long-term compression behavior of clay is significantly affected by temperature paths. However, most studies on temperature paths focus on short-term changes in volume and pore pressure, with limited research on how temperature paths affect soil secondary consolidation characteristics. To experimentally investigate the time-dependent compression behavior of lateritic clay under different temperature paths, a series of temperature-controlled isotropic consolidation tests from 5 to 50 °C were conducted with consideration of heating/cooling rate and thermal cycle paths. The results indicate that the accumulation of thermal-induced pore water pressure increases with the rate of temperature variations, but a faster rate leads to smaller volumetric changes. Moreover, thermal cycling does not cause irreversible thermoplastic volumetric strain with a suitable heating/cooling rate, and the cycle paths do not influence this outcome. Furthermore, the creep rate of heated samples increases significantly, and the heating/cooling rate also affects the creep rate: a slower heating rate results in a faster creep rate. Additionally, the creep behavior ceased after the thermal cycle, and it appears that the thermal cycle paths have no effect on the creep rate. Finally, this study summarizes the mechanism of the influence of temperature on the creep behavior of clay, and reasonable explanations are proposed for the thermo-mechanical behavior caused by different temperature paths.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103329"},"PeriodicalIF":3.5,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682290","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}

{"title":"Pore structure alteration in heated granite after LN2 treatment: An experimental study for the enhanced geothermal energy extraction","authors":"Sotirios Nik. Longinos ,&nbsp;Mohammad Asif ,&nbsp;George Mathews","doi":"10.1016/j.geothermics.2025.103326","DOIUrl":"10.1016/j.geothermics.2025.103326","url":null,"abstract":"<div><div>The cryogenic fracturing of two granite samples was performed in this paper for the pore characterization to enhance geothermal energy extraction. The samples were heated initially to 600 °C and subsequently analyzed for liquid nitrogen (LN₂) treatment for multiple freezing and freezing-thawing cycles. The mercury intrusion and low-pressure nitrogen adsorption reveal a significant alternation in the pore characteristics of granite samples. The nitrogen adsorption capacity increases from 1.08 cc/g to 1.52 cc/g after LN₂ treatment. This study also examines a significant increase in pore volume as pore volume increases by 135–152 %. Furthermore, the XRD analysis of the samples was executed to study the microscopic effect of the minerals in the granite samples. The LN₂ treatment of the sample enhances pore connectivity, as evidenced by the XRD analysis of sample 1, which reveals a high feldspar and biotite content. In contrast, sample 2 experiences limited fracturing effects due to its high quartz content. Therefore, the cryogenic fracturing of heated granite samples demonstrates significant potential for investigating pore structure modifications to improve geothermal energy recovery. This study establishes a fundamental framework for advancing geothermal energy extraction and contributes to the development of renewable energy in Kazakhstan.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103326"},"PeriodicalIF":3.5,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682387","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}

{"title":"Gas equilibrium in the H2O-H2-CO2-CO-CH4 system for wet-steam geothermal-well fluids and their sources: A case study from Krafla, Iceland","authors":"Giulio Bini ,&nbsp;Matteo Lelli ,&nbsp;Stefano Caliro ,&nbsp;Tullio Ricci ,&nbsp;Anette K. Mortensen ,&nbsp;Ásgerður K. Sigurðardóttir ,&nbsp;Alessandro Santi ,&nbsp;Antonio Costa","doi":"10.1016/j.geothermics.2025.103322","DOIUrl":"10.1016/j.geothermics.2025.103322","url":null,"abstract":"<div><div>Equilibrium in the H₂O-H₂-CO₂-CO-CH₄ gas system has been extensively applied to fumarole data for geothermal exploration and volcano monitoring. However, little is known about its application to two-phase (vapor and liquid) geothermal well fluids, which can show an excess of enthalpy. Here, we applied the H₂O-H₂-CO₂-CO-CH₄ gas indicators to two-phase geothermal well discharges from the Krafla geothermal system, Iceland, to estimate aquifer temperatures and identify secondary processes during resource exploitation. Results suggest that the Krafla resource is drawn from a deep (approximately between –500 and –1,600 m a.s.l.), two-phase aquifer with temperatures ranging from 272 to 320 °C and vapor fractions between 0.26 and 0.93, explaining the excess enthalpy observed in well fluids. These estimates align with the temperatures of the main production zones of geothermal wells, whereas solute geothermometers (SiO₂ and Na/K) appear to record lower temperatures of minor, shallower, liquid aquifers. Wells with liquid-like enthalpy are sourced from the two-phase aquifer but are also influenced by water reinjection or downflows from a colder, shallower aquifer, consistent with the isothermal zone extending approximately between 400 and –900 m a.s.l. in Leirbotnar and Vesturhlíðar subfields. Water isotopes indicate the main aquifer is recharged by meteoric and reinjection fluids. Excess-enthalpy discharges show an influx of Ar- and N₂-rich vapor, with depleted ⁴⁰Ar/³⁶Ar and δ¹⁵N values, suggesting fractionations of atmospheric gases dissolved into the reservoir liquid. On the other hand, δ¹³C_CO2 and ³He/⁴He values point to a mantle origin, despite the lower δ¹³C_CO2 and P_CO2 levels that reflect a degassed magma (i.e., a noneruptive phase). These findings underscore the usefulness of the H₂O-H₂-CO₂-CO-CH₄ gas system and isotopic methods in tracking geothermal reservoir temperatures, their sources, and secondary processes, such as water reinjection or downflows from shallower aquifers.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103322"},"PeriodicalIF":3.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143644817","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}

{"title":"Isotopic geochemistry of chlorine, boron and lithium in hydrothermal waters: A review","authors":"Mingliang Liu ,&nbsp;Lizhen Huang ,&nbsp;Ke Wang ,&nbsp;Yanlong Kong ,&nbsp;Qinghai Guo","doi":"10.1016/j.geothermics.2025.103325","DOIUrl":"10.1016/j.geothermics.2025.103325","url":null,"abstract":"<div><div>Hydrothermal water is a valuable geological resource with a wide range of applications. Understanding the genesis of hydrothermal system is fundamental and critical for the scientific and rational formulation of exploration strategies and development plans for hydrothermal resources. In recent years, with the continuous advancement of isotope analysis technologies and innovative research methods, non-traditional isotopes such as chlorine, boron, and lithium have gradually been applied in the field of hydrothermal research. Given that chlorine, boron, and lithium are highly fluid-mobile elements with relatively strong conservative behavior, these isotopes exhibit unique advantages in tracing the sources of hydrothermal waters, elucidating geochemical processes within hydrothermal systems, and understanding the geneses of these systems, demonstrating significant potential for application. This paper reviews the geochemical characteristics, fractionation mechanisms, and applications of chlorine, boron, and lithium isotopes in hydrothermal waters. Based on these discussions, it summarizes potential future research directions to provide deeper insights and scientific support for the exploration and development of hydrothermal resources.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103325"},"PeriodicalIF":3.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682386","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}

{"title":"Heat extraction performance and techno-economic analysis of a deep U-type borehole heat exchanger under intermittent operation","authors":"Chao Huan ,&nbsp;Fei Meng ,&nbsp;Zhengna Yang ,&nbsp;Wanlong Cai ,&nbsp;Zhihua Wang ,&nbsp;Fenghao Wang ,&nbsp;Chaofan Chen","doi":"10.1016/j.geothermics.2025.103307","DOIUrl":"10.1016/j.geothermics.2025.103307","url":null,"abstract":"<div><div>The deep U-type borehole heat exchanger (DUBHE) has been extensively investigated in terms of its long-term heat extraction capacity and economic feasibility. In this work, a 3D numerical model of DUBHE was established based on the open-source numerical software OpenGeoSys (OGS). Three- and sixty-day experimental data from two pilot projects in Xi’an, China, were used for the model validation. Subsequently, the model was extended to the long-term operational period by introducing different operation-shutdown ratios. In the long-term operation, the extension of the daily operational time from 8 to 24 h resulted in a reduction of the soil temperature difference from 14.87<!--> <!-->°C to 7.51<!--> <!-->°C. Compared to the continuous operational scenario with an operation-shutdown ratio of 24:0, the total heat extraction for operation-shutdown ratios of 8:16, 12:12, and 16:8 was discovered to be 65.15<!--> <!-->%, 76.14<!--> <!-->%, and 84.85<!--> <!-->%, respectively. Considering the system’s initial investment and the operational costs coupled with the heat pump and circulating water pump, a techno-economic analysis was also executed based on benchmark parameters. For the DUBHE heating system with an operation-shutdown ratio of 8:16, the investment payback period is approximately 8.2 years, which is the shortest among all scenarios. The related suggestions proposed in this work aim to provide insightful references for engineers and decision-makers in practice.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103307"},"PeriodicalIF":3.5,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629422","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}

{"title":"Assessment of geothermal waters in Yunnan, China: Distribution, quality and driving factors","authors":"Zhaojun Zeng ,&nbsp;Li Yang ,&nbsp;Yueju Cui ,&nbsp;Xiaocheng Zhou ,&nbsp;Miao He ,&nbsp;Yuwen Wang ,&nbsp;Yucong Yan ,&nbsp;Bingyu Yao ,&nbsp;Xiaojing Hu ,&nbsp;Weiye Shao ,&nbsp;Jian Li ,&nbsp;Hong Fu","doi":"10.1016/j.geothermics.2025.103323","DOIUrl":"10.1016/j.geothermics.2025.103323","url":null,"abstract":"<div><div>Geothermal energy is a vital renewable resource widely used for various applications, including drinking water, domestic supply, irrigation, and industrial purposes. However, the utilization of geothermal water for drinking can expose individuals to toxic elements, particularly arsenic, which poses significant health risks. Despite the growing interest in geothermal water, there has been a lack of systematic analysis regarding the spatial variability of its quality and health risk. This study aims to address this gap by evaluating the spatial variability of the water quality characteristics and health risks in Yunnan Province using a combination of hydrochemical and isotopic methods, Principal Component Analysis (PCA), Self-Organizing Maps (SOM) and integrated tools such as Water Quality Index (WQI) and Human Health Risk Assessment (HHRA). According to this study, atmospheric precipitation serves as the primary recharge source with Na-HCO₃, Ca-HCO₃, Na-Cl and Ca-Cl as the dominant geothermal water hydrochemical in Yunnan Province. While most samples exhibit good water quality, those from the northwestern regions (e.g., Lijiang, Lincang, Kunming, Baoshan, Jinghong, Pu'er, and Dali) show poorer water quality and significant health risks. PCA analysis reveals that the spatial variability of geothermal water quality is largely influenced by deep hydrological cycles and magma-tectonic interactions, resulting in arsenic enrichment in high-risk areas. This study addresses the research gap regarding the spatial variability of geothermal water quality and health risk assessment in Yunnan Province and provides a scientific foundation for sustainable development and management.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103323"},"PeriodicalIF":3.5,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629421","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}

{"title":"Corrigendum to “Thermal investigation of geothermally activated building systems using Thermal-Response-Test method” [Geothermics Volume 123 (2024) 103116]","authors":"Fabian Neth,&nbsp;Roland Koenigsdorff","doi":"10.1016/j.geothermics.2025.103320","DOIUrl":"10.1016/j.geothermics.2025.103320","url":null,"abstract":"","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103320"},"PeriodicalIF":3.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891975","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}

{"title":"Design of silica nanoparticle tracers with optimized dispersion stability, sorption and deposition properties based on (X)DLVO and filtration theory","authors":"Laura Spitzmüller ,&nbsp;Jonathan Berson ,&nbsp;Thomas Kohl ,&nbsp;Thomas Schimmel ,&nbsp;Fabian Nitschke","doi":"10.1016/j.geothermics.2025.103309","DOIUrl":"10.1016/j.geothermics.2025.103309","url":null,"abstract":"<div><div>Functional nanoparticles emerged as potential new tracers for geoscientific applications, such as geothermal reservoir exploration. In this study, optimization strategies based on DLVO, extended DLVO (XDLVO) and filtration theory are presented. Our results show that nanoparticle material should have a low Hamaker constant, making metallic nanoparticles unfavorable. To ensure dispersion stability and minimize sorption on commonly negatively charged reservoir minerals, the nanoparticles should exhibit ζ-potentials below -30 mV. Decreasing the size of nanoparticles increases the diffusion-driven collisions with minerals grains and the probability of deposition while keeping the particle-to-grain size ratio below 0.008 prevents size exclusion effects. The impact of gravity on particle deposition is negligible for nanoparticles, making higher-density nanoparticle tracers viable. Experimental findings and XDLVO theory confirm the applicability of surface modifications to form a steric barrier that lowers attachment efficiencies while increasing colloidal dispersion stability. The impact of temperature cannot be assessed in a straightforward manner as it depends on multiple factors that can have contradicting effects. The presented study can serve as a guideline for the design of stable nanoparticle tracers with predictable transport properties in reservoirs. It shows that selecting appropriate materials, adapting ζ-potentials or employing effective surface modifications are key strategies to improve the performance of engineered nanoparticle tracers for geothermal exploration.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"130 ","pages":"Article 103309"},"PeriodicalIF":3.5,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621428","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}