Geothermics最新文献

{"title":"Macroscopic permeability progression of Nanan granite under confining pressures and its microscopic evolution after cooling at atmospheric pressure: A comparative study","authors":"","doi":"10.1016/j.geothermics.2024.103180","DOIUrl":"10.1016/j.geothermics.2024.103180","url":null,"abstract":"<div><div>Permeability is one of the key factors for influencing the mass transfer behavior in rocks and plays a key role in heat extraction of enhanced geothermal systems (EGSs), so the practice of EGSs needs cooling water to be injected to enhance the permeability within geothermal reservoirs. Macroscopic and microscopic experimental investigation on how cool water affects permeability evolution is still limited. To solve this, we experimentally explored the permeability evolution of Nanan granite after air and water cooling under different confining pressures combined with optical microscopy and X-ray micro computed tomography (CT) observation. Lots of microdefects were observed in Nanan granite after two cooling paths, which dominantly drives the evolution of permeability from a microscopic scale. The permeabilities of granite under water-cooling conditions are always larger than those under air-cooling conditions, because the comparison shows that water-cooling treatment enhances the permeability of specimens. The permeabilities of granite specimens after two cooling paths decrease with the confining stress. More microcracks and better connectivity among microcracks produce a larger permeability within the specimen after water cooling. The observed microcracks are regarded as the seepage channels and direct microscale evidence of the permeability evolution of granite after two cooling paths. Our results provide support that cooled water injection is an efficient way for permeability enhancement due to thermal microcracks propagation in thermal simulation.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433394","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":"Damage characteristics of high-temperature coal under different cooling rates","authors":"","doi":"10.1016/j.geothermics.2024.103179","DOIUrl":"10.1016/j.geothermics.2024.103179","url":null,"abstract":"<div><div>The damage characteristics of high-temperature coal under water cooling was analyzed.As the heating temperature increases, the internal pore development and crack propagation in coal intensify, with the failure mode gradually shifting from brittle to plastic. There exists a threshold temperature that accelerates damage. The rapid temperature drop caused by water cooling accelerates damage and cracking in the coal. The thermal shock factor resulting from the rapid temperature drop can quantitatively represent the damage induced by water cooling. The results are expected to provide guidance for the utilization of thermal energy in coal field fire areas.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142423788","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":"Breakage mechanism analysis of bedded sandstone impacted by abrasive water jet using an integrated SPH-DEM-FEM and cohesive element method","authors":"","doi":"10.1016/j.geothermics.2024.103177","DOIUrl":"10.1016/j.geothermics.2024.103177","url":null,"abstract":"<div><div>Abrasive water jet (AWJ) is an emerging technique for improving the drilling efficiency for geothermal energy development. Rock bedding significantly influences the effectiveness of rock breaking during drilling. In this study, to investigate the damage modes and the mechanism of the bedded sandstone under abrasive water jet erosion, smooth particle hydrodynamics (SPH) and discrete element method (DEM) are used to establish the jet, and cohesive elements are inserted into finite elements to model the bedded sandstone, simulating the process of water and abrasive into the nozzle to form an abrasive water jet impacting bedded sandstone. The numerical results showed that the depth and diameter of fractures in bedded sandstone decrease and then stabilize as the bedding angle increases under AWJ, and the error in the ratio of erosion hole diameter and depth between the simulated and experimental results was &lt;10.8 %. In addition, two damage modes of the bedded sandstone were determined, which include Case I damage mode: the sandstone is well consolidated, and the damage is in the form of erosion holes (0°≤α≤60°), dominated by the tensile damage, and Case II damage mode: the rock is fractured along the bedding and splits into two halves (60°&lt;α≤90°), and the process can be divided into two stages during this mode. The first stage is the impact kinetic energy carried by the jet to form a crater, and the second stage is the water wedge effect to fracture the rock. The results of this study complement the damage mechanism of fractured bedded rocks by AWJ, which provides a theoretical reference for the application of AWJ to break bedded rocks in subsurface energy extraction.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424416","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 carbon dioxide blasting on hot dry rock reservoirs considering thermal damage","authors":"","doi":"10.1016/j.geothermics.2024.103174","DOIUrl":"10.1016/j.geothermics.2024.103174","url":null,"abstract":"<div><div>A cutting-edge technique for igniting hot dry rock (HDR) reservoirs is carbon dioxide blasting. The cooling effect of the drilling fluid was taken into consideration during a numerical simulation of the action range of carbon dioxide blasting-induced cracking. A temperature difference was used to determine the reservoir's material properties. Additionally, temperature distribution functions were used to create the temperature field in the reservoir. The blasting load is calculated using the pertinent theories and formulas of explosive blasting, and the process of blasting carbon dioxide to excite the HDR reservoir is modeled using COMSOL. The findings show that several stress concentrations take place during the blasting process. The fracture zone is created by the tensile stress concentration outside of the crushing zone, whereas the compressive stress concentration close to the blast hole creates the crushing zone. Furthermore, the effectiveness of carbon dioxide blasting fracturing would be affected by the beginning temperature and pressure plate thickness. Although the scope of the fracture zone is mostly unchanged, the initial temperature has a significant impact on the blasting crushing zone. The size of the crushing zone, which determines how the blasting fracture zone is distributed, is unaffected by the pressure plate's thickness.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424415","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":"GeoProp: A thermophysical property modelling framework for single and two-phase geothermal geofluids","authors":"","doi":"10.1016/j.geothermics.2024.103146","DOIUrl":"10.1016/j.geothermics.2024.103146","url":null,"abstract":"<div><div>The techno-economic evaluation of geothermal resources requires knowledge of the geofluid's thermophysical properties. While the properties of pure water and some specific brines have been studied extensively, no universally applicable model currently exists. This can result in a considerable degree of uncertainty as to how different geothermal resources will perform in practice. Geofluid modelling has historically been focused on two research fields: 1) partitioning the geofluid into separate phases, and 2) the estimation of the phases’ thermophysical properties. Models for the two fields have commonly been developed separately. Recognising their potential synergy, we introduce <em>GeoProp</em>, a novel geofluid modelling framework, which addresses this application gap by coupling existing state-of-the-art fluid partitioning simulators, such as <em>Reaktoro</em>, with high-accuracy thermophysical fluid property computation engines, like <em>CoolProp</em> and <em>ThermoFun. GeoProp</em> has been validated against field experimental data as well as existing models for some incompressible binary fluids. We corroborate GeoProp's efficacy at modelling the thermophysical properties of geothermal geofluids via a case study on the heat content of different geofluids. Our results highlight the importance of accurately characterising the thermophysical properties of geofluids in order to quantify the resource potential and optimise the design of geothermal power plants.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424414","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":"The hydrochemistry and geothermometry of thermal waters from a deep Jurassic aquifer in Lower Austria–South Moravia region","authors":"","doi":"10.1016/j.geothermics.2024.103173","DOIUrl":"10.1016/j.geothermics.2024.103173","url":null,"abstract":"<div><div>Potentially important deep hydrogeological structure containing thermal water is in the border area of Austria and the Czech Republic. Thermal water is bound to a deep Jurassic carbonate aquifer (reaching depths above 3 km) underlying the Tertiary sediments of the Alpine-Carpathian Foredeep. Its current use is limited only to spa and recreational purposes serviced by two 1.45 km deep wells. Our study is the first comprehensive study in this area to understand the origin and processes of thermal water formation and evolution. Understanding the processes in aquifers containing thermal water is of fundamental importance both for geothermal potential and for knowledge of possible natural analogues of deep CO₂ storage. The research has shown that thermal water is of dominant Na-Cl type with largely varying TDS (total dissolved solids) values between 0.4 and 56 g/L. Assumed marinogenic origin is confirmed by Cl/Br ratio. The average value of the geothermal gradient is 28.5 °C/km and the observed groundwater temperature ranges from 37 °C to 110 °C, with the highest values found in the deepest part of the aquifer, mainly on the Austrian side. The Jurassic aquifer is divided into two sections: a shallower, less mineralised northwestern section and a deeper, highly mineralised southeastern section, with a relatively impermeable barrier between them. The southeastern section contains mainly fossil seawater of high salinity ranging from 15 to 56 g/l and represents a structure with limited connection to active groundwater flow. In contrast, the thermal water in the northwestern section shows evidence of meteoric water infiltration from NW, as confirmed by TDS concentrations, hydrochemistry, and stable δ²H and δ¹⁸O isotope composition. The most reliable geothermometrical estimations are given by the K-Mg (<span><span>Giggenbach, 1988</span></span>) and Na-K (Truesdell 1976; Tonani 1980; Arnórsson 1983) geothermometers with mean reservoir temperature around 95 °C. The average temperature is higher in the water samples from the southeastern section and according to the geothermometrical evaluation, most of the water samples from both aquifer sections are mature chloride waters. Immature waters occur only in the northwestern section, indicating dilution of primary seawater by shallow cold waters of meteoric origin.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357702","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":"Comparative analysis of hybrid geothermal-solar systems and solar PV with battery storage: Site suitability, emissions, and economic performance","authors":"","doi":"10.1016/j.geothermics.2024.103175","DOIUrl":"10.1016/j.geothermics.2024.103175","url":null,"abstract":"<div><div>Renewable energy integration has become a critical focus in the global effort to reduce carbon emissions and diversify energy sources. In regions with distinct geographic features, such as Türkiye, combining different renewable technologies can offer enhanced energy security. This study investigates the site suitability and economic and environmental performance of hybrid geothermal-solar systems and solar PV systems with battery storage across the provinces of Osmaniye, Hatay, and Kilis, of Türkiye. Using the fuzzy-AHP method, site suitability is evaluated, addressing a key gap in comparing these systems' adaptability to varying geographic conditions. This study is the first to directly compare these two renewable energy technologies in terms of site suitability. The findings reveal significant differences in site suitability, with solar PV systems with battery storage demonstrating broader applicability across the region. The suitable sites (20–100 % suitability) cover 1260.82 km² for solar PV systems with battery storage and only 122.18 km² for hybrid geothermal-solar systems. In terms of environmental impact, hybrid geothermal-solar systems exhibit significantly lower carbon emissions, averaging 44.6 kg CO₂/MWh, compared to 123.8 kg CO₂/MWh for solar PV systems with battery storage. Economically, hybrid geothermal-solar systems also outperform with a lower levelized cost of electricity of $0.091 kWh versus $0.254 kWh for solar PV systems. These results highlight the environmental and economic advantages of hybrid geothermal-solar systems, while also emphasizing their limited scalability to regions with geothermal activity. Conversely, solar PV systems, despite their higher emissions and costs, offer greater flexibility and potential for widespread deployment.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357701","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":"Deconvolution of high and low-temperature alteration processes along the contact zones of basaltic-dike intrusions in basaltic host rocks of different permeabilities – implications for geothermal exploration","authors":"","doi":"10.1016/j.geothermics.2024.103171","DOIUrl":"10.1016/j.geothermics.2024.103171","url":null,"abstract":"<div><div>Magmatic intrusions serve as crucial heat sources for geothermal systems, facilitating mass transfer, mineral transformations, and elemental exchange, which result in the formation of contact aureoles. While these processes have been extensively studied in large intrusive complexes in ancient geological formations, understanding of their occurrence in active geothermal systems remains limited. The extreme conditions present in active volcanic systems often obscure the geochemical processes occurring within host rock/intrusion zones. Uncertainties persist regarding whether relatively small dike intrusions (∼0.5 m thick) possess sufficient heat content to induce textural or geochemical changes in the surrounding wall rock, and what implications this may hold for future exploratory drilling projects. The analyses in this study were conducted on two distinct outcrops, each featuring 50-cm thick basaltic intrusions within both high- and low-permeability basaltic host rocks. The low permeability host rock hosts high-temperature mineral phases (&gt;800 °C), such as sanidine + hedenbergite + albite-rich plagioclase in the contact zone, which we interpret to have formed during partial melting. Immobile, incompatible trace elements (such as Zr, Nb and La) retain the signatures of partial melting in both outcrops. We demonstrate that low degree partial melting (<em>F</em> ≈ 3–10 %) results in a compositional shift in the host rock from basalt to dacite and/or trachyandesite. Thermal modelling suggests that these small dikes, along with their partial melts in the contact zone, form over a very short period of time (&lt; 1 day), but can elevate the ambient temperature. This type of events play an important role in the development of active geothermal systems. In theory, these small dikes do not pose a significant risk during geothermal drilling, unless they are too small to be detected during geophysical exploration.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357700","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":"Mapping and delineation of steel corrosion products under geothermal-like conditions","authors":"","doi":"10.1016/j.geothermics.2024.103172","DOIUrl":"10.1016/j.geothermics.2024.103172","url":null,"abstract":"<div><div>In this paper we attempt to understand the corrosion behavior of carbon (mild) steel (a common structural component in water handling installations) and the factors that influence it, by identifying various corrosion products that form under diverse conditions relevant to geothermal systems. Hence, experiments were performed under variable stressful experimental conditions, by systematically studying the effect of certain important variables, such as temperature and brine composition. Therefore, three brines and four temperatures were selected (ambient, 60, 90, and 130 °C), while the pH was kept constant at ∼ 7. It was found that for all water qualities corrosion rates (quantified by gravimetric methods and soluble Fe measurements) are not directly proportional to the temperature, with the measured values being the lowest at RT and highest at <em>T</em> = 130 °C. In the two intermediate temperatures (60 and 90 °C) the corrosion rates are lower. A possible explanation for this could be the fact that corrosion products can form films on the metal surface, affecting the corrosion aggressiveness, and thus corrosion rates. The full characterization of precipitates collected from these experiments led to the identification of the corrosion products and to the correlation of corrosion aggressiveness (due temperature and water quality) with the identity of each corrosion product. The variability in color of the corrosion products on the metal surfaces was an indication of the formation of lepidocrocite and magnetite films, as demonstrated by the orange and black color of the films on the specimens, respectively. The identification of the corrosion products that formed under the selected experimental conditions was achieved by the physicochemical characterization (ATR-IR and powder XRD) of the iron deposits collected from the control experiments. These studies confirmed the qualitative indications based on the deposit color.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312605","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":"Numerical investigation of the geometric parameters effect of helical blades installed on horizontal geo heat exchanger","authors":"","doi":"10.1016/j.geothermics.2024.103169","DOIUrl":"10.1016/j.geothermics.2024.103169","url":null,"abstract":"<div><p>In this study, we investigate the enhancement of horizontal geothermal heat exchangers equipped with helical fins on the pipe's exterior and internally ribbed turbulators. Our approach focuses on the interplay between geometry and thermal efficiency through innovative design modifications. Utilizing the finite element method, three-dimensional numerical simulations assessed the effects of varying geometric parameters such as the diameter and thickness of the fins. Our findings indicate significant increases in heat transfer efficiency with the addition of helical fins; specifically, increasing the fin diameter from 5 mm to 10 mm results in a 15 % increase in the heat transfer rate, while doubling the fin thickness from 2 mm to 4 mm enhances the rate by 10 %. These improvements are due to the expanded surface area facilitating greater heat exchange. Optimization using the desirability function approach yielded models with high performance, achieving desirability scores of 0.9879 for outlet temperature and 0.9534 for the heat transfer coefficient. This reflects the effective tuning of geometric parameters to maximize thermal performance. The study also introduces two predictive mathematical models for the outlet temperature and convective heat transfer coefficient of the U-shaped pipe equipped with these enhancements. These models, derived from extensive numerical data, provide practical tools for future design and operational applications of geothermal heat exchangers. This research advances the design and operational efficiency of geothermal heat exchange systems, establishing new benchmarks for thermal efficiency in the field with actionable insights and robust mathematical tools.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243444","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}