Geothermics最新文献

{"title":"Experimental assessment of inter-well reinjection in standing column wells by analysis of transfer functions obtained from non-stationary deconvolution","authors":"","doi":"10.1016/j.geothermics.2024.103184","DOIUrl":"10.1016/j.geothermics.2024.103184","url":null,"abstract":"<div><div>Standing column wells are semi-open-loop ground heat exchangers that can achieve highly efficient thermal exchange rates through the strategic control of the pumping and bleed flow rates. The management of groundwater discharges associated with bleed use remains a challenge. A solution is inter-well reinjection, which proposes to imbalance the return flow rates between the standing column wells. This approach has been shown to be more efficient than fully balanced recirculation, although a direct comparison with a conventional bleed operation has not yet been conducted. To provide a robust evaluation of inter-well reinjection performance, a 35-day-long experiment is conducted on five standing column wells connected to a real building. The experimental transfer functions representing the operating modes tested (full recirculation, bleed, and inter-well reinjection) are evaluated using a non-stationary deconvolution algorithm and their adequacy with the conceptual site model is verified by comparison with numerical transfer functions obtained in a Monte-Carlo experiment. The results indicate that inter-well reinjection leads to a 10% higher thermal efficiency in the scenarios tested compared to full recirculation, albeit with a slightly reduced performance compared to typical bleed use. This confirms the potential of inter-well reinjection for boosting the efficiency of thermal exchange in SCWs while facilitating groundwater management and avoiding the installation of costly injection facilities. The methodology used to evaluate the experimental transfer functions is also found to be robust, as it allowed the reproduction of the measured temperatures with a root mean square error of 0.04 <span><math><mrow><mo>°</mo><mi>C</mi></mrow></math></span>. Lastly, comparison of the experimental transfer functions with the Monte-Carlo experiment suggests that the accuracy of the conceptual model could be improved.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593796","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":"The certainty matrix for fault data and interpretations","authors":"","doi":"10.1016/j.geothermics.2024.103197","DOIUrl":"10.1016/j.geothermics.2024.103197","url":null,"abstract":"<div><div>This paper introduces an approach for expressing certainty in the analysis and interpretation of faults, using a modification of the risk matrix commonly used in risk assessment. The <em>certainty matrix</em> uses qualitative or semi-quantitative analyses of both the data used and an interpreted characteristic of individual faults or fault systems. These characteristics may include the existence of faults, the certainty of trace lengths, the age of faults, or the influence of faults on sub-surface fluid flow. This approach improves the ability to make justifiable interpretations and decisions about faults and fault-affected areas, including about issues relevant to geothermal energy exploration or the underground storage of radioactive waste. The use of this approach is illustrated using three faults from Somerset, UK.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593797","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":"Investigation of radiogenic heat production in granites of the Goiás Tin Province, Central Brazil","authors":"","doi":"10.1016/j.geothermics.2024.103183","DOIUrl":"10.1016/j.geothermics.2024.103183","url":null,"abstract":"<div><div>This study defines the radiogenic heat production of A-type granites in the Goiás Tin Province (GTP), Central Brazil, using airborne gamma-ray spectrometry. Pedra Branca Massif and Serra Dourada Granite are rich in tin, rare earth elements, and they exhibit anomalous radiogenic heat (5.5–15 µW/m³). They are therefore classified as high heat production granites (HHPG). By integrating radiogenic heat data, RGB imaging, magnetometry, density model and geological information, we associated anomalous radiogenic heat with mineralized regions present in the granites found in the GTP. Our methodology was validated using geological information, density model and other granites worldwide. It proved to be effective for targeting HHP granites.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142571398","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":"Influence of ground source heat exchanger operation modes on multi-borehole mid-deep ground source heat pump system performance","authors":"","doi":"10.1016/j.geothermics.2024.103186","DOIUrl":"10.1016/j.geothermics.2024.103186","url":null,"abstract":"<div><div>The operation economy of mid-deep ground source heat pump (MGSHP) system is significantly influenced by the operation mode of multi-borehole mid-deep borehole heat exchangers (MMBHE). However, as to now, the understanding about it is very limited and far from enough. This study explores the effects of the MMBHE different operating modes on the performance of MGSHP system, and the factors such as full boreholes operation arrangement, circulating water flow rate variation of individual boreholes, and building heating load variations during the heating season. The study analyzed the circulating water temperature variation, underground temperature field distribution and evolution, heat pump unit COP, coefficient of system performance (CSP), heat extraction of MMBHE, reverse heat transfer depth of MBHE, and power consumption. The results indicate that the operation mode of letting all boreholes operate throughout the whole heating season and reducing circulating water flow rate when the heating load is small and increasing it while the load is large is much better than other operation modes. With this kind of operation mode, the MGSHP system has the lowest power consumption. Even though the overall borehole extracts heat from the ground, the upper section of the borehole sometimes injects heat. The length of the heat release section can be effectively shortened by reducing the circulating water flow rate and decreases as the operation time extends. The reduction is most significant when all boreholes are put into operation. Reducing the circulating water flow rate when the load is small and increasing it when the load turns large can result in a reduction of &gt;50 % in the fifth year compared to that in the first year.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554568","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":"Deep thermal state on the southern margin of the Zhangzhou Basin based on the electrical conductivity model","authors":"","doi":"10.1016/j.geothermics.2024.103188","DOIUrl":"10.1016/j.geothermics.2024.103188","url":null,"abstract":"<div><div>Exploring the internal spatial and thermal structure of the Zhangzhou Basin is of great scientific significance in understanding the properties of the deep heat sources and the heating mechanism of hot springs in this region. This study estimates the temperature distribution within the upper mantle of the Basin's southern margin using the Arrhenius equation and Hashin-Shtrikman bounds based on a two-dimensional crust-mantle electrical resistivity model. We also employ a layered simulation technique to calculate the crustal temperature distribution using a one-dimensional steady-state heat conduction equation, constrained by the upper mantle's top and ground surface temperatures. This approach displays the characteristics of the longitudinal variations and horizontal inhomogeneities in crust-mantle temperature. Additionally, we estimate the heat flow values within the study area. Our findings reveal that: (i) the upper mantle (at depths of 30 - 50 km) exhibits a temperature range of 700 - 1100 °C, with the presence of local Moho and upper mantle uplifts; (ii) the crustal temperature spans from 21 - 900 °C, with a diminishing influence of the upper mantle uplift area on crustal temperature at shallower depths; (iii) the surface heat flow values derived from our simulations range between 87 and 100 mW/m², averaging at 93.23 mW/m²; (iv) the exploration of dry heat rock in this region is likely to reach a depth of at least 6 km. These results suggest that the genesis of hot springs in the study area is not solely influenced by the heat energy extracted from large-area granitic surrounding rocks during a long transport process, but is also considerably affected by local deep thermal anomalous bodies and deep-large faults.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554569","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":"Natural recovery from Fe-oxyhydroxide clogging of a geothermal well in Osaka, Japan","authors":"","doi":"10.1016/j.geothermics.2024.103187","DOIUrl":"10.1016/j.geothermics.2024.103187","url":null,"abstract":"<div><div>Causes of clogging and the following unique recovering process of an ATES (Aquifer Thermal Energy Storage) system in Maishima (Osaka, Japan) are documented based on the geochemical analyses of groundwater and stagnant water in the system. Fe-oxyhydroxides precipitation clogged screens in an ATES geothermal well during cooling operation. Chemical analyses of waters in the aquifers and plumbing pipes found out that oxidation of dissolved Fe occurred in association with intrusion of ambient air, which was leaked through inadvertently opened air bent valve, into the well. Dual heat-extraction system was installed in the two aquifers of the same wells separated by packers, and the closing occurred in the plumbing pipe installed in the shallow aquifer of one of the thermal wells. This aquifer could not be used as the ATES until when the Fe-oxyhydroxides were naturally dissolved in about a half year after the clogging. Then, the ATES system recovered to be useful. Increasing dissolved Fe with increasing NH₄⁺ and decreasing oxidation–reduction potential indicated that the Fe-oxyhydroxides were dissolved by microbially induced reduction reactions. This case suggests that some clogs can be mitigated without chemical and/or physical treatment, and that monitoring of groundwater chemistry is essential for diagnosing and treating clogs.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531420","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":"Numerical modeling of the Nevados de Chillán fractured geothermal reservoir","authors":"","doi":"10.1016/j.geothermics.2024.103181","DOIUrl":"10.1016/j.geothermics.2024.103181","url":null,"abstract":"<div><div>Numerical models can be utilized to understand and anticipate the future behavior of a geothermal reservoir, and hence aid in the development of efficient reservoir engineering strategies. However, as each system has a unique geological context, individual characterization is required. In this research, the Nevados de Chillán Geothermal System (NChGS) in the Southern Volcanic Zone of the Andes is considered. The NChGS is controlled by the geology of the active Nevados de Chillán Volcanic Complex (NChVC) including their basement units (Miocene lavas and volcaniclastic layers from Cura-Mallín Formation and the Miocene, Santa Gertrudis granitoids) as well as the key structural control from crustal scale faults, all of which combine to influence the reservoir characteristics. The presence of faults acts to generate a high secondary permeability which favors the circulation of hydrothermal fluids. Based on previous studies in the NChGS, we designed a thermo-hydraulic model in COMSOL Multiphysics® combining equations of heat transfer and Darcy's law in order to determine the distribution of isotherms and surface heat flux. The boundary conditions of the model were informed by a conceptual model of depth 3 km and width of 6.6 km which considers a highly fractured granitic reservoir, a clay cap behavior of Miocene lavas and volcaniclastic units, and transitional zones between a regional zone and the reservoir. A low-angle reverse fault affecting the clay cap unit was also incorporated into the models. Results indicate convective behavior in the reservoir zone and a surface heat flux of 0.102 W/m² with a local peak up to 0.740 W/m² in the area affected by the low-angle reverse fault zone. The models suggest hydrothermal fluid residence times of around 9–15 thousand years are required to reach a steady-state thermal configuration, which is consistent with the deglaciation age proposed for the NChVC latitude of the complex (<em>c.</em> 10–15 ka). Permeability in the fractured reservoir is one of the most complex parameters to estimate and the most sensitive and hence requires further constraint. Finally, using the volumetric method and the results obtained in this research, we estimate a geothermal potential of 39 ± 1 MWe for the NChGS.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531180","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":"Modeling proppant transport and settlement in 3D fracture networks in geothermal reservoirs","authors":"","doi":"10.1016/j.geothermics.2024.103176","DOIUrl":"10.1016/j.geothermics.2024.103176","url":null,"abstract":"<div><div>In this paper, we develop an efficient proppant transport model using the Eulerian-Eulerian approach for simulating proppant transport in fractures and 3D fracture networks in geothermal reservoirs. The proposed model accounts for proppant settling, pack/bed formation, bridging/screenout, proppant concentration effect, fracture wall effect, and the transition from Poiseuille flow (fracture channel) to Darcy flow (proppant pack). Notably, the heat transfer process and its impact on proppant transport are also considered—a facet often overlooked in previous proppant transport models. A three-dimensional displacement discontinuity method (3D DDM) that incorporates the stress shadow effect is employed to generate the fracture geometry. The governing equations for slurry flow, proppant transport, and heat transfer are discretized and solved using the finite volume method (FVM). The model is verified against analytical solutions and published experimental data, demonstrating good agreement with these references. To demonstrate the proposed model, we applied it to both low-temperature (depleted hydrocarbon wells) and high-temperature (dry hot rocks) enhanced geothermal systems (EGS). The simulation results highlight the significant influence of reservoir temperature on proppant transport and settlement in a reservoir environment. Heating of the slurry by higher temperature reservoir rocks reduces fluid viscosity and accelerates proppant settling, thereby shortening the transport distance and reducing the coverage area of the proppant. Both ultra-light and micro-proppant are effective in mitigating proppant settlement in enhanced geothermal systems. However, proppant is susceptible to bridging at fracture intersections, where the fracture widths are narrower due to more pronounced stress shadow effects in these areas. Consequently, the use of micro-proppant could offer substantial benefits over ultra-light proppant in enhancing proppant coverage area in enhanced geothermal systems.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531181","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":"Three-dimensional electrical imaging of the Aravali-Tural-Rajwadi geothermal system, West Coast of India","authors":"","doi":"10.1016/j.geothermics.2024.103185","DOIUrl":"10.1016/j.geothermics.2024.103185","url":null,"abstract":"<div><div>The West Coast geothermal system is a prominent geothermal region in the Indian subcontinent, and understanding its geothermal reservoirs is crucial for societal benefits. In the present study, we employed 3D modeling of Audio and broad-band Magnetotelluric (AMT &amp; MT) data for the first time in the West Coast geothermal region, covering the Aravali, Tural, and Rajwadi geothermal zones, to gain insights into the evolution of geothermal zone and geothermal reservoir characteristics. The 3D inversion results revealed the presence of a thin layer of granitic crustal layer, which decreases in thickness towards the west. The rifting process along the western continental margin of India has introduced magmatism (underplated) to the crustal level, which manifests as a moderate conductivity (100–500 Ωm) layer in shallow depths (∼10 km). The cooling and solidification of underplating materials contribute to the heat flux along the West Coast geothermal zone (WCGZ). The circulation of meteoric water within the deep layers gets heated up by these mantle materials and is ejected along the fracture and fault zones that appear as hot springs. Considering a thin crustal layer, a shallow Moho, and an upwelling asthenosphere along the west coast, the WCGZ is considered a convective geothermal play type. This study enhances an understanding of the WCGZ geothermal potential and geological processes, which can have significant implications for harnessing this valuable energy resource.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531179","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":"Experimental and numerical research on the thermal performance of a vertical earth-to-air heat exchanger system","authors":"","doi":"10.1016/j.geothermics.2024.103182","DOIUrl":"10.1016/j.geothermics.2024.103182","url":null,"abstract":"<div><div>The Earth-to-Air Heat Exchanger (EAHE) system is an efficient and clean geothermal application technology that can be used for pre-cooling in summer and heating in winter. This paper proposes a novel Vertical Earth-to-Air Heat Exchanger (VEAHE) system that uses baffles to divide the vertical duct into two ventilation tunnels with a hollow area at the bottom for air circulation. This system occupies a small land area and has a relatively high geothermal energy utilization efficiency. This study evaluates the thermal performance of the system through experimental tests under various operating conditions. Additionally, a numerical model of the system was established to explore the influence of baffles length, thickness, and duct depth on its thermal performance. The experimental results show that the 2.5-meter deep VEAHE system achieves an average air pre-cooling temperature reduction of 5.42 °C, with a maximum temperature reduction of up to 7.58 °C. Below the 1.2-meter mark of the system, the cooling capacity of the descending pipe is 1.52 times that of the ascending pipe. The simulation showed a Maximum Absolute Relative Error (MARE) of 3.15 % compared to the experimental results. As the length and thickness of the baffles, duct length, and soil thermal conductivity increase, the average outlet air temperature gradually decreases, while the system's heat exchange capacity significantly improves, in contrast to the duct diameter. Among the influencing factors, the duct length has the greatest impact on the system. Under the recommended configuration, the system's maximum pre-cooling potential is 915.90 W, with the outlet air temperature ranging from 12.05 °C to 14.79 °C.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442824","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}