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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 不同渗透率玄武岩母岩中玄武岩-堤侵入体接触带高温和低温蚀变过程的解卷积--对地热勘探的影响
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-28 DOI: 10.1016/j.geothermics.2024.103171
Byron F. Pilicita M , Enikő Bali , Guðmundur H. Guðfinnsson , Guðmundur Ó. Friðleifsson , Eemu Ranta , Sigurður G. Kristinsson
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 (>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 (F ≈ 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 (< 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.
岩浆侵入体是地热系统的重要热源,可促进质量传递、矿物转化和元素交换,从而形成接触金星。虽然这些过程在古代地质构造中的大型侵入复合体中得到了广泛研究,但对其在活动地热系统中发生的了解仍然有限。活火山系统中存在的极端条件往往掩盖了发生在主岩/侵入带中的地球化学过程。关于相对较小的堤状侵入体(厚度在 0.5 米以下)是否具有足够的热量来引起周围岩壁岩石的纹理或地球化学变化,以及这对未来勘探钻井项目的影响,仍然存在不确定性。本研究对两个不同的露头进行了分析,每个露头都有 50 厘米厚的玄武岩侵入体,分别位于高渗透性和低渗透性玄武岩母岩中。低渗透性母岩含有高温矿物相(>800 °C),如接触带的辉绿岩+辉长岩+富斜长石,我们认为这些矿物相是在部分熔融过程中形成的。在两个露头中,不移动、不相容的微量元素(如锆、铌和镭)保留了部分熔融的特征。我们证明,低度局部熔融(F ≈ 3-10%)会导致母岩成分从玄武岩转变为英安岩和/或闪长岩。热模拟表明,这些小型岩钉及其在接触区的部分熔体形成的时间很短(1 天),但却能使环境温度升高。这类事件在活跃地热系统的发展中起着重要作用。从理论上讲,这些小堤在地热钻探过程中不会构成重大风险,除非它们太小,在地球物理勘探过程中无法探测到。
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引用次数: 0
Mapping and delineation of steel corrosion products under geothermal-like conditions 类地热条件下钢铁腐蚀产物的制图和划分
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-24 DOI: 10.1016/j.geothermics.2024.103172
Stefania Liakaki-Stavropoulou, Konstantinos D. Demadis
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 T = 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.
在本文中,我们试图通过确定在地热系统相关的各种条件下形成的各种腐蚀产物,来了解碳(低碳)钢(水处理装置中的常见结构部件)的腐蚀行为及其影响因素。因此,通过系统研究某些重要变量(如温度和盐水成分)的影响,在不同的应力实验条件下进行了实验。因此,实验选择了三种盐水和四种温度(常温、60、90 和 130 °C),pH 值保持在 ∼ 7。研究发现,对于所有水质,腐蚀率(通过重量法和可溶性铁测量法量化)与温度并不成正比,在常温下测量值最低,而在 T = 130 °C 时测量值最高。在两个中间温度(60 和 90 °C)下,腐蚀率较低。可能的解释是,腐蚀产物会在金属表面形成薄膜,影响腐蚀侵蚀性,从而影响腐蚀速率。通过对从这些实验中收集到的沉淀物进行全面表征,可以确定腐蚀产物,并将腐蚀侵蚀性(由于温度和水质)与每种腐蚀产物的特性联系起来。金属表面腐蚀产物颜色的变化表明形成了鳞片岩和磁铁矿薄膜,试样上的薄膜颜色分别为橙色和黑色。通过对从对照实验中收集的铁沉积物进行物理化学表征(ATR-IR 和粉末 XRD),确定了在选定实验条件下形成的腐蚀产物。这些研究证实了基于沉积物颜色的定性指标。
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引用次数: 0
Numerical investigation of the geometric parameters effect of helical blades installed on horizontal geo heat exchanger 对安装在水平地缘热交换器上的螺旋叶片几何参数影响的数值研究
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-18 DOI: 10.1016/j.geothermics.2024.103169
Abdulwahab A. Alnaqi, Abdullah A.A.A. Al-Rashed, Jalal Alsarraf

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.

在这项研究中,我们探讨了如何提高水平地热换热器的热效率,该换热器在管道外部装有螺旋翅片,内部装有带肋涡轮。我们的研究重点是通过创新的设计改造,研究几何形状与热效率之间的相互作用。利用有限元方法,三维数值模拟评估了不同几何参数(如翅片直径和厚度)的影响。我们的研究结果表明,增加螺旋形散热片后,传热效率明显提高;具体而言,将散热片直径从 5 毫米增加到 10 毫米后,传热率提高了 15%,而将散热片厚度从 2 毫米增加一倍到 4 毫米后,传热率提高了 10%。这些改进都是由于扩大了表面积,促进了更大的热交换。使用可取函数法进行优化后,模型的性能很高,出口温度的可取分数达到 0.9879,传热系数达到 0.9534。这反映出通过有效调整几何参数,实现了热性能的最大化。该研究还引入了两个预测数学模型,用于预测配备这些增强功能的 U 型管道的出口温度和对流传热系数。这些模型源自大量数值数据,为地热换热器未来的设计和运行应用提供了实用工具。这项研究提高了地热换热系统的设计和运行效率,通过可操作的见解和强大的数学工具为该领域的热效率建立了新的基准。
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引用次数: 0
A segmented analytical solution heat transfer model of U-tube ground heat exchanger based on finite solid cylindrical heat source method 基于有限实体圆柱热源法的 U 型管地面换热器分段解析解传热模型
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-16 DOI: 10.1016/j.geothermics.2024.103170
Jingjing Wang , Juntao Deng , Jianguo Zheng , Yongtang Yu , Jianmin Zhu , Xin Huang

Effectively describing the heat transfer process of ground heat exchangers is crucial for fully utilizing geothermal energy. The current progress in heat transfer analysis models is to divide the soil into several non-isothermal soil layers based on the assumption of uniform borehole wall temperature and heat flux in traditional models, but the temperature and heat flux inside the layers are uniform. Rarely consider the non-uniformity of heat flux within the layer and the boundary problem of vertical heat flux at the ground level. This article adopts a composite medium method to modify the segmented model, considering the heat transfer problem between soil layers. The assumption of uniform temperature of the borehole wall was removed to improve the fluid analysis model. Afterwards, analyze the impact of the heat transfer process inside and outside the borehole on the heat flux of the borehole wall. Using the segmented trial-and-error technique to couple the fluid and soil heat transfer models, a new comprehensive model of the U-shaped grounded heat exchanger was established. Conducted initial underground soil temperature distribution and thermal response tests in different geomorphic units in Guanzhong, Shaanxi, and verified the model's reliability based on experimental data. Analyze three influencing factors, namely fluid mass flow rate, initial underground soil temperature considering variable temperature layer, and temperature difference between average initial underground soil temperature and inlet fluid temperature, to evaluate system performance. The results indicate that the recommended range of fluid mass flow rate in the Guanzhong region is 0.32–0.42 kg/s. It was found that the heat transfer capacity of the heat exchanger will be underestimated if it ignores the influence of the variable temperature layer. Furthermore, the determination of the heat extraction result is not due to the high inlet fluid temperature but rather to the high difference between the inlet fluid temperature and the initial underground soil temperature. This study can promote better system design and achieve higher system performance.

有效描述地热交换器的传热过程对于充分利用地热能至关重要。目前传热分析模型的研究进展是在传统模型中基于钻孔壁温度和热通量均匀的假设,将土壤划分为多个非等温土壤层,但各层内部的温度和热通量是均匀的。很少考虑层内热通量的不均匀性和地层垂直热通量的边界问题。本文采用复合介质法修改分段模型,考虑了土层间的传热问题。取消了井壁温度均匀的假设,改进了流体分析模型。然后,分析钻孔内外传热过程对孔壁热通量的影响。利用分段试错技术将流体和土壤传热模型耦合,建立了新的 U 型接地换热器综合模型。在陕西关中不同地貌单元进行了地下土壤初始温度分布和热响应试验,并根据试验数据验证了模型的可靠性。分析流体质量流量、考虑变温层的地下土壤初始温度、地下土壤平均初始温度与入口流体温度之间的温差三个影响因素,评价系统性能。结果表明,关中地区流体质量流量的推荐范围为 0.32-0.42 kg/s。研究发现,如果忽略变温层的影响,换热器的传热能力将被低估。此外,热量提取结果的确定并非由于入口流体温度过高,而是由于入口流体温度与地下土壤初始温度之间的差异过大。这项研究可以促进更好的系统设计,实现更高的系统性能。
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引用次数: 0
Geothermal distribution and evolution of fault-controlled Linyi geothermal system: Constrained from hydrogeochemical composition and numerical simulation 断层控制的临沂地热系统的地热分布与演化:来自水文地质化学成分和数值模拟的约束
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-15 DOI: 10.1016/j.geothermics.2024.103155
Yuzhong Liao , Wei Zhang , Yuwei Rong , Long Li , Guoqing Hu

This study explores the Linyi geothermal field, located in Shandong Province, China, characterized by its non-magmatic, active fault-controlled geothermal system. Utilizing a combination of geochemical analyses, temperature measurements, and numerical simulations, a detailed genetic model of the geothermal system has been developed. The analysis included extensive water geochemical and isotopic characterization to determine reservoir temperature, depth, and origin of the geothermal waters. The thermal-hydro coupling model was integrated with these data to refine the thermal distribution and assess the evolutionary dynamics of the geothermal system. Our findings indicate that the geothermal anomalies in the Linyi field are predominantly controlled by hydrothermal convection within the Ordovician and Cambrian carbonate layers, facilitated by the high permeability of the Yishu Fault. The fault acts as a crucial conduit for meteoric water recharge, which undergoes significant heating due to the geothermal gradient in deeper rock formations. Isotopic analyses of hydrogen and oxygen revealed the meteoric origin of the geothermal waters, with recharge likely originating from the nearby Yimeng Mountains. Furthermore, the study established a conceptual evolutionary model to understand the mechanisms driving the geothermal resource development in the area. It was determined that the geothermal resources are typically fault-controlled, with significant potential for further exploration due to the identified hydrothermal anomalies at the fault's footwall. The model predicts the preservation of heated meteoric water in the reservoir rock for periods ranging from 10 to 50 thousand years, providing a sustainable source of geothermal energy. This comprehensive approach not only enhances the understanding of the heat accumulation mechanism but also highlights the potential for optimizing geothermal exploration strategies within fault-controlled geothermal systems.

本研究探讨了位于中国山东省的临沂地热田,该地热田的特点是非岩浆活动断层控制地热系统。综合利用地球化学分析、温度测量和数值模拟,建立了详细的地热系统遗传模型。分析包括广泛的水地球化学和同位素特征,以确定储层温度、深度和地热水的来源。热-水耦合模型与这些数据相结合,完善了热分布并评估了地热系统的演化动态。我们的研究结果表明,临沂油田的地热异常主要是由奥陶纪和寒武纪碳酸盐岩层内的热液对流控制的,沂沭断层的高渗透性为其提供了便利。该断层是陨石水补给的重要通道,由于深部岩层的地热梯度,陨石水会发生显著的加热。氢和氧的同位素分析表明,地热水源于流星水,补给可能来自附近的沂蒙山。此外,研究还建立了一个概念演化模型,以了解该地区地热资源开发的驱动机制。研究确定,地热资源通常受断层控制,由于在断层底壁发现了热液异常,因此具有进一步勘探的巨大潜力。该模型预测,加热的陨石水在储层岩石中可保存 1 万至 5 万年,从而提供可持续的地热能源。这种全面的方法不仅增强了对热量积累机制的理解,还凸显了在断层控制的地热系统中优化地热勘探战略的潜力。
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引用次数: 0
Structural controls on hydrothermal fluid flow in a carbonate geothermal reservoir: Insights from giant carbonate veins in western Germany 碳酸盐岩地热储层中热液流体流动的结构控制:德国西部巨型碳酸盐矿脉的启示
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-13 DOI: 10.1016/j.geothermics.2024.103149
Luca Smeraglia , Alessandro Verdecchia , Chelsea Pederson , Onyedika Anthony Igbokwe , Mathias Mueller , Rebecca Harrington

This study examines the impact of polyphase tectonics on the development of structurally controlled hydrothermal fluid pathways in carbonate geothermal reservoirs. Our case study focuses on hydrothermal carbonate veins and vein-filled faults in Devonian carbonates from the North Rhine-Westphalia region in western Germany, currently being explored as a potential low-enthalpy geothermal reservoir at depths of 4–5 km. These veins, which can be up to 20 m thick, are subvertical and strike NNW, N, or ESE. They exhibit pinch-and-swell undulating geometries, faulted vein-wall contacts, and occasional fillings of hydrothermal breccias. Vein-filled normal faults show hybrid shear-dilatant openings, with fault tips characterized by horsetail vein terminations. The textures, orientations, and age of the veins suggest their formation at low confining pressures and at depths < 2 km during the Post-Variscan East-West extension. Orthogonal North- and East-striking strike slip faults, inherited from the Variscan orogeny, were likely reactivated during post-Variscan extension, with a significant dilatant component that formed the observed veins. In the Ruhr Basin, the dilation tendency analysis indicates that NNW-striking veins or joints are optimally oriented for re-opening under the current strike-slip stress regime, characterized by NNW-trending maximum horizontal stress. The intersections of fractures may currently create moderately SSE-plunging linear zones of enhanced fluid flow. The main uncertainty regards the presence of similar structures at geothermal reservoir depths of ∼4–5 km in the Middle Devonian carbonates underneath the Ruhr Basin. As the study veins are likely to have formed at depths <2 km, the existence of analogous dilatant conduits at greater depths remains speculative. Eventually, we propose that zones characterized by open discontinuities and channelized fluid flow in carbonate geothermal reservoir in strike-slip tectonic settings can be: (a) dilational jogs between overlapping strike-slip faults, (b) bends along faults, and (c) strike-slip fault terminations with horsetail extensional structures. These zones can also be prone to enhanced karstification.

本研究探讨了多相构造对碳酸盐岩地热储层中受构造控制的热液通道发展的影响。我们的案例研究侧重于德国西部北莱茵-威斯特法伦地区泥盆纪碳酸盐岩中的热液碳酸盐岩脉和充满岩脉的断层。这些矿脉厚度可达 20 米,呈亚垂直分布,走向为西北、北或东南。这些矿脉呈现出夹凹起伏的几何形状,矿脉壁与断层接触,偶尔会有热液角砾岩填充。充满矿脉的正断层呈现剪切-扩张混合开口,断层顶端以马尾状矿脉终端为特征。这些矿脉的质地、方向和年代表明,它们是在后华力斯坎时期东西向延伸过程中,在低封闭压力和 2 千米深处形成的。瓦利斯坎造山运动遗留下来的北向和东向正交走向滑动断层,很可能在后瓦利斯坎时期的延伸过程中被重新激活,其中重要的扩张成分形成了所观察到的矿脉。在鲁尔盆地,扩张倾向分析表明,在当前的走向滑动应力机制下,NNW 走向的矿脉或节理是重新开放的最佳方向,其最大水平应力呈 NNW 走向。目前,断裂的交汇处可能会形成适度向 SSE 倾斜的线性流体流动增强区。主要的不确定性在于鲁尔盆地下的中泥盆世碳酸盐岩地热储层深度 4-5 千米处是否存在类似结构。由于所研究的矿脉很可能是在 2 千米深处形成的,因此在更深的地方是否存在类似的扩张导管仍有待推测。最终,我们提出,在走向滑动构造环境中,碳酸盐岩地热储层中以开放性不连续和通道化流体流动为特征的区域可能是:(a) 重叠走向滑动断层之间的扩张斜坡,(b) 沿断层的弯曲,以及 (c) 具有马尾状延伸构造的走向滑动断层终端。这些地带也容易加强岩溶化。
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引用次数: 0
Experiences as heuristics for geothermal public perception: Testing the correlation between thermal waters recreation and geothermal energy perception 作为地热公众认知启发式方法的经验:测试热水域娱乐与地热能认知之间的相关性
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-12 DOI: 10.1016/j.geothermics.2024.103168
Maja Turnšek, Katja Kokot

This research focuses on the question of how geothermal energy public perception is formed within a national context where news media do not pay attention to geothermal energy, and there is no active opposition to geothermal energy. The research builds on theoretical underpinnings of heuristics in energy perceptions and highlights the importance of physical experiences and associations as sources of experiential learning. Through a survey conducted among members of the general public in Slovenia, the role of thermal water recreation in shaping public perception of geothermal energy is empirically tested. The results show that, in this context, geothermal energy is highly positively assessed compared to hydro energy and nuclear energy, and that there is a correlation between frequency of thermal recreation and certain aspects of public perception of geothermal energy. The policy implications go beyond the simple recommendation of including tourism in public awareness campaigns but point to the specific vulnerability of energy acceptance in this context, where perceptions are formed based on “thinking fast”, and where the media and the public discourse on geothermal energy have not (yet) considered the potential risks and opposition to geothermal projects.

这项研究的重点是,在新闻媒体不关注地热能源,也没有积极反对地热能源的国家背景下,地热能源的公众认知是如何形成的。这项研究建立在能源认知启发式的理论基础之上,并强调了实际体验和联想作为经验学习来源的重要性。通过对斯洛文尼亚公众进行调查,对热水娱乐在塑造公众对地热能源的认知方面所起的作用进行了实证检验。结果表明,在这种情况下,与水能和核能相比,地热能得到了高度积极的评价,而且热能娱乐的频率与公众对地热能某些方面的看法存在相关性。对政策的影响不仅仅是建议将旅游业纳入公众宣传活动,而是指出了在这种情况下接受能源的特殊脆弱性,因为人们的观念是在 "快速思考 "的基础上形成的,媒体和公众对地热能源的讨论(尚未)考虑到地热项目的潜在风险和反对意见。
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引用次数: 0
Understanding the latent needs of diverse stakeholders unfamiliar with geothermal energy 了解不熟悉地热能源的各利益相关方的潜在需求
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-12 DOI: 10.1016/j.geothermics.2024.103154
Hanae Saishu, Momo Takada, Tetsuo Yasutaka, Nobukazu Soma

Understanding stakeholders’ needs is crucial for promoting geothermal energy usage and gaining social acceptance. While local people are the key stakeholders in many geothermal projects, other groups have the potential to become directly or indirectly involved, even if they are initially unfamiliar with geothermal power generation. Variability in respondents’ knowledge and the uncertain and biased information associated with geothermal energy make it difficult to extract stakeholders’ needs when formulating a communication strategy. To evaluate stakeholders’ latent needs without providing respondents with detailed information of geothermal energy, this study develops a survey method using conjoint analysis. A web-based questionnaire survey conducted in Japan asked respondents to rank their preferences among seven power generation methods and various electricity supply conditions, which provided the factors necessary to evaluate the latent needs relating to each type of power generation. Subject knowledge is found to be lower for geothermal power generation than for the other power generation methods, although geothermal energy performs well in terms of both expressed and latent needs. Obvious differences in relative preferences among the other power generation methods are also revealed. The proposed method supports both local and outside stakeholders in identifying the various effects of geothermal projects and expressing their needs without undue burden. It is hoped that this approach will encourage stakeholders to understand each other, discuss which advantages/disadvantages of geothermal projects they can accept, and design a sustainable society that incorporates geothermal energy.

了解利益相关者的需求对于推广地热能源的使用和获得社会认可至关重要。虽然当地人是许多地热项目的主要利益相关者,但其他群体也有可能直接或间接参与其中,即使他们最初对地热发电并不熟悉。受访者的知识水平参差不齐,地热能源相关信息的不确定性和偏差性使得在制定传播策略时很难提取利益相关者的需求。为了在不向受访者提供地热能源详细信息的情况下评估利益相关者的潜在需求,本研究开发了一种使用联合分析的调查方法。在日本进行的一项网络问卷调查要求受访者在七种发电方式和各种电力供应条件中排列自己的偏好,这为评估与每种发电方式相关的潜在需求提供了必要的因素。调查发现,虽然地热能在明示需求和潜在需求方面表现良好,但地热发电的主体知识低于其他发电方式。其他发电方法之间的相对偏好也存在明显差异。所提出的方法有助于当地和外部利益相关者识别地热项目的各种影响,并在没有过多负担的情况下表达他们的需求。我们希望这种方法能够鼓励利益相关者相互理解,讨论他们可以接受地热项目的哪些优势/劣势,并设计一个包含地热能源的可持续发展社会。
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引用次数: 0
Distribution and genesis of geothermal waters in the Xianshuihe fault zone, Western Sichuan plateau, China: Constraints on fracture system and regional seismic activities 中国川西高原咸水河断裂带地热水的分布与成因:断裂系统和区域地震活动的制约因素
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-11 DOI: 10.1016/j.geothermics.2024.103150
Rui Cao , Yongqiang Cai , Ji Dor , Qijun Liu , Mariia Poliakova , Defan Chen , Shuangshuang Wan , Yiming Yan

The Xianshuihe fault zone (XSFZ), which is characterized by intense tectonic activities, frequent earthquakes and great number of hot springs, has significant potential for exploiting geothermal resources. Previous studies primarily focus on certain hydrothermal systems in southeastern segment of XSFZ, such as Kangding hydrothermal system, but lack the synthetical comparison and systematic analysis of geothermal waters along the XSFZ. Based on detailed geological investigation, the XSFZ hydrothermal system has divided into six geothermal activity areas: Luhuo (LH), Daofu (DF), Qianning-Bamei (QB), Yalahe-Zhonggu (YZ), Kangding (KD) and Moxi (MX). According to the 87Sr/86Sr ratios and elements behaving in water-rock interactions, the dissolution of silicate minerals is the primarily source of the hydrogeochemical compositions in geothermal waters. The δD and δ18O composition indicate that geothermal waters primarily originated from meteoric waters, but also affected by deep fluids. However, the contribution of deep fluids to the southeastern geothermal areas (YZ, KD and MX) with high concentrations of Cl- is greater than that of the northwestern (LH, DF and QB). The reservoir temperatures and chlorine-enthalpy model reveal that there are three distinct geothermal systems along the XSFZ: YZ and KD geothermal waters are originated from a common deep reservoir (R1), MX are from R3, and LH, DF, and QB are from R4. Due to the uneven thermal structural distribution along XSFZ, the southeastern segments generated stronger thermal stress and have more frequent earthquake occurrence. Thus, the study of geothermal waters along XSFZ can provide valuable insights into deep tectonic activities and geochemical indicators of earthquake monitoring in the region.

咸水河断裂带(XSFZ)构造活动强烈、地震频繁、温泉众多,具有开发地热资源的巨大潜力。以往的研究主要集中于 XSFZ 东南段的某些热液系统,如康定热液系统,但缺乏对 XSFZ 沿线地热水的综合比较和系统分析。根据详细的地质调查,XSFZ 热液系统划分为六个地热活动区:泸火(LH)、道孚(DF)、黔宁-八美(QB)、雅拉河-中谷(YZ)、康定(KD)和磨西(MX)。根据 87Sr/86Sr 比值和元素在水岩相互作用中的表现,硅酸盐矿物的溶解是地热水水文地质化学成分的主要来源。δD和δ18O成分表明,地热水主要来源于流星水,但也受到深层流体的影响。不过,深层流体对 Cl- 浓度较高的东南部地热区(YZ、KD 和 MX)的贡献大于西北部地热区(LH、DF 和 QB)。储层温度和氯-焓模型显示,XSFZ沿线有三个不同的地热系统:YZ和KD地热水源于一个共同的深储层(R1),MX源于R3,LH、DF和QB源于R4。由于 XSFZ 沿线热结构分布不均,东南段产生较强的热应力,地震发生较频繁。因此,对 XSFZ 沿线地热水的研究可以为该地区深部构造活动和地震监测的地球化学指标提供有价值的见解。
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引用次数: 0
Compression-shear failure of thermally treated granite: insights from digital image correlation analysis 热处理花岗岩的压缩-剪切破坏:数字图像相关分析的启示
IF 3.5 2区 工程技术 Q3 ENERGY & FUELS Pub Date : 2024-09-11 DOI: 10.1016/j.geothermics.2024.103157
Chenxi Zhang , Diyuan Li , Pingkuang Luo , Xiaoli Su , Aohui Zhou

Understanding the temperature-dependent shear failure behavior of rock under compression-shear loads is significant for evaluating the stability of deep surrounding rock with high temperature. In this study, a series of variable angle shear (VAS) tests, were conducted on cubic granite specimens exposed to different high temperatures, observed by two-dimensional digital image correlation (2D-DIC) technique during the tests. The results show that the peak shear stress, the peak shear strain and shear modulus decrease with the shear angle α, regardless of the treatment temperature. The peak shear stress increases slightly as the high temperature rises to 400 °C, then decrease rapidly. Both the peak shear strain and shear modulus do not change significantly until 400 °C and 500 °C respectively, then reduce rapidly. The cohesion reduces and the internal friction angle increases with increasing temperature. Based on the principal strain field, the damage evolution and crack extension processes of typical specimen are analyzed. It shows that the cracks initiate from the upper and lower loading points, which further coalesce with each other at the middle part of shear band. The shear angle α has a significant effect on the compression-shear failure behavior of granite. The tension failures become less visible with increase of α and dominant failure patterns transform from mixed tension-shear failure to shear failure. The ratio of crack initiation force to peak load reduces obviously at 600 °C. In addition, the underlying failure mechanism of specimens under compression-shear load is explained by an established mechanical model in the paper.

了解岩石在压缩-剪切载荷作用下随温度变化的剪切破坏行为,对于评估深层围岩在高温下的稳定性具有重要意义。本研究对暴露在不同高温下的立方体花岗岩试样进行了一系列变角剪切(VAS)试验,并在试验过程中采用二维数字图像相关(2D-DIC)技术进行了观察。结果表明,无论处理温度如何,峰值剪切应力、峰值剪切应变和剪切模量都随剪切角 α 的增大而减小。当高温升至 400 °C 时,峰值剪切应力略有增加,然后迅速减小。峰值剪切应变和剪切模量分别在 400 °C 和 500 °C 之前变化不大,然后迅速减小。内聚力随温度升高而减小,内摩擦角随温度升高而增大。根据主应变场,分析了典型试样的损伤演变和裂纹扩展过程。结果表明,裂纹从上部和下部的加载点开始,在剪切带的中间部分进一步相互凝聚。剪切角 α 对花岗岩的压缩-剪切破坏行为有显著影响。随着α的增大,拉伸破坏变得不明显,主要破坏模式从拉伸-剪切混合破坏转变为剪切破坏。600 °C时,裂纹起始力与峰值载荷之比明显降低。此外,本文还通过一个已建立的力学模型解释了试样在压缩-剪切载荷作用下的基本破坏机理。
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Geothermics
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