Geothermics最新文献_第3页

Geothermal resources pathways: the hydrochemical evolution and genesis of geothermal waters in the Xianshuihe fault Zone, eastern Qinghai-Xizang plateau 地热资源途径：青藏高原东部鲜水河断裂带地热水的水化学演化与成因

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2025-12-03 DOI: 10.1016/j.geothermics.2025.103551

Yunhui Zhang , Jinhang Huang , Xingze Li , M. Santosh , Ying Wang , Xingcheng Yuan , Yangshuang Wang , Hongyang Guo , Xiaoyan Zhao , Xun Huang

Exploiting and utilizing geothermal resources require a clear understanding of their genesis mechanisms. Regional fault zones often host abundant geothermal resources whose genesis connections are not well understood. This study aims to elucidate the hydrochemical properties and formation mechanisms of diverse geothermal systems within the Xianshuihe Fault Zone (XFZ), eastern Qinghai-Xizang Plateau. The Self-Organizing Maps and Positive Matrix Factorization algorithms, hydrochemical analysis, and hydrogen-oxygen isotope analysis were employed to identify the intrinsic genesis connections among different types of geothermal waters in the XFZ. The geothermal waters along the XFZ were classified into three groups (Groups 1 − 3). Group 1 is predominantly Cl-Na and Cl·HCO₃-Na types; Group 2 is of HCO₃-Na and SO₄·HCO₃-Na types; and Group 3 primarily belongs to HCO₃-Na and HCO₃-Ca types. The primary source of geothermal water in Groups 1–3 is from fluids stored in deep granitic reservoirs, accounting for 40.1%, 28.8%, and 25.0% in each respective group. The secondary source is the infiltrating cold water leaching the shallow sedimentary rock, contributing 33.5%, 23.6%, and 25.7%, respectively. The primary sources of recharge for the geothermal water in the study area are snow-melting and meteoric water. Group 1 exhibits the highest reservoir temperatures (124.5 °C to 224.1 °C), followed by Group 2 (93.6 °C to 191.7 °C), and Group 3 (75.1 °C to 164.2 °C). This study indicates that the spatial distribution of geothermal water from Group 1 ('Deep Initial Geothermal Water') to Group 2 ('Evolved Shallow Geothermal Water') and Group 3 ('Mixed Shallow Geothermal Water') is a common phenomenon along the XFZ. Based on these findings, this study establishes a conceptual model for different groups of geothermal waters, which also helps establish interconnections among geothermal systems in regional fault zones.

地热资源的开发利用需要对其成因机制有清晰的认识。区域性断裂带往往蕴藏着丰富的地热资源，其成因联系尚不清楚。本研究旨在阐明青藏高原东部鲜水河断裂带不同地热系统的水化学性质及其形成机制。利用自组织图（Self-Organizing Maps）和正矩阵分解（Positive Matrix Factorization）算法、水化学分析和氢氧同位素分析等方法，确定了XFZ不同类型地热水的内在成因联系。沿XFZ的地热水可划分为3类（1 ~ 3类）。第1组以Cl- na型和Cl·HCO3-Na型为主；第2组为HCO3-Na型和SO4·HCO3-Na型；第3族主要属于HCO3-Na型和HCO3-Ca型。1 ~ 3组地热水的主要来源为深部花岗质储层流体，占比分别为40.1%、28.8%和25.0%。次源为浅层沉积岩的渗透冷水淋滤，贡献率分别为33.5%、23.6%和25.7%。研究区地热水补给的主要来源是融雪和大气降水。组1表现出最高的储层温度（124.5°C至224.1°C），其次是组2（93.6°C至191.7°C）和组3（75.1°C至164.2°C）。研究表明，从第1组（“深层初始地热水”）到第2组（“演化浅层地热水”）和第3组（“混合浅层地热水”）地热水的空间分布是XFZ沿线普遍存在的现象。在此基础上，本研究建立了不同组地热水的概念模型，有助于建立区域断裂带地热系统之间的相互联系。

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引用次数: 0

Thermal properties of the lower continental crust: Variabilities and link to other rock properties based on DIVE drill cores and boreholes (Ivrea-Verbano Zone) 下大陆地壳的热性质：基于DIVE岩心和钻孔的变异性及其与其他岩石性质的联系（Ivrea-Verbano区）

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2025-12-24 DOI: 10.1016/j.geothermics.2025.103564

Kim Lemke , György Hetényi , Alexia Secrétan , Junjian Li , Andrew Greenwood , Eva Caspari , Christoph Schmidt , Georgina King , Ueli Schärli , Ludovic Baron , Othmar Müntener

Scarcity of thermal property data on lower crustal rocks and their variability is a major hindrance in constraining the continental geotherm. As part of the ICDP project DIVE, two boreholes have recently sampled 1.5 km of rocks across a lower crustal metasedimentary and a mafic-ultramafic section of the Ivrea-Verbano Zone. Complete drill core recovery and borehole logging allowed us to generate a new, representative dataset of thermal properties ranging from high-resolution measurements to larger scale profiles. Thermal conductivity under ambient conditions varies considerably within every lithology type: felsic lithologies are more variable and show higher averages (∼3.0 W/(m⋅K)) than mafic lithologies (∼2.4 W/(m⋅K)). Radiogenic heat production is generally low and varies considerably between mafic-ultramafic lithologies (∼0.05 µW/m³), felsic lithologies and granulite-facies metasediments (∼0.5 µW/m³), and amphibolite-facies metasediments (∼1.5 µW/m³). Overall, metasediments are the largest contributor to the heat budget of the lower crust, where heat production seems to be related to the protolith, not to the metamorphic grade. Measurements of specific heat capacity, density, and thermal diffusivity also reveal primary differences between felsic and mafic lithologies. There is an inverse semi-logarithmic correlation between density and heat production. The variability of all measured thermal properties is significant at all spatial scales, and increases with increasing scales. Thermal conductivity and diffusivity vary by a factor of ca. 4 within each borehole, and heat production by a factor of 10 between the boreholes. These findings prompt for detailed sampling and comprehensive assessment of thermal property variabilities for applications involving the thermal field.

下地壳岩石热物性资料的缺乏及其变化是制约大陆地热的主要障碍。作为ICDP项目DIVE的一部分，两个钻孔最近在Ivrea-Verbano带的下地壳变质沉积岩和基性-超基性部分取样了1.5公里的岩石。完整的岩心回收和井眼测井使我们能够生成一个新的、具有代表性的热物性数据集，从高分辨率测量到更大规模的剖面。每种岩性类型在环境条件下的导热系数差异很大：长英质岩性变化更大，平均温度（~ 3.0 W/(m⋅K)）高于基性岩性（~ 2.4 W/(m⋅K)）。放射成因产热通常较低，在基性-超基性岩性（~ 0.05 μ W/m3）、长英质岩性和麻粒岩相变质沉积岩（~ 0.5 μ W/m3）和角闪岩相变质沉积岩（~ 1.5 μ W/m3）之间差异很大。总的来说，变质沉积物是下地壳热量收支的最大贡献者，其中热量的产生似乎与原岩有关，而与变质等级无关。比热容、密度和热扩散率的测量也揭示了长英质和基性岩性之间的主要差异。密度和产热之间呈半对数反比关系。所有测量的热物性在所有空间尺度上都具有显著的变异性，并随着尺度的增加而增加。每个井眼内的导热系数和扩散系数变化约为4倍，井眼之间的产热系数变化约为10倍。这些发现促使对涉及热场的应用的热性能变化进行详细采样和全面评估。

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引用次数: 0

Prioritizing resource protection and understanding potential susceptibility of springs to surficial changes in a low-temperature geothermal system 在低温地热系统中，优先考虑资源保护和了解温泉对地表变化的潜在敏感性

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2026-01-24 DOI: 10.1016/j.geothermics.2026.103615

Connor P. Newman , Jeff D. Pepin

Geothermal systems are vulnerable to changes in water budget and composition, requiring science-based management. This study uses a dataset of spring water temperatures, time series of groundwater residence time tracers (tritium and carbon-14), and stable isotopes of water to understand geothermal flow in a low-temperature geothermal system in north west Colorado, United States (Steamboat Springs). The geothermal system is bisected by the Yampa River, necessitating a stream mass balance approach to quantify total discharge. Time series analysis of water temperature data provides a ranked list of features more susceptible to surficial changes, which is corroborated using time series of tritium which indicate spatially distinct patterns of mixing between modern and pre-modern groundwater. All springs contain a portion of pre-modern groundwater that is thousands to tens of thousands of years old, a period coinciding with melting of extensive Pleistocene glaciers that was likely one of the recharge sources to the geothermal system. Stream mass balance indicates that greater than 80% of the total geothermal discharge is derived from diffuse or small springs, highlighting the extensive nature of the geothermal outflow zone and the association with local geologic structures. This study provides baseline data to support management of the Steamboat Springs geothermal system and indicates the utility of these approaches in developing science-based geothermal management.

地热系统容易受到水收支和组成变化的影响，需要基于科学的管理。本研究利用泉水温度数据集、地下水停留时间示踪剂（氚和碳-14）时间序列和水的稳定同位素来了解美国科罗拉多州西北部（Steamboat Springs）低温地热系统中的地热流。地热系统被扬帕河（Yampa River）一分为二，因此需要采用溪流质量平衡方法来量化总排放量。水温数据的时间序列分析提供了一个更容易受地表变化影响的特征列表，这是用氚的时间序列证实的，它表明现代和前现代地下水之间的混合模式在空间上是不同的。所有的泉水都含有数千到数万年前的前现代地下水，这一时期与广泛的更新世冰川融化相吻合，而更新世冰川很可能是地热系统的补给来源之一。水流质量平衡表明，80%以上的地热流量来自漫射或小泉，突出了地热流出带的广泛性及其与当地地质构造的联系。本研究为蒸汽船温泉地热系统的管理提供了基础数据，并指出了这些方法在发展科学地热管理方面的效用。

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引用次数: 0

Professor Manfred Hochstein (1932–2025) 曼弗雷德·霍克斯坦教授（1932-2025）

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2025-12-15 DOI: 10.1016/j.geothermics.2025.103562

Eva Hochstein , Sadiq J. Zarrouk , Alan Nunns

引用次数: 0

Direction-dependent permeability and resistivity of fractured rocks tuned to New Zealand geothermal reservoirs 新西兰地热储层裂缝性岩石的定向渗透率和电阻率

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2026-02-05 DOI: 10.1016/j.geothermics.2026.103620

Alison Kirkby, Cécile Massiot

Understanding permeability in the Earth is vital to optimizing sustainable geothermal development. In many geothermal fields, permeability is controlled by faults, resulting in high spatial and directional variability, difficult to characterise without costly drilling. Electrical resistivity, however, can be measured from the surface, and like permeability, is sensitive to fluids if they are sufficiently conductive. Modelling of resistivity-based geophysical data has largely focussed on isotropic properties to map clay caps and deep heat sources. However, faults commonly have a preferred orientation, and fluid-filled faults often have lower resistivity than the matrix, so anisotropy of permeability and resistivity is expected. This study models faults from the borehole to field scale to characterise direction-dependent permeability and resistivity. Parameters are derived from active faults and geothermal fields in the Taupō Volcanic Zone (TVZ), New Zealand. In our base-case model, permeability is highest (6 × 10^–13 m²) in the horizontal along-dominant-strike direction, lower vertically (5 × 10^–14 m²), and lowest in the across-dominant strike direction (2 × 10^–14 m²), with significant uncertainty in across-strike permeability (4 × 10^–15 m² to 5 × 10^–14 m²). For typical TVZ fluids (0.5 Ωm) and 1000 Ωm matrix, resistivity is lowest along dominant strike (235 Ωm), slightly higher vertically (285 Ωm) and highest across-strike (575 ± 30 Ωm). Resistivity anisotropy ratios along-strike/across-strike are relatively consistent regardless of fault length distribution (∼0.38–0.5), but vary strongly with the proportion of along-strike faults. Anisotropy ratios for permeability are more variable (1–300). The calculated petrophysical properties help link reservoir models with geophysical data, which may guide fractured reservoir models and resource use.

了解地球的渗透率对优化可持续地热开发至关重要。在许多地热田中，渗透率受断层控制，导致空间和方向变化很大，如果不进行昂贵的钻井，很难对其进行表征。然而，电阻率可以从表面测量，和渗透率一样，如果流体具有足够的导电性，电阻率对流体很敏感。基于电阻率的地球物理数据建模主要集中在各向同性属性上，以绘制粘土盖层和深部热源。然而，断层通常有一个优选的方向，并且充满流体的断层通常比基质的电阻率低，因此渗透率和电阻率的各向异性是预期的。该研究从井眼到野外尺度对断层进行建模，以表征方向相关的渗透率和电阻率。参数来源于新西兰陶普火山带（TVZ）的活动断层和地热田。在我们的基本情况模型中，渗透率在沿优势走向的水平方向最高（6 × 10-13 m2），垂直方向较低（5 × 10-14 m2），横向优势走向的渗透率最低（2 × 10-14 m2），横向渗透率（4 × 10-15 m2至5 × 10-14 m2）具有显著的不确定性。对于典型的TVZ流体（0.5 Ωm）和1000 Ωm基质，沿主走向电阻率最低（235 Ωm），垂直电阻率略高（285 Ωm），跨走向电阻率最高（575±30 Ωm）。无论断层长度分布如何，电阻率各向异性比沿走向/沿走向相对一致（~ 0.38 ~ 0.5），但随沿走向断层的比例变化很大。渗透率的各向异性比变化更大（1-300）。计算的岩石物性有助于将储层模型与地球物理数据联系起来，从而指导裂缝性储层模型和资源利用。

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引用次数: 0

Fracture properties, structural heterogeneity, and permeability in the Þeistareykir geothermal system, NE Iceland 冰岛东北部Þeistareykir地热系统裂缝性质、结构非均质性和渗透率

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2026-01-09 DOI: 10.1016/j.geothermics.2026.103596

Aastha , Emma Bramham , Andy Nowacki , Nick Shaw , Anette Mortensen , David Healy

Permeability in the Þeistareykir geothermal system of Iceland is structurally controlled. Natural fracture networks are abundant in Þeistareykir and contribute significantly to fluid flow. Understanding which features enhance permeability and hydraulic conductivity, and how their properties interact with lithology and reservoir structure, is key to predicting reservoir behaviour. To address this, we utilise a range of borehole data to characterise natural fractures in terms of their occurrence, orientation, relative distribution, their relationship with the major lithological units and permeable flow zones in the subsurface. Results show systematic variations in fracture density, thickness, and distribution pattern across different lithologies and depths, with orientations ranging from NNW-SSE, N-S, NNE-SSW to NE-SW. Fractures exhibit the highest intensity in the deeper acidic intrusive units or coarser grained basalt with a predominant N-S-trend and bimodal dip distribution. However, permeability is controlled by a complex interplay of fracture geometry, openness and connectivity rather than simply high fracture abundance or a preferential set of fractures. Permeable feed zones show diverse structural expressions, ranging from high-density fracture clusters and large-aperture fractures to intensely fractured damage zones and multiple intersecting fracture sets. These findings demonstrate that the structural character of the potential fluid-flow channels is highly variable in Þeistareykir. The results of this study can be incorporated into fracture and flow models to enhance our understanding of the permeability distribution and fluid pathways in the Þeistareykir geothermal system.

冰岛Þeistareykir地热系统的渗透率受构造控制。Þeistareykir地区天然裂缝网络丰富，对流体流动有重要贡献。了解哪些特征可以提高渗透率和导电性，以及它们的性质如何与岩性和储层结构相互作用，是预测储层行为的关键。为了解决这个问题，我们利用一系列钻孔数据来描述天然裂缝的产状、方向、相对分布、与主要岩性单元的关系以及地下的可渗透流动带。结果表明，不同岩性和深度的裂缝密度、厚度和分布模式存在系统性变化，取向范围为NNW-SSE、N-S、NNE-SSW至NE-SW。裂缝强度在较深的酸性侵入单元或粗粒玄武岩中最高，以n - s走向为主，呈双峰型倾角分布。然而，渗透率是由裂缝几何形状、开放性和连通性的复杂相互作用控制的，而不仅仅是高裂缝丰度或一组优先裂缝。渗透进料带的结构表现多样，既有高密度裂缝簇和大孔径裂缝，也有强烈的裂缝损伤区和多个相交裂缝组。这些发现表明Þeistareykir中潜在流体流动通道的结构特征是高度可变的。该研究结果可用于裂缝和流动模型，以增强我们对Þeistareykir地热系统渗透率分布和流体路径的认识。

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引用次数: 0

Unveiling geothermal potential in Pinrang regency, Indonesia: Integrated geochemical and geoelectrical characterization 揭示印尼平让地区的地热潜力：综合地球化学和地电学表征

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2025-12-08 DOI: 10.1016/j.geothermics.2025.103565

Muhammad Altin Massinai , Hendra Grandis , Ilham Arisbaya , Muh.Farid Wajedy , Fahruddin Fahruddin , Muhammad Fawzy Ismullah Massinai

Geothermal energy offers a sustainable and low-carbon pathway to meet rising global energy demands, particularly in tectonically active regions such as Pinrang Regency, South Sulawesi, Indonesia. This study presents the first integrated geochemical and geoelectrical characterization of the Lemosusu and Sulili hot springs to evaluate their geothermal potential. Field measurements show surface temperatures between 41 and 46 °C. Geochemical classification using Cl–SO₄–HCO₃ diagrams and silica/Na–K geothermometry indicates that Lemosusu hosts a shallow, bicarbonate-dominated low-enthalpy system (44–77 °C), whereas Sulili contains chloride-rich fluids with reservoir temperatures up to 178 °C, reflecting a more evolved hydrothermal regime. Two-dimensional resistivity imaging reveals distinct subsurface signatures: Lemosusu is characterized by a shallow conductive layer (<5 Ωm) overlying volcaniclastics of the Loka Formation at depths of 10–15 meters, suggesting fluid circulation within porous horizons. In contrast, Sulili displays a vertically continuous conductive zone (<5 Ωm) extending to depths 13 m, coinciding with a mapped fault zone interpreted as a potential main upflow pathway. These findings demonstrate that Lemosusu appears suitable for small-scale direct-use applications such as balneotherapy and greenhouse heating, while Sulili holds potential for binary-cycle power generation. Overall, the integration of geochemical and geoelectrical data provides new insight into how lithologic porosity and fault structures jointly control geothermal fluid flow in mixed volcanic–sedimentary terrains, offering a replicable framework for exploration in under-explored geothermal provinces worldwide.

地热能为满足不断增长的全球能源需求提供了可持续和低碳的途径，特别是在印度尼西亚南苏拉威西岛平朗摄政等构造活跃地区。本文首次对Lemosusu和Sulili温泉进行了地球化学和地电综合表征，以评价其地热潜力。现场测量显示表面温度在41至46°C之间。利用Cl-SO₄-HCO₃图解和silica/ Na-K地热方法进行地球化学分类表明，Lemosusu为浅层碳酸盐岩为主的低焓体系（44 ~ 77℃），而Sulili为富氯化物流体，储层温度高达178℃，反映了更为演化的热液体系。二维电阻率成像显示了明显的地下特征：Lemosusu的特征是在10-15米深的Loka组火山碎屑上覆盖了一层浅层导电层（<5 Ωm），表明孔隙层内存在流体循环。相比之下，Sulili显示出一个垂直连续的导电带（<5 Ωm），延伸至深度13 m，与被解释为潜在主要上行通道的地图断裂带相吻合。这些发现表明，Lemosusu似乎适合小规模的直接使用应用，如水疗和温室加热，而Sulili具有双循环发电的潜力。总体而言，地球化学和地电数据的整合为火山-沉积混合地形中岩性孔隙度和断裂构造如何共同控制地热流体流动提供了新的视角，为全球地热勘探不足地区的勘探提供了可复制的框架。

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引用次数: 0

Identifying the genesis and evolution of geothermal water in the coal mining area, North China: Insights from hydrochemistry and δ2H, δ18O, δ13C, δ34S and 87Sr/86Sr isotopes 华北矿区地热水成因演化：水化学及δ2H、δ18O、δ13C、δ34S和87Sr/86Sr同位素的启示

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2026-01-24 DOI: 10.1016/j.geothermics.2026.103611

Jie Zhang , Herong Gui , Luwang Chen , Manli Lin , Huifang Rong , Jun Li , Ruirui Li , Mingda Cao

Investigating geothermal resources in coal mining regions constitutes an important measure for promoting the green transformation of coal industry in China. In this study, the primary genesis and evolution of geothermal water in the southern Huaibei coalfield, North China was proposed based on hydrochemistry combining with multi-isotopes. The diversity of hydrochemical types and the variance of correlation coefficients among ions signify the complexity of hydrogeochemical processes in geothermal waters. The δD and δ¹⁸O values indicate that the geothermal water originated from paleo-meteoric water during the cold period. The dissolution of carbonate and sulfate minerals is the primary cause of the observed increase in δ¹³C_DIC and δ³⁴S_SO4 values with depth. Furthermore, the decrease in ⁸⁷Sr/⁸⁶Sr ratios with depth is jointly controlled by the composition of the recharge end-member and water-rock interactions. The maximum temperature of the geothermal reservoir calculated by silica geothermometers is 44.9 °C, with the corresponding circulation depth being 1282 m. The shallow cold water circulates to the depth along fissures, gets heated through thermal conduction and undergoes a series of water-rock interactions during the process, resulting in constant variations in the temperature and hydrogeochemistry. Given that deep geothermal water may ascend to the working face through fault zones and trigger water inrush disasters, it is currently managed primarily through controlled pumping and drainage. The findings of this work would provide a sound basis for the utilization of geothermal water in the Huaibei coalfield, as well as the majority of coalfields in North China.

开展矿区地热资源调查是推动中国煤炭产业绿色转型的重要举措。以水化学和多同位素相结合的方法，提出了淮北煤田南部地热水的主要成因和演化。水化学类型的多样性和各离子间相关系数的差异性反映了地热水水文地球化学过程的复杂性。δD值和δ18O值表明该区地热水来源于寒冷期的古大气水。碳酸盐岩和硫酸盐矿物的溶蚀作用是δ13CDIC和δ34SSO4值随深度增大的主要原因。87Sr/86Sr比值随深度的减小受补给端元组成和水岩相互作用的共同控制。石英地温计计算的地热储层最高温度为44.9℃，对应的循环深度为1282 m。浅层冷水沿裂隙向深部循环，通过热传导受热，并在此过程中发生一系列的水岩相互作用，导致温度和水文地球化学的不断变化。由于深部地热水可能通过断裂带上升到工作面，引发突水灾害，目前主要采用控制抽排的方式进行管理。研究结果将为淮北煤田以及华北大部分煤田地热水的开发利用提供理论依据。

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引用次数: 0

Reservoir temperature prediction utilizing a least squares boosting model optimized by kepler optimization algorithm 利用kepler优化算法优化的最小二乘提升模型预测储层温度

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2026-01-24 DOI: 10.1016/j.geothermics.2026.103612

Ling Zhou , Xiangzhe Chen , Ruzhen Hu , Peng Yan , Jingchao Sun

Geothermal energy, as a renewable, sustainable, widely-distributed, stable and reliable energy source, holds significant potential in resolving the global energy crisis and reducing carbon emissions. The development of reservoir temperature prediction models is a crucial aspect for assessing this potential. In this context, machine learning has addressed the limitations of conventional approaches through its capacity to efficiently handle complex nonlinear problems, overcoming operational complexity, high costs, and substantial uncertainties associated with traditional methods. Therefore, this paper selected 120 data from Turkey and China to establish a machine learning model. The extreme gradient boosting (XGBoost) and Least Squares Boosting (LSBoost) models were trained with pH, EC, Na⁺, K⁺, SiO₂, and Cl^- as input features and reservoir temperature as the output feature. During the training process, LSBoost was also separately optimized for hyperparameters through Ivy algorithm (IVYA) and Kepler optimization algorithm (KOA), resulting in the Ivy algorithm based Least Squares Boosting (IVYA-LSB) and Kepler optimization algorithm based Least Squares Boosting (KOA-LSB) models. In order to achieve better prediction results, five evaluation indicators including Coefficient of determination (R²) were established to assess the performance of the models. The results show that the KOA-LSB model has the best predictive ability with an R² value of 0.98064 and can achieve accurate prediction of reservoir temperature. Furthermore, The acquisition of a deeper understanding of the relationship between reservoir temperature and various input feature values, Shapely Additive exPlanations (SHAP) analysis was adopted to conduct an interpretable analysis of the machine learning results. The results indicated that SiO₂ was the most significant factor influencing reservoir temperature, while pH was the least influential factor. This research not only proposes a novel machine learning method but also conducts an interpretable analysis of the machine learning results, providing reliable model selection tools for geothermal professionals while enhancing their confidence in machine learning and promoting a better understanding of geothermal resources.

地热能作为一种可再生、可持续、分布广泛、稳定可靠的能源，在解决全球能源危机、减少碳排放方面具有巨大潜力。开发储层温度预测模型是评估这种潜力的一个关键方面。在这种情况下，机器学习通过其有效处理复杂非线性问题的能力，克服了与传统方法相关的操作复杂性，高成本和大量不确定性，解决了传统方法的局限性。因此，本文选择了土耳其和中国的120个数据来建立机器学习模型。以pH、EC、Na+、K+、SiO2和Cl-为输入特征，以储层温度为输出特征，对极值梯度增压（XGBoost）和最小二乘增压（LSBoost）模型进行训练。在训练过程中，LSBoost还分别通过Ivy算法（IVYA）和Kepler优化算法（KOA）对超参数进行了优化，得到了基于Ivy算法的最小二乘Boosting （IVYA- lsb）和基于Kepler优化算法的最小二乘Boosting （KOA- lsb）模型。为了获得更好的预测结果，我们建立了决定系数（R2）等5个评价指标来评价模型的性能。结果表明，KOA-LSB模型预测能力最好，R²值为0.98064，能较准确地预测储层温度。此外，为了更深入地了解储层温度与各种输入特征值之间的关系，采用Shapely Additive explanation （SHAP）分析对机器学习结果进行可解释性分析。结果表明：SiO2对储层温度的影响最大，pH对储层温度的影响最小；本研究不仅提出了一种新颖的机器学习方法，而且对机器学习结果进行了可解释性分析，为地热专业人员提供了可靠的模型选择工具，同时增强了他们对机器学习的信心，促进了对地热资源的更好理解。

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引用次数: 0

Influence of evaluation methods on mechanical properties of cement under thermal cycling: A comparative study between small-scale samples and full-scale annular systems 热循环条件下评价方法对水泥力学性能的影响：小尺寸样品与全尺寸环空体系的对比研究

IF 3.9 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2026-03-01 Epub Date: 2026-01-24 DOI: 10.1016/j.geothermics.2026.103608

Niantao Zhou , Hong Zhang , Yuan Jiajie , Yuhan Pang , Fuping Xiao , Yuanhua Lin , Kuanhai Deng , Junping Zhou , Qiqoping Liu

The cement sheath integrity in geothermal wells is prone to damage under ultra-high temperature thermal cycling induced by periodic cold water injection and steam extraction, posing critical safety risks such as annular pressure and wellbore leakage. Based on the typical working conditions in geothermal wells, a high temperature kettle is developed to perform thermal cycling tests on bulk cement samples in a saturated environment, while a full-scale experimental device of the "Φ139.7 mm production casing-cement sheath-Φ244.5 mm intermediate casing" (PC-CS-IC) system is used for evaluating the cement sheath under realistic wellbore conditions. Mechanical property tests are performed after thermal cycling (25°C∼150°C and 25°C∼250°C), by which the behavior of bulk cement samples and cement sheaths is compared, and additional thermal damage induced by casing-cement interface thermal stress is quantified. The results show that thermal cycling induces a non-monotonic evolution in mechanical properties: the uniaxial compressive strength (UCS) and elastic modulus of both specimens first increase and then decrease with increasing cycles, while peak axial strain decreases monotonically. Notably, after the same thermal cycling, the UCS, elastic modulus, and peak axial strain of the cement sheath are 18%∼32%, 15%∼28%, and 16%∼22% lower than those of the bulk cement samples, respectively. This discrepancy is attributed to additional thermal stress at the casing-cement interface, arising from mismatched thermal expansion between casing steel and cement, which accelerates crack propagation in the cement sheath. The findings provide critical experimental data for optimizing geothermal well cementing designs, emphasizing the necessity of annular system evaluations to ensure long-term wellbore integrity.

在周期性冷水注汽引起的超高温热循环下，地热井水泥环完整性容易受到破坏，存在环空压力、井筒泄漏等重大安全隐患。根据地热井的典型工况，研制了高温釜，可在饱和环境下对大量水泥样品进行热循环测试，并利用“Φ139.7 mm生产套管-水泥环-Φ244.5 mm中间套管”（PC-CS-IC）系统的全尺寸实验装置，对水泥环在实际井眼条件下进行评估。在热循环（25°C ~ 150°C和25°C ~ 250°C）后进行力学性能测试，通过该测试比较了散装水泥样品和水泥护套的行为，并量化了套管-水泥界面热应力引起的额外热损伤。结果表明：热循环引起了两种试样力学性能的非单调演化：随着循环次数的增加，两种试样的单轴抗压强度和弹性模量均呈现先增大后减小的趋势，而峰值轴向应变呈单调减小趋势；值得注意的是，经过相同的热循环后，水泥环的UCS、弹性模量和峰值轴向应变分别比散装水泥样品低18% ~ 32%、15% ~ 28%和16% ~ 22%。这种差异是由于套管与水泥之间不匹配的热膨胀导致套管与水泥界面产生额外的热应力，从而加速了水泥环中的裂缝扩展。研究结果为优化地热井固井设计提供了关键的实验数据，强调了环空系统评估的必要性，以确保井筒的长期完整性。

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