Geothermics最新文献

{"title":"Geothermal resource potential from intraplate magmatic–volcanic activities: A case study of Mt. Changbai in Northeast China","authors":"Chujie Cheng ,&nbsp;Runchao Liu ,&nbsp;Hui Wu ,&nbsp;Bo Zhang ,&nbsp;Jianlei Zheng ,&nbsp;Bingrou Peng ,&nbsp;Jinjiang Zhang","doi":"10.1016/j.geothermics.2024.103053","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103053","url":null,"abstract":"<div><p>Mount Changbai is an active volcano in Northeast China that has erupted several times since the Miocene. Investigating the potential high–temperature geothermal reservoirs associated with magma chambers under the volcano has a significant meaning for clean energy development and utilization. Through a geological field survey combined with drilling data and collected geophysical data, including seismic and magnetotelluric data, of the Mt. Changbai area, we constructed a geological model extending from the upper mantle to the surface. Based on the geological model, we performed thermal simulations to understand the evolution of temperature profiles under Mt. Changbai since the Miocene (∼25 Ma). The results were compared with temperature measurements from geothermal drilling and hot springs for validation. We found that: (1) The total temperature increase can reach ∼263 °C at –6 km (absolute depth) under the Mt. Changbai volcano. While the temperature increase has reached ∼224 °C since the shallow magma chamber appeared at ∼1.5 Ma, which accounts for &gt;80 % of the total temperature increase. (2) Surface cold–water infiltration caused the decrease of subsurface temperature. However, the water can result in local accumulation of heat with a temperature increase up to 44 °C. (3) Both hydrothermal and hot dry rock geothermal resources are abundant in the Mt. Changbai area. Sedimentary strata of the Meso–Neoproterozoic and above that have good porosity and permeability, forming hydrothermal reservoirs. The temperature can reach 150 °C at a depth of 3 km under the Tianchi crater and are transferred to the surface by water through faults. While, metamorphic rock of the Archean–Paleoproterozoic and intrusive rock of the Mesozoic can form hot dry rock geothermal reservoirs with a temperature of 200–400 °C at a depth of 4–7 km under the Tianchi crater and surrounding areas.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141243529","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":"Geothermal resource evaluation of the Middle Permian Qixia-Maokou Formation in the southern Sichuan Basin, China","authors":"Yigao Sun ,&nbsp;Yinhui Zuo ,&nbsp;Luquan Zhang ,&nbsp;Chao Zhang ,&nbsp;Yingchun Wang ,&nbsp;Tao Zhang ,&nbsp;Xiao Li ,&nbsp;Meihua Yang ,&nbsp;Kangnan Yan ,&nbsp;Longqing Cui","doi":"10.1016/j.geothermics.2024.103073","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103073","url":null,"abstract":"<div><p>The southern Sichuan Basin is an abnormal area of high present geothermal fields in the Sichuan Basin. It is a favorable area for the development of geothermal resources in the Sichuan Basin. But its evaluation of geothermal resources is lagging, which has severely affected the development of geothermal resources in the southern Sichuan Basin. In the paper, firstly, based on the temperature data of wells, the geothermal gradients and heat flows of typical wells in the study area were calculated, and the temperatures at the top and bottom of the reservoir in the Qixia-Maokou Formation were calculated using a one-dimensional steady-state heat conduction equation. Then, geothermal resource intensities and reserves of the Middle Permian Qixia-Maokou Formation in the southern Sichuan Basin were evaluated by using a method for rapidly calculating geothermal resources in sedimentary basins by multi-data fusion. Finally, suggestions for geothermal development were proposed. The results show that the geothermal gradient and heat flow values in the southern Sichuan Basin range from 15.6 to 33.70 °C/km and 49 to 85 mW/m², respectively, and the temperature of the reservoir in the Qixia-Maokou Formation ranges from 50 to 120 °C. The geothermal resources are 3.09 × 10²¹ J, equivalent to 105 billion tons of standard coal, and the recoverable resources are 6.18 × 10²⁰ J, equivalent to 21 billion tons of standard coal. The development of demonstration projects will focus on the mid- to low-temperature geothermal power generation, geothermal grain drying and geothermal agriculture in the southwestern region of the southern Sichuan Basin. The research results can provide a resource basis for the development of geothermal resources in the southern Sichuan Basin.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141243530","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":"A thermo-hydro-mechanical simulation on the impact of fracture network connectivity on the production performance of a multi-fracture enhanced geothermal system","authors":"Zhihong Lei ,&nbsp;Yulong Zhang ,&nbsp;Xingjie Lin ,&nbsp;Yu Shi ,&nbsp;Yunhui Zhang ,&nbsp;Ling Zhou ,&nbsp;Yaping Shen","doi":"10.1016/j.geothermics.2024.103070","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103070","url":null,"abstract":"<div><p>Connectivity is an inherent feature of heterogeneous hydraulic conductivity fields and determines the paths of least resistance along which fluid fluxes converge in multi-fracture enhanced geothermal systems (EGS). In this work, numerical algorithms are used to construct fractured porous media models to analyze fractures and the rock matrix in EGS systems. Connectivity coefficients are defined to quantify the connectivity of the fractured system. Based on this, the impacts of fracture connectivity, non-connected fractures, and injection-production pressure differences on EGS production performance are investigated. The research results confirm that the connected area ratio (<em>R_s</em>) is an effective indicator of the connectivity level of the fracture network. Fluid flow and heat exchange predominantly take place within the interconnected area of fractures. When <em>R_s</em> = 0, geothermal energy cannot be efficiently extracted, resulting in significant waste of geothermal resources; when 0 &lt; <em>R_s</em> &lt; 0.1, thermal short-circuit easily occurs in the reservoir; then, as <em>R_s</em> continues to increase, the thermal extraction performance improves. The thermal output power increases with the square of <em>R_s</em>. Dead-end and discontinuous fractures improve the reservoir's fluid mobility, but their contribution to fluid flow is limited. In addition, very high fluid mobility in the matrix of the connected zone weakens the ability of fractures to act as flow channels and triggers a premature thermal breakthrough, shortening the EGS's lifespan. Therefore, striking a balance between the reservoir's lifespan and heat extraction capacity requires precise control of the injection-production pressure difference. Developing a 500 × 500 m² (on a horizontal plane) multi-fracture EGS in deep granite formations, <em>R_s</em> of the fractured zones should be greater than 0.5 to reduce fluid resistance and ensure effective heat extraction. In such a case, it is advisable to maintain a pressure differential of no more than 10 MPa between the injection and production wells to achieve at least 30 years of continuous heat extraction.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141243511","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 investigations on thermo-mechanical behaviors of energy pile group under different operational strategies","authors":"Weibo Yang,&nbsp;Chengrong Wang,&nbsp;Chaoyi Yan,&nbsp;Feng Wang","doi":"10.1016/j.geothermics.2024.103072","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103072","url":null,"abstract":"<div><p>Energy piles are often operated in the form of pile group, and their thermo-mechanical (TM) behaviors are strongly affected by the operational strategies. A model experimental bench of energy pile group with the layout of 3 × 3 was established to investigate the TM behaviors of energy pile group under different start-stop time ratios and pipe connection forms. The test results show that under the current test conditions, raising the start-stop time ratio leads to the increase of heat storage and extraction amount by the pile group, but the temperature of soil around the pile is not well recovered, which in turn results in the rise of deformation degree of pile. For the connection forms of pile buried pipe, the heat storage amount under three kinds of series connection forms is less than that under the conventional parallel connection form. However, the mechanical properties of pile group under the series connection forms are better than those of parallel connection form, which helps to alleviate the pile deformation degree. A 4 × 4 group pile model was developed to further find the effects of two operation strategies, namely, opening partial piles at different locations in winter mode and non-uniform intensity operation of piles in the inner and outer zones, on the TM characteristics of energy pile group. The results showed that opening partial piles increased the axial force of pile in the running piles relative to opening all the piles. Meanwhile, opening eight side piles extracted more heat per month during the heat extraction period relative to opening four internal piles and four corner piles. The four kinds of internal and external zoned non-uniform strength operation modes have different energy storage and thermodynamic properties. The most suitable mode should be selected considering the actual situation.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141243510","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":"Temperature transient analysis: Static formation temperature test (SFTT) an overview","authors":"Jorge Alberto Rangel-Arista,&nbsp;Sadiq J. Zarrouk,&nbsp;Eylem Kaya","doi":"10.1016/j.geothermics.2024.103058","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103058","url":null,"abstract":"<div><p>When drilling a geothermal well, obtaining real-time measurements of the static formation temperature is impractical due to the cooling effect of drilling fluids on the surrounding rock, which masks the actual reservoir temperatures. To overcome this, the site engineers undertake a static formation temperature test (SFTT) to ascertain the stable reservoir temperature. The present work reviews existing methods for analysing data using five different temperature sets sourced from published literature. Based on our analysis, we provide recommendations on the application of the various analytical techniques. We recommend utilising the spherical method when using bottom-hole data, whilst, for any other depth, we recommend one of the cylindrical methods. These recommendations aim to enhance the accuracy and reliability of SFTT assessments during geothermal well drilling operations.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0375650524001470/pdfft?md5=2a55dd822ab84fc1427b7d7f8b13a2ac&pid=1-s2.0-S0375650524001470-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141095048","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":"Assessment of two recent hot dry rock thermal energy production projects","authors":"Balnur Mindygaliyeva,&nbsp;Ozan Uzun,&nbsp;Kaveh Amini,&nbsp;Hossein Kazemi,&nbsp;William Fleckenstein","doi":"10.1016/j.geothermics.2024.103051","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103051","url":null,"abstract":"<div><p>In this paper, we present analyses of laboratory and field data indicating that the current two-well, injection-production system, connected with multiple hydraulic fractures, is a very promising method for extracting heat from hot dry rock (HDR) systems to generate electricity. The current two-well system could be expanded to a three-well system consisting of one injection well and two symmetric producing wells connected via the central hydraulic fracture emanating from the injection well. To improve a uniform distribution of the injected fluid among all hydraulic fracture stages in the injection well, we advocate for field implementation of a newly designed well stimulation technique, the GeoThermOPTIMAL.</p><p>We first present an analysis of the post-fracturing flow data obtained from an HDR geothermal injection well at the Utah FORGE Enhanced Geothermal System (EGS) research field site. The site is adjacent to the Roosevelt hydrothermal (HT) field. The objective of the study is to assess the effectiveness of well stimulation in extracting heat from the low-permeability, hot dry granitoid rock in the Utah FORGE research site. The study includes interpreting pressure falloff data obtained during the well stimulation process and employing laboratory-measured core data as a major input in the interpretation of the field falloff data. As a confirmation of the robustness of our analysis in Utah FORGE, we reviewed and analyzed the flow test results published for an injection-production doublet at the Blue Mountain EGS (Project Red) commercial site in Nevada. From the analyses of these two field tests, we have concluded that the interpretation and findings of the Blue Mountain EGS pilot test are consistent with the interpretation and findings from the Utah FORGE field research project test results.</p><p>In summary, our engineering assessments began with laboratory experiments conducted on various core samples, including those from a granite outcrop and the Utah FORGE geothermal reservoir. These experiments aimed to measure key parameters such as matrix and fracture permeabilities, and porosities (<span><math><mrow><msub><mi>k</mi><mi>m</mi></msub><mo>≈</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>18</mn></mrow></msup><mspace></mspace><msup><mrow><mi>m</mi></mrow><mn>2</mn></msup></mrow></math></span>, <span><math><mrow><msub><mi>k</mi><mrow><mi>f</mi><mo>,</mo><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msub><mo>≈</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup><msup><mrow><mi>m</mi></mrow><mn>2</mn></msup><mo>,</mo><mspace></mspace><msub><mi>ϕ</mi><mi>m</mi></msub><mo>≈</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mo>,</mo><mspace></mspace><mtext>and</mtext><mspace></mspace><msub><mi>ϕ</mi><mi>f</mi></msub><mo>≈</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span>). These data served as guides and inputs for analytical and numerical solut","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141097766","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":"Geology of the Utah Frontier Observatory for Research in Geothermal Energy (FORGE) Enhanced Geothermal System (EGS) Site","authors":"Clay Jones,&nbsp;Stuart Simmons,&nbsp;Joseph Moore","doi":"10.1016/j.geothermics.2024.103054","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103054","url":null,"abstract":"<div><p>The Utah FORGE field-scale laboratory was established to advance and accelerate development of Enhanced Geothermal System (EGS) resources, and this report provides an update on the geological understanding of the EGS reservoir. The succession of rock types intersected by deep wells beneath the site comprise sedimentary basin fill strata and underlying crystalline basement rocks made of: 1) sheared rhyolite; 2) sheared granitoid; 3) granitoid; and 4) interfingered metamorphic and granitoid. Within the intervals dominated by granitoid, igneous rock compositions range from granite to diorite. Below ∼2300 m, metamorphic rocks are primarily made of orthogneisses, with minor marble, quartzite, and schist engulfed by granitoid. Determining the distribution of granitoid and orthogneiss is complicated by similarities in mineralogy (quartz, plagioclase, K-feldspar, biotite, titanite, hornblende) and log responses, as well as the lack of macroscopic textures in cuttings, whereas metasedimentary rocks are more readily recognizable due to their distinctive mineralogies. The uplift and exhumation of the Mineral Mountains batholith induced early plastic deformation represented by subtle foliation of granitoids, the development of penetrative fabrics, and development of narrow mylonite zones. Overprinting by later brittle deformation involved shearing, alteration, and veining, which are most intense at the top of basement and diminish with increasing depth. The distribution of fractures in the EGS reservoir is heterogeneous, and localized intervals of intense fracturing developed along the contacts between granitoids and metamorphic rocks. Secondary minerals (clay minerals and Mg- and Fe-carbonates; minor epidote, actinolite, albite and quartz; trace anhydrite and halite) comprising open-space fillings and replacement of precursor phases tend to be concentrated in fracture zones, with paragenetic relationships reflecting cooling over time.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0375650524001433/pdfft?md5=d6f82242e948fa07a8bc5f3d3aeae1ff&pid=1-s2.0-S0375650524001433-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141097807","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":"Relationship of geothermal surface manifestations with the geology of northeastern Mexico, according to the interpretation of magnetic, gravimetric, and electrical resistivity data","authors":"José Alberto Batista-Rodríguez,&nbsp;Ramón Yosvanis Batista-Cruz,&nbsp;Yuri Almaguer-Carmenates,&nbsp;Felipe de Jesús López-Saucedo,&nbsp;Janet Tolentino-Álvarez","doi":"10.1016/j.geothermics.2024.103059","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103059","url":null,"abstract":"<div><p>We present geophysics data analysis from northeastern Mexico in areas with superficial geothermal manifestations. We interpreted magnetic anomalies reduced to the pole, gravimetric anomalies, and 2D electrical resistivity tomography models. The results show that the superficial geothermal manifestations are associated with deep or shallow faults in NW-SE and NE-SW directions. These faults may be the main outlet conduits for thermal fluids to the surface and their dynamic activity may constitute a great heat source for the fluids. This heat can also be associated with the cooling of igneous rocks and the radioactive decay of geological materials.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141095047","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":"Isotope geochemical study of carbonate formation in the 84N-3t well in the Oku-Aizu geothermal area: Natural analog study of fluid origin during caprock formation","authors":"Dongyang Mao ,&nbsp;Jing Zhang ,&nbsp;Akira Ueda ,&nbsp;Yukiko Hoshino ,&nbsp;Ryosuke Oochi ,&nbsp;Kensuke Matsumoto ,&nbsp;Hisae Kaneko ,&nbsp;Amane Terai","doi":"10.1016/j.geothermics.2024.103061","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103061","url":null,"abstract":"<div><p>In Japan, a method of power generation is under consideration, which involves the injection of supercritical CO₂, serving as a heat transfer fluid, into high-temperature geothermal reservoirs to extract thermal energy from the subsurface. During this process, it is anticipated that some of the CO₂ will dissolve in the reservoir fluid and react with the surrounding rocks, leading to the precipitation of carbonates and clay minerals. As part of a natural analog study, we investigated the origin of the fluid and carbon that formed the carbonate minerals by analyzing the carbon content and isotope composition of rocks in the 84N-3t well, which is drilled at the Yanaizu-Nishiyama geothermal power plant in Oku-Aizu. Using the results and downhole temperature data, we estimated the oxygen isotope composition of the fluid and carbon isotope composition of HCO₃⁻ and CO₂ in the fluid. The carbon content in the rocks increased sharply in the depth interval from 400 to 900 m, which was attributed to the precipitation of large amounts of carbonate minerals. The origin of the fluid responsible for the precipitation of the carbonate minerals was determined to be a mixture of meteoric water and fossil seawater at a depth of &lt;400 m and a mixture of magmatic fluid and fossil seawater at deeper levels. The carbon content originated from organic sources in the shallow part at a depth of &lt;900 m and from magmatic CO₂ in the deep part. Based on these results, the depth interval from 400 to 900 m was identified as the caprock and the formation temperature of the caprock layer was estimated to be 90−150 °C. Carbonate minerals were also detected at depths of &gt;900 m but in lower amounts. This suggests that when supercritical CO₂ is injected into the subsurface from an injection well, some CO₂ is fixed as carbonate minerals in shallow depths where the temperature is relatively low, forming an artificial caprock.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141095046","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":"Study on the influence of a single fracture on the performance of backfill heat exchangers in underground stopes","authors":"Bo Zhang,&nbsp;Wenxuan Zhang,&nbsp;Rui Zhan,&nbsp;Lang Liu,&nbsp;Chao Huan,&nbsp;Yujiao Zhao,&nbsp;Xiaoyan Zhang","doi":"10.1016/j.geothermics.2024.103056","DOIUrl":"https://doi.org/10.1016/j.geothermics.2024.103056","url":null,"abstract":"<div><p>Thermal hazards in deep mines can be mined synergistically with the deposit as associated geothermal energy resources. Backfill heat exchangers (BFHEs) as a combination of mine backfilling and ground heat exchanger technology are one of the effective methods to realize ore deposit-geothermal energy synergy mining. However, in the complex environment of deep mines, BFHEs will inevitably suffer from fracture damage during long-term heat storage/release cycle operation, which will affect their working performance. To address this problem, this paper established a scaled-down experimental setup for fractured BFHEs units, and used the experimental data to verify the accuracy of the established three-dimensional transient heat transfer mathematical model of the BFHEs unit. Numerical simulation methods were used to investigate the effects of the position, aperture and fractured depth of a single fracture on the heat extraction performance of the BFHEs unit under fully dry or fully saturated working conditions. Significant differences were found in the effect of different fracture positions on the heat extraction capacity of the BFHEs unit. The extraction of geothermal heat by the BFHEs unit was favored when it was in the middle of two tubes, while the opposite was true for other positions. The effect of fracture on the heat extraction capacity of the BFHEs unit increased linearly with fracture aperture. The effect of the fractured depth was relatively greater in the 1/2–3/4 <em>H</em>_b range. The presence of groundwater significantly reduced the effect of the fracture. The effect of the fracture on the heat extraction capacity of the BFHEs unit was reduced by more than 80 % by changing the operating conditions from fully dry to fully saturated condition. The overall effect of a fracture on the heat extraction capacity of the BFHEs unit was not significant, with a 5 mm wide fracture having an effect of no more than 2.5 %, even under the fully dry condition. However, there was a combined effect of multiple fractures, and for a deposit size of 900 × 7 × 80 m, ten 2 mm apertures fractures would results in a maximum reduction of geothermal extraction from BFHEs by 8527 GJ in 10 years, which was equivalent to the heat load of a 13,753 m² building for one winter in the cold climate of China.</p></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141073313","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}