Pub Date : 2024-08-16DOI: 10.3389/feart.2024.1448238
Jie Wang, Jiping Wang, Yuanyuan Zhang, Daofeng Zhang, Lei Sun, Jianning Luo, Wei Wang, Lei Gong, Zongbao Liu, Shuai Gao
A well-connected network formed by multi-scale fractures is a key factor in the formation of high-quality reservoirs and the achievement of high and stable oil and gas production in tight sandstones. Taking the Upper Paleozoic of the Qingshimao gas field in the Ordos Basin, China, as an example, based on data from image logs, cores, and thin sections, fine quantitative characterization of multi-scale natural fractures in tight sandstone reservoirs was carried out. We also established a method for dividing network patterns of multi-scale fractures and discussed the effect of each fracture network pattern on the gas enrichment and production capacity. Results indicate regular changes in the length, density, aperture, porosity, permeability, and connectivity of natural fractures at different scales. Based on the spatial combination patterns and connectivity of fractures of different scales, four types of fracture network patterns were established: multi-scale fracture network with high density and multi-orientations, multi-scale fracture network with moderate-high density and dual orientations, small-scale fracture network with moderate density and dual orientations, small-scale fracture network with low density and single orientation. The first fracture network pattern can destroy the integrity of the cap layer, causing natural gas leakage. The second fracture network pattern is a favorable area for natural gas enrichment. The third fracture network pattern requires the use of hydraulic fracturing to obtain commercial airflow. The fourth fracture network pattern has little effect on reservoir control and storage. The study of natural fractures in tight sandstone reservoirs is usually based on a single-scale perspective. Understanding the development characteristics of multi-scale fractures and their controlling effects on the reservoir helps to comprehensively understand the spatial configuration relationship of multi-scale fracture network structure patterns and promotes the development of multi-scale fractures in tight reservoir research.
{"title":"Multi-scale fracture patterns and their effects on gas enrichment in tight sandstones: a case study of the Upper Paleozoic in the Qingshimao gas field, Ordos Basin, China","authors":"Jie Wang, Jiping Wang, Yuanyuan Zhang, Daofeng Zhang, Lei Sun, Jianning Luo, Wei Wang, Lei Gong, Zongbao Liu, Shuai Gao","doi":"10.3389/feart.2024.1448238","DOIUrl":"https://doi.org/10.3389/feart.2024.1448238","url":null,"abstract":"A well-connected network formed by multi-scale fractures is a key factor in the formation of high-quality reservoirs and the achievement of high and stable oil and gas production in tight sandstones. Taking the Upper Paleozoic of the Qingshimao gas field in the Ordos Basin, China, as an example, based on data from image logs, cores, and thin sections, fine quantitative characterization of multi-scale natural fractures in tight sandstone reservoirs was carried out. We also established a method for dividing network patterns of multi-scale fractures and discussed the effect of each fracture network pattern on the gas enrichment and production capacity. Results indicate regular changes in the length, density, aperture, porosity, permeability, and connectivity of natural fractures at different scales. Based on the spatial combination patterns and connectivity of fractures of different scales, four types of fracture network patterns were established: multi-scale fracture network with high density and multi-orientations, multi-scale fracture network with moderate-high density and dual orientations, small-scale fracture network with moderate density and dual orientations, small-scale fracture network with low density and single orientation. The first fracture network pattern can destroy the integrity of the cap layer, causing natural gas leakage. The second fracture network pattern is a favorable area for natural gas enrichment. The third fracture network pattern requires the use of hydraulic fracturing to obtain commercial airflow. The fourth fracture network pattern has little effect on reservoir control and storage. The study of natural fractures in tight sandstone reservoirs is usually based on a single-scale perspective. Understanding the development characteristics of multi-scale fractures and their controlling effects on the reservoir helps to comprehensively understand the spatial configuration relationship of multi-scale fracture network structure patterns and promotes the development of multi-scale fractures in tight reservoir research.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"11 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-16DOI: 10.3389/feart.2024.1428097
Qiyu Huang, Yifan Li, Shunyi Ai, Yuxin Chen, Yongchao Liu
Introduction: Coastal areas are densely populated, economically developed, and form complex social-ecological systems. Any regional changes within these areas have profound consequences for their socio-economic development and ecological environments.Methods: Based on multi-source remote sensing image data, a detailed analysis of the coastline of the Ningbo-Taizhou-Wenzhou region (Yong-Tai-Wen region) from 1980 to 2020 was conducted, and the spatiotemporal changes of the coastline were analyzed. Regression analysis was employed to investigate the correlation between the coastline length and various factors, including the degree of industrialization, GDP, urban land, and arable land.Results and Discussion: The results show that: 1) From 1980 to 2020, the overall length of the coastline in the Yong-Tai-Wen region exhibited a decreasing trend, accompanied by a continual increase in the degree of artificial coastline. Consequently, the coastline became increasingly fragmented and tortuous. Notably, the intensity of coastline change fluctuated significantly, peaking in 2010. 2) At the regional scale, there is a strong negative correlation between the length of the coastline in the Yong-Tai-Wen region and GDP and land use, whereas the correlation with cultivated land area remains relatively low. Conversely, the proportion of human-made coastlines demonstrates a strong positive correlation with GDP and urban land use but a significant negative correlation with cultivated land area. 3) At the city scale, the length of the coastline in Ningbo shows a significant negative correlation with GDP while exhibiting a certain correlation with urban land use. Similarly, the coastline length in Taizhou also displays a strong negative association with both GDP and urban land use. In contrast, the correlation patterns observed in Wenzhou are opposite to those in Taizhou. Notably, the correlation between the length of the coastline and cultivated land area remains relatively weak across all three cities. Additionally, the proportion of artificial coastlines in Ningbo and Taizhou aligns with the overall trend in the Yong-Tai-Wen region. Specifically, the proportion of artificial coastlines in Wenzhou exhibits a positive correlation with GDP and urban land use and a negative correlation with cultivated land area.
导言：沿海地区人口稠密，经济发达，形成了复杂的社会生态系统。这些地区的任何区域变化都会对其社会经济发展和生态环境产生深远影响：方法：基于多源遥感影像数据，对宁波-台州-温州地区（甬台温地区）1980-2020 年的海岸线进行了详细分析，并对海岸线的时空变化进行了分析。采用回归分析法研究了海岸线长度与工业化程度、GDP、城市用地、耕地等多种因素的相关性：结果表明1）从 1980 年到 2020 年，甬台温地区海岸线总长度呈下降趋势，同时人工海岸线程度持续上升。因此，海岸线变得越来越破碎和曲折。值得注意的是，海岸线变化的强度波动很大，在 2010 年达到顶峰。2) 在区域尺度上，甬台温地区的海岸线长度与 GDP 和土地利用之间存在较强的负相关，而与耕地面积之间的相关性则相对较低。相反，人造海岸线的比例与 GDP 和城市土地利用呈很强的正相关，但与耕地面积呈显著的负相关。3) 在城市尺度上，宁波的海岸线长度与 GDP 呈显著负相关，而与城市土地利用呈一定的相关性。同样，台州的海岸线长度也与 GDP 和城市土地利用呈较强的负相关。相比之下，温州的相关模式与台州相反。值得注意的是，三个城市的海岸线长度与耕地面积之间的相关性仍然相对较弱。此外，宁波和台州的人工海岸线比例与甬台温地区的整体趋势一致。具体而言，温州的人工海岸线比例与 GDP 和城市用地呈正相关，与耕地面积呈负相关。
{"title":"Impact of regional economic development on the spatiotemporal changes of coastlines: a case study of Ningbo-Taizhou-Wenzhou region","authors":"Qiyu Huang, Yifan Li, Shunyi Ai, Yuxin Chen, Yongchao Liu","doi":"10.3389/feart.2024.1428097","DOIUrl":"https://doi.org/10.3389/feart.2024.1428097","url":null,"abstract":"Introduction: Coastal areas are densely populated, economically developed, and form complex social-ecological systems. Any regional changes within these areas have profound consequences for their socio-economic development and ecological environments.Methods: Based on multi-source remote sensing image data, a detailed analysis of the coastline of the Ningbo-Taizhou-Wenzhou region (Yong-Tai-Wen region) from 1980 to 2020 was conducted, and the spatiotemporal changes of the coastline were analyzed. Regression analysis was employed to investigate the correlation between the coastline length and various factors, including the degree of industrialization, GDP, urban land, and arable land.Results and Discussion: The results show that: 1) From 1980 to 2020, the overall length of the coastline in the Yong-Tai-Wen region exhibited a decreasing trend, accompanied by a continual increase in the degree of artificial coastline. Consequently, the coastline became increasingly fragmented and tortuous. Notably, the intensity of coastline change fluctuated significantly, peaking in 2010. 2) At the regional scale, there is a strong negative correlation between the length of the coastline in the Yong-Tai-Wen region and GDP and land use, whereas the correlation with cultivated land area remains relatively low. Conversely, the proportion of human-made coastlines demonstrates a strong positive correlation with GDP and urban land use but a significant negative correlation with cultivated land area. 3) At the city scale, the length of the coastline in Ningbo shows a significant negative correlation with GDP while exhibiting a certain correlation with urban land use. Similarly, the coastline length in Taizhou also displays a strong negative association with both GDP and urban land use. In contrast, the correlation patterns observed in Wenzhou are opposite to those in Taizhou. Notably, the correlation between the length of the coastline and cultivated land area remains relatively weak across all three cities. Additionally, the proportion of artificial coastlines in Ningbo and Taizhou aligns with the overall trend in the Yong-Tai-Wen region. Specifically, the proportion of artificial coastlines in Wenzhou exhibits a positive correlation with GDP and urban land use and a negative correlation with cultivated land area.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"28 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-16DOI: 10.3389/feart.2024.1418293
Li Liang, Da-Lang Tian, Zheng-Chuan Li
Compared with engineering materials for earth structures subjected to prolonged, sustained hydraulic loading, the internal erosion process of widely graded loose soils (WGLS) under short-term, fluctuating hydraulic loading conditions remains insufficiently elucidated. Therefore, a novel fixed-wall permeameter is developed, capable of applying hydraulic loading at a constant flow rate and collecting effluent flowing out of specimens. A testing protocol is proposed to separate eroded silty clay particles, sandy gravel particles, and seepage water from the collected effluent. Several seepage tests are conducted on remolded specimens with various initial porosity at different inflow rates. The test results show that under a constant inflow rate, the WGLS specimens may undergo suffusion, suffosion, and stabilization stages while seeking the ultimate equilibrium state. The proposed particle migration pattern adeptly reveals the microscale mechanisms of the internal erosion phenomena observed at different stages. The inflow rate is independent of the suffusion critical hydraulic gradient but impacts the suffosion critical hydraulic gradient and internal erosion behavior following suffusion. Because hydraulic shear stress is a comprehensive indicator that considers both hydraulic gradient and initial porosity, it is more appropriate to use it to evaluate the internal stability potential of WGLS.
{"title":"Internal erosion process and its influence factors in widely graded loose soils due to rainfall infiltration","authors":"Li Liang, Da-Lang Tian, Zheng-Chuan Li","doi":"10.3389/feart.2024.1418293","DOIUrl":"https://doi.org/10.3389/feart.2024.1418293","url":null,"abstract":"Compared with engineering materials for earth structures subjected to prolonged, sustained hydraulic loading, the internal erosion process of widely graded loose soils (WGLS) under short-term, fluctuating hydraulic loading conditions remains insufficiently elucidated. Therefore, a novel fixed-wall permeameter is developed, capable of applying hydraulic loading at a constant flow rate and collecting effluent flowing out of specimens. A testing protocol is proposed to separate eroded silty clay particles, sandy gravel particles, and seepage water from the collected effluent. Several seepage tests are conducted on remolded specimens with various initial porosity at different inflow rates. The test results show that under a constant inflow rate, the WGLS specimens may undergo suffusion, suffosion, and stabilization stages while seeking the ultimate equilibrium state. The proposed particle migration pattern adeptly reveals the microscale mechanisms of the internal erosion phenomena observed at different stages. The inflow rate is independent of the suffusion critical hydraulic gradient but impacts the suffosion critical hydraulic gradient and internal erosion behavior following suffusion. Because hydraulic shear stress is a comprehensive indicator that considers both hydraulic gradient and initial porosity, it is more appropriate to use it to evaluate the internal stability potential of WGLS.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"25 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-16DOI: 10.3389/feart.2024.1438185
Shadman H. Khan, Sourav Kumar Sahoo, Ismael Himar Falcon-Suarez, Hector Marin-Moreno, Hanif Sutiyoso, B. N. Madhusudhan, C. B. Majumder, Amit Arora, Angus I. Best
We present a time-lapse 4-D high-resolution synchrotron imaging study of the morphological evolution of methane gas bubbles and hydrate film growth on these bubbles. Methane gas and partially water-saturated sand were used to form hydrate with a maximum hydrate saturation of 60%. We investigated the transient evolution of gas bubble size distribution during hydrate formation and observed three distinct stages: a) nucleation and hydrate film formation, b) rapid bubble break-up, c) gas bubble coalescence and hydrate framework formation. Our results show that the average gas bubble size distribution decreases from 34.17 µm (during hydrate nucleation) to 8.87 µm (during secondary bubble formation). The small-size methane bubble population (mean diameter below 10 µm) initially increases at the expense of the larger methane bubble population (mean diameter above 50 µm) due to breakage of the larger bubbles and coalescence of the smaller bubbles. We quantified that the average hydrate film thickness increases from 3.51 to 14.7 µm by tracking the evolution of a particular gas bubble. This thickness increase agrees with an analytical model with an average deviation error of 3.3%. This study provides insights into gas bubble distribution and hydrate film growth during hydrate formation, both of which impact the geophysical and mechanical properties of hydrate-bearing sediments.
{"title":"Investigation of methane gas bubble dynamics and hydrate film growth during hydrate formation using 4-D time-lapse synchrotron X-ray computed tomography","authors":"Shadman H. Khan, Sourav Kumar Sahoo, Ismael Himar Falcon-Suarez, Hector Marin-Moreno, Hanif Sutiyoso, B. N. Madhusudhan, C. B. Majumder, Amit Arora, Angus I. Best","doi":"10.3389/feart.2024.1438185","DOIUrl":"https://doi.org/10.3389/feart.2024.1438185","url":null,"abstract":"We present a time-lapse 4-D high-resolution synchrotron imaging study of the morphological evolution of methane gas bubbles and hydrate film growth on these bubbles. Methane gas and partially water-saturated sand were used to form hydrate with a maximum hydrate saturation of 60%. We investigated the transient evolution of gas bubble size distribution during hydrate formation and observed three distinct stages: a) nucleation and hydrate film formation, b) rapid bubble break-up, c) gas bubble coalescence and hydrate framework formation. Our results show that the average gas bubble size distribution decreases from 34.17 µm (during hydrate nucleation) to 8.87 µm (during secondary bubble formation). The small-size methane bubble population (mean diameter below 10 µm) initially increases at the expense of the larger methane bubble population (mean diameter above 50 µm) due to breakage of the larger bubbles and coalescence of the smaller bubbles. We quantified that the average hydrate film thickness increases from 3.51 to 14.7 µm by tracking the evolution of a particular gas bubble. This thickness increase agrees with an analytical model with an average deviation error of 3.3%. This study provides insights into gas bubble distribution and hydrate film growth during hydrate formation, both of which impact the geophysical and mechanical properties of hydrate-bearing sediments.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"6 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-15DOI: 10.3389/feart.2024.1444679
Fenquan Xie, Wenzhou Xiao, Mabrouk Sami, Ioan V. Sanislav, Mohamed S. Ahmed, Chenguang Zhang, Yongkui Wang, Bingpeng Yan, Bing Hu, Ning Li, Douaa Fathy
The Triassic tectonic evolution and affinity among the Yangtze Block, Qinling Orogenic Belt and Songpan-Ganzi Terrane remain subjects of ongoing scientific debate. In this context, the sedimentary rocks of Xujiahe Formation (second segment) (T3x2) represent an ideal case for addressing this issue. In this study, new stratigraphic, geochemical and detrital zircon analyses have been conducted on two sections of the T3x2. The stratigraphic assemblage and features suggests a braided delta as the depositional setting. Whole-rock geochemical results indicate that the sandstones from the T3x2 exhibit moderate palaeo-weathering and primarily originate from upper crustal felsic rocks, mostly S-type granites. The detrital zircons within these sandstones display distinctive age peaks at intervals of 200–300 Ma, 700–900 Ma, and 1800–2000 Ma, similar to those from the Qinling Orogenic Belt. Both the clastic particle composition and whole-rock geochemistry indicates that the T3x2 sections were deposited in a tectonic environment transitioning from a passive to an active continental margin, highlighted by a braided delta influenced by rivers flowing from the northeast to the southwest.
三叠纪构造演化以及长江地块、秦岭造山带和松潘-甘孜地块之间的亲缘关系仍是科学界争论不休的问题。在此背景下，徐家河地层（第二段）（T3x2）沉积岩是解决这一问题的理想案例。本研究对 T3x2 的两个剖面进行了新的地层、地球化学和碎屑锆石分析。地层组合和特征表明沉积环境为辫状三角洲。全岩地球化学结果表明，T3x2 的砂岩表现出中等程度的古风化，主要源自上地壳长英岩，大部分为 S 型花岗岩。这些砂岩中的碎屑锆石在 200-300 Ma、700-900 Ma 和 1800-2000 Ma 之间显示出明显的年龄峰值，与秦岭造山带的砂岩相似。碎屑颗粒组成和全岩地球化学均表明，T3x2 断面沉积于从被动大陆边缘向活动大陆边缘过渡的构造环境中，其突出特点是受到从东北流向西南的河流影响的辫状三角洲。
{"title":"Tectonic evolution of the Northeastern Paleo-Tethys Ocean during the late Triassic: insights from depositional environment and provenance of the Xujiahe formation","authors":"Fenquan Xie, Wenzhou Xiao, Mabrouk Sami, Ioan V. Sanislav, Mohamed S. Ahmed, Chenguang Zhang, Yongkui Wang, Bingpeng Yan, Bing Hu, Ning Li, Douaa Fathy","doi":"10.3389/feart.2024.1444679","DOIUrl":"https://doi.org/10.3389/feart.2024.1444679","url":null,"abstract":"The Triassic tectonic evolution and affinity among the Yangtze Block, Qinling Orogenic Belt and Songpan-Ganzi Terrane remain subjects of ongoing scientific debate. In this context, the sedimentary rocks of Xujiahe Formation (second segment) (T<jats:sub>3</jats:sub>x<jats:sub>2</jats:sub>) represent an ideal case for addressing this issue. In this study, new stratigraphic, geochemical and detrital zircon analyses have been conducted on two sections of the T<jats:sub>3</jats:sub>x<jats:sub>2</jats:sub>. The stratigraphic assemblage and features suggests a braided delta as the depositional setting. Whole-rock geochemical results indicate that the sandstones from the T<jats:sub>3</jats:sub>x<jats:sub>2</jats:sub> exhibit moderate palaeo-weathering and primarily originate from upper crustal felsic rocks, mostly S-type granites. The detrital zircons within these sandstones display distinctive age peaks at intervals of 200–300 Ma, 700–900 Ma, and 1800–2000 Ma, similar to those from the Qinling Orogenic Belt. Both the clastic particle composition and whole-rock geochemistry indicates that the T<jats:sub>3</jats:sub>x<jats:sub>2</jats:sub> sections were deposited in a tectonic environment transitioning from a passive to an active continental margin, highlighted by a braided delta influenced by rivers flowing from the northeast to the southwest.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"30 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lithium in coal, as a new type of associated mineral resource, has considerable potential for exploration. Exploration of high-lithium coal seams is essential for developing and using the associated lithium resources. To explore the distribution of lithium resources in the early stages of development in coal seams, the relationship between coal seam logging data and lithium content was analyzed by taking Guojiadi Coal Mine (China) as example. By analyzing the correlation between the different logging curves and the lithium content in coal and combining the K-means algorithm to identify the logging characteristics of different lithium-containing coal seams, we finally obtained the logging identification characteristics of high-lithium coal seams. The results reveal differences in the logging curves of coal seams with different lithium contents. The natural gamma and lateral resistivity of high-lithium coal seams are approximately 80 API and 100 Ω.M, respectively. Our study shows that the early identification of high-lithium coal seams can be evaluated from a logging perspective. We propose a preliminary identification method of high-lithium coal seam based on logging curve parameters by clustering analysis of borehole logging data to achieve accurate prediction.
煤中锂作为一种新型伴生矿物资源，具有相当大的勘探潜力。高锂度煤层的勘探对于开发和利用伴生锂资源至关重要。为了探索煤层中锂质资源在开发初期的分布情况，以中国郭家店煤矿为例，分析了煤层测井数据与锂含量之间的关系。通过分析不同测井曲线与煤中含锂量的相关性，并结合 K-means 算法识别不同含锂煤层的测井特征，最终得到了高锂煤层的测井识别特征。结果显示，不同含锂煤层的测井曲线存在差异。高锂煤层的自然伽马值和侧向电阻率分别约为 80 API 和 100 Ω.M。我们的研究表明，高锂煤层的早期识别可以从测井角度进行评估。我们提出了一种基于测井曲线参数的高锂度煤层初步识别方法，通过对井眼测井数据进行聚类分析，实现精确预测。
{"title":"Logging response prediction of high-lithium coal seam based on K-means clustering algorithm","authors":"Xiwei Mu, Yanming Zhu, Kailong Dou, Ying Shi, Manli Huang","doi":"10.3389/feart.2024.1443458","DOIUrl":"https://doi.org/10.3389/feart.2024.1443458","url":null,"abstract":"Lithium in coal, as a new type of associated mineral resource, has considerable potential for exploration. Exploration of high-lithium coal seams is essential for developing and using the associated lithium resources. To explore the distribution of lithium resources in the early stages of development in coal seams, the relationship between coal seam logging data and lithium content was analyzed by taking Guojiadi Coal Mine (China) as example. By analyzing the correlation between the different logging curves and the lithium content in coal and combining the K-means algorithm to identify the logging characteristics of different lithium-containing coal seams, we finally obtained the logging identification characteristics of high-lithium coal seams. The results reveal differences in the logging curves of coal seams with different lithium contents. The natural gamma and lateral resistivity of high-lithium coal seams are approximately 80 API and 100 Ω.M, respectively. Our study shows that the early identification of high-lithium coal seams can be evaluated from a logging perspective. We propose a preliminary identification method of high-lithium coal seam based on logging curve parameters by clustering analysis of borehole logging data to achieve accurate prediction.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"3 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-15DOI: 10.3389/feart.2024.1437605
Fan Zheng, Tao Xu, Yinshuang Ai, Yunping Ge, Qingdong Zeng, Laicheng Miao, Weiyu Dong, José Badal
During the Mesozoic, the North China Craton experienced intense tectonic movements that resulted in the formation of numerous gold deposits on the Liaodong and Jiaodong Peninsulas in northeastern China. To investigate the relationship between deep crustal structure and gold mineralization in the Liaodong Peninsula, we deployed 334 dense seismic stations in the Wulong goldfield (WLGF) with the idea of analysing numerous receiver functions at different array stations. The purpose focused on knowing the potential for gold mineralization in the area. The study revealed the following: (1) The WLGF is characterized by a crustal thickness of approximately 32 km and an average Vp/Vs ratio of 1.76. The high value of the Vp/Vs ratio near the Wulong gold deposit suggests that mantle materials have penetrated into the crust and contributed to the mineralization process. (2) A low-velocity layer located at a depth of 10–18 km below the WLGF seems to support the existence of a potentially brittle-ductile transition zone. Also, hydrothermal magma upwelling channels are observed in the upper crust beneath the Wulong gold deposit. (3) The presence of a discontinuous low-velocity layer in the middle crust beneath the Liaodong Peninsula suggests promising prospects for gold ore exploration. The receiver functions method based on a dense seismic array employed in this study can offer valuable references and guidance for the fine exploration and research of ore deposits in other regions globally.
{"title":"Deep structure of the Wulong goldfield, Liaodong Peninsula, China, revealed by receiver functions: implications for the tectonic and mineralization dynamics","authors":"Fan Zheng, Tao Xu, Yinshuang Ai, Yunping Ge, Qingdong Zeng, Laicheng Miao, Weiyu Dong, José Badal","doi":"10.3389/feart.2024.1437605","DOIUrl":"https://doi.org/10.3389/feart.2024.1437605","url":null,"abstract":"During the Mesozoic, the North China Craton experienced intense tectonic movements that resulted in the formation of numerous gold deposits on the Liaodong and Jiaodong Peninsulas in northeastern China. To investigate the relationship between deep crustal structure and gold mineralization in the Liaodong Peninsula, we deployed 334 dense seismic stations in the Wulong goldfield (WLGF) with the idea of analysing numerous receiver functions at different array stations. The purpose focused on knowing the potential for gold mineralization in the area. The study revealed the following: (1) The WLGF is characterized by a crustal thickness of approximately 32 km and an average Vp/Vs ratio of 1.76. The high value of the Vp/Vs ratio near the Wulong gold deposit suggests that mantle materials have penetrated into the crust and contributed to the mineralization process. (2) A low-velocity layer located at a depth of 10–18 km below the WLGF seems to support the existence of a potentially brittle-ductile transition zone. Also, hydrothermal magma upwelling channels are observed in the upper crust beneath the Wulong gold deposit. (3) The presence of a discontinuous low-velocity layer in the middle crust beneath the Liaodong Peninsula suggests promising prospects for gold ore exploration. The receiver functions method based on a dense seismic array employed in this study can offer valuable references and guidance for the fine exploration and research of ore deposits in other regions globally.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"39 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-15DOI: 10.3389/feart.2024.1443095
Ahmed Nasser Mahgoub, Monika Korte, Sanja Panovska, Maximilian Schanner
Paleomagnetic data enables the global reconstruction of the geomagnetic field, allowing the investigation of significant events like polarity reversals and excursions. When compared to prior polarity reversals, the most recent one, the Matuyama-Brunhes (MB), is the best recorded reversal in terms of number of available paleomagnetic data. Nevertheless, several of these data have poor age control, and they are not distributed equally worldwide. Few global models have been presented for the MB; the most recent is the GGFMB (Global Geomagnetic Field Model for the MB reversal). Limitations imposed by input data and subjective assumptions about the data that are made in modelling restrict the resolution and reliability of these models. This study presents a suite of eight additional global models that reconstruct the magnetic field during the interval 700–900 ka ago, including the MB reversal and Kamikatsura (KKT) excursion. Through model comparisons, the robustness of the models in resolving MB reversal characteristics is assessed. The majority of models indicate that the reversal was mainly driven by the axial dipole field contribution gradually decreasing, while non-dipole parts slightly increased. At the core-mantle boundary, two high-latitude reverse flux patches appear at the beginning of the reversal, and it seems like a few precursors in the form of regionally seen transitional field occurred, related to variations in the decaying dipole moment. The main global polarity change occurred close to 778 ka, with the axial dipole quickly strengthening in the opposite direction in the following, completing the full polarity transition. All the models confirm the previously reported asymmetry of slow dipole decay and fast recovery, and indicate that the dipole moment was clearly lower in the late Matuyama than the early Brunhes. The whole reversal process occurred on average between 800 and 770 ka, with a duration of approximately 30 kyr. Out of four apparent excursions discovered in some of the models between 900 and 800 ka, the KKT excursion (890–884 ka), can be confirmed as a robust magnetic field feature. Additional, well dated paleomagnetic records in particular from the southern hemisphere are required to confirm several details suggested by the models that should only be interpreted with caution so far.
古地磁数据可以重建全球地磁场，从而对极性反转和偏移等重大事件进行研究。与之前的极性反转相比，最近的一次极性反转，即松山-布鲁内斯（MB）极性反转，是在可用古地磁数据数量方面记录最好的一次极性反转。然而，其中一些数据的年龄控制较差，而且在全球的分布也不均衡。针对甲基溴逆转提出的全球模型很少；最近提出的是甲基溴逆转全球地磁场模型（GGFMB）。输入数据和建模时对数据的主观臆断限制了这些模型的分辨率和可靠性。本研究提出了一套额外的八个全球模型，重建了距今 700-900 ka 年间的磁场，包括 MB 逆转和上葛浦（KKT）偏移。通过模型比较，评估了这些模型在解析 MB 逆转特征方面的稳健性。大多数模型表明，逆转主要是由轴向偶极子场贡献逐渐减少，而非偶极子部分略有增加所驱动的。在地核-地幔边界，反转开始时出现了两个高纬度反向通量斑块，似乎出现了一些区域性过渡场形式的前兆，这与衰减偶极矩的变化有关。主要的全球极性变化发生在 778 ka 附近，随后轴向偶极子迅速向相反方向增强，完成了整个极性转换。所有模型都证实了之前报道的偶极子衰减慢、恢复快的不对称现象，并表明晚马图亚玛期的偶极子矩明显低于早期的布鲁内斯期。整个反转过程平均发生在 800 至 770 ka 之间，持续时间约为 30 kyr。在 900 ka 到 800 ka 之间的一些模型中发现的四个明显偏移中，KKT 偏移（890-884 ka）可以确认为一个强大的磁场特征。还需要更多的，特别是来自南半球的年代久远的古地磁记录来证实模型所提出的几个细节，到目前为止，对这些细节的解释还需谨慎。
{"title":"Robustness of characteristics of the Matuyama-Brunhes geomagnetic field reversal found in global models","authors":"Ahmed Nasser Mahgoub, Monika Korte, Sanja Panovska, Maximilian Schanner","doi":"10.3389/feart.2024.1443095","DOIUrl":"https://doi.org/10.3389/feart.2024.1443095","url":null,"abstract":"Paleomagnetic data enables the global reconstruction of the geomagnetic field, allowing the investigation of significant events like polarity reversals and excursions. When compared to prior polarity reversals, the most recent one, the Matuyama-Brunhes (MB), is the best recorded reversal in terms of number of available paleomagnetic data. Nevertheless, several of these data have poor age control, and they are not distributed equally worldwide. Few global models have been presented for the MB; the most recent is the GGFMB (Global Geomagnetic Field Model for the MB reversal). Limitations imposed by input data and subjective assumptions about the data that are made in modelling restrict the resolution and reliability of these models. This study presents a suite of eight additional global models that reconstruct the magnetic field during the interval 700–900 ka ago, including the MB reversal and Kamikatsura (KKT) excursion. Through model comparisons, the robustness of the models in resolving MB reversal characteristics is assessed. The majority of models indicate that the reversal was mainly driven by the axial dipole field contribution gradually decreasing, while non-dipole parts slightly increased. At the core-mantle boundary, two high-latitude reverse flux patches appear at the beginning of the reversal, and it seems like a few precursors in the form of regionally seen transitional field occurred, related to variations in the decaying dipole moment. The main global polarity change occurred close to 778 ka, with the axial dipole quickly strengthening in the opposite direction in the following, completing the full polarity transition. All the models confirm the previously reported asymmetry of slow dipole decay and fast recovery, and indicate that the dipole moment was clearly lower in the late Matuyama than the early Brunhes. The whole reversal process occurred on average between 800 and 770 ka, with a duration of approximately 30 kyr. Out of four apparent excursions discovered in some of the models between 900 and 800 ka, the KKT excursion (890–884 ka), can be confirmed as a robust magnetic field feature. Additional, well dated paleomagnetic records in particular from the southern hemisphere are required to confirm several details suggested by the models that should only be interpreted with caution so far.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"5 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction: This study investigates the characteristics of sediment disturbance caused by impeller rotation in reservoirs of inland rivers with high sediment content in China. A scaled experimental model, reflecting typical environmental conditions of inland water reservoirs in Northwest China, was established in Lanzhou, Gansu Province, following the principle of similarity.Methods: The study integrates numerical simulations using Ansys Fluent software and corroborates the findings through hydraulic experiments. Computational Fluid Dynamics (CFD) and the κ–ε Realizable model were employed to simulate the solid-liquid mixing process, which was verified against the experimental model.Results: The results indicate that increasing the impeller velocity from 2 rad/s to 8 rad/s, while submerged at a depth of 1000 mm in the flow field, enhances the rate of bottom sediment suspension. Furthermore, the rate of suspended sediment discharge from the model outlet increased with inflow velocity ranging from 0.1 m/s to 0.8 m/s. A decrease in the impeller’s submersion depth from 600 mm to 1200 mm was found to reduce the maximum disturbance radius affecting the bottom sediment.Discussion: The reliability of the simulation was confirmed by comparing the software results with experimental data. This study provides insights into the mechanisms of sediment-laden flow disturbance in the reservoir areas of inland rivers in China and lays the groundwork for more comprehensive investigations into sediment discharge in these environments.
{"title":"Investigating the dynamics of water and sediment disruption due to impeller action in silt-rich reservoir zones of inland waterways in China","authors":"Hao Wang, Yu Wang, Kaiqing Liu, Tianfeng Luo, Jinping Li, Ying Zhang, Tian Miao, Miao Tian, Zhehui Wang, Xiaolong Zhang","doi":"10.3389/feart.2024.1427707","DOIUrl":"https://doi.org/10.3389/feart.2024.1427707","url":null,"abstract":"Introduction: This study investigates the characteristics of sediment disturbance caused by impeller rotation in reservoirs of inland rivers with high sediment content in China. A scaled experimental model, reflecting typical environmental conditions of inland water reservoirs in Northwest China, was established in Lanzhou, Gansu Province, following the principle of similarity.Methods: The study integrates numerical simulations using Ansys Fluent software and corroborates the findings through hydraulic experiments. Computational Fluid Dynamics (CFD) and the κ–ε Realizable model were employed to simulate the solid-liquid mixing process, which was verified against the experimental model.Results: The results indicate that increasing the impeller velocity from 2 rad/s to 8 rad/s, while submerged at a depth of 1000 mm in the flow field, enhances the rate of bottom sediment suspension. Furthermore, the rate of suspended sediment discharge from the model outlet increased with inflow velocity ranging from 0.1 m/s to 0.8 m/s. A decrease in the impeller’s submersion depth from 600 mm to 1200 mm was found to reduce the maximum disturbance radius affecting the bottom sediment.Discussion: The reliability of the simulation was confirmed by comparing the software results with experimental data. This study provides insights into the mechanisms of sediment-laden flow disturbance in the reservoir areas of inland rivers in China and lays the groundwork for more comprehensive investigations into sediment discharge in these environments.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"18 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-15DOI: 10.3389/feart.2024.1392098
Susanna F. Jenkins, Ame McSporran, Thomas M. Wilson, Carol Stewart, Graham Leonard, Sandrine Cevuard, Esline Garaebiti
Building damage from tephra falls can have a substantial impact on exposed communities around erupting volcanoes. There are limited empirical studies of tephra fall impacts on buildings, with none on tephra falls impacting traditional thatched timber buildings, despite their prevalence across South Pacific island nations and parts of Asia. The 2017/2018 explosive eruption of Manaro Voui, Ambae Island, Vanuatu, resulted in damage to traditional (thatched timber), non-traditional (masonry), and hybrid buildings from tephra falls in March/April and July 2018. Field and photographic surveys were conducted across three separate field studies with building characteristics and damage recorded for a total of 589 buildings. Buildings were classified using a damage state framework customised for this study. Overall, increasing tephra thicknesses were related to increasing severity of building damage, corroborating previous damage surveys and vulnerability estimates. Traditional buildings were found to be less resistant to tephra loading than non-traditional buildings, although there was variation in resistance within each building type. For example, some traditional buildings collapsed under ∼40 mm thickness while others sustained no damage when exposed to >200 mm. We attribute this to differences in the pre-eruption condition of the building and the implementation of mitigation strategies. Mitigation strategies included covering thatched roofs with tarpaulins, which helped shed tephra and consequently reduced loading, and providing an internal prop to the main roof beam, which aided structural resistance. As is typical of post-event building damage surveys, we had limited time and access to the exposed communities, and we note the limitations this had for our findings. Our results contribute to the limited empirical data available for tephra fall building damage and can be used to calibrate existing fragility functions, improving our evidence base for forecasting future impacts for similar construction types globally.
{"title":"Tephra fall impacts to buildings: the 2017–2018 Manaro Voui eruption, Vanuatu","authors":"Susanna F. Jenkins, Ame McSporran, Thomas M. Wilson, Carol Stewart, Graham Leonard, Sandrine Cevuard, Esline Garaebiti","doi":"10.3389/feart.2024.1392098","DOIUrl":"https://doi.org/10.3389/feart.2024.1392098","url":null,"abstract":"Building damage from tephra falls can have a substantial impact on exposed communities around erupting volcanoes. There are limited empirical studies of tephra fall impacts on buildings, with none on tephra falls impacting traditional thatched timber buildings, despite their prevalence across South Pacific island nations and parts of Asia. The 2017/2018 explosive eruption of Manaro Voui, Ambae Island, Vanuatu, resulted in damage to traditional (thatched timber), non-traditional (masonry), and hybrid buildings from tephra falls in March/April and July 2018. Field and photographic surveys were conducted across three separate field studies with building characteristics and damage recorded for a total of 589 buildings. Buildings were classified using a damage state framework customised for this study. Overall, increasing tephra thicknesses were related to increasing severity of building damage, corroborating previous damage surveys and vulnerability estimates. Traditional buildings were found to be less resistant to tephra loading than non-traditional buildings, although there was variation in resistance within each building type. For example, some traditional buildings collapsed under ∼40 mm thickness while others sustained no damage when exposed to &gt;200 mm. We attribute this to differences in the pre-eruption condition of the building and the implementation of mitigation strategies. Mitigation strategies included covering thatched roofs with tarpaulins, which helped shed tephra and consequently reduced loading, and providing an internal prop to the main roof beam, which aided structural resistance. As is typical of post-event building damage surveys, we had limited time and access to the exposed communities, and we note the limitations this had for our findings. Our results contribute to the limited empirical data available for tephra fall building damage and can be used to calibrate existing fragility functions, improving our evidence base for forecasting future impacts for similar construction types globally.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"28 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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