Pub Date : 2024-08-22DOI: 10.3389/feart.2024.1443764
Zhang Junke, Zhou Lei, Wang Xinyu, Xie Xingbing, Mao Yurong, Yan Liangjun
The borehole induced polarization method has been widely used in deep mineral exploration, oil and gas resource exploration, and water resource exploration because of its high efficiency and good exploration effect. At present, the related research on the cross-well induced polarization method assumes that the underground medium is isotropic, but the electrical characteristics of the actual earth medium are anisotropic. To analyze the influence of the anisotropic characteristics on the cross-well induced polarization method, in this paper, the anisotropic forward algorithm of conductivity and polarizability in different principal axis directions based on the finite element method is studied. A three-dimensional forward simulation of the cross-well induced polarization method in anisotropic media is realized. The effectiveness and correctness of the algorithm are verified by testing and comparing complex 3-D isotropic and anisotropic models. Anisotropic geological models of the horizontal plate and inclined plate are constructed to analyze the anisotropic influences of conductivity and polarizability in different principal axis directions on the cross-well induced polarization response. The results show that the emitter sources with different depths in the well have different influences on the electrical response of the plates. Anisotropic conductivity and polarizability in horizontal plates exhibit most pronounced characteristics in the x-direction, significantly influencing the apparent polarizability curves. However, when the resistivity and polarizability are both anisotropic, the change in the z-direction is the most complicated. When the plate is inclined, the amplitude of the electrical response curve decreases to a certain extent, and the position where the amplitude appears shifts to different degrees. Notably, the response curves of the y-direction anisotropy are basically consistent with the response curves of the isotropy, regardless of the anisotropy of the conductivity and polarizability or anomalous body tilts. The results of this study improve our understanding of the influence of anisotropy on cross-well induced polarization and provide theoretical support for the interpretation of cross-well induced polarization data considering anisotropy.
钻孔诱导极化法因其效率高、勘探效果好而被广泛应用于深部矿产勘探、油气资源勘探和水资源勘探等领域。目前，关于跨井诱导极化法的相关研究都假定地下介质是各向同性的，但实际地球介质的电特性却是各向异性的。为了分析各向异性特征对跨井诱导极化方法的影响，本文研究了基于有限元法的不同主轴方向电导率和极化率的各向异性正演算法。实现了各向异性介质中交叉井诱导偏振法的三维正演模拟。通过测试和比较复杂的三维各向同性和各向异性模型，验证了算法的有效性和正确性。建立了水平板和倾斜板的各向异性地质模型，分析了不同主轴方向的电导率和极化率对跨井诱导极化响应的各向异性影响。结果表明，井中不同深度的发射源对平板的电响应有不同的影响。水平板的各向异性电导率和极化率在 x 轴方向表现出最明显的特征，极大地影响了表观极化率曲线。然而，当电阻率和极化率均为各向异性时，z 方向的变化最为复杂。当平板倾斜时，电响应曲线的振幅会在一定程度上减小，振幅出现的位置也会发生不同程度的移动。值得注意的是，y 方向各向异性的响应曲线与各向同性的响应曲线基本一致，与电导率和极化率的各向异性或异常体倾斜无关。该研究结果加深了我们对各向异性对跨井诱导偏振影响的理解，为考虑各向异性的跨井诱导偏振数据解释提供了理论支持。
{"title":"Study of response characteristics of cross-well induced polarization method in anisotropic media","authors":"Zhang Junke, Zhou Lei, Wang Xinyu, Xie Xingbing, Mao Yurong, Yan Liangjun","doi":"10.3389/feart.2024.1443764","DOIUrl":"https://doi.org/10.3389/feart.2024.1443764","url":null,"abstract":"The borehole induced polarization method has been widely used in deep mineral exploration, oil and gas resource exploration, and water resource exploration because of its high efficiency and good exploration effect. At present, the related research on the cross-well induced polarization method assumes that the underground medium is isotropic, but the electrical characteristics of the actual earth medium are anisotropic. To analyze the influence of the anisotropic characteristics on the cross-well induced polarization method, in this paper, the anisotropic forward algorithm of conductivity and polarizability in different principal axis directions based on the finite element method is studied. A three-dimensional forward simulation of the cross-well induced polarization method in anisotropic media is realized. The effectiveness and correctness of the algorithm are verified by testing and comparing complex 3-D isotropic and anisotropic models. Anisotropic geological models of the horizontal plate and inclined plate are constructed to analyze the anisotropic influences of conductivity and polarizability in different principal axis directions on the cross-well induced polarization response. The results show that the emitter sources with different depths in the well have different influences on the electrical response of the plates. Anisotropic conductivity and polarizability in horizontal plates exhibit most pronounced characteristics in the x-direction, significantly influencing the apparent polarizability curves. However, when the resistivity and polarizability are both anisotropic, the change in the z-direction is the most complicated. When the plate is inclined, the amplitude of the electrical response curve decreases to a certain extent, and the position where the amplitude appears shifts to different degrees. Notably, the response curves of the y-direction anisotropy are basically consistent with the response curves of the isotropy, regardless of the anisotropy of the conductivity and polarizability or anomalous body tilts. The results of this study improve our understanding of the influence of anisotropy on cross-well induced polarization and provide theoretical support for the interpretation of cross-well induced polarization data considering anisotropy.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"298 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223640","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 : 2024-08-22DOI: 10.3389/feart.2024.1454962
Xiao Liu, Qi-Ji Sun
Electrical anisotropy has a significant impact on the observation data of the magnetotelluric (MT) method; therefore, it is necessary to develop forward and inverse methods in electrical anisotropic media. Based on the axis anisotropic electric field control equations, forming a large linear equation through staggered finite difference approximation, adding boundary conditions, and using the quasi-minimum residual method to solve the equation, this study obtained MT forward modeling results in axis anisotropic media. The correctness of the algorithm was verified by comparing it with the 2D quasi-analytic solution. By designing several sets of axis anisotropic 3D models, the characteristics of the apparent resistivity tensor and tipper were analyzed. The results indicated that the ρxya, ρyya and Tzy are sensitive to changes in resistivity in the X direction of the anomalous body, whereas the ρyxa, ρxxa and Tzx are sensitive to changes in resistivity in the Y direction. The apparent resistivity tensor and tipper are insensitive to changes in resistivity in the Z direction of the anomalous body. For exploration of anisotropic media, the apparent resistivity tensor and tipper of MT can identify the changes in resistivity in two horizontal axes directions and the boundaries of the anomalous body, which has the advantages for exploration.
电各向异性对磁测（MT）方法的观测数据有很大影响，因此有必要发展电各向异性介质中的正演和反演方法。本研究以轴各向异性电场控制方程为基础，通过交错有限差分近似形成大线性方程，加入边界条件，利用准最小残差法求解方程，得到了轴各向异性介质中的 MT 正演建模结果。通过与二维准解析解的比较，验证了算法的正确性。通过设计几组轴向各向异性三维模型，分析了视电阻率张量和翻板的特征。结果表明，ρxya、ρyya 和 Tzy 对异常体 X 方向的电阻率变化敏感，而 ρyxa、ρxaa 和 Tzx 对 Y 方向的电阻率变化敏感。视电阻率张量和翻板对异常体 Z 方向的电阻率变化不敏感。在勘探各向异性介质时，MT 的视电阻率张量和倾角可以识别两个水平轴方向的电阻率变化和异常体的边界，具有勘探优势。
{"title":"A study of 3D axis anisotropic response of MT","authors":"Xiao Liu, Qi-Ji Sun","doi":"10.3389/feart.2024.1454962","DOIUrl":"https://doi.org/10.3389/feart.2024.1454962","url":null,"abstract":"Electrical anisotropy has a significant impact on the observation data of the magnetotelluric (MT) method; therefore, it is necessary to develop forward and inverse methods in electrical anisotropic media. Based on the axis anisotropic electric field control equations, forming a large linear equation through staggered finite difference approximation, adding boundary conditions, and using the quasi-minimum residual method to solve the equation, this study obtained MT forward modeling results in axis anisotropic media. The correctness of the algorithm was verified by comparing it with the 2D quasi-analytic solution. By designing several sets of axis anisotropic 3D models, the characteristics of the apparent resistivity tensor and tipper were analyzed. The results indicated that the <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mi>ρ</mml:mi><mml:mrow><mml:mi>x</mml:mi><mml:mi>y</mml:mi></mml:mrow><mml:mi>a</mml:mi></mml:msubsup></mml:mrow></mml:math></jats:inline-formula>, <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mi>ρ</mml:mi><mml:mrow><mml:mi>y</mml:mi><mml:mi>y</mml:mi></mml:mrow><mml:mi>a</mml:mi></mml:msubsup></mml:mrow></mml:math></jats:inline-formula> and <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi>z</mml:mi><mml:mi>y</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula> are sensitive to changes in resistivity in the X direction of the anomalous body, whereas the <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mi>ρ</mml:mi><mml:mrow><mml:mi>y</mml:mi><mml:mi>x</mml:mi></mml:mrow><mml:mi>a</mml:mi></mml:msubsup></mml:mrow></mml:math></jats:inline-formula>, <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mi>ρ</mml:mi><mml:mrow><mml:mi>x</mml:mi><mml:mi>x</mml:mi></mml:mrow><mml:mi>a</mml:mi></mml:msubsup></mml:mrow></mml:math></jats:inline-formula> and <jats:inline-formula><mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi>z</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math></jats:inline-formula> are sensitive to changes in resistivity in the Y direction. The apparent resistivity tensor and tipper are insensitive to changes in resistivity in the Z direction of the anomalous body. For exploration of anisotropic media, the apparent resistivity tensor and tipper of MT can identify the changes in resistivity in two horizontal axes directions and the boundaries of the anomalous body, which has the advantages for exploration.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"2672 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179560","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 : 2024-08-22DOI: 10.3389/feart.2024.1440729
Yu Qi, Kui Wu, Bo Wang, Xiaowen Zheng, Wenlan Li, Dan Li
During the exploration and development of deep coalbed methane (CBM), delineating the thickness of coal seam and lithofacies of the roof and floor is one of the major challenging tasks. In past attempts, the prediction methods of these parameters have been limited to the conventional inversion. However, the effect of coal shielding on adjacent reflecting layers restricts the identification of underlying sand effectively by conventional inversion. Also, the depth at which the deep CBM zone is located (1,500–2000 m) produces a significant overlap of P-wave impedance and Vp/Vs of sands and shale which increases classification uncertainty between these two lithofacies. We proposed a new workflow for high-precision quantitative seismic interpretation of deep CBM reservoir. Not only P-wave impedance but also GR is selected as the optimized attributes for lithofacies classification. To reduce the effect of strong reflection of coal seam and identifying thin coal layers, the seismic waveform indication inversion method is used to obtain high-resolution results of P-wave impedance and GR. It uses horizontal changes in seismic waveforms to reflect lithological assemblage characteristics for facies-controlled constraints. Then, Bayesian classification theory is used to achieve three-dimensional lithofacies classification with multi-source data. To improve the continuity and accuracy of the interpreted results, a Markov chain is applied in the Bayesian rule as the spatial prior constraint. A well-associated synthetic test and field data application in Ordos Basin demonstrates the accuracy of the proposed workflow. Compared with conventional inversion, the results of proposed workflow showed higher resolution and accuracy. By providing a new solution for the identification of roof and floor lithofacies of deep CBM reservoir, this workflow aims to contribute to the better exploration and development of deep CBM.
在深部煤层气（CBM）的勘探和开发过程中，煤层厚度和顶底板岩性的划分是具有挑战性的主要任务之一。在过去的尝试中，这些参数的预测方法仅限于常规反演。然而，煤层对相邻反射层的屏蔽效应限制了常规反演对下伏砂层的有效识别。此外，深层煤层气区所处的深度（1500-2000 米）会使砂和页岩的 P 波阻抗和 Vp/Vs 产生明显的重叠，从而增加了这两种岩性之间分类的不确定性。我们提出了一种新的深层煤层气储层高精度定量地震解释工作流程。不仅选择 P 波阻抗，还选择 GR 作为岩性分类的优化属性。为减小煤层强反射的影响和识别薄煤层，采用地震波形指示反演方法获得高分辨率的 P 波阻抗和 GR 结果。它利用地震波形的水平变化来反映岩性组合特征，进行面控约束。然后，利用贝叶斯分类理论实现多源数据的三维岩性分类。为了提高解释结果的连续性和准确性，在贝叶斯规则中应用了马尔科夫链作为空间先验约束。在鄂尔多斯盆地进行的相关合成试验和野外数据应用证明了所提出工作流程的准确性。与传统反演相比，所提工作流程的结果显示出更高的分辨率和精度。通过为深层煤层气储层顶底板岩性识别提供新的解决方案，该工作流程旨在为更好地勘探和开发深层煤层气做出贡献。
{"title":"Lithofacies identification of deep coalbed methane reservoir based on high-resolution seismic inversion","authors":"Yu Qi, Kui Wu, Bo Wang, Xiaowen Zheng, Wenlan Li, Dan Li","doi":"10.3389/feart.2024.1440729","DOIUrl":"https://doi.org/10.3389/feart.2024.1440729","url":null,"abstract":"During the exploration and development of deep coalbed methane (CBM), delineating the thickness of coal seam and lithofacies of the roof and floor is one of the major challenging tasks. In past attempts, the prediction methods of these parameters have been limited to the conventional inversion. However, the effect of coal shielding on adjacent reflecting layers restricts the identification of underlying sand effectively by conventional inversion. Also, the depth at which the deep CBM zone is located (1,500–2000 m) produces a significant overlap of P-wave impedance and Vp/Vs of sands and shale which increases classification uncertainty between these two lithofacies. We proposed a new workflow for high-precision quantitative seismic interpretation of deep CBM reservoir. Not only P-wave impedance but also GR is selected as the optimized attributes for lithofacies classification. To reduce the effect of strong reflection of coal seam and identifying thin coal layers, the seismic waveform indication inversion method is used to obtain high-resolution results of P-wave impedance and GR. It uses horizontal changes in seismic waveforms to reflect lithological assemblage characteristics for facies-controlled constraints. Then, Bayesian classification theory is used to achieve three-dimensional lithofacies classification with multi-source data. To improve the continuity and accuracy of the interpreted results, a Markov chain is applied in the Bayesian rule as the spatial prior constraint. A well-associated synthetic test and field data application in Ordos Basin demonstrates the accuracy of the proposed workflow. Compared with conventional inversion, the results of proposed workflow showed higher resolution and accuracy. By providing a new solution for the identification of roof and floor lithofacies of deep CBM reservoir, this workflow aims to contribute to the better exploration and development of deep CBM.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"5 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179561","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 : 2024-08-22DOI: 10.3389/feart.2024.1377367
Junaid Ali, Fakhrul Islam, Tehmina Bibi, Ijazul Islam, Muhammad Rizwan Mughal, Muhammad Sabir, Fuad Awwad, Emad Ismail
Urbanization poses a significant threat to environmental sustainability, particularly in Pakistan, where uncontrolled urban growth and water mismanagement have exacerbated water scarcity and climate variability. This study investigates the spatiotemporal impacts of urbanization and climate change on groundwater in Lahore District, Pakistan. various parameters were considered to execute the study including land use/land cover (LULC), rainfall, Land Surface Temperature (LST), ground wells and population data using advanced techniques such as Random Forest machine learning algorithm, Climate Hazards Group Infrared Precipitation, and geographically weighted regression (GWR) analysis. Our findings reveal that urbanization has severely impacted the water table in the north, northwest, and southwest areas. There is a significant negative negative correlation (−0.333) between the quantity of groundwater level (GWL) and the annual average LST whereas, the p-value (0.75) is also showing highly significant relation of GWL and LST in the study area. Whereas a positive association (0.666) exist (p-value 0.333 moderately significant) between yearly GWL and the mean precipitation. This research provides crucial insights for policymakers to understand the effects of urbanization and climate change on groundwater and develop strategies to mitigate adverse impacts in the study area.
{"title":"Quantifying the impact of climate change and urbanization on groundwater resources using geospatial modeling","authors":"Junaid Ali, Fakhrul Islam, Tehmina Bibi, Ijazul Islam, Muhammad Rizwan Mughal, Muhammad Sabir, Fuad Awwad, Emad Ismail","doi":"10.3389/feart.2024.1377367","DOIUrl":"https://doi.org/10.3389/feart.2024.1377367","url":null,"abstract":"Urbanization poses a significant threat to environmental sustainability, particularly in Pakistan, where uncontrolled urban growth and water mismanagement have exacerbated water scarcity and climate variability. This study investigates the spatiotemporal impacts of urbanization and climate change on groundwater in Lahore District, Pakistan. various parameters were considered to execute the study including land use/land cover (LULC), rainfall, Land Surface Temperature (LST), ground wells and population data using advanced techniques such as Random Forest machine learning algorithm, Climate Hazards Group Infrared Precipitation, and geographically weighted regression (GWR) analysis. Our findings reveal that urbanization has severely impacted the water table in the north, northwest, and southwest areas. There is a significant negative negative correlation (−0.333) between the quantity of groundwater level (GWL) and the annual average LST whereas, the <jats:italic>p</jats:italic>-value (0.75) is also showing highly significant relation of GWL and LST in the study area. Whereas a positive association (0.666) exist (<jats:italic>p</jats:italic>-value 0.333 moderately significant) between yearly GWL and the mean precipitation. This research provides crucial insights for policymakers to understand the effects of urbanization and climate change on groundwater and develop strategies to mitigate adverse impacts in the study area.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"60 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223623","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 : 2024-08-22DOI: 10.3389/feart.2024.1453178
Wenbing Tao, Yingwen Wen, Xia Bian, Zhilin Ren, Long Xu, Fei Wang, Hu Zheng
For the expansion soil slope in the JiangHuai area before the disposal of the neglect of expansion of the weak defects and slope disposal after the poor long-term stability of the current situation. This study investigates the ability of ecological slope protection technology to cope with the destabilizing geohazard of expansive soil slopes. Analyzing the collapse reasons of weak expansive soil slopes in the JiangHuai region based on the reinforcement project of expansive soil slopes along highways in the JiangHuai region, combined with actual engineering research, a “storage-resistance” water regulation ecological prevention and control technology is proposed. The feasibility and sustainability of the ecological slope protection technology is discussed in terms of its principles and influencing factors, and the protection effect is verified by combining numerical simulation and field test methods. Research findings suggest that the “storage-resistance” technology effectively prevents rainwater infiltration, particularly under light rain conditions, with continuous blocking capability. Under rainstorm conditions, it can prevent infiltration for about 4 h, significantly enhancing slope stability. Slope rate variations show no significant impact on reinforced slope stability, with maximum deformation occurring at the slope’s foot after rainfall. Reinforcement plans should prioritize strengthening support at the slope’s base. Proper selection and optimization of technical parameters can lead to more economical and sustainable solutions while extending protection time. Field trials confirm the suitability of the “storage and blocking” water regulation ecological control technology for the JiangHuai region, particularly where light rain prevails. These findings suggest that ecological control techniques for expansive soil slopes can effectively regulate slope moisture changes and reduce the geohazard risk of expansive soil slope instability.
{"title":"Analysis of ecological prevention and control technology for expansive soil slope","authors":"Wenbing Tao, Yingwen Wen, Xia Bian, Zhilin Ren, Long Xu, Fei Wang, Hu Zheng","doi":"10.3389/feart.2024.1453178","DOIUrl":"https://doi.org/10.3389/feart.2024.1453178","url":null,"abstract":"For the expansion soil slope in the JiangHuai area before the disposal of the neglect of expansion of the weak defects and slope disposal after the poor long-term stability of the current situation. This study investigates the ability of ecological slope protection technology to cope with the destabilizing geohazard of expansive soil slopes. Analyzing the collapse reasons of weak expansive soil slopes in the JiangHuai region based on the reinforcement project of expansive soil slopes along highways in the JiangHuai region, combined with actual engineering research, a “storage-resistance” water regulation ecological prevention and control technology is proposed. The feasibility and sustainability of the ecological slope protection technology is discussed in terms of its principles and influencing factors, and the protection effect is verified by combining numerical simulation and field test methods. Research findings suggest that the “storage-resistance” technology effectively prevents rainwater infiltration, particularly under light rain conditions, with continuous blocking capability. Under rainstorm conditions, it can prevent infiltration for about 4 h, significantly enhancing slope stability. Slope rate variations show no significant impact on reinforced slope stability, with maximum deformation occurring at the slope’s foot after rainfall. Reinforcement plans should prioritize strengthening support at the slope’s base. Proper selection and optimization of technical parameters can lead to more economical and sustainable solutions while extending protection time. Field trials confirm the suitability of the “storage and blocking” water regulation ecological control technology for the JiangHuai region, particularly where light rain prevails. These findings suggest that ecological control techniques for expansive soil slopes can effectively regulate slope moisture changes and reduce the geohazard risk of expansive soil slope instability.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"3 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179562","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 : 2024-08-22DOI: 10.3389/feart.2024.1396784
Jifei Cao, Deyong Zou, Qilong Xue, Jin Wang, Leilei Huang, Feng Guo, Chong Wang, Jun Qu
During the operation of the drill string, it displays a degree of flexibility. Simultaneously, its dynamic properties, influenced by complex stress conditions, manifest nonlinearity and uncertainty. A comprehensive investigation into the dynamics of flexible drill strings is imperative for deep well drilling. This paper presents a model that simulates random interactions between a flexible drill string and the borehole wall, simplifying the actual drill string model using analogous principles. Dynamic simulation software is utilized for analysis, and an indoor experimental setup has been established. The results reveal that with a constant weight on bit (WOB), higher drill string rotational speeds correlate with increased susceptibility to buckling deformation. Additionally, the critical time for deformation onset exhibits a nearly linear relationship with rotational speed. Maintaining a constant rotational speed, an increase in WOB enhances the likelihood of buckling deformation. The experimental findings suggest a correlation between the drill string’s rotation frequency and the WOB.
{"title":"Analysis on the dynamics of flexible drillstring under different drilling parameters","authors":"Jifei Cao, Deyong Zou, Qilong Xue, Jin Wang, Leilei Huang, Feng Guo, Chong Wang, Jun Qu","doi":"10.3389/feart.2024.1396784","DOIUrl":"https://doi.org/10.3389/feart.2024.1396784","url":null,"abstract":"During the operation of the drill string, it displays a degree of flexibility. Simultaneously, its dynamic properties, influenced by complex stress conditions, manifest nonlinearity and uncertainty. A comprehensive investigation into the dynamics of flexible drill strings is imperative for deep well drilling. This paper presents a model that simulates random interactions between a flexible drill string and the borehole wall, simplifying the actual drill string model using analogous principles. Dynamic simulation software is utilized for analysis, and an indoor experimental setup has been established. The results reveal that with a constant weight on bit (WOB), higher drill string rotational speeds correlate with increased susceptibility to buckling deformation. Additionally, the critical time for deformation onset exhibits a nearly linear relationship with rotational speed. Maintaining a constant rotational speed, an increase in WOB enhances the likelihood of buckling deformation. The experimental findings suggest a correlation between the drill string’s rotation frequency and the WOB.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"9 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179668","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 : 2024-08-21DOI: 10.3389/feart.2024.1452977
Jihede Haj Messaoud, Nicolas Thibault, Brahimsamba Bomou, Thierry Adatte, Mohammed H. Aljahdali, Chokri Yaich
The Early Bartonian Reneiche/Siouf member is one of the primary conventional carbonate oil/gas reservoirs to be assessed in Tunisia that demands detailed evaluation. Accurate zonation and modeling of this reservoir require an integrated approach combining surface and subsurface studies. This research focuses on the depositional, diagenetic, and stratigraphic factors affecting reservoir quality and porosity within the Reneiche/Siouf member, utilizing an integrated surface-subsurface analysis. The primary aim is to understand the reservoir zonation of the Reineche Member near Kerkennah archipelago (eastern Tunisian offshore) and its lateral equivalents in central Tunisia the Siouf Member (outcrop analogue). Gamma-ray and sonic logs from the Reineche Member in the southern and southeastern Pelagian Platform (Tunisian offshore) identify three distinct limestone units (A, C, and E). These units transition into a single mud-dominated limestone unit (C) to the east and northeast of the Kerkennah archipelago. In contrast, the western Pelagian Platform (onshore) and Central Tunisia present a different stratigraphy for the Reineche/Siouf Member, comprising two limestone units: the Lower Reneiche Limestone (LRL) and the Upper Reneiche Limestone (URL), corresponding to Units C and E, respectively, separated by the Upper Reneiche Shale (URS) unit. Reservoir porosity and permeability analyses of the outcrop analogs reveal hybrid pore types (depositional and diagenetic), including intragranular, biomouldic, and vuggy pores, resulting from significant dissolution of large bioclasts. In the northern Gulf of Gabes, the Nummulite barrier of the Reineche Member (SW of the Kerkennah archipelago) demonstrates substantial reservoir quality improvement, with porosity reaching up to 30% in Unit C, attributed to intense dissolution, dolomitization (intercrystalline porosity), and fracturing. Diagenetic processes observed in the Siouf Member (Central Tunisia) differ from those in the Reineche Limestone Member (Pelagian Platform). In the Reineche Member, CO2-rich fluids entering through faults and fissures during deep burial diagenesis drive dissolution and dolomitization. Conversely, in the Siouf Member, these processes occur due to short subaerial exposures during meteoric to shallow-burial diagenesis. A key outcome of our study is the comparison between Central Tunisia and the eastern Tunisian offshore, highlighting local tectonic control on reservoir thickness and identifying three upward-thickening sequences in the Siouf Member outcrop. This research is crucial for understanding the Gulf of Gabes and Libyan offshore nummulitic Eocene reservoirs, emphasizing the role of tectonics and sea level changes in shaping reservoir characteristics.
{"title":"Frontiers | Integrated surface-subsurface reservoir zonation of the Early Bartonian nummulitic limestone in central Tunisia and eastern Tunisian offshore","authors":"Jihede Haj Messaoud, Nicolas Thibault, Brahimsamba Bomou, Thierry Adatte, Mohammed H. Aljahdali, Chokri Yaich","doi":"10.3389/feart.2024.1452977","DOIUrl":"https://doi.org/10.3389/feart.2024.1452977","url":null,"abstract":"The Early Bartonian Reneiche/Siouf member is one of the primary conventional carbonate oil/gas reservoirs to be assessed in Tunisia that demands detailed evaluation. Accurate zonation and modeling of this reservoir require an integrated approach combining surface and subsurface studies. This research focuses on the depositional, diagenetic, and stratigraphic factors affecting reservoir quality and porosity within the Reneiche/Siouf member, utilizing an integrated surface-subsurface analysis. The primary aim is to understand the reservoir zonation of the Reineche Member near Kerkennah archipelago (eastern Tunisian offshore) and its lateral equivalents in central Tunisia the Siouf Member (outcrop analogue). Gamma-ray and sonic logs from the Reineche Member in the southern and southeastern Pelagian Platform (Tunisian offshore) identify three distinct limestone units (A, C, and E). These units transition into a single mud-dominated limestone unit (C) to the east and northeast of the Kerkennah archipelago. In contrast, the western Pelagian Platform (onshore) and Central Tunisia present a different stratigraphy for the Reineche/Siouf Member, comprising two limestone units: the Lower Reneiche Limestone (LRL) and the Upper Reneiche Limestone (URL), corresponding to Units C and E, respectively, separated by the Upper Reneiche Shale (URS) unit. Reservoir porosity and permeability analyses of the outcrop analogs reveal hybrid pore types (depositional and diagenetic), including intragranular, biomouldic, and vuggy pores, resulting from significant dissolution of large bioclasts. In the northern Gulf of Gabes, the Nummulite barrier of the Reineche Member (SW of the Kerkennah archipelago) demonstrates substantial reservoir quality improvement, with porosity reaching up to 30% in Unit C, attributed to intense dissolution, dolomitization (intercrystalline porosity), and fracturing. Diagenetic processes observed in the Siouf Member (Central Tunisia) differ from those in the Reineche Limestone Member (Pelagian Platform). In the Reineche Member, CO2-rich fluids entering through faults and fissures during deep burial diagenesis drive dissolution and dolomitization. Conversely, in the Siouf Member, these processes occur due to short subaerial exposures during meteoric to shallow-burial diagenesis. A key outcome of our study is the comparison between Central Tunisia and the eastern Tunisian offshore, highlighting local tectonic control on reservoir thickness and identifying three upward-thickening sequences in the Siouf Member outcrop. This research is crucial for understanding the Gulf of Gabes and Libyan offshore nummulitic Eocene reservoirs, emphasizing the role of tectonics and sea level changes in shaping reservoir characteristics.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"95 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227599","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 : 2024-08-19DOI: 10.3389/feart.2024.1456122
Junping Liu, Huailai Zhou, Luyao Liao, Cong Niu, Qiuyu Li
Granite buried hill oil and gas reservoirs are relatively scarce worldwide, and the fine prediction and characterization of their fractures have always been a significant industry challenge. Particularly in the South China Sea region, large and thick granite buried-hill reservoirs are influenced by various geological processes such as weathering and tectonics, resulting in a complex internal fracture system. The seismic reflection characteristics exhibit high steepness, discontinuity, and significant amplitude differences, posing significant difficulties for the fine characterization of fractures. A systematic and comprehensive research approach has not yet been established. Therefore, this study considers the large granite-buried hill A reservoir in the South China Sea as a typical case study and proposes a multi-scale fracture fine prediction and characterization methodology system. The method starts with analyzing the fracture scale and genesis to refine the fracture scales identifiable by conventional seismic data. Based on this, the U-SegNet model and transfer learning are utilized to achieve fine detection of large-scale fractures. Meanwhile, using high-resolution ant tracking technology based on MVMD frequency division and sensitive attribute preferences realizes a fine prediction of medium-to-small-scale fractures. Furthermore, the discrete fracture network is used for fracture deterministic modeling, ranging from geometric morphology to percolation behavior. Ultimately, a post-stack seismic multi-scale fracture prediction and characterization workflow is established. The results indicate that the buried hill in the study area exhibits a high degree of fracture development with evident multi-scale characteristics. Among them, large-scale fractures have a relatively low development density, primarily oriented in the NW and NE directions; medium-to-small-scale fractures exhibit high-density and omnidirectional development. The development of fractures significantly improves the storage space and fluid flow capacity of the buried hill. Compared with traditional methods, the proposed method notably enhances the accuracy of characterizing the degree of fracture development, spatial morphology, and percolation behavior in the buried hill reservoir, providing a scientific basis for oil and gas exploration and development.
{"title":"Post-stack multi-scale fracture prediction and characterization methods for granite buried hill reservoirs: a case study in the Pearl River Mouth Basin, South China Sea","authors":"Junping Liu, Huailai Zhou, Luyao Liao, Cong Niu, Qiuyu Li","doi":"10.3389/feart.2024.1456122","DOIUrl":"https://doi.org/10.3389/feart.2024.1456122","url":null,"abstract":"Granite buried hill oil and gas reservoirs are relatively scarce worldwide, and the fine prediction and characterization of their fractures have always been a significant industry challenge. Particularly in the South China Sea region, large and thick granite buried-hill reservoirs are influenced by various geological processes such as weathering and tectonics, resulting in a complex internal fracture system. The seismic reflection characteristics exhibit high steepness, discontinuity, and significant amplitude differences, posing significant difficulties for the fine characterization of fractures. A systematic and comprehensive research approach has not yet been established. Therefore, this study considers the large granite-buried hill A reservoir in the South China Sea as a typical case study and proposes a multi-scale fracture fine prediction and characterization methodology system. The method starts with analyzing the fracture scale and genesis to refine the fracture scales identifiable by conventional seismic data. Based on this, the U-SegNet model and transfer learning are utilized to achieve fine detection of large-scale fractures. Meanwhile, using high-resolution ant tracking technology based on MVMD frequency division and sensitive attribute preferences realizes a fine prediction of medium-to-small-scale fractures. Furthermore, the discrete fracture network is used for fracture deterministic modeling, ranging from geometric morphology to percolation behavior. Ultimately, a post-stack seismic multi-scale fracture prediction and characterization workflow is established. The results indicate that the buried hill in the study area exhibits a high degree of fracture development with evident multi-scale characteristics. Among them, large-scale fractures have a relatively low development density, primarily oriented in the NW and NE directions; medium-to-small-scale fractures exhibit high-density and omnidirectional development. The development of fractures significantly improves the storage space and fluid flow capacity of the buried hill. Compared with traditional methods, the proposed method notably enhances the accuracy of characterizing the degree of fracture development, spatial morphology, and percolation behavior in the buried hill reservoir, providing a scientific basis for oil and gas exploration and development.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"20 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179563","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.2024.1453098
Wen Tang, Cong Tuo, Shaoguang Ma, Yongjun Yao, Dongxi Liu, Xinrui Yang, Licheng Yang, Hu Li
Recent exploration efforts have revealed significant industrial gas flow from the Wujiaping Formation marine shale in the Longmen–Wushankan area of the eastern Sichuan Basin, underscoring its considerable exploration potential. In this study, the reservoir characteristics and exploration potential of the Wujiaping Formation shale gas in this area are further evaluated. On the basis of well rock electrical properties, experimental analyses, and depositional and structural patterns in the eastern region, we characterize the reservoir properties and identify the primary factors controlling shale gas accumulation. The results indicate that the Wujiaping shale is characterized by a high organic matter content, favorable pore types, high porosity, and a high content of brittle minerals, which are conducive to subsequent development and fracturing. A positive correlation is observed between the total organic carbon (TOC) content, porosity, brittle mineral content, and shale gas content. The TOC content is strongly correlated with the gas content (the correlation coefficient is 0.75). The high shale gas yield of the Wujiaping Formation is attributed to a combination of favorable sedimentary environments, pore conditions, roof and floor conditions, and fracturing capabilities. However, compared with the Longmaxi Formation in the Sichuan Basin, the Wujiaping Formation shale is characterized by a lower porosity, thinner shale, and deeper burial, posing challenges for exploration and development. In this study, criteria for evaluating Wujiaping Formation shale gas are established, and four favorable exploration areas are identified. Overall, the Permian Wujiaping Formation marine shale in the Longmen–Wushankan area holds promising exploration and development potential. Further exploration and an enhanced understanding of this formation will provide valuable guidance for future marine shale gas exploration and development in this area.
{"title":"Frontiers | Shale reservoir characterization and implications for the exploration and development of the upper Permian Wujiaping Formation, Longmen-Wushankan area, eastern Sichuan Basin","authors":"Wen Tang, Cong Tuo, Shaoguang Ma, Yongjun Yao, Dongxi Liu, Xinrui Yang, Licheng Yang, Hu Li","doi":"10.3389/feart.2024.1453098","DOIUrl":"https://doi.org/10.3389/feart.2024.1453098","url":null,"abstract":"Recent exploration efforts have revealed significant industrial gas flow from the Wujiaping Formation marine shale in the Longmen–Wushankan area of the eastern Sichuan Basin, underscoring its considerable exploration potential. In this study, the reservoir characteristics and exploration potential of the Wujiaping Formation shale gas in this area are further evaluated. On the basis of well rock electrical properties, experimental analyses, and depositional and structural patterns in the eastern region, we characterize the reservoir properties and identify the primary factors controlling shale gas accumulation. The results indicate that the Wujiaping shale is characterized by a high organic matter content, favorable pore types, high porosity, and a high content of brittle minerals, which are conducive to subsequent development and fracturing. A positive correlation is observed between the total organic carbon (TOC) content, porosity, brittle mineral content, and shale gas content. The TOC content is strongly correlated with the gas content (the correlation coefficient is 0.75). The high shale gas yield of the Wujiaping Formation is attributed to a combination of favorable sedimentary environments, pore conditions, roof and floor conditions, and fracturing capabilities. However, compared with the Longmaxi Formation in the Sichuan Basin, the Wujiaping Formation shale is characterized by a lower porosity, thinner shale, and deeper burial, posing challenges for exploration and development. In this study, criteria for evaluating Wujiaping Formation shale gas are established, and four favorable exploration areas are identified. Overall, the Permian Wujiaping Formation marine shale in the Longmen–Wushankan area holds promising exploration and development potential. Further exploration and an enhanced understanding of this formation will provide valuable guidance for future marine shale gas exploration and development in this area.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"56 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179583","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}
The Late Quaternary activity characteristics of secondary faults located between the main active faults at the boundaries of large basins are of great significance to the overall understanding of regional seismic hazards. The Wulashan Northern Fault (WNF) is located on the northern side of the Ordos Block, within the Northern Margin Fault Basin in North China, between the Sertengshan Piedmont Fault and Daqingshan Piedmont Fault. Current research on the geometry and kinematics of the WNF needs to be improved. In this study, we aimed to determine the shallow structural characteristics and Late Quaternary activity of the WNF using shallow seismic exploration and composite drilling geological cross-sectional analysis. The results indicate that the WNF is not a single surface fault but multiple branches with a northward-dipping stepped surface distribution. The latest activity of the F1 branch with a maximum coseismic vertical dislocation of 0.9 m occurred before 47.08 ± 3.7 ka B.P. The latest and older activities of the branch of F2 with a maximum coseismic vertical dislocation of 0.96 m and 1.15 m occurred before 73.8 ± 2.8 ka B.P. and 91.2 ± 4.4 ka B.P., respectively. According to a series of empirical relationships between length of surface rupture and magnitude, the maximum potential magnitude of the earthquake was determined to be M = 6.5–7.0. We argue that even though the Late Quaternary activity of the WNF was weaker than that of the other boundary faults of the Hetao Basin, the local urban and rural planning and land and resources construction in the Hetao Basin region should pay attention to the seismic risk of the WNF as an independent section in the future for the effect of secular tectonic loading.
位于大型盆地边界主活动断层之间的次级断层的第四纪晚期活动特征对于全面了解区域地震灾害具有重要意义。乌拉山北麓断层（WNF）位于鄂尔多斯地块北侧，华北北缘断陷盆地内，介于色楞山皮山断层和大青山皮山断层之间。目前对 WNF 的几何和运动学研究有待改进。本研究旨在通过浅层地震勘探和复合钻探地质断面分析，确定 WNF 的浅层构造特征和第四纪晚期活动。结果表明，WNF 并非单一的地表断层，而是多条分支，地表呈北倾阶梯状分布。F1 支的最晚活动期为公元前 47.08±3.7 ka 年，最大同震垂直位移为 0.9 m；F2 支的最晚和较早活动期分别为公元前 73.8±2.8 ka 年和公元前 91.2±4.4 ka 年，最大同震垂直位移分别为 0.96 m 和 1.15 m。根据地表破裂长度与震级之间的一系列经验关系，确定地震的最大潜在震级为 M = 6.5-7.0。我们认为，尽管西部断裂带第四纪晚期活动性弱于河套盆地其他边界断层，但在未来河套盆地地区的城乡规划和国土资源建设中，应将西部断裂带作为一个独立断面，关注其在世俗构造荷载作用下的地震风险。
{"title":"Late Quaternary activity of Wulashan Northern fault, North China","authors":"Leihua Wei, Weimin He, Yueren Xu, Yanlin Du, Aopeng Dai, Xiaopeng Song, Shuya Xu, Jingjing Qin","doi":"10.3389/feart.2024.1437012","DOIUrl":"https://doi.org/10.3389/feart.2024.1437012","url":null,"abstract":"The Late Quaternary activity characteristics of secondary faults located between the main active faults at the boundaries of large basins are of great significance to the overall understanding of regional seismic hazards. The Wulashan Northern Fault (WNF) is located on the northern side of the Ordos Block, within the Northern Margin Fault Basin in North China, between the Sertengshan Piedmont Fault and Daqingshan Piedmont Fault. Current research on the geometry and kinematics of the WNF needs to be improved. In this study, we aimed to determine the shallow structural characteristics and Late Quaternary activity of the WNF using shallow seismic exploration and composite drilling geological cross-sectional analysis. The results indicate that the WNF is not a single surface fault but multiple branches with a northward-dipping stepped surface distribution. The latest activity of the F1 branch with a maximum coseismic vertical dislocation of 0.9 m occurred before 47.08 ± 3.7 ka B.P. The latest and older activities of the branch of F2 with a maximum coseismic vertical dislocation of 0.96 m and 1.15 m occurred before 73.8 ± 2.8 ka B.P. and 91.2 ± 4.4 ka B.P., respectively. According to a series of empirical relationships between length of surface rupture and magnitude, the maximum potential magnitude of the earthquake was determined to be <jats:italic>M</jats:italic> = 6.5–7.0. We argue that even though the Late Quaternary activity of the WNF was weaker than that of the other boundary faults of the Hetao Basin, the local urban and rural planning and land and resources construction in the Hetao Basin region should pay attention to the seismic risk of the WNF as an independent section in the future for the effect of secular tectonic loading.","PeriodicalId":12359,"journal":{"name":"Frontiers in Earth Science","volume":"170 1","pages":""},"PeriodicalIF":2.9,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142179585","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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