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Keywords = seepage pressure monitoring

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13 pages, 2751 KiB  
Article
Experimental Study on Grouting Visualization of Cover Layer Based on Transparent Soil
by Pengfei Guo and Weiquan Zhao
Appl. Sci. 2025, 15(14), 7854; https://doi.org/10.3390/app15147854 - 14 Jul 2025
Viewed by 206
Abstract
Grouting, as a widely applicable and versatile foundation treatment technology, plays a crucial role in addressing seepage control problems in cover layers due to its flexibility and convenience. The effectiveness of grouting largely depends on slurry diffusion; however, due to the opaque nature [...] Read more.
Grouting, as a widely applicable and versatile foundation treatment technology, plays a crucial role in addressing seepage control problems in cover layers due to its flexibility and convenience. The effectiveness of grouting largely depends on slurry diffusion; however, due to the opaque nature of geotechnical media, the diffusion mechanism of slurry in the cover layers remains insufficiently understood. To investigate this, a visual grouting model device was designed and fabricated, and grouting tests were conducted using transparent soil materials to simulate the cover layers. The slurry diffusion patterns and the velocity field within the transparent soil were analyzed. The results show that, based on refractive-index matching, fused quartz sand of specific gradation and white mineral oil were selected as simulation materials for the cover layers. A stable slurry suitable for transparent grouting was also chosen to satisfy visualization requirements. The transparent soil grouting model, integrated with a Digital Image Correlation (DIC) monitoring system, has the advantages of demonstrating simple operation, real-time monitoring, and high precision. These tests verify the feasibility of visualizing slurry diffusion in cover layers. Furthermore, step-pressure grouting tests preliminarily reveal the dynamic mechanism of slurry diffusion. The results suggest that, in the cover layer, the cover layer in this grouting test is mainly splitting grouting, accompanied by compaction grouting. These methods offer new insights and methods for model testing of cover layer grouting mechanisms. Full article
(This article belongs to the Section Civil Engineering)
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19 pages, 4770 KiB  
Article
In-Depth Analysis of Shut-In Time Using Post-Fracturing Flowback Fluid Data—Shale of the Longmaxi Formation in the Luzhou Basin and Weiyuan Basin of China as an Example
by Lingdong Li, Xinqun Ye, Zehao Lyu, Xiaoning Zhang, Wenhua Yu, Tianhao Huang, Xinxin Yu and Wenhai Yu
Processes 2025, 13(6), 1832; https://doi.org/10.3390/pr13061832 - 10 Jun 2025
Viewed by 448
Abstract
The development of shale gas relies on hydraulic fracturing technology and requires the injection of a large amount of fracturing fluid. The well shut-off period after fracturing can promote water infiltration and suction. Optimizing the well shut-off time is crucial for enhancing the [...] Read more.
The development of shale gas relies on hydraulic fracturing technology and requires the injection of a large amount of fracturing fluid. The well shut-off period after fracturing can promote water infiltration and suction. Optimizing the well shut-off time is crucial for enhancing the recovery rate. Among existing methods, the dimensionless time model is widely used, but it has limitations because it does not represent the length of on-site scale features. In this study, we focused on the shut-in time for a deep shale gas well (Lu-A) in Luzhou and a medium-deep shale gas well (Wei-B) in Weiyuan. By integrating the spontaneous seepage and aspiration experiments in the laboratory and the post-pressure backflow data (including mineralization degree, liquid volume recovery rate, etc.), a multi-scale well shutdown time prediction model considering the characteristic length was established. The experimental results show that the spontaneous resorption characteristic times of Lu-A and Wei-B are 3 h and 22 h, respectively. Based on the inversion of crack monitoring data, the key parameters such as the weighted average crack width (1.73/1.30 mm) and crack spacing (0.20/0.32 m) of Lu-A and Wei-B were obtained. Through the scale upgrade calculation of the feature length (0.10/0.16 m), the system determined that the optimal well shutdown times for the two wells were 14.5 days and 16.7 days, respectively. The optimization method based on a multi-parameter analysis of backflow fluid proposed in this study not only solves the limitations of the traditional dimensionless time model in characterizing the feature length but also provides a theoretical basis for the formulation of the well shutdown system and nozzle control strategy of shale gas wells. Full article
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29 pages, 21376 KiB  
Article
Numerical Simulation of Fracture Failure Propagation in Water-Saturated Sandstone with Pore Defects Under Non-Uniform Loading Effects
by Gang Liu, Yonglong Zan, Dongwei Wang, Shengxuan Wang, Zhitao Yang, Yao Zeng, Guoqing Wei and Xiang Shi
Water 2025, 17(12), 1725; https://doi.org/10.3390/w17121725 - 7 Jun 2025
Cited by 1 | Viewed by 518
Abstract
The instability of mine roadways is significantly influenced by the coupled effects of groundwater seepage and non-uniform loading. These interactions often induce localized plastic deformation and progressive failure, particularly in the roof and sidewall regions. Seepage elevates pore water pressure and deteriorates the [...] Read more.
The instability of mine roadways is significantly influenced by the coupled effects of groundwater seepage and non-uniform loading. These interactions often induce localized plastic deformation and progressive failure, particularly in the roof and sidewall regions. Seepage elevates pore water pressure and deteriorates the mechanical properties of the rock mass, while non-uniform loading leads to stress concentration. The combined effect facilitates the propagation of microcracks and the formation of shear zones, ultimately resulting in localized instability. This initial damage disrupts the mechanical equilibrium and can evolve into severe geohazards, including roof collapse, water inrush, and rockburst. Therefore, understanding the damage and failure mechanisms of mine roadways at the mesoscale, under the combined influence of stress heterogeneity and hydraulic weakening, is of critical importance based on laboratory experiments and numerical simulations. However, the large scale of in situ roadway structures imposes significant constraints on full-scale physical modeling due to limitations in laboratory space and loading capacity. To address these challenges, a straight-wall circular arch roadway was adopted as the geometric prototype, with a total height of 4 m (2 m for the straight wall and 2 m for the arch), a base width of 4 m, and an arch radius of 2 m. Scaled physical models were fabricated based on geometric similarity principles, using defect-bearing sandstone specimens with dimensions of 100 mm × 30 mm × 100 mm (length × width × height) and pore-type defects measuring 40 mm × 20 mm × 20 mm (base × wall height × arch radius), to replicate the stress distribution and deformation behavior of the prototype. Uniaxial compression tests on water-saturated sandstone specimens were performed using a TAW-2000 electro-hydraulic servo testing system. The failure process was continuously monitored through acoustic emission (AE) techniques and static strain acquisition systems. Concurrently, FLAC3D 6.0 numerical simulations were employed to analyze the evolution of internal stress fields and the spatial distribution of plastic zones in saturated sandstone containing pore defects. Experimental results indicate that under non-uniform loading, the stress–strain curves of saturated sandstone with pore-type defects typically exhibit four distinct deformation stages. The extent of crack initiation, propagation, and coalescence is strongly correlated with the magnitude and heterogeneity of localized stress concentrations. AE parameters, including ringing counts and peak frequencies, reveal pronounced spatial partitioning. The internal stress field exhibits an overall banded pattern, with localized variations induced by stress anisotropy. Numerical simulation results further show that shear failure zones tend to cluster regionally, while tensile failure zones are more evenly distributed. Additionally, the stress field configuration at the specimen crown significantly influences the dispersion characteristics of the stress–strain response. These findings offer valuable theoretical insights and practical guidance for surrounding rock control, early warning systems, and reinforcement strategies in water-infiltrated mine roadways subjected to non-uniform loading conditions. Full article
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13 pages, 5825 KiB  
Article
Investigating the Physical Mechanisms of Quicksand Using a Custom-Designed Experimental Apparatus
by Jianhui Long, Rui Dong, Kaixin Zhang, Hangyu Weng and Zhiqiang Yi
Appl. Sci. 2025, 15(12), 6415; https://doi.org/10.3390/app15126415 - 6 Jun 2025
Viewed by 476
Abstract
Quicksand initiation in saturated sandy soils represents a critical geohazard with significant implications for geotechnical infrastructure stability. Despite its importance, the granular-scale mechanisms driving the physical state transitions during quicksand remain insufficiently understood. This study employs a custom-designed hydrodynamic seepage testing system to [...] Read more.
Quicksand initiation in saturated sandy soils represents a critical geohazard with significant implications for geotechnical infrastructure stability. Despite its importance, the granular-scale mechanisms driving the physical state transitions during quicksand remain insufficiently understood. This study employs a custom-designed hydrodynamic seepage testing system to investigate these mechanisms, enabling precise regulation of hydrodynamic velocity and real-time monitoring of pressure variations. Through experiments on quartz sand specimens with varying particle gradations, we demonstrate that particle gradation primarily governs quicksand susceptibility, while hydrodynamic velocity controls its initiation timing and exhibits a linear correlation with seepage discharge. The quicksand process evolves through three distinct stages: self-consolidation, reorganization, and quicksand initiation, with the reorganization stage identified as the pivotal phase where particle rearrangement dictates system stability. These findings elucidate the intrinsic physical mechanisms of quicksand as a hydraulic failure phenomenon, offering valuable insights for predictive modeling and geohazard mitigation in granular media. Full article
(This article belongs to the Section Civil Engineering)
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20 pages, 8410 KiB  
Review
CO2-ECBM from a Full-Chain Perspective: Mechanism Elucidation, Demonstration Practices, and Future Outlook
by Yinan Cui, Chao Li, Yuchen Tian, Bin Miao, Yanzhi Liu, Zekun Yue, Xuguang Dai, Jinghui Zhao, Hequn Gao, Hui Li, Yaozu Zhang, Guangrong Zhang, Bei Zhang, Shiqi Liu and Sijian Zheng
Energies 2025, 18(11), 2841; https://doi.org/10.3390/en18112841 - 29 May 2025
Viewed by 444
Abstract
CO2-enhanced coalbed methane recovery (CO2-ECBM) represents a promising pathway within carbon capture, utilization, and storage (CCUS) technologies, offering dual benefits of methane production and long-term CO2 sequestration. This review provides a comprehensive analysis of CO2-ECBM from [...] Read more.
CO2-enhanced coalbed methane recovery (CO2-ECBM) represents a promising pathway within carbon capture, utilization, and storage (CCUS) technologies, offering dual benefits of methane production and long-term CO2 sequestration. This review provides a comprehensive analysis of CO2-ECBM from a full-chain perspective (Mechanism, Practices, and Outlook), covering fundamental mechanisms and key engineering practices. It highlights the complex multi-physics processes involved, including competitive adsorption–desorption, diffusion and seepage, thermal effects, stress responses, and geochemical interactions. Recent progress in laboratory experiments, capacity assessments, site evaluations, monitoring techniques, and numerical simulations are systematically reviewed. Field studies indicate that CO2-ECBM performance is strongly influenced by reservoir pressure, temperature, injection rate, and coal seam properties. Structural conditions and multi-field coupling further affect storage efficiency and long-term security. This work also addresses major technical challenges such as real-time monitoring limitations, environmental risks, injection-induced seismicity, and economic constraints. Future research directions emphasize the need to deepen understanding of coupling mechanisms, improve monitoring frameworks, and advance integrated engineering optimization. By synthesizing recent advances and identifying research priorities, this review aims to provide theoretical support and practical guidance for the scalable deployment of CO2-ECBM, contributing to global energy transition and carbon neutrality goals. Full article
(This article belongs to the Special Issue Advances in Unconventional Reservoirs and Enhanced Oil Recovery)
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17 pages, 4932 KiB  
Article
Numerical Simulation of Flow Characteristics in CO2 Long-Term Storage in Bedded Salt Cavern
by Bo Cao, Xuehai Fu, Junqiang Kang, Pan Tang, Hui Xu and Yuanyuan Zhang
Processes 2025, 13(5), 1563; https://doi.org/10.3390/pr13051563 - 18 May 2025
Viewed by 526
Abstract
The salt layer, characterized by its low permeability and excellent damage self-healing properties, is an ideal geological body for CO2 geological storage. However, the relatively high permeability of mudstone interlayers may reduce the safety of CO2 long-term storage in bedded salt [...] Read more.
The salt layer, characterized by its low permeability and excellent damage self-healing properties, is an ideal geological body for CO2 geological storage. However, the relatively high permeability of mudstone interlayers may reduce the safety of CO2 long-term storage in bedded salt caverns. This study establishes a thermal–hydraulic–mechanical (THM) coupled physical and mathematical model for CO2 geological storage in the Huaian salt cavern, analyzes the factors affecting CO2 flow behavior, and proposes measures to enhance the safety of CO2 storage in salt caverns. The results indicate that the permeability of both salt layers and mudstone interlayers is influenced by stress-induced deformation within the salt cavern. From the salt cavern edge to the simulation boundary, the permeability and volume strain exhibit a trend of rapid decline, followed by a gradual increase, and an eventual stabilization or slight reduction. The seepage velocity, pore pressure, and flow distance of CO2 in the mudstone interlayer are significantly higher than those in the salt layer, leading to CO2 migration along the interfaces between the mudstone and salt layer. With the increase in storage time, the permeability of the mudstone interlayer gradually decreases, while the permeability of the salt layer shows a general tendency to increase. The elevated storage pressure reduces the permeability of the mudstone interlayer, while increasing the permeability of the salt layer, and enhances the seepage velocity in both the mudstone and salt layers. To enhance the safety of CO2 long-term storage in bedded salt caverns, it is recommended to minimize the presence of mudstone interlayers during site selection and cavern construction, optimize the storage pressure, and strengthen monitoring systems for potential CO2 leakage. Full article
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20 pages, 11415 KiB  
Article
Online Identification and Correction Methods for Multi-Type Abnormal Values in Seepage Pressure of Earth-Rock Dams
by Ke Fan, Chunfang Yue, Lilang Pi and Jiachen Shi
Appl. Sci. 2025, 15(10), 5550; https://doi.org/10.3390/app15105550 - 15 May 2025
Viewed by 366
Abstract
With the increasing service duration of dams, the analysis of seepage pressure monitoring data plays a crucial role in ensuring the safety of seepage behavior. However, seepage pressure monitoring systems are often subject to environmental disturbances, sensor failures, and other interfering factors, leading [...] Read more.
With the increasing service duration of dams, the analysis of seepage pressure monitoring data plays a crucial role in ensuring the safety of seepage behavior. However, seepage pressure monitoring systems are often subject to environmental disturbances, sensor failures, and other interfering factors, leading to anomalous measurements during data acquisition. To objectively reflect the true operational state of dams and address the limitations of conventional detection and identification methods—such as low efficiency, high subjectivity in evaluation, and ineffective recognition of multi-category outliers—this study constructed an online detection, identification, and correction method for multi-category anomalous values. Specifically, an enhanced particle filter incorporating a Bernoulli probability model is constructed to characterize multi-category outliers in seepage pressure monitoring data, building upon the traditional particle filter framework. Following online detection and identification, the MissForest imputation method is employed to rectify the anomalous values. In the case study, both the false detection rate and missed detection rate ranged between 0% and 10%. Comparative experiments with three alternative methods revealed significant differences in data reconstruction performance, with the proposed method achieving the highest R2 score (0.861) and the lowest RMSE (0.050) and MAE (0.052). The results demonstrate that the proposed method effectively identifies outliers, achieves superior reconstruction of seepage pressure data, and minimizes errors. Furthermore, this research provides a novel approach for detecting anomalous seepage pressure measurements and evaluating dam safety conditions. Full article
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24 pages, 9917 KiB  
Article
Experimental Investigation of Soil Settlement Mechanisms Induced by Staged Dewatering and Excavation in Alternating Multi-Aquifer–Aquitard Systems
by Cheng Zhao, Yimei Cheng, Guohong Zeng, Guoyun Lu and Yuwen Ju
Buildings 2025, 15(9), 1534; https://doi.org/10.3390/buildings15091534 - 2 May 2025
Viewed by 455
Abstract
Dewatering and excavation are fundamental processes influencing soil deformation in deep foundation pit construction. Excavation causes stress redistribution through unloading, while dewatering lowers the groundwater level, increases effective stress, and generates seepage forces and compressive deformation in the surrounding soil. To systematically investigate [...] Read more.
Dewatering and excavation are fundamental processes influencing soil deformation in deep foundation pit construction. Excavation causes stress redistribution through unloading, while dewatering lowers the groundwater level, increases effective stress, and generates seepage forces and compressive deformation in the surrounding soil. To systematically investigate their combined influence, this study conducted a scaled physical model test under staged excavation and dewatering conditions within a layered multi-aquifer–aquitard system. Throughout the experiment, soil settlement, groundwater head, and pore water pressure were continuously monitored. Two dimensionless parameters were introduced to quantify the contributions of dewatering and excavation: the total dewatering settlement rate ηdw and the cyclic dewatering settlement rate ηdw,i. Under different experimental conditions, ηdw ranges from 0.35 to 0.63, while ηdw,i varies between 0.32 and 0.82. Both settlement rates decrease with increasing diaphragm wall insertion depth and increase with greater dewatering depth inside the pit and higher soil permeability. An analytical formula for dewatering-induced soil settlement was developed using a modified layered summation method that accounts for deformation coordination between soil layers and includes correction factors for unsaturated zones. Although this approach is limited by scale effects and simplified boundary conditions, the findings offer valuable insights into soil deformation mechanisms under the combined influence of excavation and dewatering. These results provide practical guidance for improving deformation control strategies in complex hydrogeological environments. Full article
(This article belongs to the Special Issue Advances in Foundation Engineering for Building Structures)
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19 pages, 8589 KiB  
Article
Study on the Deformation Mechanism of Shallow Soil Landslides Under the Coupled Effects of Crack Development, Road Loading, and Rainfall
by Peiyan Fei, Qinglin Yi, Maolin Deng, Biao Wang, Yuhang Song and Longchuan Liu
Water 2025, 17(8), 1196; https://doi.org/10.3390/w17081196 - 16 Apr 2025
Viewed by 549
Abstract
This study investigated the deformation characteristics and mechanisms of the Baiyansizu landslide under the coupled effects of crack development, rainfall infiltration, and road loading. Numerical simulations were performed using GeoStudio software (Version 2018; Seequent, 2018) to analyze geological factors and external disturbances affecting [...] Read more.
This study investigated the deformation characteristics and mechanisms of the Baiyansizu landslide under the coupled effects of crack development, rainfall infiltration, and road loading. Numerical simulations were performed using GeoStudio software (Version 2018; Seequent, 2018) to analyze geological factors and external disturbances affecting landslide deformation and seepage dynamics. Four additional landslides (Tanjiawan, Bazimen, Tudiling, and Chengnan) were selected as comparative cases to investigate differences in deformation characteristics and mechanisms across these cases. The results demonstrate that rear-edge deformation of the Baiyansizu landslide was predominantly governed by rainfall patterns, with effective rainfall exhibiting a dual regulatory mechanism: long-term rainfall reduced shear strength through sustained infiltration-induced progressive creep, whereas short-term rainstorms generated step-like deformation via transient pore water pressure amplification. GeoStudio simulations further revealed multi-physics coupling mechanisms and nonlinear stability evolution controls. These findings highlight that rear-edge fissures substantially amplify rainfall infiltration efficiency, thereby establishing these features as the predominant deformation determinant. Road loading was observed to accelerate shallow landslide deformation, with stability coefficient threshold values triggering accelerated creep phases when thresholds were exceeded. Through comparative analysis of five typical landslide cases, it was demonstrated that interactions between geological factors and external disturbances resulted in distinct deformation characteristics and mechanisms. Variations in landslide thickness, crack evolution, road loading magnitudes, and rainfall infiltration characteristics were identified as critical factors influencing deformation patterns. This research provides significant empirical insights and theoretical frameworks for landslide monitoring and early warning system development. Full article
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26 pages, 9640 KiB  
Article
AI-Powered Digital Twin Technology for Highway System Slope Stability Risk Monitoring
by Jianshu Xu and Yunfeng Zhang
Geotechnics 2025, 5(1), 19; https://doi.org/10.3390/geotechnics5010019 - 12 Mar 2025
Viewed by 2091
Abstract
This research proposes an artificial intelligence (AI)-powered digital twin framework for highway slope stability risk monitoring and prediction. For highway slope stability, a digital twin replicates the geological and structural conditions of highway slopes while continuously integrating real-time monitoring data to refine and [...] Read more.
This research proposes an artificial intelligence (AI)-powered digital twin framework for highway slope stability risk monitoring and prediction. For highway slope stability, a digital twin replicates the geological and structural conditions of highway slopes while continuously integrating real-time monitoring data to refine and enhance slope modeling. The framework employs instance segmentation and a random forest model to identify embankments and slopes with high landslide susceptibility scores. Additionally, artificial neural network (ANN) models are trained on historical drilling data to predict 3D subsurface soil type point clouds and groundwater depth maps. The USCS soil classification-based machine learning model achieved an accuracy score of 0.8, calculated by dividing the number of correct soil class predictions by the total number of predictions. The groundwater depth regression model achieved an RMSE of 2.32. These predicted values are integrated as input parameters for seepage and slope stability analyses, ultimately calculating the factor of safety (FoS) under predicted rainfall infiltration scenarios. The proposed methodology automates the identification of embankments and slopes using sub-meter resolution Light Detection and Ranging (LiDAR)-derived digital elevation models (DEMs) and generates critical soil properties and pore water pressure data for slope stability analysis. This enables the provision of early warnings for potential slope failures, facilitating timely interventions and risk mitigation. Full article
(This article belongs to the Special Issue Recent Advances in Geotechnical Engineering (2nd Edition))
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18 pages, 6347 KiB  
Article
Supercritical CO2 Injection-Induced Fracturing in Longmaxi Shales: A Laboratory Study
by Xiufeng Zhang, Xuehang Song, Xingyu Li, Shuyuan Liu, Jiangmei Wang, Junjie Wei and Min Zhang
Energies 2025, 18(4), 855; https://doi.org/10.3390/en18040855 - 12 Feb 2025
Cited by 1 | Viewed by 948
Abstract
Although supercritical CO2 (SC-CO2) fracturing has shown promise in oil and gas development with demonstrated potential, its application in shale gas extraction remains in its infancy globally. In this study, fracturing experiments were conducted with water, liquid CO2 (L-CO [...] Read more.
Although supercritical CO2 (SC-CO2) fracturing has shown promise in oil and gas development with demonstrated potential, its application in shale gas extraction remains in its infancy globally. In this study, fracturing experiments were conducted with water, liquid CO2 (L-CO2), and SC-CO2, as well as SC-CO2 at varying pump rates. The results reveal that SC-CO2 fracturing produces a highly complex fracture network characterized by fractures of varying numbers, deflection angles, and tortuosity. Analysis of CO2 temperature and pressure data showed a sharp drop in injection pressure and temperature at breakdown, followed by fluctuations until injection stopped. Acoustic emission (AE) monitoring demonstrated that energy released during main fracture initiation significantly exceeded that from CO2 phase transition-driven fracture extension, underscoring the dominant role of main fractures in energy dissipation. Compared to hydraulic fracturing, SC-CO2 fracturing created a seepage area 2.2 times larger while reducing the breakdown pressure by 37.2%, indicating superior stimulation performance. These findings emphasize the potential of SC-CO2 to form intricate fracture networks, offering a promising approach for efficient shale gas extraction. Full article
(This article belongs to the Special Issue The Technology of Oil and Gas Production with Low Energy Consumption)
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13 pages, 5465 KiB  
Article
Monitoring-Based Study of Migration Characteristics of Highly Saline Mine Water During Deep Well Injection and Storage in the Ordos Basin
by Qiaohui Che, Song Du, Degao Zhang, Donglin Dong, Yinglin Fan, Xiang Li, Zhan Yang and Xiao Zhang
Processes 2025, 13(2), 494; https://doi.org/10.3390/pr13020494 - 10 Feb 2025
Cited by 1 | Viewed by 584
Abstract
Deep well injection and storage (DWIS) has recently been proposed and implemented to achieve zero mine water emissions. In 2023, DWIS for highly saline mine water was successfully applied to a local mine in the Ordos Basin for the first time with excellent [...] Read more.
Deep well injection and storage (DWIS) has recently been proposed and implemented to achieve zero mine water emissions. In 2023, DWIS for highly saline mine water was successfully applied to a local mine in the Ordos Basin for the first time with excellent performance. However, the storage characteristics of highly saline mine water in the storage layer during DWIS remain unclear. This study was conducted in situ with real-time, online monitoring of instantaneous flow and injection pressure, along with synchronous micro-seismic monitoring during the early stages of DWIS, based on the geological conditions and spatial structure of the storage layer. The results indicated that the early seepage characteristics of the fluid geological storage did not conform to Darcy’s law. Within a certain pressure range, as the water pressure increased, the flow also increased. However, beyond this range, further increases in pressure caused a gradual decline in the flow. During the initial phase of storage, the migration of high-salinity mine water within the storage layer occurred in two stages: breakthrough and stabilization. During the breakthrough stage, the water injection pressure propagated to the flooding front, overcoming the formation stress and expanding the storage space. At this stage, mine water primarily filled the pore microcracks within the flooding front. In the initial 10 days of storage, high-salinity mine water in the study area affected approximately 42,104 m2 of the storage layer plane. The injection well affected an area nearly 200 m in depth, extending approximately 190 m northward and approximately 40 m upward. The predominant diffusion directions were northeast and east–southeast from the injection well. These findings could provide valuable insights into the treatment of highly saline mine water in the Ordos Basin, demonstrate the feasibility and safety of DWIS, and offer significant scientific contributions to the prevention and control of mine water pollution. Full article
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15 pages, 9063 KiB  
Article
Study on the Imbibition Law of Laminated Shale Oil Reservoir During Injection and Shut-In Period Based on Phase Field Method
by Kun Yang, Shenglai Yang, Xinyue Liu, Shuai Zhao and Jilun Kang
Processes 2025, 13(2), 481; https://doi.org/10.3390/pr13020481 - 10 Feb 2025
Viewed by 773
Abstract
Laminated shale oil reservoirs feature well-developed microcracks, with significant differences in wettability on either side of these fractures. The complex pore structure of laminated shale oil reservoirs makes capillary imbibition prevalent during both water injection and well shut-in periods. Therefore, based on the [...] Read more.
Laminated shale oil reservoirs feature well-developed microcracks, with significant differences in wettability on either side of these fractures. The complex pore structure of laminated shale oil reservoirs makes capillary imbibition prevalent during both water injection and well shut-in periods. Therefore, based on the phase field method, this study investigates the imbibition behavior and the influencing factors during the injection and shut-in stage. This research shows that the imbibition mode determines the recovery rate: co-current imbibition > co-current imbibition + counter-current imbibition > counter-current imbibition. Co-current imbibition predominantly occurs in the dominant seepage channels, while counter-current imbibition mainly takes place in pore boundary regions. During the water injection stage, a low injection rate is beneficial for synergistic oil recovery through imbibition and displacement. As the injection rate increases, the capillary imbibition effect diminishes. Increased water saturation strengthens the co-current imbibition effect. Compared to injecting for 5 ms, injecting for 10 ms resulted in a 4.53% increase in imbibition recovery during the shut-in stage. The water sweep efficiency increases with the tortuosity of fractures. The wettability differences on either side of the fractures have a certain impact on imbibition. Around the fracture, the recovery in the strongly wetted area is 35% higher than that in the weakly water-wetted area. The wettability difference across fractures causes water to penetrate along the strongly water-wet pores, while only the inlet end and the pores near the fracture in the weakly water-wet zone are affected. Therefore, it is crucial to monitor the injection pressure to maximize the synergistic effects of displacement and imbibition during the development of laminated shale oil reservoirs. Additionally, surfactants should be used judiciously to prevent fingering due to wettability differences. Full article
(This article belongs to the Topic Enhanced Oil Recovery Technologies, 3rd Edition)
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19 pages, 7456 KiB  
Article
Disaster-Causing Mechanism of the Continuous Failure of Deep Foundation Pits in Tropical Water-Rich Sandy Strata
by Ping Lu, Zheng Shao, Jiangang Han and Ying Wang
Appl. Sci. 2025, 15(1), 72; https://doi.org/10.3390/app15010072 - 26 Dec 2024
Viewed by 902
Abstract
To investigate the mechanisms underlying the continuous failure of deep foundation pits in tropical water-rich sandy strata, this study comprehensively examines a foundation pit project in Haikou city, China. Using the PLAXIS3D 24.1 software, a three-dimensional finite element numerical model was developed. [...] Read more.
To investigate the mechanisms underlying the continuous failure of deep foundation pits in tropical water-rich sandy strata, this study comprehensively examines a foundation pit project in Haikou city, China. Using the PLAXIS3D 24.1 software, a three-dimensional finite element numerical model was developed. The analysis integrates design schemes, field investigations, monitoring data, and other relevant information to elucidate the mechanisms of disaster damage, such as foundation pit water inrush, floor collapse, and sidewall failure. The results indicate that the water barrier layer is the thinnest at the elevator shaft foundation pit, with a rapid shortening of seepage paths following the extraction of steel sheet piles; the seepage velocity increases by approximately 120%, leading to groundwater breaching both the water barrier and cushion layers. The inadequate length of the suspended impervious curtain in the confined aquifer results in a maximum seepage velocity at the defect site that is 40 times greater than that at other locations, facilitating groundwater influx into the foundation pit. As the excavation deepens, significant alterations occur in the groundwater seepage field at the defect location in the water-resisting curtain, with the seepage velocity increasing from 6.4 mm/day outside the pit to 78.8 mm/day inside the pit, thereby threatening the stability of the pit foundation. Additionally, construction quality defects arising from the three-axis mixing method in the silty sand layer cause a downward shift in the maximum horizontal displacement of the supporting structure, with displacement increments near the defects reaching 63%. Unreasonable emergency pumping measures can lead to floor collapses and sidewall damage. The soil in the pit significantly affects the back pressure, but it is also affected by the distance, and the increase in seepage velocity in the elevator shaft remains under 1% and does not significantly impact the damaging incident. Full article
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12 pages, 4355 KiB  
Article
Effect of Seepage on Sand Levee Failure Due to Lateral Overtopping
by Woochul Kang, Seongyun Kim and Eunkyung Jang
Water 2024, 16(24), 3617; https://doi.org/10.3390/w16243617 - 16 Dec 2024
Cited by 1 | Viewed by 964
Abstract
Recent increases in rainfall duration and intensity due to climate change have heightened the importance of levee stability. However, previous studies on levee failure, primarily caused by seepage and overtopping, have mostly examined these causes independently owing to their distinct characteristics. In this [...] Read more.
Recent increases in rainfall duration and intensity due to climate change have heightened the importance of levee stability. However, previous studies on levee failure, primarily caused by seepage and overtopping, have mostly examined these causes independently owing to their distinct characteristics. In this study, we conducted lateral overtopping failure experiments under seepage conditions that closely resembled those in experiments conducted in previous studies. Seepage was monitored using water pressure sensors and a distributed optical fiber cable that provided continuous heat for temperature monitoring in the levee. Τhe analysis of levee failure due to lateral overtopping, in the presence of seepage, was conducted using image analysis with digitization techniques and machine learning-based color segmentation techniques on the protected lowland side of the levee, targeting the same area. The results revealed that levee failure occurred more than twice as fast in experiments where seepage conditions were considered compared to the experiments where they were not. Thus, levees weakened by seepage are more vulnerable to overtopping and breaching. Consequently, employing a comprehensive approach that integrates various monitoring and analysis methods for assessing levee stability is preferable to relying on a single method alone. Full article
(This article belongs to the Special Issue Safety Monitoring of Hydraulic Structures)
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