Geofluids最新文献

Water inrush poses a serious threat to the safety and sustainability of coal mining operations, particularly in arid–semiarid regions where confined aquifers overlie coal seams. Therefore, an accurate assessment of roof water inrush risk is essential to prevent water hazards on the roof. In this study, a water abundance assessment model was developed for the Zhuanlongwan mining area (ZMA) to identify zones of varying inrush vulnerability. In the model, five key controlling indicators, that is, the roof-sandstone thickness, fault density, unit inflow, hydraulic conductivity, and lithologic coefficient, were determined with the fuzzy analytic hierarchy process (FAHP) and Random Forest (RF) approaches, and the roof aquifer was subsequently classified by using the natural breaks classification method (Jenks). The model performance was validated through metrics of the overall accuracy (A), Cohen′s κ coefficient, and the area under the receiver operating characteristic curve (AUC). Furthermore, the water inrush effect is also affected by the roof geological properties. By considering the relation between roof water abundance and the residual roof layer thickness influenced by the water-conducting fracture zone (WCFZ), a synthetic water inrush risk assessment system was finally organized, classified into four categories: the water-inrush risk zone, potential leakage zone, relative safe zone, and the safe zone. The results demonstrated a high level of agreement between predicted and observed vulnerability patterns, indicating the robustness of the FAHP-RF approach. This study provides a practical and data-driven framework for evaluating the water abundance of roof aquifers and mitigating water inrush hazards in arid–semiarid confined coal seam mining.

Understanding the groundwater environments for ancient Mars and other terrestrial bodies is of great interest for evaluating their habitability. Here, we experimentally tested simulated aqueous alterations of two Mars simulants (variants of MGS-1) using a continuous-flow packed bed reactor, reacting with three ionic simulated groundwater analog solutions containing MgSO₄, FeSO₄, or LiCl to explore the impact of the aqueous alteration on the minerals. The minerals from these experiments were analyzed via Mars mission–relevant and field-relevant techniques (LIBS, Vis-NIR, and XRF). We demonstrated that the liquid collected from the column outflow and the solid samples were impacted by the alteration. With the MGS-1 standard, we found that sulfate mineral dissolution occurred in all tested experimental conditions; however, in cases with FeSO₄ and MgSO₄, dissolution of gypsum might have been disfavored. In addition, when the simulants were exposed to LiCl solution, Li was easily detectable by LIBS analysis of the residual mineral material. We then contextualize how these results could inform observations by ongoing Mars missions.

In the construction of an F-type cross-passage in an overlapping-type shield tunnel using the artificial ground freezing method, the development of the distal frozen wall is difficult to control, and ground deformation is influenced by the superimposed disturbance of successive construction steps. Existing studies are insufficient to fully characterize the evolution of the frozen temperature field and frozen displacement field. To address this, the F-type cross-passage between Lingbi Road Station and Yaoyuan Road Station of Hefei Metro Line 8 adopted measures such as installing inclined freeze pipes for reinforcement and applying time-sequence construction to control the distal cooling capacity and ground displacement field. Numerical simulation combined with analysis of field test data was conducted to investigate the evolution laws of the frozen temperature field and frozen displacement field in this F-type cross-passage. The results indicate that by installing long inclined freeze pipes on both sides of the main frozen reinforcement zone, the minimum thickness of the frozen wall at the control section (X = −12.03 m) reached 2.51 m after 55 days of active freezing, satisfying the design requirements. At the same time, after 55 days of ground freezing, the soil temperature in the central region of the Y = 0 m section ranged from 2.5°C to −2.5°C. This indicates that the soil was at the critical freezing temperature, which is favorable for the underground excavation of the F-type cross-passage. Regarding ground deformation, during both the freezing reinforcement and excavation stages, a pancake-shaped heave/settlement zone appeared on the surface above the cross-passage, with slight shifts in its center position. The surface displacement field generally showed a decreasing or increasing trend outward from this central position.

This study is aimed at identifying the ultradeep gas reservoir structure and gas-rich areas in the middle section of the southern margin of the Junggar Basin. Based on high-precision microgravity data collected from the complex terrain areas of Huxi and Tudong in the middle section of the southern margin of the Junggar Basin, residual gravity anomalies of deep reservoirs were extracted after numerical conversion and various corrections. Combined with comprehensive geological interpretation, favorable areas for natural gas exploration in the Lower Cretaceous and Upper Jurassic were delineated. The results demonstrate that high-precision microgravity detection offers significant advantages including cost-effectiveness, environmental friendliness, rapid implementation, and the ability to reflect overall planar effects in optimizing gas reservoir targets. The microgravity results show strong consistency with geological features seismic profile characteristics and gas enrichment patterns observed in drilling wells. Continuous and stable low residual gravity anomalies effectively characterize gas traps and enrichment zones. As a geophysical method for oil and gas exploration, microgravity technology can be integrated with seismic methods or applied independently in areas where seismic data acquisition is challenging. This study significantly expands the application of microgravity detection in natural gas exploration marking its first use in the exploration of deep sandstone gas reservoirs at burial depths exceeding 7300 m. Moreover, in complex mountainous terrain where seismic acquisition and processing are difficult, high-precision microgravity detection proves to be an effective technique for gas reservoir exploration.

H. Gong, R. Han, P. Wu, G. Chen, and L. Li, “Constraints of S–Pb–Sr Isotope Compositions and Rb–Sr Isotopic Age on the Origin of the Laoyingqing Noncarbonate-Hosted Pb–Zn Deposit in the Kunyang Group, SW China,” Geofluids 2021, no. 1 (2021): 8844312, https://doi.org/10.1155/2021/8844312.

In the article titled “Constraints of S–Pb–Sr Isotope Compositions and Rb–Sr Isotopic Age on the Origin of the Laoyingqing Noncarbonate-Hosted Pb–Zn Deposit in the Kunyang Group, SW China”, there were errors in multiple statements in the Abstract, 6.4.1. Ore Genesis, and Conclusion sections. These errors are shown below:

- In the abstract,

“We conclude that the Laoyingqing deposit and most of the Pb–Zn deposits in the SYGT are Mississippi Valley-type deposits.”

should have read:

“We conclude that the Laoyingqing deposit in the SYGT is a MVT-like or Huize-style epigenetic hydrothermal Zn–Pb deposit.”

- In Section 6.4.1,

“Many previous studies have suggested that the SYGT carbonate-hosted Pb–Zn deposits belong to the MVT considering their similarities in host rocks, tectonic setting, and ore-forming fluids [2, 7, 24, 85, 122].”

should have read:

“Some previous studies have suggested that the SYGT carbonate-hosted Pb–Zn deposits belong to the MVT considering their similarities in host rocks, tectonic setting, and ore-forming fluids [2, 7, 24, 85, 122]. Han et al. have suggested that these deposits belong to Huize-style or Huize-type [5, 9, 65].”

- In Section 6.4.1,

“Therefore, the origin of the Laoyingqing Pb–Zn deposit is obviously different from the VHMS type, and Sedimentary Exhalative type (SEDEX) Pb–Zn deposits, and most likely belongs to the MVT deposits like most deposits in the SYGT.”

should have read:

“Therefore, the origin of the Laoyingqing Pb–Zn deposit is obviously different from the typical MVT-type and Sedimentary Exhalative (SEDEX) type Pb–Zn deposits, and most likely belongs to MVT-like or Huize-style epigenetic hydrothermal Zn–Pb deposit because of its similarity with most deposits in the SYGT.”

- In the conclusion,

“This deposit and most of the Pb–Zn deposits in the SYGT belong to the MVT deposits.”

should have read:

“This deposit in the SYGT belongs to the MVT-like or Huize-style epigenetic hydrothermal Zn–Pb deposit.”

We apologize for these errors.

S. Ali, M. K. Roy, Md. M. Islam et al., “Textural Characteristics and Depositional Regime of the Shitalakshya River Sediments, Bangladesh”, Geofluids 2024 (2024): 1957253, 10.1155/2024/1957253

In the article titled “Textural Characteristics and Depositional Regime of the Shitalakshya River Sediments, Bangladesh” there was an error in the author affiliation. The correct author “Zillur Rahman” affiliation list is shown below:

Sohag Ali¹, Mrinal Kanti Roy¹, Md. Mahmodul Islam², Zillur Rahman⁴, Faruk Ahmed¹, Abdul Alim¹, Md. Yeasin Arafath³

¹Department of Geology and Mining

University of Rajshahi

Rajshahi 6205, Bangladesh

²Department of Petroleum & Mining Engineering

Chittagong University of Engineering & Technology

Chittagong 4349, Bangladesh

³Department of Geology and Mining

University of Barishal

Barishal 8254, Bangladesh

⁴Wisdom for Welfare Foundation

Dhaka, Bangladesh

We apologize for this error.

With the increasing scale and intensity of coal mining, the subsidence range of the goaf continues to expand, seriously affecting the stability of surface buildings and restricting the ecological environment protection of mining areas. To enrich the discipline system of mining subsidence and improve prediction accuracy, this study clarifies the mechanical relationship between the movement of the primary key stratum and surface subsidence. The method integrates key stratum theory with stochastic medium theory. The coupling prediction method of surface subsidence is constructed, and its reliability is verified by the working face of the Bulianta 31401 measured data. This paper constructs a coupled prediction method for surface subsidence and verifies its reliability through measured data. The results indicate that the coupled method achieves high accuracy, with a mean absolute error of 0.09 m and a mean relative error of 7.58%. The coupling prediction method is superior to the probability integration method. The surface subsidence morphology of the prediction results changes with the breaking and subsidence of the primary key stratum. The coupling prediction method addresses the issues of oversized subcritical mining prediction results and the rapid convergence of subsidence edge prediction results in the probability integration method.

Small-radius curved shield tunnels have gradually become a popular research topic in the field of urban underground space development. This study presents a comprehensive numerical investigation of the construction mechanics of large-diameter shield tunnels in small-radius curved sections based on the Wuhan Lianghu Tunnel project. A three-dimensional finite element model was developed using ABAQUS, featuring dimensions of 160 m (width) × 111 m (length) × 110 m (depth). The dynamic construction process was accurately simulated through sequential modeling of tunnel advancement, segment assembly, and shield tail grouting using the element birth and death technique. The study investigated the influences of the shield tail clearance, construction load, and grouting parameters on the deformation of the tunnel segments and surrounding soil. The results show that surface displacement evolves into a characteristic “V”-shaped deformation pattern with maximum settlement reaching 16.03 mm. Quantitative analysis revealed that reducing shield tail clearance from 115 to 35 mm decreased crown settlement by 46.2%. Furthermore, optimal performance was achieved with hardened grout elastic modulus exceeding 120 MPa, which reduced segment tensile stress by 16.7% compared to the 40 MPa condition. Therefore, the results of this study provide a practical reference for the expanded application of shield tunnel construction technology and parameter design.

This study investigates the critical issue of water-bearing sand layer frozen walls in deep artificial ground freezing (AGF) projects subjected to complex three-dimensional (3D) stress states. The influence of the intermediate principal stress coefficient b (0–1) on the directional shear behavior (enabled by the independent control of the major principal stress direction angle, α) of high-pressure frozen saturated medium sand was systematically examined under controlled conditions (T = −10^°C, mean principal stress p = 4 MPa, major principal stress direction angle α = 30^°), utilizing a self-developed frozen soil hollow cylinder apparatus (FS-HCA). Key findings reveal that (1) the peak generalized shear strength (q_f) exhibits pronounced nonlinear attenuation with increasing b, accurately characterized by the quadratic function q_f = −2.41b2 + 0.38b + 10.31 (MPa) (R² = 0.99). Strength diminishes from 10.31 MPa at b = 0 to 7.90 MPa at b = 1, representing a significant 23.38% reduction relative to the strength at b = 0. This significant strength reduction underscores the risk of overestimating frozen wall capacity in deep AGF projects if the intermediate principal stress effect is neglected. (2) Strain evolution demonstrates fundamental divergence: axial strain (ε_z) transitions from compression (b ≤ 0.5) to tension (b ≥ 0.75), reaching 0.37% tensile strain at b = 1, whereas peak torsional shear strain ($$) attenuates linearly from 17.80% to 7.86% (a 55.8% reduction) governed by $$. (3) Failure modes undergo critical transitions: compressive-torsional composite failure without distinct shear bands (b ≤ 0.25), single primary shear band formation (b = 0.5), and development of primary–secondary conjugate shear bands (b > 0.5). The primary shear band dip angle (β) correlates linearly with b (β = 12.33b + 32 (R² = 0.98)). (4) An extended spatially mobilized plane (SMP) strength criterion, incorporating temperature-dependent ice cementation effects via principal stress translation, is proposed. This novel criterion accurately characterizes the convex triangular failure envelope in the π-plane, demonstrating exceptional predictive accuracy (error < 3%). This research elucidates the mechanistic control of intermediate principal stress on macroscopic strength attenuation and furnishes a robust theoretical framework for the 3D strength design of deep frozen walls.

Gravel packing is a primary method for sand control in hydrocarbon wells, with its effectiveness primarily governed by gravel particle size and packing structure. Current gravel packing designs primarily rely on empirical engineering experience, while rock physics models for quantifying gravel packing permeability remain underdeveloped. This methodological gap hinders the effective design and optimization of gravel packing operations. We develop a pseudo-gravity stacking algorithm to simulate the gravel packing process, constructing gravel packing models with varying particle sizes and packing structures. We employed the pore network model to conduct fluid flow simulations and calculate absolute permeability values of the packing models. Results indicate that permeability values decay exponentially with decreasing particle size. Critical turning points in permeability occur at 10-mesh and 60-mesh particle sizes. Maximum particle size predominantly controls the upper bound of permeability. When the average particle size of the packing layer remains constant, increasing the size distribution range enhances gravel pack permeability. This paper establishes quantitative models correlating gravel particle size with permeability. Based on these findings, we propose optimized design methods for gravel packing sand control applications, providing a theoretical framework for gravel packing sand control engineering.