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Investigation of Groundwater Quality with Borehole Depth in the Basin Granitoids of the Ashanti Region of Ghana
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作者 Bernard Ofosu Augustine Kofi Asante +2 位作者 Festus Anane Mensah Umar-Farouk Usman Naa Korkoi Ayeh 《Journal of Water Resource and Protection》 CAS 2024年第5期381-394,共14页
The dependence of groundwater quality on borehole depth is usually debatable in groundwater studies, especially in complex geological formations where aquifer characteristics vary spatially with depth. This study ther... The dependence of groundwater quality on borehole depth is usually debatable in groundwater studies, especially in complex geological formations where aquifer characteristics vary spatially with depth. This study therefore seeks to investigate the relationship between borehole depth and groundwater quality across the granitoid aquifers within the Birimian Supergroup in the Ashanti Region. Physicochemical analysis records of groundwater quality data were collected from 23 boreholes of public and private institutions in the Ashanti Region of Ghana, and the parametric values of iron, fluoride, total hardness, pH, nitrate, and nitrite were used to study the groundwater quality-depth relationship. The results showed that the depth-to-groundwater quality indicated a marginal increase in water quality in the range of 30 to 50 m, which is mathematically represented by the low-value correlation coefficient (r<sup>2</sup> = 0.026). A relatively significant increase occurs in the depth range of 50 to 80 m, which is given by a correlation coefficient of r<sup>2</sup> = 0.298. The mean percent parameter compatibility was 74%, 82%, 89%, and 97% at 50, 60, 70, and 80 m depths, respectively. The variations in groundwater quality per depth ratio ranged from 1.48, 1.37, 1.27, and 1.21 for 50, 60, 70, and 80 m depth, respectively. The recommended minimum borehole depth for excellent groundwater quality is suggested with a compatibility per meter depth ratio of 1.37. This results in a range between 50 and 70 m as the most desirable drilling depth for excellent groundwater quality within the granitoids of the Birimian Supergroup of the Ashanti Region in Ghana. 展开更多
关键词 Groundwater Quality borehole Depth Birimian Supergroup Granitoid Aquifers Ashanti Region
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Inverting the rock mass P-wave velocity field ahead of deep buried tunnel face while borehole drilling
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作者 Liu Liu Shaojun Li +5 位作者 Minzong Zheng Dong Wang Minghao Chen Junbo Zhou Tingzhou Yan Zhenming Shi 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第5期681-697,共17页
Imaging the wave velocity field surrounding a borehole while drilling is a promising and urgently needed approach for extending the exploration range of the borehole point.This paper develops a drilling process detect... Imaging the wave velocity field surrounding a borehole while drilling is a promising and urgently needed approach for extending the exploration range of the borehole point.This paper develops a drilling process detection(DPD)system consisting of a multifunctional sensor and a pilot geophone installed at the top of the drilling rod,geophones at the tunnel face,a laser rangefinder,and an onsite computer.A weighted adjoint-state first arrival travel time tomography method is used to invert the P-wave velocity field of rock mass while borehole drilling.A field experiment in the ongoing construction of a deep buried tunnel in southwestern China demonstrated the DPD system and the tomography method.Time-frequency analysis of typical borehole drilling detection data shows that the impact drilling source is a pulse-like seismic exploration wavelet.A velocity field of the rock mass in a triangular area defined by the borehole trajectory and geophone receiving line can be obtained.Both the borehole core and optical image validate the inverted P-wave velocity field.A numerical simulation of a checkerboard benchmark model is used to test the tomography method.The rapid convergence of the misfits and consistent agreement between the inverted and observed travel times validate the P-wave velocity imaging. 展开更多
关键词 Deep buried tunnel Wave velocity field borehole drilling Tomography Rock mass
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Fracture geometry and breakdown pressure of radial borehole fracturing in multiple layers
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作者 Yu-Ning Yong Zhao-Quan Guo +3 位作者 Shou-Ceng Tian Lu-Yao Ma Tian-Yu Wang Mao Sheng 《Petroleum Science》 SCIE EI CAS CSCD 2024年第1期430-444,共15页
Radial borehole fracturing that combines radial boreholes with hydraulic fracturing is anticipated to improve the output of tight oil and gas reservoirs.This paper aims to investigate fracture propagation and pressure... Radial borehole fracturing that combines radial boreholes with hydraulic fracturing is anticipated to improve the output of tight oil and gas reservoirs.This paper aims to investigate fracture propagation and pressure characteristics of radial borehole fracturing in multiple layers.A series of laboratory experiments with artificial rock samples(395 mm×395 mm×395 mm)was conducted using a true triaxial fracturing device.Three crucial factors corresponding to the vertical distance of adjacent radial borehole layers(vertical distance),the azimuth and diameter of the radial borehole are examined.Experimental results show that radial borehole fracturing in multiple layers generates diverse fracture geometries.Four types of fractures are identified based on the connectivity between hydraulic fractures and radial boreholes.The vertical distance significantly influences fracture propagation perpendicular to the radial borehole axis.An increase in the vertical distance impedes fracture connection across multiple radial borehole layers and reduces the fracture propagation distance along the radial borehole axis.The azimuth also influences fracture propagation along the radial borehole axis.Increasing the azimuth reduces the guiding ability of radial boreholes,which makes the fracture quickly curve to the maximum horizontal stress direction.The breakdown pressure correlates with diverse fracture geometries observed.When the fractures connect multi-layer radial boreholes,increasing the vertical distance decreases the breakdown pressure.Decreasing the azimuth and increasing the diameter also decrease the breakdown pressure.The extrusion force exists between the adjacent fractures generated in radial boreholes in multiple rows,which plays a crucial role in enhancing the guiding ability of radial boreholes and results in higher breakdown pressure.The research provides valuable theoretical insights for the field application of radial borehole fracturing technology in tight oil and gas reservoirs. 展开更多
关键词 Multi-layer radial boreholes Hydraulic fracturing Fracture propagation Pressure characteristic
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Effects of confining pressure and pore pressure on multipole borehole acoustic field in fluid-saturated porous media
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作者 赵志强 刘金霞 +1 位作者 刘建宇 崔志文 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期468-476,共9页
In-situ stress is a common stress in the exploration and development of oil reservoirs. Therefore, it is of great significance to study the propagation characteristics of borehole acoustic waves in fluid-saturated por... In-situ stress is a common stress in the exploration and development of oil reservoirs. Therefore, it is of great significance to study the propagation characteristics of borehole acoustic waves in fluid-saturated porous media under stress.Based on the acoustoelastic theory of fluid-saturated porous media, the field equation of fluid-saturated porous media under the conditions of confining pressure and pore pressure and the acoustic field formula of multipole source excitation in open hole are given. The influences of pore pressure and confining pressure on guided waves of multipole borehole acoustic field in fluid-saturated porous media are investigated. The numerical results show that the phase velocity and excitation intensity of guided wave increase significantly under the confining pressure. For a given confining pressure, the phase velocity of the guided wave decreases with pore pressure increasing. The excitation intensity of guided wave increases at low frequency and then decreases at high frequency with pore pressure increasing, except for that of Stoneley wave which decreases in the whole frequency range. These results will help us get an insight into the influences of confining pressure and pore pressure on the acoustic field of multipole source in borehole around fluid-saturated porous media. 展开更多
关键词 confining pressure pore pressure fluid-saturated porous media multipole borehole acoustic field
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CO_(2)flooding in shale oil reservoir with radial borehole fracturing for CO_(2)storage and enhanced oil recovery
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作者 Jia-Cheng Dai Tian-Yu Wang +3 位作者 Jin-Tao Weng Kang-Jian Tian Li-Ying Zhu Gen-Sheng Li 《Petroleum Science》 SCIE EI CAS CSCD 2024年第1期519-534,共16页
This study introduces a novel method integrating CO_(2)flooding with radial borehole fracturing for enhanced oil recovery and CO_(2)underground storage,a solution to the limited vertical stimulation reservoir volume i... This study introduces a novel method integrating CO_(2)flooding with radial borehole fracturing for enhanced oil recovery and CO_(2)underground storage,a solution to the limited vertical stimulation reservoir volume in horizontal well fracturing.A numerical model is established to investigate the production rate,reservoir pressure field,and CO_(2)saturation distribution corresponding to changing time of CO_(2)flooding with radial borehole fracturing.A sensitivity analysis on the influence of CO_(2)injection location,layer spacing,pressure difference,borehole number,and hydraulic fractures on oil production and CO_(2)storage is conducted.The CO_(2)flooding process is divided into four stages.Reductions in layer spacing will significantly improve oil production rate and gas storage capacity.However,serious gas channeling can occur when the spacing is lower than 20 m.Increasing the pressure difference between the producer and injector,the borehole number,the hydraulic fracture height,and the fracture width can also increase the oil production rate and gas storage rate.Sensitivity analysis shows that layer spacing and fracture height greatly influence gas storage and oil production.Research outcomes are expected to provide a theoretical basis for the efficient development of shale oil reservoirs in the vertical direction. 展开更多
关键词 Shale oil Radial borehole fracturing Embedded discrete fracture model Enhanced oil recovery Carbon storage
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Borehole stability in naturally fractured rocks with drilling mud intrusion and associated fracture strength weakening:A coupled DFN-DEM approach
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作者 Yaoran Wei Yongcun Feng +4 位作者 Zhenlai Tan Tianyu Yang Xiaorong Li Zhiyue Dai Jingen Deng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第5期1565-1581,共17页
Borehole instability in naturally fractured rocks poses significant challenges to drilling.Drilling mud invades the surrounding formations through natural fractures under the difference between the wellbore pressure(P... Borehole instability in naturally fractured rocks poses significant challenges to drilling.Drilling mud invades the surrounding formations through natural fractures under the difference between the wellbore pressure(P w)and pore pressure(P p)during drilling,which may cause wellbore instability.However,the weakening of fracture strength due to mud intrusion is not considered in most existing borehole stability analyses,which may yield significant errors and misleading predictions.In addition,only limited factors were analyzed,and the fracture distribution was oversimplified.In this paper,the impacts of mud intrusion and associated fracture strength weakening on borehole stability in fractured rocks under both isotropic and anisotropic stress states are investigated using a coupled DEM(distinct element method)and DFN(discrete fracture network)method.It provides estimates of the effect of fracture strength weakening,wellbore pressure,in situ stresses,and sealing efficiency on borehole stability.The results show that mud intrusion and weakening of fracture strength can damage the borehole.This is demonstrated by the large displacement around the borehole,shear displacement on natural fractures,and the generation of fracture at shear limit.Mud intrusion reduces the shear strength of the fracture surface and leads to shear failure,which explains that the increase in mud weight may worsen borehole stability during overbalanced drilling in fractured formations.A higher in situ stress anisotropy exerts a significant influence on the mechanism of shear failure distribution around the wellbore.Moreover,the effect of sealing natural fractures on maintaining borehole stability is verified in this study,and the increase in sealing efficiency reduces the radial invasion distance of drilling mud.This study provides a directly quantitative prediction method of borehole instability in naturally fractured formations,which can consider the discrete fracture network,mud intrusion,and associated weakening of fracture strength.The information provided by the numerical approach(e.g.displacement around the borehole,shear displacement on fracture,and fracture at shear limit)is helpful for managing wellbore stability and designing wellbore-strengthening operations. 展开更多
关键词 borehole stability Naturally fractured rocks Weakening of fracture strength Discrete fracture network Distinct element method
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Impact of elliptical boreholes on in situ stress estimation from leak-off test data 被引量:2
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作者 Hong Xue Han Shunde Yin Bernt Sigve Aadnoy 《Petroleum Science》 SCIE CAS CSCD 2018年第4期794-800,共7页
We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-... We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-off test data were used to construct a mathematical model, which was in turn applied to finding the inverse of an overdetermined system of equations.The method has been demonstrated by a case study in the Appalachian Basin, USA. The calculated horizontal stresses are in reasonable agreement with the reported regional stress study of the area, although there are no field measurement data of the studied well for direct calibration. The results also indicate that 2% of axis difference in the elliptical borehole geometry can cause a 5% difference in minimum horizontal stress calculation and a 10% difference in maximum horizontal stress calculation. 展开更多
关键词 INVERSION Leak-off test data Elliptical borehole In situ stress
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STABILITY OF BOREHOLES IN A GEOLOGIC MEDIUM INCLUDING THE EFFECTS OF ANISOTROPY 被引量:2
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作者 Dinesh Gupta, Musharraf Zaman (School of Civil Engineering and Environmental Science, University of Oklahoma, Norman, OK 73019, U S A) (Communicated by Chien Weizang) 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1999年第8期16-45,共21页
An analytical formulation is developed to investigate the stability of a deep, inclined borehole drilled in a geologic medium and subjected to an internal pressure and a non_hydrostatic stress field. The formulation c... An analytical formulation is developed to investigate the stability of a deep, inclined borehole drilled in a geologic medium and subjected to an internal pressure and a non_hydrostatic stress field. The formulation consists of a three_dimensional (3_D) analysis of stresses around a borehole, combined with internal pressurization of the borehole to obtain an approximate solution of the overall stress distribution. The orientation of the borehole, the in_situ stresses and bedding plane can all be arbitrarily related to each other to represent the actual field situations. Both tensile failure and shear failure potentials of a borehole are investigated. The failure criteria applied assume that when the least principal stress exceeds the strength of the formation in tension, a tensile failure occurs. Shear failure is represented using the modified Drucker_Prager failure criterion for anisotropic materials. A parametric study is carried out to assess the effect of material anisotropy, bedding plane inclination and in_situ stress conditions on borehole stability. Results of the parametric study indicate that wellbore stability is significantly influenced by a high borehole inclination, high degree of material anisotropy, in_situ stress conditions and high formation bedding plane inclination. The stability of a borehole in an elasto_plastic medium is also investigated. In order to evaluate the extent of the plastic zone around a borehole and the effect of anisotropy of the material on this plastic zone, a mathematical formulation is developed using theories of elasticity and plasticity. The borehole is assumed to be vertical, subjected to hydrostatic stresses, and drilled in a transversely isotropic geologic medium. A parametric study is carried out to investigate the effect of material anisotropy on the plastic behavior of the geologic medium. Results indicate that the stress distribution around a borehole, the extent of the plastic zone, and the failure pressure are influenced by the degree of material anisotropy and value of in_situ overburden stresses. It was observed that the borehole becomes less stable as the degree of anisotropy of the geologic medium increases. 展开更多
关键词 stability of borehole tensile failure shear failure failure criteria stress distribution
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Inversion of breakout data from inclined boreholes for stress state of the upper crust in Jizhong depression 被引量:1
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作者 俞言祥 许忠淮 《Acta Seismologica Sinica(English Edition)》 CSCD 1996年第2期317-325,共9页
The forward and inverse problems of studying crustal stress state from breakout data of inclined boreholes are concisely stated. direction of the maximum horizontal principal stress (compressive) and relative magnitud... The forward and inverse problems of studying crustal stress state from breakout data of inclined boreholes are concisely stated. direction of the maximum horizontal principal stress (compressive) and relative magnitudes of the horizontal stresses to the vertical stress in the upper crust in two regions of the Jizhong depression, the North of China, are obtained by analyzing the breakout data of 6 inclined wells. To get stable results in the analysis wesearched for the unknown parameters both forwardly and inversely. The results show that the maximum azimuths of the horizontal Principal compressive stresses in the central and southern part of the Jizhong depressionare N86°E and N77°E, respeCtively, while the relative magnitudes of the three principal stresses in the uppercrust (about 1000-4000 m) of the depression are variable. In the centra; part of the Jizhong depression we havefound SH : Sv: SK= 1. 38: 1. 00: 0. 57, where SH, SV and Sh are the maximum horizontal, vertical and minimum horizontal stress, resistively. This indicates that the present stress regime in this area is of strike-slipfaulting type. In the southern part of the depreSSion we have obtained SH: Sv: Sh=0. 80: 1. 00 1 0. 62, indicating a normal faulting stress regime in the shallow Part Of the crust. 展开更多
关键词 BREAKOUT stress state Jizhong depression inclined borehole.
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Influence of combination forms of intact sub-layer and tectonically deformed sub-layer of coal on the gas drainage performance of boreholes: a numerical study 被引量:3
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作者 Wei Zhao Kai Wang +3 位作者 Rong Zhang Huzi Dong Zhen Lou Fenghua An 《International Journal of Coal Science & Technology》 EI 2020年第3期571-580,共10页
High concentration and large flow flux of gas drainage from underground coal seams is the precondition of reducing emission and large-scale use of gas.However,the layered occurrence of coal seams with tectonically def... High concentration and large flow flux of gas drainage from underground coal seams is the precondition of reducing emission and large-scale use of gas.However,the layered occurrence of coal seams with tectonically deformed sub-layers and intact sub-layers makes it difficult to effectively drain gas through commonly designed boreholes.In this study,the gas drainage performance in coal seams with different combinations of tectonically deformed sub-layers and intact sub-layers was numerically analyzed.The analysis results show that the gas drainage curve changes from a single-stage line to a dual-stage curve as the permeability ratios of Zone II(kII)and Zone I(kI)increase,raising the difficulty in gas drainage.Furthermore,a dual-system pressure decay model based on the first-order kinetic model was developed to describe the dual-stage characteristics of pressure decay curves with different permeability ratios.In the end,the simulation results were verified with reference to in-situ drainage data from literature.The research results are helpful for mines,especially those with layered coal seams comprising tectonically deformed sub-layers and intact sub-layers,to choose appropriate gas drainage methods and develop the original drainage designs for achieving better gas drainage performance. 展开更多
关键词 Tectonically deformed coal Pressure decay Permeability Hydraulic flushing boreholes
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Antimicrobial Resistance Profile of Bacteria Isolated from Boreholes and Hand Dug Wells Water in Ngaoundere Municipality of Adamawa Region in Cameroon 被引量:1
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作者 Bernard Viban Tangwa Horline Keubou +1 位作者 Emmanuel N. Nfor Albert Ngakou 《Advances in Microbiology》 2019年第7期629-645,共17页
Uncontrolled uses of antibiotics have led to rapid evolution of antibiotic-resistance bacteria and antibiotic resistance gene transfer, especially in a pool of aquatic system where resistance, intermediate and suscept... Uncontrolled uses of antibiotics have led to rapid evolution of antibiotic-resistance bacteria and antibiotic resistance gene transfer, especially in a pool of aquatic system where resistance, intermediate and susceptible bacteria to some antibiotics strive together. Consequently, there is a transfer of resistance genes. In this study, bacteria of the Enterobacteriaceae family and some gram positive bacteria isolated from some boreholes and hand dug wells water of public use were tested on 19 antibiotics of different classes. This was achieved through a disk diffusion technique to determine the antimicrobial resistance profile of the said bacteria, microbial resistance index of the drugs used (and their ability to produce Beta-lactamase). These isolates were shown to demonstrate a very high resistance to the drugs used in the area. The resistance was highest in Escherichia coli 1 (73.68%) and lowest in Streptococcus pneumoniae (47.82%). These isolates also indicated very high levels of multi-drug resistance. The minimum resistance index was 0.47, indicating that bacteria isolates were of fecal origin. It is evident from the present study that multiple antibiotic-resistant bacteria can thrive in water as an environmental reservoir, and can therefore provide a route to multidrug-resistant pathogens to enter human and animal population. 展开更多
关键词 boreholes WELLS Drug RESISTANCE BACTERIA MICROBIAL RESISTANCE Index
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Method for designing the optimal sealing depth in methane drainage boreholes to realize efficient drainage 被引量:1
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作者 Minghao Yi Liang Wang +2 位作者 Congmeng Hao Qingquan Liu Zhenyang Wang 《International Journal of Coal Science & Technology》 EI CAS CSCD 2021年第6期1400-1410,共11页
The purpose of underground methane drainage technology is to prevent methane disasters and enable the efficient use of coal mine methane(CMM),and the sealing depth is a key factor that affects the performance of under... The purpose of underground methane drainage technology is to prevent methane disasters and enable the efficient use of coal mine methane(CMM),and the sealing depth is a key factor that affects the performance of underground methane drainage.In this work,the layouts of in-seam and crossing boreholes are considered to analyze the stress distribution and failure characteristics of roadway surrounding rock through a numerical simulation and field stress investigation to determine a reasonable sealing depth.The results show that the depths of the plastic and elastic zones in two experimental coal mines are 16 and 20 m respectively.Borehole sealing minimizes the air leakage through the fractures around the roadway when the sealing material covers the failure and plastic zones,and the field test results for CMM drainage at different sealing depths indicate that the CMM drainage efficiency increases with increasing sealing depth but does not change once the sealing depth exceeds the plastic zone.Moreover,sealing in the high-permeability roadway surrounding rock does not have a strong influence on the borehole sealing performance.Considering these findings,a new CMM drainage system for key sealing in the low-permeability zone was developed that is effective for improving the CMM drainage efficiency and prolonging the high-concentration CMM drainage period.The proposed approach offers a valuable quantitative analysis method for selecting the optimum sealing parameters for underground methane drainage,thereby improving considerably the drainage and utilization rates of CMM. 展开更多
关键词 Coal mine methane Methane drainage borehole sealing Mining safety Methane utilization
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Thermo-hydro-mechanical coupled mathematical model for controlling the pre-mining coal seam gas extraction with slotted boreholes 被引量:11
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作者 Xue Yi Gao Feng +3 位作者 Gao Yanan Liang Xin Zhang Zhizhen Xing Yan 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第3期473-479,共7页
Drainage influence radius is the basic parameter for borehole arrangement, while the effect of high pressure water jet slotting technology on borehole drainage influence radius has not been studied systematically. In ... Drainage influence radius is the basic parameter for borehole arrangement, while the effect of high pressure water jet slotting technology on borehole drainage influence radius has not been studied systematically. In this paper, a fully thermo-hydro-mechanical(THM) coupled model which represents the non-linear responses of gas extraction was implemented to demonstrate the reliability of this model through history data matching. Based on this model, the susceptibilities of gas extraction with single slotted borehole, including the permeability, the gas pressure, the temperature, the coal adsorption characteristics and the radius of slot, were quantified through a series of simulations. The simulation results revealed that increasing the permeability, initial gas pressure and temperature could develop the influence radius of single slotted borehole. This finite element model and its simulation results can improve the understanding of the coal-gas interactions of underground gas drainage and provide a scientific basis for the optimization of drainage systems. 展开更多
关键词 耦合数学模型 排水系统 煤层气开采 预钻孔 影响半径 控制 瓦斯压力 仿真结果
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Optimization of gob ventilation boreholes design in longwall mining 被引量:1
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作者 Saqib Ahmad Saki Jürgen F.Brune Muhammad Usman Khan 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2020年第6期811-817,共7页
Gob ventilation boreholes(GVBs)are widely used for degasification in U.S.longwall coal mines.Depending on geological conditions,30–50%of methane can be recovered from longwall gob using GVBs.A NIOSH funded research a... Gob ventilation boreholes(GVBs)are widely used for degasification in U.S.longwall coal mines.Depending on geological conditions,30–50%of methane can be recovered from longwall gob using GVBs.A NIOSH funded research at the Colorado School of Mines confirmed that GVBs can efficiently reduce methane at the face.However,GVBs can also draw some fresh air from the face and create explosive gas zones(EGZs).Explosive gas mixtures may be formed in gob areas due to the increased ingress of oxygen from GVBs.It is critical to identify the locations for GVBs for maximizing extraction of methane and minimizing hazards of explosion.This study analyzes the effect of operating parameters and design of GVB on methane extraction,EGZs formation,and face and tailgate methane concentrations.Methane extraction,formation of EGZs,and concentration of methane in working areas are significantly impacted by various factors.These factors include the distance of work face and tailgate from GVBs,diameter of GVBs,vacuum pressure of wellhead,GVB distance from the roof of the coal seam,and number of operating GVBs in a panel.Computational fluid dynamics(CFD)evaluations suggest optimal design and operating parameters of GVBs that can contribute to maximum benefits with minimum risks. 展开更多
关键词 Longwall mining Explosive gas zones Computational fluid dynamics Gob ventilation boreholes
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Safety analysis of stability of surface gas drainage boreholes above goaf areas 被引量:12
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作者 刘玉洲 李晓红 《Journal of Coal Science & Engineering(China)》 2007年第2期149-153,共5页
关键词 采空区 地面钻井 瓦斯抽采技术 井筒稳定性分析 煤矿安全
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Water Analysis for Heavy Metals Content in Selected Boreholes in Port Harcourt Metropolis (A Case Study during 2010-2011) 被引量:1
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作者 Kalagbor Ihesinachi Appolonia Mgbodom-Okah Chidinma Juliet 《Journal of Environmental Science and Engineering(A)》 2013年第7期418-426,共9页
关键词 重金属含量 水质分析 钻孔 大都会 安全饮用水 案例 地球化学过程 污染物质
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THEORETICAL AND EXPERIMENTAL STUDIES ON FRACTURE PLANE CONTROL BLAST WITH NOTCHED BOREHOLES
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作者 Dexin, Ding 《中国有色金属学会会刊:英文版》 EI CSCD 1999年第1期190-193,共4页
1INTRODUCTIONDuringrecentyears,quiteafewinvestigatorshaveworkedonfractureplanecontrolblastwithnotchedboreho... 1INTRODUCTIONDuringrecentyears,quiteafewinvestigatorshaveworkedonfractureplanecontrolblastwithnotchedboreholes.Succesfulappl... 展开更多
关键词 FRACTURE PLANE CONTROL BLAST notched boreholE FRACTURE mechanics
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Feasibility Study of Boreholes Hand Drilling in Senegal—Identification of Potentially Favorable Areas
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作者 Cheikh Hamidou Kane Fabio Fussi +1 位作者 Moustapha Diène Déthie Sarr 《Journal of Water Resource and Protection》 2013年第12期1219-1226,共8页
Drilling techniques commonly used in Africa are rather well suited for areas where geologic formations are hard and groundwater is not located at higher depths. Thus, for a large number of people living in rural areas... Drilling techniques commonly used in Africa are rather well suited for areas where geologic formations are hard and groundwater is not located at higher depths. Thus, for a large number of people living in rural areas, access to improved drinking water sources is often limited, due to the high cost of drilled boreholes that is closely linked to geographical, geological and hydrogeological factors. The analysis of various contexts has revealed that, in order to improve access to safe drinking water for underserved communities and populations, it is possible to consider less costly alternative solutions, compared to current options for water supply which are still expensive. In this paper, a simplified drilling technology at a very low cost has been demonstrated: “the manual or hand drilling”, which is a practical solution for less than 40-m deep water points in alluvial terrains or low resistance rock formations. The feasibility study of manual drilling in Senegal has revealed that, even if it is not practical in all geological formations of the country, manual drilling remains an alternative solution for reducing costs and improving accessibility to drinking water in several areas in Senegal, particularly in the Senegal River Valley, along the northern coast, in Fatick and Casamance coastal zones. This study was used to set up map of areas suitable for manual drilling boreholes;it aims to strengthen the local private sector capacity to meet growing drinking water needs in rural areas. 展开更多
关键词 MANUAL DRILLING ROCK Resistance boreholes DEPTH
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Perimeters of Protection Demarcation for New Boreholes of Bonoua Aquifer (Southeastern, Côte d’Ivoire) through Hydrogeological Modeling
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作者 Kouamé Kan Jean Aké Gabriel Etienne +2 位作者 Koblan Armel Kouadio Djé Kouakou Bernard Jourda Jean Patrice 《Journal of Geoscience and Environment Protection》 2017年第11期118-138,共21页
Located in the southeastern of C&#244te d’Ivoire, Bonoua aquifer contains an enormous groundwater potential. The new boreholes have been realized in this region to support the water supply of the populations. Mor... Located in the southeastern of C&#244te d’Ivoire, Bonoua aquifer contains an enormous groundwater potential. The new boreholes have been realized in this region to support the water supply of the populations. Moreover, in this region, agriculture is the main activity, whose pesticides used to guarantee the productivity, constitute a threat for groundwater. Thus, this study was undertaken in order to design a hydrogeological model able to simulate the piezometry of the Bonoua aquifer and determine the perimeters of protection for the new boreholes. The model, carried out under the Visual Modflow interface, was designed in steady-state mode and calibrated manually from the piezometry of the year 2000. The value of the standardized root mean squared residual of 4.86% (<10%) allows to say that the calibration obtained is considered satisfactory. Also, the correlation coefficient between observed and simulated heads of 0.95 permits to confirm a good calibration of the model. Perimeters of protection values were determined by simulating the paths of the virtual particles of water from the calibrated model. The simulations show that generally, the groundwater of Bonoua aquifer flows from north to south and the piezometric levels obtained vary between 65 m in the north and 5 m in the south. Upstream radius of the closed perimeters of protection calculated from the model varies from 172 to 482 m. However, those of distant perimeters of protection vary from 2877 to 6441 m. 展开更多
关键词 boreholes Hydrogeological Modeling Perimeters of PROTECTION Visual MODFLOW Bonoua AQUIFER
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Selected Trace Elements in Domestic Water Boreholes and Their Implications on Human Health, in Huruma Estate, Eldoret Municipality, Uasin-Gishu County, Kenya
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作者 Taratisio Ndwiga 《Journal of Environmental Protection》 2014年第1期65-70,共6页
Trace elements constitute less than 1% of the rocks in the crust (Stumm and Morgan, 1991). In the human body, they constitute less than 100 mg/kg (0.01%). These elements are released to the environment naturally by we... Trace elements constitute less than 1% of the rocks in the crust (Stumm and Morgan, 1991). In the human body, they constitute less than 100 mg/kg (0.01%). These elements are released to the environment naturally by weathering and volcanic activities (Flint and skinner, 1997). It has been observed that trace elements are greatly absorbed and retained in the body when in liquid diet. This phenomenon also influences the risk to human health, especially of infants and children whose immature digestive system further promote absorption of toxic heavy metals. The study was based on the analysis of domestic borehole water supplies in Huruma estate of Eldoret Municipality for selected trace elements and their implications on human health. The boreholes were systematically selected for sampling points and trace elements, Cr, Cu and Se analyzed using AAS. Statistical analysis for mean, standard deviation and confidence interval limits was done using SPSS. The statistical t-test was used to test for significance differences at (p = 0.05). The graphs were drawn using the Microsoft Excel package. The resulting data obtained from analysis were compared with WHO data for drinking water. In the study, the mean values of the following parameters were as follows: Chromium 17.9 μg/L, Copper 563 μg/L and Selenium 22.7 μg/L. There was a significant difference at 5% level of significance (p = 0.000) in all the parameter values among the sampling points in Huruma estate. The above mean values were far below the WHO recommended limits for drinking water. It was concluded that the borehole water from Huruma was fit for drinking and therefore could not cause cancer and cardiovascular diseases. However, borehole water should be used if other water sources (tap water etc.) were not available. All the industries near Huruma estate should carefully analyze and regularly monitor their liquid waste effluents to ensure that no harmful discharges get into the soil. 展开更多
关键词 Trace Elements Human Health Chronic Exposure boreholE Non-Communicable Disease
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