Earth Sciences Commons^™

Performance Test And Proportioning Optimization Of Loess-Based Grouting Materials In Coal Mining Subsidence Area Of Northern Shaanxi, Cao Xiaoyi, Wang Yutao, Liu Xiaoping, Cao Zubao, Wu Boqiang

Coal Geology & Exploration

Grouting is the main treatment method of mining subsidence area, and the grouting materials have great influence on the grouting effect and cost. Taking the grout mix composed of loess and cement used in northern Shaanxi as the research object, the viscosity, the gelation time, the stone rate and 28 d uniaxial unconfined compressive strength of loess grout were studied by single factor and orthogonal tests. The influencing factors and changing rule of each index were analyzed. Meanwhile, the GA-BPNN prediction model of loess-based grout was established, and the multi-objective global optimization was carried out through GA. The grout ratio …

Exploration And Quantitative Evaluation Of Overburden Strata “Three Zones” In Deep Strip Mining, Liu Zhen, Wang Yutao, Liu Xiaoping, Wang Xiaodong

Coal Geology & Exploration

In order to study the height of overburden fractures in deep strip mining, engineering geological drilling, borehole television and coalfield well logging have been applied to detect and analyze the overburden fractures in a coal mine in Jining coalfield. The results indicate that, under the strip mining with gentle dip(6°), deep depth(538 m) and 1:2 mining-retention ratio(mining -50 m and remaining -100 m), the “three zones” develop prominently, presenting “wavy” destruction in space, and the goaf has no obvious cavity. The height of caving zone is 8.45 m which is 3.0 times of the mining height, and the fault zone …

Stacking Angle Of Slurry-Aeolian Sand Dual-Phase Medium Filling Material, Bai Zhongrong

Coal Geology & Exploration

Stacking angle is an important parameter to describe the spatial accumulation pattern of filling material in the goaf. It has important guiding significance for determining the drilling distance, optimizing the slurry configuration and adjusting the grouting process parameters. In order to grasp the variation law of stacking angle of slurry-aeolian sand dual-phase medium filling material, using self-flow stacking model experiment of tailings and rheological properties experiment, the mixing ratio of aeolian sand was taken as a variable to determine the slurry accumulation parameters and rheological parameters on different conditions of sand ratio. Based on this, Sofra & Boger formula was …

The Structural Characteristics And Their Influence On Production Of Buliangou Coal Mine, Ma Liang, Guo Rui

Coal Geology & Exploration

Jungar coalfield is located at the turning point of Yimeng uplift and Jinxi flexure belt in Ordos basin. There are many kinds of mine structures in the coalfield, and the structural complexity has changed greatly before and after the exposure by mine production. Taking the fold, fault, karst collapse column, igneous rock intrusion and other geological structures exposed by geological exploration and mining as the research object, quantitative or semi-quantitative evaluation of structural development characteristics in the mine was carried out by means of mathematical statistics, and the formation mechanism, evolution background of different geological structures were analyzed. The main …

Physical Simutation Experiment Investigation On Hydraulic Fracture Propagation In High-Dip Coal Seam, Jiang Wei, Zhang Jun, Zhong Jie, Zhao Chen, Tang Zhuyun, Lu Haibing, Yi Xinbin, Wang Hai

Coal Geology & Exploration

In order to study the hydraulic fracture geometry in high-dip coal seam, a large-scale true triaxial fracturing simulation system was used to carry out physical simulation experiments, and the hydraulic fracture geometry of the maximum horizontal principal stress along the strike direction and along the dip direction-in 60° dip coal seam were investigated respectively. Experimental results of the maximum principal stress direction along the strike direction show that: hydraulic fracture initiation is easily; fracture height is limited in the whole time; fracture connectivity is good; fracture propagates mainly along bedding and natural fracture, vertical fracture is formed; the influence of …

Practice And Understanding Of Multi-Layer Drainage Of Cbm Wells In Liupanshui Area, Liu Jiang, Sang Shuxun, Zhou Xiaozhi, Bi Caiqin, Jin Jun, Shan Yansheng

Coal Geology & Exploration

To improve the effect of drainage and extraction of coalbed methane wells, it is necessary to divide the drainage and production stages reasonably and formulate corresponding control measures. Based on the previous exploration and trial production of coalbed methane in Liupanshui area, this paper analyzed the geological characteristics of coalbed methane and the development characteristics of coal reservoirs in the area, and studied the drainage effect of the combined layers of two wells comparatively. The research shows that the area has several basic characteristics, including many coal seams, thin single-layer thickness, high gas content, high reservoir pressure, low coal seam …

Application Of Time Series Model In Water Inflow Prediction Of Working Face, Shi Longqin, Wang Yaru, Qiu Mei, Gao Weifu

Coal Geology & Exploration

In practical production of mines, the prediction of mine water inflow is of great significance for mine water prevention and control. Taking working face 1301 of Yuncheng coal mine as the research object, and without considering the influence of seasonal factors, ARIMA-the time series analysis model-is used to establish the functional relationship between mine water inflow and time, which proves that the time series of water inflow in working face 1301 of Yuncheng coal mine is affected by seasonal factors. Then, based on the principle of addition and decomposition of time series, the long-term trend, seasonal indexes, circulating factors and …

Experiment Of Mesostructure And Hydrologic Characteristics Of Weakly Cemented Soft Rocks In Western China, Zhang Jiafan, Cheng Shufan, Wang Huan, Gao Zhuang, Zhou Feiwen, Zhou Hongwen

Coal Geology & Exploration

In order to accurately grasp the hydrologic characteristics of weakly cemented soft rocks in western China, the hydraulic and mechanical properties of red sandstone collected from northern Shaanxi mining area were tested. Based on the scanning image of scanning electron microscope(SEM), the mesostructural characteristics of the rocks were analyzed, and the relationship between the mesostructure of rocks and its macroscopic hydrologic characteristics was established. The results show that red sandstone has obvious characteristics of water saturation and water absorption and expansion, and its softening coefficient is 0.64. Under the action of pressure water erosion and dry and wet cycle, the …

Acoustic Emission Characteristics And Damage Evolution Of Coal-Rock Under Different Confining Pressures, Yu Jie, Liu Xiaohui, Hao Qijun

Coal Geology & Exploration

Using PCI-2 acoustic emission(AE) system, the AE experiments of different confining pressures (0, 8, 16, 5 MPa) were carried out in Baijiao coal mine in Furong, Sichuan Province, in order to reveal the change rule of ringing count rate, the temporal and spatial distribution of AE, b value of AE and damage characteristics of damaged coal-rock under different confining pressures, and to provide a theoretical basis for prediction of coal-rock damage. The results show that the AE phenomenon can reflect the crack propagation of coal-rock and the confining pressure can restrain the damage of coal-rock. With the increase of confining …

Test Of Mechanical Properties Of Limestone Under Hydraulic Pressure-Stress Coupling, Tian Shukun

Coal Geology & Exploration

To study the mechanical properties of limestone with water-rich saturated circumstance under water pressure-stress coupling, compression failure tests of limestone samples with different water pressure were carried out by using a self-developed permeability test device, the device can realize uniaxial compression test. Then, the stress-strain characteristics of limestone, the effect of hydraulic pressure on uniaxial compressive strength, the elastic modulus and the deformation modulus, and the correlation between breaking characteristics and hydraulic pressure were tested. The results show that the increased hydraulic pressure has a significant influence on the stress-strain curve and strength characteristics. With the increase of hydraulic strength, …

Influence Factors And Formation Properties Of Temperature Field In The Frozen Wall Of Double Ring Pipes, Li Huaixin, Lin Bin, Wang Peng

Coal Geology & Exploration

In order to research the change law of the temperature field of the frozen wall of double-circle pipes, an auxiliary shaft in Huainan coalmine was taken as the research object, the FLAC^3D software was used to numerically simulate the formation process of the temperature field of the frozen wall of double-circle pipes and the influence of different factors on average temperature of frozen wall based on the relevant geological parameters. The research results show that temperature of the soil in the double-circle pipes is the lowest, and temperature on both sides increases gradually, the interval between frozen holes is …

Detection Technique And Application Of Transmission In-Seam Wave In Thin Coal Seam, Yang Hui

Coal Geology & Exploration

Aiming at the problem of serious attenuation of channel wave in thin seam and its limited distance of propagation, a method of restricted CT imaging was proposed by using the furthest in-seam wave propagation distance. Firstly, the variation of in-seam wave frequency with different thickness of coal seam was studied by theoretical derivation. Taking a 1.5m thin seam as the main research object, the attenuation characteristics of channel wave were simulated by forward modeling, and the effective propagation distance of channel wave was determined. The actual data of No. 15 coal seam in a coal mine in Shandong Province shows …

Common Midpoint Gather Constraint-Based Impedance Inversion Of Ground Penetrating Radar, Dai Qianwei, Ning Xiaobin, Zhang Bin

Coal Geology & Exploration

GPR impedance inversion is an effective method to obtain accurately the intrinsic parameters of the subsurface medium. This method relies on low frequency information provided by logging data, but it is rarely accompanied by drilling in practical applications. To solve the problem, the common midpoint velocity analysis is employed to provide more low frequency component information for impedance inversion of GPR to finely reconstruct the dielectric parameter of subsurface in the framework of velocity-constrained inversion technique. Firstly, a layer model is specifically set up as an example to verify the feasibility of the developed velocity- constrained inversion to regulate the …

Developing And Implementing A 100% Renewable Electricity Resolution: A Research-Based Framework, Emily E. Skill, Roslynn Brain Mccann, Sarah C. Klain

All Current Publications

While it may seem that the efforts of local governments have only a marginal impact on the global issue of climate change, local action can spread to generate large-scale change. Local action can inspire other communities to adopt policies, creating the potential to expand and form regional action on climate change. Furthermore, local policies can influence state and federal policies. This guide will walk you through a five-step framework that was developed from the results of a qualitative research study that explored how three Utah cities, Salt Lake City, Park City, and Moab, successfully adopted 100% renewable electricity resolutions.

Chemostratigraphy Of Carbonate Gravity Flows Of The Wolfcamp Formation In Crockett County, Midland Basin, Texas, Alex Blizzard, Julie Bloxson

Electronic Theses and Dissertations

Sediment gravity flows into deep-water environments are important stratigraphic traps in lithologically diverse reservoirs generating multiple plays for hydrocarbon exploration. These highly heterogeneous deposits can be studied by utilizing chemostratigraphy and higher-order sequence stratigraphy; being an accurate method for reservoir characterization. Studying these gravity flows along a carbonate platform’s slope can further expand an understanding of the stratigraphy that is filling adjacent basins. The application of elemental analyses can support in identifying mineralogy that impact reservoir quality, especially when conventional testing cannot be applied.

This study utilizes five cores containing the Wolfcamp Formation from the southeastern slope of the Central …

A Geochemical Perspective On The Hydrocarbon Compositional Variation Within East Malay Basin: Implication For Oil Exploration, Mohd Sharef Nurfadhila

Student Works (2020-2029)

Malay Basin is a prospective basin which perceived to be matured basin in terms of hydrocarbon generating potential. Many significant oil discoveries made since 1970’s includes Seligi, Pulai, Tapis and Bekok oil fields. These fields have been producing until now. Despite its matured stage, there are still more oil discoveries in various parts of Malay Basin until now. Oil discoveries include light and high density oils with various challenges in oil development project. This dissertation focuses on oil fields in East Malay Basin particularly Lerek, Chermingat, Lawang and Serudon oil fields. The objectives of this research are to study the …

Key Technology For Rapidly Drilling Large Diameter Destressing-Drillhole In Rockburst Coal Seam, Wei Hongchao, Wang Yi, Wang Bo

Coal Geology & Exploration

In order to improve the hole forming rate and construction efficiency of large diameter destressing-drillhole in rockburst mine, based on the analysis of the stress characteristics of coal rock in rockburst coal mine, the dynamic instability characteristics of destressing-drillhole and the construction features, the key points for drilling large diameter destressing-drillhole, the efficient discharge of cuttings and fast drilling/lifting were proposed. Combining with the discharge of cuttings method by dual-power, the technology and equipment for rapidly drilling large diameter destressing-drillhole in rockburst coal seam were formed finally after the design and optimization of key equipment, drilling tools, technology and drilling …

Foam Drilling Technology And Application For Broken Soft Coal Seam In Underground Coal Mine, Ji Qianhui, Dong Mengmeng, Liu Jianlin, Shi Lei

Coal Geology & Exploration

Aiming at the limitation of middle pressure air drilling for gas drainage in soft and broken coal seam, such as limited drill cutting removal capacity, and dust pollution, foam drilling technique research in underground coal mines was carried out. CFD simulation of the flow field during the drilling process was conducted to obtain the optimized drilling tool structure parameters for efficient drill cutting transportation. Optimal structural parameters of wide-blade milled auger drill rod with the number of heads 3, the groove width 26 mm, and the pitch 110 mm were determined. A foam perfusion system suitable for underground coal mining …

Distribution And Resource Prospect Of Metal Ore Spots(Deposits) In Coal Of Different Coal-Forming Ages In Northern China, Ning Shuzheng, Huang Shaoqing, Zhang Li, Huang Wenhui, Cao Daiyong, Yuan Jianjiang, Zhang Jianqiang, Zhu Shifei, Yan Deyu, Liu Kang

Coal Geology & Exploration

In some cases, metals such as germanium, gallium, lithium and rare earth elements can be enriched in coal, which is an important potential source of these metals. There are abundant coal resources in northern China, and a large number of coal-metal ore spots(deposits) have been found, and the distribution of these ore spots(deposits) shows certain temporal and spatial characteristics: Metals in Permo-Carboniferous coal occur mainly as gallium and lithium-enriched ore spots, mainly are distributed in the northern coalfields of North China coal bearing regions and mining areas such as Pingshuo and Jincheng in Shanxi Province; the metal enrichment in Early-Middle …

Causes Of Anomaly Of Rare Earth Elements Of Seam 2 Of Yan’An Formation In The Northern Margin Of Ordos Basin And Its Geological Significance, Yang Yi, Lyu Dawei, Zhang Jianqiang, Wu Dun

Coal Geology & Exploration

The cause of rare earth elements(REE) anomalies in No.2 coal seam of the Yan’an Formation in the northern margin of the Ordos basin has been controversial. This paper takes Dahaize coal mine, Yulin area with well developed No.2 coal as an example to analyze REE, mineralogical characteristics of coal and partings, and to reveal the causes of anomaly of REE by Inductive Coupled Plasma Mass Spectrometry(ICP-MS) and Scanning Electron Microscopy(SEM). The results show that the total rare earth element(∑REE) concentration in the coal samples ranges from 3.71 to 46.21 μg/g. Light rare earths elements(LREE, La-Eu) are more abundant than heavy …

Influencing Factors Of The Dynamic Permeability Of Cbm Reservoir And Cbm Well Drainage Control Measures, Wang Qing, Yang Fei, Gong Weicheng, Xu Tianxin, Li Yichao

Coal Geology & Exploration

The drainage and production control method has significant impact on the permeability of coalbed methane reservoir. Based on the main control factors of the permeability at different stages of drainage and production of coalbed methane wells, this paper puts forward targeted drainage and production countermeasures with the goal of improving the permeability. When the bottom-hole flow pressure was greater than the original reservoir pressure, the step-down velocity was between 0.08 and 0.1 MPa/d to reduce fracturing fluid and velocity-sensitive damage. When the bottom hole flow pressure was between reservoir pressure and desorption pressure, the pressure could be reduced at a …

Dynamic Evolution Law Of Water Accumulation Range In Coal Mining Subsidence Area With High-Level Groundwater, Chen Xiaoxie, Zhang Wentao, Zhu Xiaojun, Liu Hui, Zhang Min, Sun Aiguo, Yang Xiaoyu

Coal Geology & Exploration

In order to study the dynamic evolution law of the water accumulation range with high-level groundwater, the working face 1031 of Wugou coal mine was taken as the research area. Based on Landsat-8 remote sensing data, the evolution law of water accumulation range above working face 1031 during 2013-2017 was summarized and the influence of factors such as net rainfall, groundwater depth and working surface propulsion distance on the evolution of water accumulation range was analyzed. The concept of the boundary angle of the water accumulation range was proposed, and the functional relationship between the angle and the mining time …

Preparation Of Underwater Quick-Set And Expansion Polyurethane Grouting Material And Its Properties, Yang Zhu, Xue Ren, Wang Jun, Lan Zhili

Coal Geology & Exploration

Quick plugging and dynamic grouting technology under complex geologic conditions in mines is a technical problem in the field of grouting and one of the effective solutions is to develop new chemical grouting materials. Based on the reaction principle of polyurethane materials, we carried out the research and development on production formula of polyurethane grouting materials. By analyzing the polyurethane synthesis reaction temperature and the way of adding reagents as well as conducting contrast experiments on various auxiliaries and additives the best formula for the material was determined. It was found that the grouting material prepared by 4% nano silica …

Classification Of Hidden Faults In Coal Seam Floor And Measures For Water Inrush Prevention, Liu Zewei, Liu Qisheng, Liu Yang

Coal Geology & Exploration

The floor hidden faults with mine water bursting coefficient between 0.06 and 0.1 MPa/m have not been classified scientifically in combination with mining. Based on the characteristics of hidden faults in coal seam floor and the vertical relationship between the location of the top interface of the hidden fault and the " Three Underlying Belts", the hidden faults in coal seam floor are classified into three types: high, middle, and low from the perspective of mine water prevention of the floor. Through theoretical analysis and case analysis of water inrush, it is pointed out that the high hidden fault with …

Application Of Mjs Construction Method In Gravel Layer And Pile Forming Difference, Zhang Yan, Tian Zenglin, Cao Haidong, Dang Yakun, Wang Hai, Li Heping, Han Qiang

Coal Geology & Exploration

During the construction of water cutoff curtain in an open-pit coal mine in China, parts of the grouting groove couldnot be constructed due to many obstacles such as overhead high-voltage wire, buried optical cable and buried drainage pipe, and MJS construction method was chosen instead to build the cutoff curtain. The results of MJS pile tests show that the quality of piles formed by this method was obviously different in the construction area of gravel layer on the east and west sides. By the methods of geological exploration, gravity penetration test and pumping test, this paper makes a comparative analysis …

Mineralogical Characteristics And Genesis Of The Illite In Jurassic Coal Of The Jingxi Coalfield, North China, Huang Bo, Zheng Qiming, Shi Songlin

Coal Geology & Exploration

In order to study the indicating effect of illite for coalification and sedimentary environments, the Jurassic coal seam gangue in Jingxi coalfield of North China was taken as the research object. X-ray diffraction(XRD) and X-ray fluorescence(XRF) were used to determine the mineral composition and chemical composition of the gangue sandwiched in the coal seam gangue. The mineralogical characteristics and genesis of illite in the gangue were studied. The results indicated that the intra-seam partings are mainly composed of illite, chlorite and quartz, followed by small amount of calcite and albite. The illite has an average proportion of 62.92%. According to …

Changes Of Petrographic Characteristics And Quality Of Contact-Metamorphosed Coals In The Datong Coalfield, Ma Hongtao, Song Xiaoxia, Li Kaijie, Zhao Jingui, Zhang Tianguang, Liu Jianping

Coal Geology & Exploration

Igneous intrusions in the Datong coalfield caused a considerable amount of contact metamorphosed coal, reducing the industrial value of coal. The effect of a dike in roadway 5222 in Tashan coal mine was determined from analysis of 16 samples collected near the intrusive body. Microscopic and macroscopic observation, proximate and ultimate analysis were used to determine the petrographic characteristics. The results demonstrate that contact-metamorphosed coal experienced significant thermal alteration during intrusive event. Microscopically, various natural coke microstructures, such as mosaic structure, flow structure and pyrolytic carbon were formed under excess heat; instant heating for coals resulted in the elevation of …

Creep Acoustic Emission And Fractal Characteristics Of Coal Rock Under High Temperature Pre-Damage, Shi Hongcai

Coal Geology & Exploration

The thermal damage and triaxial creep acoustic emission experiments of coal samples at different temperatures were carried out to investigate and analyze the mechanical characteristics of coal and rock after high temperature pre-damage. The results show that the thermal damage of coal and rock increases exponentially with the increase of temperature; the brittle-ductile failure characteristics of coal and rock appear at lower temperature(≤200℃) and the accelerated creep characteristics are not obvious; the brittle-brittle failure characteristics of coal and rock appear at higher temperature(＞200℃) and the accelerated creep characteristics are more obvious; the value of steady creep rate is between pre-damage …

Directional Drilling Technology And Equipment Of Pneumatic Screw Motor In Soft Seam, Zhang Jie, Wang Yi, Huang Hanjing

Coal Geology & Exploration

Aiming at the drilling problems of shallow depth, uncontrollable trajectory and blind area of extraction in soft coal seam, the directional drilling technology of pneumatic screw motor was invented, and the directional drilling equipment consisting of pneumatic screw motor, narrow structure directional drilling rig and MWD system were formed. The air directional drilling technology and hole-completion technology were studied and developed. The technology of drilling and hole-completion solves the problem of long-distance safe drilling and hole protection of directional drilling along soft coal seam. The technology has been successfully tested in a coal mine, Huainan, with 30 test boreholes with …

Numerical Simulation Of Propagation Law Of Pore-Fracture Under Uniaxial Stress, Guo Xiucheng

Coal Geology & Exploration

in order to study the law of crack propagation under different pore-fracture conditions, the crack propagation process, acoustic emission law and stress-strain curve under different crack inclination angle and different heterogeneous coefficient were numerically simulated by using RFPA software. At the same time, the results are compared with the experimental results. The results show that the cracks of the intact specimen are produced along the shear direction, while the cracks of the specimens with pores occur along the side of the crack tip and the orifice. The secondary cracks in horizontal direction and bifurcation at the prefabricated crack tip or …