To study the effects of three deformation instability modes gas drainage borehole on drainage, mechanism soft coal seams is analyzed, are proposed for seams, namely, complete holes, collapse and plug a solid‐fluid coupling model incorporating dynamic change suction pressure established. The results show following. (1) When there no (i.e., borehole), loss system in very small, whose effect can be neglected. (2) In case collapse, big at segment, total bigger than that hole. However, it smaller...

Abstract Forecasting microseismic cloud shape as a proxy of stimulated rock volume may improve the design an energy extraction system. The created during hydraulic stimulation geothermal reservoirs is known empirically to extend in general direction maximum principal stress. However, this empirical relationship often inconsistent with reported results, and growth process remains poorly understood. This study investigates using data obtained from project Basel, Switzerland, explores its...

The pore characteristics of coal have an important influence on the adsorption methane. liquid nitrogen method was used to study structure low- and middle-rank samples from two aspects: specific surface area shape. Low-field nuclear magnetic resonance (NMR) technology difference in methane under same conditions. mechanism middle- low-rank gas are discussed analyzed. results show following: (1) There differences capacity medium- samples. Within 1 h inflation, coals such as Henan Pingdingshan...

In view of the ground drilling N2206 working face in Shanxi Wangzhuang Coal Mine, gas concentration is low and extraction effect not good. Fluent computational fluid dynamics software was used to simulate position goaf (the distance from top coal seam return wind). The numerical simulation results show that when final hole 16 m roof air 45 m, optimal. average volume 9.78 3 /min, 43.95%, best obtained. After optimizing combining with site implementation, maximum scouring amount 12.59 which...

The Yangtze River Basin serves as an essential ecological shelter in China, yet it has encountered escalating aquatic challenges. Exploring the spatial–temporal changes and trade-off–synergy relationships of water-related ecosystem services (WESs) is necessary for formulating management planning policies targeting sustainable development watersheds. In this study, InVEST model utilized to evaluate variations water yield (WY), purification (WP), soil conservation (SC) using remote-sensed data...

To accurately and quantitatively characterize the evolution of coal microstructures before after supercritical CO2 treatment, this paper proposes a microstructural analysis for coal-rock based on low-field nuclear magnetic resonance (LNMR) technology, L-weighing method. The experimental results method LNMR were compared analyzed. showed that there differences between method, but overall laws basically same. characterizes water content in determines consumption microscopic component...

Pore and fracture structures in coals their distribution features play an important role the enrichment osmosis migration of coalbed methane (CBM). The modification antireflection pore coal reservoir through ultrahigh ultralow temperature stress, such as liquid nitrogen frozen‐induced cracking thermal reservoir, have attracted wide research attention. This study conducted a nuclear magnetic resonance (NMR) experiment samples under two extreme temperatures (100°C, −196°C) using Meso...

In the coal mine industry, permeability is a key factor to air leakage in gob, its value and distribution influence greatly of leakage. CFD applied simulate gob at various magnitudes. Gob refers porous medium made from loose collapsed stratum mixture. It shows that quantity velocity, three zones spontaneous combustion vary largely under condition different magnitude permeability. The seen gradually reduce. small velocity waste low, zone close working face. graph relation between distance...

To reveal the influence of water on gas adsorption process medium rank lump coals, four groups coals were selected for study, and pore analysis experiments low-field nuclear magnetic resonance (NMR) isothermal with different contents carried out. The microscopic structure characteristics characterized by combined mercury-pressure method nitrogen method; water-bearing coal samples was quantitatively analyzed based NMR experimental platform, endowment state content reservoirs discussed....

Using the borehole instability model based on theory of microscopic scale elastic damage, authors conducted numerical analysis deformation characteristics drainage at different burial depths and proposed mode for borehole. Results showed that (1) shallow depth had less remained in quasi-circular shape; as increased, wall became more significant, top area slight caving, lower displayed coal spalling, whole changed into "ellipse-like shape"; large was subjected to severe collapse or even...

To deeply study the variation characteristics of gas content in process adsorption for coal samples under different pressures and confining pressures, low-field nuclear magnetic resonance technology was used to carry out experimental research on coal. The relationship between T 2 spectrum amplitude integral quantity analyzed. results show following: (1) When were inflated 11 h at each pressure point (0.31, 0.74, 1.11, 1.46 MPa), after ∼5 adsorption, amount adsorbed exceeded 85.0% total...

The distribution of air leakage between working face and gob area migration gas are simulated by using commercial CFD software Fluent. Mesh generation is one the most important factors influencing calculation accuracy airflow field in area. If a coarse grid used to simulate, accurate results cannot be obtained. However, finer need spend much more time. In this paper, near-wall boundary layer mesh various spacing constructed with Gambit respectively Fluent simulation encryption different gob....

Determining the optimal extrication location of high extraction roadway can improve gas effect highly gassy mine and solve problem concentration overrun at upper corner, which is great significance to safety efficient production. According actual situation mine, gushing amount in goaf, pressure difference both ends working face, 3D porosity, permeability distribution caving zone fissure were obtained by field measurement numerical calculation. Through theoretical calculation, proper site a...

To study the decompression effects of shaft explosion‐proof door at different lifting heights, this paper designed gas explosion testing system. Based on test results, made a numeric analysis change regularities shock wave overpressure when was lifted heights. Finally, determined proper height and put forward active concept. The research showed that (1) decreased in power exponential relationship as increased. When increased from 0 cm to 5 cm, peak 36.06 kPa 22.47 kPa, dropping by 37.7%. it...

Gas explosion is one of the main causes casualties in coal mines. Studying propagation law shock wave mine gas can reduce economic loss and personnel injury caused by explosion. To solve difficulty research scale, segmented relay simulation method a was put forward, related key problems were studied, results successfully applied Yangchangwan No. 2 Mine. The show following: (1) When length forked roadway exceeds 50 m, has little effect on overpressure roadway. short, closure great influence...

The adsorption properties of coal determine the economic benefits coalbed methane (CBM) extraction. To investigate gas behavior raw after heating, tests and pore characterization were conducted. Meanwhile, influence high temperature on structure polymorphic was analyzed. results showed that gradually increased with increase grade at same temperature. For coals, adsorbed content decreased 5.96%-21.53% non-adsorbed 51.25%-95.47% has a dilating effect pores, causing proportion tiny pores to...

With the continuous development of mining industry and advancements in deep technology, mine environment optimization has become key to ensuring safety improving efficiency mining. The high-temperature environment, particularly mines, not only poses a serious threat miners’ health but also significantly reduces operational efficiency. These issues have been determined based on current application status trends cooling including traditional mechanical non-mechanical technologies, as well...

Aiming at the “light wind start, light power generation” of vertical axis turbine, a new T-shaped radial passive magnetic bearing with high suspension characteristics is proposed. Passive bearings used in turbines usually have small capacity and difficult magnetization. The PMB can improve capacity, three rings all adopt simple axial combined mechanical auxiliary to form system turbine. In stable state, realize suspension. structure working principle are briefly described. Through finite...