Advanced Materials Research Vols. 962-965

Abstract: The paper analyzed the process of the microwave drill for rock, and established the theoretical analysis model and the system equations. And through the numerical simulation, the electric field intensity and the temperature of the top of the microwave generator increased with the increase of the depth that the conductor was inserted, and the thermal runaway effect was strengthened. So the microwave assisted rock breaking scheme with microwave near field energy and thermal runaway effect is feasible.

Abstract: Pore structure characteristics and the effect of lithotype and maceral on pore for three types of high-volatile bituminous coals from Binchang area were investigated by combined low-temperature nitrogen adsorption/desorption, nuclear magnetic resonance (NMR), scanning electron microscope (SEM) and maceral analysis. The low temperature N₂ adsorption/desorption test results show that: micropores are more abundant than transitional pores with high BET surface area; two types of pore structures can be identified by adsorption/desorption isotherms; Pore morphology is mainly represented by well-connected, ink-bottled, cylindrical and parallel plate pores. NMR T₂ distributions at full saturated condition are apparent or less obvious trimodal and three types of T₂ distributions are identified; Seepage pores are better developed when compared with the middle-high rank coal. Further research found that the three coal lithotypes are featured by remarkably different pore structure characteristics and maceral contents of coal are linearly correlated to some of pore structure parameters.

Abstract: China is rich in coal-bed methane (CMB) resources, and has a vast exploitable volume, but the surface gathering system is not perfect. In order to solve the problems of high degree of difficulty in surface gathering system design and lower economic efficiency caused by the characteristics of CBM gas field geographically remote, more wells, large water production in single well and gas containing pulverized coal etc, we studied the select method of the piping material of CBM, process and the treatment technologies of produced water in F block of the southern Qinshui Basin. Finally, the first phase production can reach 6 × 10⁸m³/a and the central processing plant size is 10 × 10⁸m³/a in the F block. The application of this study not only reduced the capital investment but also met the requirement of good environmental protection. This gathering process design can be applied to other development and construction of CBM gas fields.

Abstract: Based on the minimum start-up pressure gradient have been obtained from experiment, and the relationship between the minimum starting pressure gradient with maximum starting pressure gradient and the throat radius, first put forward the calculating the limit shear stress, then calculating the maximum starting pressure gradient method. Non-linear seepage corresponding to the pressure gradient range are obtained by regression analysis, nonlinear seepage flow in low permeability reservoir distribution area can be derived. Two well group examples of the Bei301 block of Hailaer oilfield, shows that calculating the method of nonlinear seepage flow area is available, and the results can reflect the symmetry oil well production performance, this method has application value. The On the basis of the formula of pressure gradient between oil wells and injection wells, New method to calculate the limit injection production well spacing is proposed. It is of importance for injection production well spacing in oilfield development plan.

Abstract: Mining with stowing is an environmentally friendly way for coal mine, and stowing material is the key to realize environmental protection and harmonious development. This paper focused on the stowing materials, and evaluation for the stowing material would be made. Stowing materials could be sorted as chemical reaction material, solid refuses from coal mine and natural material for stowing. In the light of the cost and sustainable application of the stowing material, we suggest solid refuses from coal mine are the first choice as stowing materials for now.Urban pollutants could be a good kind of stowing materials, but further study should be made for this material. Also the stowing materials should be as cheap and environmentally friendly as they could.

Abstract: Coal and gas outburst and rock burst are the main threats of the island working face in outburst coal seam. According to the characteristic of No. 11061 island face in outburst coal seam, Liangbei coal mine, China, the dynamic disaster mechanism of island working face in outburst coal seam was analyzed. Based on the monitor of gas concentration and electromagnetic radiation and hydraulic supports resistance in the 11061 island face, the comprehensive forecasting technology of the island face in outburst coal seam was built, then the critical values of gas concentration and electromagnetic radiation and hydraulic supports resistance are calculated by three-ratio method. Finally, the comprehensive forecasting technology is used in the island working face. The results show that the combined action of gas content and stress induces the dynamic disaster of the island working face in outburst coal seam, and the comprehensive forecasting technology can forecast accurately dynamic disaster in the 11061 island face, which has brought successful engineering experience and distinct economic benefit. It can improve significantly the mine production safety level to research the forecasting technology of the island working face in outburst coal seam.

Abstract: Coal mine gas disaster has the characteristic of destructive and complexity, in connection with the frequently of coal mine gas disaster, the paper studied on the propagation of gas explosion shock wave while pipe cross-sectional area changing from the experimental angle, designed the test system, the data of shock wave pressure when the pipe turning angle more or less than 90 degree was given, analyzed two situations: one was to analysis the influence of initial shock pressure effect on the attenuation coefficient under determination of pipeline turning angle; another was to analysis the influence of pipe turning angles effect on the attenuation coefficient under determination of initial shock wave overpressure, pointed out that the shock wave initial pressure and pipe turning angles were the two important factors which affect the shock wave overpressure attenuation coefficient. By comparison, the initial shock pressure had the larger influence. At last, the shock wave overpressure attenuation coefficient diversification formula was given when pipe turning angles was more or less than 90 degree.

Abstract: The material failure induced coal bump and structure failure induced coal bump were paid attention to in this paper. Mechanism of coal mining and stowing with upper entry for preventing coal bump was analyzed. The mechanism of mining with upper entry for preventing material failure induced coal bump is that the stowing material can recover the integrity of the cracked roof, and for preventing structure failure induced coal bump is that water infusion to the roof could release the energy in the roof, and the backfilling could support the roof, both of them could change the stress condition of the roof. It hopes that coal mining and stowing with upper entry for preventing coal bump is a rational way to realize safety mining, but there still are some questions should be the further studied.

Abstract: Research on the support of anchor rod+ Anchor cable and anchor+ sprayed concrete

Abstract: Based on the instance of extremely thick coal seam mining under aquifer in Gonggeyingzi Coal Mine, the theoretical calculation for the height of water flowing fracture zone in this coal mine was 30.6m and calculation model was established. Analyzed by the UDEC software, the surface displacement of backfill mining was 1532mm and the height of overburden rock plastic zone was 36.5m. Compared with 135m away from coal roof to aquifer, slicing backfill mining under aquifer was confirmed to be safe and feasible based on the theoretical calculation and analysis of UDEC. The results provided the basis for the safety of extremely thick coal seam mining under aquifer in this coal mine.