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Ni X.,Henan Polytechnic University | Jia B.,Shanxi Jincheng Anthracite Coal Mining Group Co. | Wang Y.,China University of Mining and Technology
Natural Gas Industry | Year: 2012

When the multi-layer hydraulic fracturing is operated in well-developed multiple coal seams with thin single layer and small space between layers, the reasonable number of ball sealers is the guarantee for smooth operation of the said fracturing and the best cumulative stimulation result. The difference in reservoir properties between coal seams and sandstone beds will lead to such problems as the accelerating pressure in operation, bad frac result in coal seams, etc. Therefore, the determination of actual ball sealers under different geological conditions will help solve those bottlenecking problems. Then, according to the basic principle of the multilayer hydraulic fracturing, this paper thoroughly analyzes the influencing factors. On this basis, the geological and mathematical models of the number of ball sealers are built for the multi-layer hydraulic fracturing in different hard coal seams or the interbedded hard and soft coal seams. With the above models, the number of ball sealers was designed for the multi-layer hydraulic fracturing in the 8 # and 9 # Luling Coal Mine of the Huaibei area. The application result shows that this study will provide theoretical basis for the determination of the number of ball sealers for the multi-layer hydraulic fracturing in different coal seam combinations. Source

Wang Z.-F.,Henan Polytechnic University | Tian F.-C.,Henan Polytechnic University | Zhao B.,Shanxi Jincheng Anthracite Coal Mining Group Co. | Chen X.-J.,Henan Polytechnic University | Yu B.-Z.,Henan Polytechnic University
Meitan Xuebao/Journal of the China Coal Society | Year: 2010

Studied the areal gas drainage characteristics and advantage of feather-veined 1000 m longitudinal length-drillhole, combined with coal seam gas drainage principle, analyzed the relationship between drillhole gas flow and negative pressure, length of drillhole, pointed out that 1000 m length-drillhole was a new technology which applied to areal prevention of gas outburst and underground coalbed methane drainage in gassy mine. As the technology applied to Nos.1 and 2, 1000 m length-drillhole which in the west gathering main roadway of Sihe Coal Mine, Shanxi Jincheng Anthracite Coal Mining Group Co. Ltd., the effect indicates that the areal gas drainage from virgin coal seam rate can reach more than 42%, under the relative invariant condition of gas permeability coefficient and drainage negative pressure, the longer the drillhole is, the more the drillhole gas flux per 100 meters and the smaller the attenuation coefficient, so the gas drainage efficiency will increase in identical time. Source

Yang Y.,Taiyuan University of Technology | Song J.,Taiyuan University of Technology | Ma C.,Taiyuan University of Technology | Fu J.,Shanxi Jincheng Anthracite Coal Mining Group Co. | Yang D.,Shanxi Jincheng Anthracite Coal Mining Group Co.
Chinese Journal of Sensors and Actuators | Year: 2013

As one kind of main equipment in the fully mechanized working face, the hydraulic support plays an important role in coal mining process. Whether the mining work can be conducted normally is largely depended on the accuracy of the hydraulic support's moving position. Generally, the moving operation of the hydraulic support is taken by the pushing-moving oil cylinder. A displacement sensor has been designed and developed, which can be used to measure the moving position of the hydraulic support pushed by pushing-moving oil cylinder installed on hydraulic support accurately. Based on the on-off principle of reed switch under the condition of moving the magnetic ring set on metal tube, the signal of displacement of magnetic ring can be changed to voltage signal correspondingly. When the magnetic ring is moved along the metal tube, the reed switch at the corresponding position turns on and the output voltage of the displacement sensor changes. It has been tested that the measuring range is from 0 to 1000 mm, the relative accuracy of the displacement sensor is 0.80000%, the linearity is about 0.0958%, and the fluctuation range of the output voltage is ±0.001 V. It has been shown by the experiment in laboratory and measurement in field that the displacement sensor can be used to measure the moving position of the hydraulic support accurately and stably, which meets the requirements of displacement measurement for the hydraulic support in the fully mechanized working face. Source

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