High efficiency simultaneous extraction technology system of coal and gas in close-distance seam group：taking shaqu mining area in luliang, shanxi province as an example

In order to grasp the law of stress fracture gas seepage in the superposition mining of close seam group, and to construct the technical system and dynamic evaluation model of high efficiency Simultaneous Extraction of coal and gas in close distance coal seam, taking Shaqu mining area as the research object, the research method of combining physical similarity simulation, ultrasonic test and SF6 tracer gas field monitoring is adopted, Analyzing the occurrence characteristics of coalbed methane resources in the short distance coal seam group of Shaqu coal mine, which is characterized by "gas overrun in the north wing and gas outburst in the South Wing", Based on the exploration of the variation law of the damage variable of coal and rock with the stress under the multiple disturbance of the close seam group in Shaqu mine, the Boltzmann damage equation of coal and rock is established, and the characteristic law of mining stress evolution fracture development gas migration under the condition of superposition mining of the close seam group in Shaqu mine is obtained. The results show that the characteristics of pore and fracture structure of Shaqu coal seam are not conducive to the migration of gas. The influence on the stress field and fracture field of overburden under the condition of close distance coal seam superposition mining is not simple effect superposition, but the effect of "1 + 1 > 2" appears, and the overburden coal seam produces through type fracture under the superposition mining, and large cracks are derived around it The amount of secondary fractures provides the dominant channel for the gas migration in coal seam in time; and according to the time and space conditions of different stages of coal and gas simultaneous extraction in Shaqu mine and the requirements of outburst control, the technical system of simultaneous extraction of coal and gas in short distance coal seam group is formed, that is to say, in the planning area, a variety of surface wells are used for large-scale and long-term pre extraction of coalbed methane. In the preparation area, multi branch horizontal wells are used for directional joint mining and protective layer mining + bottom extraction roadway for directional drilling group mining. In the production area, large mining height along goaf and large diameter directional drilling group mining technologies are used for simultaneous extraction of coal and gas; by analyzing the influencing factors of simultaneous extraction of coal and gas, the dynamic evaluation index system of simultaneous extraction of coal and gas in short distance coal seam group is put forward, the Bayesian evaluation model of simultaneous extraction of coal and gas is established, and the evaluation of simultaneous extraction effect of coal and gas and the rationality of mine deployment in Shaqu mine are realized, that is , the dynamic rationality probability of coal and gas simultaneous extraction in Shaqu No.1 mine is 0.65, and the rationality grade of simultaneous extraction of coal and gas is relatively reasonable; At last, the bottleneck of simultaneous extraction technology of coal and gas in close seam group is discussed, and the future development direction of simultaneous extraction technology of coal and gas in close seam group is prospected.