榆树田煤矿地质构造特征及其对煤层瓦斯赋存的影响

Geological structure characteristics of Yushutian Coal Mine and its influence on coal seam gas occurrence

为了明确地质构造特征对新疆榆树田煤矿煤层瓦斯赋存的影响,采用理论分析、数值模拟、数理统计、实验测试等方法对井田地质构造及演化特征、含煤地层埋藏—抬升史、煤层变质作用、瓦斯生成与赋存特征等开展研究,为榆树田煤矿瓦斯灾害防治提供理论指导。研究结果表明,井田构造整体表现为向西倾伏的不对称宽缓向斜,属于切向应变主动褶皱作用模式。井田煤层瓦斯主要经历了3个生成—逸散阶段,煤层所经历最大埋深约2900 m,所经历最高地温超过110℃,煤层瓦斯累计生成量至少50 m^(3)/t,构造抬升造成约80%的煤层瓦斯逸散。受切向应变主动褶皱(向斜)作用及埋深等影响,井田由两翼的低应力—弱应变—高渗透条件逐渐向核部的高应力—强应变—低渗透条件过渡,进而导致煤层瓦斯逸散路径愈来愈长,逸散阻力愈来愈大,煤层瓦斯含量及压力愈来愈高。差异性构造挤压变形作用导致南翼地层相对北翼处于更强的高应力—强应变—低渗透条件,进而导致南翼煤层具有更高的瓦斯逸散阻力、瓦斯含量及压力。

In order to clarify the influence of geological structure characteristics on coal seam gas occurrence in Yushutian Coal Mine,Xinjiang Province,theoretical analysis,numerical simulation,mathematical statistics,experimental testing and other methods was adopted to study the geological structure and evolution characteristics of the mine field,the history of buried and uplifted coal-bearing strata,coal seam metamorphism,gas generation and occurrence characteristics,etc.,providing theoretical guidance for gas disaster prevention and control in Yushutian Coal mine.The results show that the structure of the mine field as a whole is an asymmetric broad and gentle syncline with westward dip,which belongs to the tangential strain active folding mode.The coalbed methane in the mine field mainly undergoes three stages of generation and escape.The maximum buried depth of coal seam is about 2900 m,the maximum ground temperature is over 110℃,the cumulative production of coal seam gas is at least more than 50 m^(3)/t,and the structural uplift causes about 80%of coal seam gas escape.Under the influence of tangential strain active folding(synclinal)and burial depth,the well field gradually transitions from the low stress-weak strain-high permeability condition on the two wings to the high stress-strong strain-low permeability condition in the core,which leads to longer and longer gas escape path,greater and greater escape resistance,and higher gas content and pressure in the coal seam.The differential structural compression deformation causes the southern wing strata to be under stronger high stress,strong strain,and low permeability conditions compared to the northern wing,resulting in higher gas escape resistance,gas content,and pressure in the southern wing coal seams.