Gob ventilation boreholes (GVBs) are widely used for degasification in U.S. longwall coal mines. Depending on geological conditions, 30–50% of methane can be recovered from longwall gob using GVBs. A NIOSH funded research at the Colorado School of Mines confirmed that GVBs can efficiently reduce methane at the face. However, GVBs can also draw some fresh air from the face and create explosive gas zones (EGZs). Explosive gas mixtures may be formed in gob areas due to the increased ingress of oxygen from GVBs. It is critical to identify the locations for GVBs for maximizing extraction of methane and minimizing hazards of explosion. This study analyzes the effect of operating parameters and design of GVB on methane extraction, EGZs formation, and face and tailgate methane concentrations. Methane extraction, formation of EGZs, and concentration of methane in working areas are significantly impacted by various factors. These factors include the distance of work face and tailgate from GVBs, diameter of GVBs, vacuum pressure of wellhead, GVB distance from the roof of the coal seam, and number of operating GVBs in a panel. Computational fluid dynamics (CFD) evaluations suggest optimal design and operating parameters of GVBs that can contribute to maximum benefits with minimum risks.

采空区通风孔（GVB）在美国长壁煤矿中广泛用于脱气。根据地质条件，使用GVB可以从长壁采空区回收30–50％的甲烷。由NIOSH资助的科罗拉多矿业学院的一项研究证实，GVB可有效减少脸上的甲烷。但是，GVB还可从工作面吸入一些新鲜空气，并形成爆炸性气体区域（EGZ）。由于氧气从GVB进入的增加，可能在料滴区域形成爆炸性气体混合物。确定GVB的位置对于最大程度地提取甲烷和最小化爆炸危险至关重要。这项研究分析了运行参数和GVB设计对甲烷提取，EGZs形成以及正面和后挡板甲烷浓度的影响。甲烷萃取，EGZ的形成，而且工作区域中的甲烷浓度受各种因素的影响很大。这些因素包括工作面和后挡板距GVB的距离，GVB的直径，井口的真空压力，GVB距煤层顶板的距离以及面板中可操作的GVB的数量。计算流体动力学（CFD）评估表明，GVB的最佳设计和操作参数可有助于以最小的风险获得最大的收益。