A series of gas inrush events occurred during development at Grosvenor Mine resulting in exposure to elevated levels of methane at the production face. A total of 22 gas inrush events occurred, with between 15 and 130 m³ of methane released during each event. The presence of an undrained seam in the immediate floor, geotechnical characteristics of the floor, and the stress environment all contributed to these dynamic floor events, while the geological characteristics of the seam below, such as the seam thickness and ash content of 75%, prevented effective predrainage. However, events only occurred in headings mined parallel to the principal horizontal stress direction. In cut-throughs (C/T) perpendicular to the principal stress direction no events occurred, and higher methane levels were observed at the production face. The solution to preventing the gas inrush events involved creating a conduit in the interburden between the mined seam and the seam in the immediate floor to allow the gas to be drained during the development of the headings, as occurred in the cut-throughs (cut-through and cross-cut are regional terms that are analogous). A series of underground inseam (UIS) holes were drilled using the directional drill rig with the aim of fracturing this interburden ahead of the face and promote floor failure to allow the gas to release consistently. The floor fracturing was conducted using water pressure generated from a longwall salvage pump, with the current UIS drilling equipment retrofitted with a series of subs, packers and a fracturing tool. The packers and the fracturing tool were shifted to desired locations along the drilled UIS borehole to achieve the required fracture. The fractures were monitored using a proving hole and with a HYDAC data logger attached to the salvage pack, with the results analysed on the surface to ensure connectivity to the working seam.

格罗夫纳矿在开发过程中发生了一系列瓦斯涌入事件，导致生产面上的甲烷浓度升高。总共发生了22起瓦斯涌入事件，介于15和130 m ^3之间在每个事件中释放的甲烷 相邻底板中存在不排水的接缝，底板的岩土特征以及应力环境均导致了这些动态底板事件，而下面接缝的地质特征（如接缝厚度和灰分为75％）防止有效的预排水。但是，事件仅发生在平行于主水平应力方向开采的航向中。在垂直于主应力方向的直通孔（C / T）中，未发生任何事件，并且在生产面上观察到较高的甲烷含量。防止瓦斯涌入事件的解决方案包括在采煤层和紧邻层的煤层之间的衬层中创建一个导管，以在抽放井头的过程中排出瓦斯，就像在直通广告中一样（直通广告和交叉广告是类似的区域性术语）。使用定向钻机钻了一系列的地下下se（UIS）孔，目的是在工作面之前压裂该岩层并促进底板破坏，以使气体持续释放。使用长壁打捞泵产生的水压进行地板压裂，对当前的UIS钻井设备进行了改造，配备了一系列潜水器，封隔器和压裂工具。封隔器和压裂工具沿UIS钻孔移至所需位置，以实现所需的压裂效果。使用探洞和将打捞包连接到HYDAC数据记录仪对裂缝进行监测，并在地面上分析结果，以确保与工作缝的连通性。