井下长距离定点保压密闭煤层瓦斯含量测定取样技术

Sampling technology for measuring gas content in coal seam with long distance fixed-point pressure sealing in underground mine

针对煤矿井下现有瓦斯含量测试技术存在的取样深度浅、精度低、瓦斯易逸散等不足,将定向钻进技术与密闭取心技术结合,开发了基于井下定向孔的煤样长距离定点保压密闭采心方法,即先利用定向钻孔长距离精确钻进至取样点,然后采用煤层密闭取样装置进行煤样保压密闭采取,主要包括取样定向孔设计、套管孔段和定向孔段施工、单点煤样采取和单孔多次取样等工艺步骤,选配了配套钻进与取样装备,并在焦作某矿进行了现场试验。结果表明,采用经改进的采样工艺方法和装备,成功完成5次煤样采取,煤样采取率100%,保压密闭成功率100%,最大取样深度达到491 m,是现有技术取样深度的6倍以上,实际取样点与设计位置偏差小于0.5%,显著提高了井下煤样采取精度,并减少了瓦斯逸散,确保煤层瓦斯参数测试的准确性,可为矿井工程设计与评估提供准确的参考依据。

According to the low depth coal sampling,low accuracy,gas easy escape and other disadvantages existed in the available gas content test technology applied in the underground mine,the directional drilling technology and the closed coring technology were combined and applied to develop a coal sampling method from a long distance pressure maintained and closed sealing fixed point of the directional borehole based on the underground mine. The method would firstly have a long distance accurate drilling with a directional drilling to the coal sampling point and then a closed sampling device in seam was applied to make a pressure maintained and closed sealing coal sampling,mainly including the design of the coal sampling directional borehole,construction of the casing borehole section and directional borehole section,a single point coal sampling and a borehole multi sampling and other technical procedures. A matched drilling and sampling equipment was selected and equipped. A site trial was conducted in a mine at Jiaozuo. The results showed that the modified and improved technical method and equipment were applied to successfully complete five coal samplings with a coal sampling rate of 100%,successful pressure maintaining and closed sealing rate of 100% and a max sampling depth of 491 m. The max sampling depth was over six times of the available technical sampling depth. There was a deviation less than 0.5% between the actual sampling point the designed location. The accuracy of the coal sampling in the underground mine was obviously improved and the gas escape was reduced to ensure the test accuracy of the seam gas parameters and to provide the accurate reference basis to the engineering design and evaluation of the mine.