基于电阻率成像的区域防突效果评价方法

    Evaluation method of regional anti-outburst effect based on resistivity image

    • 摘要: 煤层瓦斯压力是区域防突效果评价的重要指标。由于煤层残余瓦斯压力受煤层裂隙影响很难准确测定,为提高区域防突效果评价的时效性和可靠度,提出一种由抽放空白带、钻孔电阻率、残余瓦斯压力相结合的综合评价方法,并确定了临界指标。现场考察阳泉煤田新景矿15号煤层底抽巷穿层钻孔水力造穴和瓦斯抽放的防突效果,定期测试钻孔抽放量和瓦斯含量、瓦斯压力等瓦斯参数,不定期地测试并记录存储造穴抽放钻孔内的钻孔轨迹、侧向电阻率、自然电位和自然伽马等钻孔测井数据,分析水力造穴抽放钻孔煤层段不同时间的钻孔测井与考察孔瓦斯压力的变化和瓦斯抽放效果。通过数据回归并拟合发现,抽放钻孔的侧向电阻率与考察孔的瓦斯压力之间呈常用对数负相关关系,由此获得电阻率评价瓦斯压力的数学模型及相应系数;当抽放孔内煤层段平均电阻率达到750 Ω·m时,与考察孔瓦斯压力0.74 MPa相当,这就相当于考察孔煤层瓦斯压力临界指标相对应的电阻率指标值;同时利用钻孔轨迹考察区域防突钻孔的施工偏差和钻孔孔底的间距,评价防突措施范围内是否存在空白带,并借助造穴抽放影响半径确定是否需要增加或者补充区域防突钻孔;综合电阻率和钻孔轨迹,形成一种钻孔施工效果评价与防突效果考察于一体、即时有效、可适应于大区域长距离的连续防突效果检验方法。

       

      Abstract: Coal seam gas pressure is an important indicator for the evaluation of regional outburst prevention effect. Due to the influence of coal seam fractures, it is difficult to accurately measure the residual gas pressure of coal seams. In order to improve the timeliness and reliability of the evaluation of regional outburst prevention effect, a comprehensive evaluation method based on the combination of blank zone drainage, borehole resistivity and residual gas pressure is proposed, and the critical index is determined. The on-site investigation was conducted on the anti-outburst effect of hydraulic hole-making and gas drainage in the borehole of the No.15 coal seam bottom pumping roadway in Xinjing Mine, Yangquan Coalfield. The drainage volume of the borehole, gas content, gas pressure and other gas parameters were regularly tested. The borehole trajectory, lateral resistivity, natural potential and natural gamma and other borehole logging data in the caving and drainage borehole were tested and recorded and stored irregularly. The changes in borehole logging and the gas pressure of the investigation borehole in the coal seam section of the hydraulic hole-making drainage borehole at different times, as well as the gas drainage effect are analyzed. Through data regression and fitting, it is found that there is a common logarithmic negative correlation between the lateral resistivity of the drainage borehole and the gas pressure of the investigated borehole. Thus, the mathematical model and corresponding coefficients for evaluating gas pressure by resistivity are obtained. When the average resistivity of the coal seam section in the drainage hole reaches 750 Ω·m, it is equivalent to the gas pressure of the exploration hole at 0.74 MPa. This is equivalent to the resistivity index value corresponding to the critical index of the gas pressure of the coal seam in the exploration hole; meanwhile, the construction deviation of the regional outburst prevention boreholes and the spacing at the bottom of the boreholes are investigated by using the borehole trajectories to evaluate whether there are blank zones within the range of outburst prevention measures, and determine whether it is necessary to add or supplement regional outburst prevention boreholes by means of the influence radius of caving and drainage. By integrating the resistivity and the drilling trajectory, a continuous anti-outburst effect inspection method that integrates the evaluation of drilling construction effect and the investigation of anti-outburst effect, is immediate and effective, and can be adapted to large areas and long distances is formed.

       

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