Study on long drilling long-distance fixed-point gas content measurement

The sampling time of long drilling fixed-point gas content measurement is long. And it is unable to measure the gas content in coal seams accurately due to the absence of desorption on site. In order to solve the above problems, a method of using analogy to estimate gas loss and atmospheric gas desorption during sampling is proposed. In the same geological conditions and gas geological unit, the ratio of gas loss and on-site gas desorption to the total gas content in the measurement results of the gas content of the shallow drilling air exhaust powder sampling of the common rotary drilling rig is used as the standard. The analogy is the ratio of gas loss and on-site gas desorption to the total gas content in the deep drilling fixed-point sampling of the kilometer directional drilling rig. The ratio of gas loss and on-site gas desorption is added to the final measured residual gas content. The total gas content of the deep drilling fixed-point sampling of the kilometer directional drilling rig is obtained. This method is used to measure the gas content of long drilling in the Ji16-17-24070 working face of No.11 Pingdingshan Coal Mine, and to correct the gas content measured values of the kilometer directional drilling sampling. The test results show that compared with the gas content measurement of the short drilling direct method, the average error of the long drilling gas content measurement corrected by the analogy method is reduced from 12.07% to 0.19%. Compared with the content prediction values, the average error of the long drilling gas content measured values corrected by analogy method is reduced from 12.90% to 4.71%.