A new method for accurate and rapid measurement of underground coal seam gas content

Abstract

Coal seam gas content is one of the basic parameters for gas disaster prevention and gas utilization in underground coal mines. It is also an important index for coal seam outburst danger evaluation and gas extraction effect investigation, which require a lot of measuring work and must be tested in large areas in underground coal mines. Due to the calculated error of the lost gas in the direct method and difficulties in accurately measuring the gas pressure used to calculate the gas content in the indirect method, the accurate determination of gas content remains a difficult problem. In this paper, the main component of gas content and current measurement methods used in China were discussed, and a new method of coal seam gas content measurement based on the small gap of gas adsorption and desorption characteristics of coal seams in the same geologic unit was proposed. In this new method, we first established a reasonable calculation model for the lost and residual gas contents based on laboratory measurements of desorption characteristics; an accurate and rapid determination of the underground gas content could then be directly obtained. This method requires a small workload and a short measuring time and is particularly applicable to a single underground coal seam with a demand for large quantity measurement. From an engineering perspective, this method not only can rapidly determine coal seam gas content but also can reflect the real gas pressure, satisfying the large area multi-point measurement of coal seam gas content with higher reliability and safety.