In this paper, the variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage were investigated by testing seven coal samples obtained from the coal seam #10 of Yangliu Coal Mine. The MICP and N 2 GA were combined to characterise the pore-size distribution. It is revealed that the residual coalbed gas content decreases substantially with the decrease in boreholes distances. Nevertheless, the variations in initial gas desorption velocity and coal hardiness coefficient represent an opposite tendency. In the microscopic aspect, the variation in pore-size distribution is notable. With the decrease in the boreholes distances, the adsorption pore proportion decreases and the seepage pore proportion increases. The drilling-slotting integration technique and gas drainage affect the aforementioned three macroscopic indices by changing the pore characteristics and moisture content. Besides, the guiding significance for field application of this technique is elaborated.

In this paper, numerical method which is dominated by inversion is used to analyze CLYJ saturated limestone samples. Elastic parameters of rock framework and pore fluid are estimated from the overall measured density and velocity data in different porosities based on the effective inversion method. A critical porosity model is used, and elastic parameters are calculated after grouping. The estimating process includes grouping, calculating, counting and evaluating. Firstly, three samples are chosen as a group and there are N different ways to group. The samples are grouped in both integral way and individual way. Secondly, for each group the component elastic parameters are calculated based on the critical porosity model and N groups of results are obtained. Third, the results are analyzed to estimate the elastic parameters of samples. At last, the results are evaluated through comparisons of statistic parameters between the estimated values and measured ones, such as maximum, minimum, mean, and standard deviation. The results indicate that the method to estimate the elastic parameters of rock framework and pore fluid is effective and reliable. The component elastic parameters reflect the elastic properties of CLYJ limestone samples, and enrich the contents of these samples.

In this paper, the variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage were investigated by testing seven coal samples obtained from the coal seam #10 of Yangliu Coal Mine. The MICP and N 2 GA were combined to characterise the pore-size distribution. It is revealed that the residual coalbed gas content decreases substantially with the decrease in boreholes distances. Nevertheless, the variations in initial gas desorption velocity and coal hardiness coefficient represent an opposite tendency. In the microscopic aspect, the variation in pore-size distribution is notable. With the decrease in the boreholes distances, the adsorption pore proportion decreases and the seepage pore proportion increases. The drilling-slotting integration technique and gas drainage affect the aforementioned three macroscopic indices by changing the pore characteristics and moisture content. Besides, the guiding significance for field application of this technique is elaborated.