Calculation method of gas extraction ratio from different seams in crossing holes and its application

To measure the gas extraction ratio and the residual gas content of different seams during gas extraction of multiple seams through crossing boreholes, the paper put forward the corresponding solutions respectively. It was proposed that when calculating the gas extraction ratio of different seams during gas extraction of multiple seams through crossing boreholes, the product of the seam thickness, the primitive gas content and the permeability coefficient were used as the correlative parameter of gas extraction, Determining the multi-seam gas extraction borehole gas extraction ratio of each layer, proposed coal seam thickness, the original gas content, the product of permeability coefficient as the amount of extraction-related, the extraction-related normalized is calculated, considering the main influence factors of penetration borehole gas extraction. When prediction residual gas content of penetration borehole extraction multi-seam gas, the original gas content and gas extraction volume of each ton were used, gas extraction volume of each ton is related with penetration borehole total gas extraction quantity, gas extraction ratio in the coal seam, and the coal seam reserves. The results showed, the method multi-seam gas extraction borehole gas extraction ratio of each layer proposed, the maximum relative error is 2.03% compared with measured results on site, can meet the need of engineering practice.