Study on the effect of acidification on the increase of permeability in different seam directions of high rank coal
In order to study the effect of acidificationon the permeability enhancement of high rank coal in Sihe Mine in vertical and parallel bedding directions,This study carried out the dissolution tests of multi-component acid pulverized coal and coal column,optimized the appropriate acid solution system for acidification,and analyzed the acidification dissolution effect of coal column in two bedding directions under different acidification duration.And triaxial adsorption desorption seepage experiment and low field nuclear magnetic resonance experiment of coal and rock of coal pillars in two bedding directions before and after acidification were carried out,and the changes of permeability,porosity and pore size distribution of coal pillars in two bedding directions before and after acidification were compared.The results show that:(1)After the dissolution experiment of pulverized coal,it is found that the acid solution ratio of 2％HCl+2％CH3 COOH+5％HF has the best dissolution effect;(2)After the coal column dissolution experiment,acidification makes the porosity of coal column in the vertical bedding direction increase more than that in the parallel bedding direction,and the coal column in the parallel bedding direction can reach the maximum increase faster;(3)After acidification,the permeability and porosity of coal pillars in the vertical and parallel bedding directions are increased.The former has a larger increase in porosity,but the increase in permeability is less than the latter,and the increase in permeability of coal pillars in the two bedding directions is the smallest at the inflection point of slippage effect;(4)By comparing the pore size distribution of coal pillars in the two bedding directions before and after acidification,it is found that acidification reduces the proportion of gas adsorption pores in coal pillars in the two bedding directions,and the proportion of coal pillars in the parallel bedding direction is greater,and the proportion of medium and large pores before and after acidification is higher;It is determined that after acidification in Sihe Mine,the direction of coal sample parallel to bedding is taken as the direction of gas drainage in borehole,which can better improve the gas drainage rate.
safety engineeringacidificationdissolution rateNuclear Magnetic Resonance(NMR)permeabilityporositypore size distribution
NETL
NSTL
万方数据
维普
