Effect of optimized pore structure on sealing performance of drilling sealing materials in coal mine

摘要

To enhance the drilling sealing material's performance, SiO2, sodium silicate, and styrene-acrylic emulsion are selected to optimize the pore structure. Through the uniaxial compression experiment, NMR, SEM, and combined with fractal theory, each substance's influence on the pore structure and physical strength of the sealing material is analyzed qualitatively and quantitatively. The results show that the synergistic effect of styrene-acrylic emulsion and SiO2 on cement performance improvement is better than that of a single substance. The porosity of the optimized material decreases by more than 13.49%, and the peak stress of uniaxial compression is increased by more than 18.08%. Besides, the styrene-acrylic emulsion can improve the material's elastic modulus and enhance the material's ability to resist harmful external factors. Sodium silicate can hinder the optimization effect of SiO2 and styrene-acrylic emulsion. Compared with ordinary cement, the peak stress of materials containing these three substances is reduced by 3.05%, and the porosity is decreased only by 0.73%. Comparing the fractal dimension of each material, SiO2 and styrene-acrylic emulsion increases the total pore fractal dimension (D-w) and the percolation pore fractal dimension (D-s) of the material. The fractal dimension has a positive linear correlation with the porosity, which indicates that the pore structure of the material is optimized, and the pore connectivity is reduced. (C) 2020 Elsevier Ltd. All rights reserved.