Abstract:The frequent water gushing in sandstone mining strata of Luohe Formation has seriously affected the safety production of the mine. The traditional grouting systems are faced with the problems of serious percolation effect and uncontrollable gelation performance, which is difficult to achieve effective regulation of fissure water. In this work, the microscopic characteristics of sandstone pores are clarified by analyzing the mineral composition and microscopic morphology of typical core samples. A solid-free polymer gel system with low cost and excellent stability is constructed for grouting, and the grouting performance evaluation is further carried out. The results show that the small pore diameter and poor connectivity are the geological reasons for the difficulty of smooth injection and long-distance migration of the traditional grouting systems. The noval polymer gel system with low cost, solid-free and easy injection for grouting can achieve gelation within 48h and has excellent long-term aging stability. The system has good injectivity and the pressure attenuation is not obvious after continuous flooding, with the plugging ratio remaining above 80 %. The system increases the seepage resistance and blocks the subsequent fluid by occupying the large channel or fracture space, which realizes the effective plugging of the water layer. The results of this work provide new ideas for the grouting and water plugging in Luohe Formation sandstone.