Abstract:
In recent years, with the large-scale development and utilization of Jurassic coal resources in western China, the impact and threat of water damage to the coal seam roof has become increasingly apparent. In order to stop the water leakage in the overlying aquifer of the coal seam and to reduce the water inflow in the target area, a technical method for preventing and controlling water in the roof of thick sandstone flood damage is proposed. This method adheres to the concept of “water-preserving coal mining”, is based on fine exploration, takes precise grouting as the main engineering method, and has been applied in Gaojiapu Coal Mine in Huanglong Coalfield. First, the natural gamma curve (GR) is selected as a sensitive curve that can distinguish sand and mudstone in the study area, and the lithological distribution pattern of the overlying strata of the coal seam is precisely interpretated by the waveform indication inversion. On the basis of lithologic interpretation and pumping test results, the response characteristics of different aquifers in the overlying strata in the study area are analyzed. The water-rich distribution of the overlying strata of the coal seam is characterized by combining lithology, shale content (VSH), spontaneous potential (SP), and porosity (POR). The interpretation results show that the most hidden danger to coal seam mining is the upper layer of the middle section of the Luohe Formation(K1lm). The rock formations in this area are mainly medium-coarse-grained sandstone, which is a medium-strong water-rich aquifer. Then, the primary fissures in the overlying strata of the coal seam are finely described by using the multi-attribute fusion technology. The distribution law in the longitudinal direction has the characteristics of intermittent distribution, and the development has the characteristics of segmentation, and it is relatively concentrated in the middle and lower members of the Luohe Formation. On the plane, the main development direction of fractures is NW-NWW. With the well 27-2 as the boundary, the upper fractures are relatively developed. Finally, considering the lithology, water-rich and primary fracture distribution characteristics of the overlying strata of the coal seam and the prediction results of the development height of the water-conducting fracture zone, the bottom of the middle section of the Luohe Formation is selected to be grouted through horizontal holes. The project can strengthen the weak stratum and block the water discharge in the middle and upper sections of the Luohe Formation. After surface pre-grouting treatment, the mine water inflow is reduced by more than 1000 m
3/h during the mining process of the 204 working face. At the same time, the production conditions are improved and
350000tons more coal resources are recovered than the adjacent working faces, which provides a feasible method for controlling the water damage of thick sandstone in Huanglong Coalfield.