Key Technologies of Rockburst Prevention-Oriented Surface Horizontal Well Staged Hydraulic Fracturing Under the Condition of Excavated Roadways

Abstract

Surface horizontal well staged hydraulic fracturing is an effective technique for preventing and controlling rockbursts induced by hard roofs in coal mines. For working faces with excavated roadways, the induced fracture network not only fully cover the hard roof across the entire working face but also avoid uncontrollable secondary damage to the roadways. Using a working face in Zhaoxian Coal Mine, Shaanxi Province, China, as a case study, this study investigates the key technologies for rockburst-prevention horizontal well fracturing from three aspects: optimization of the target key stratum within the thick hard roof, control of the horizontal well trajectory, and optimization of fracturing parameters. By integrating structural analysis of overburden strata, identification of rockburst-inducing layers, evaluation of energy release characteristics, and measurement of the development heights of the caving zone and water-conducting fracture zone, the target key stratum was determined to be located 51–64 m above the coal seam roof. Accordingly, the horizontal well was positioned within the siltstone layer at approximately 51 m above the coal seam roof. Based on geological features revealed by the roadways, the dip angle of the working face was corrected in real time, and a geological-guided model was developed to precisely control the horizontal section trajectory within the siltstone layer. Furthermore, parameter optimization ensured that the fracture network effectively covered the entire hard roof area while minimizing secondary roadway damage. Microseismic monitoring confirmed fracture heights of 52–55 m and lengths of 304–335 m, successfully covering the target roof. During coal extraction, 89% of monitored microseismic events exhibited low energy levels (0–10 3 J), with no high-energy events (≥10 4 J), demonstrating the effectiveness of the proposed rockburst prevention method. These results provide both theoretical support and engineering guidance for the optimal design of staged hydraulic fracturing in rockburst-prevention horizontal wells under excavated roadway conditions.