Research and Application on Directional Drilling and Obstacle Bypassing Exploration and Release Technology for Old Goaf Water in the Downhole Goaf of Liyuanhe Coal Mine

The form of old goaf water accumulation is complex, the exploration and release difficulty is large, and the threat of water damage is serious in the 51104 working face goaf of Liyuanhe Coal Mine. In view of the problems of short drilling distance, uncontrollable trajectory, difficulty in bypassing obstacles and others in the traditional drilling method, a type of long-distance directional drilling exploration and release technology based on the "U"-shaped trajectory design is proposed. This technology combines SVR trajectory prediction algorithm, MWD system, and real-time trajectory measurement and control method to construct a drilling system that integrates trajectory planning, dynamic control, and risk avoidance, three-dimensional obstacle bypassing and precise penetration in old goaf water areas are innovatively achieved. In field applications, the cumulative drainage volume of No.1 borehole reaches 30 000 m³, with a maximum water inflow of 123 m³/h, the accumulated water level is successfully reduced from 54.1 m to 17.6 m, and the drilling penetration error is controlled within 1 m. The research results show that this technology exhibits high efficiency, safety under complex geological conditions, and it has promotional value.