Research and application of casing milling and fishing technology in floor comb-shaped directional borehole

In order to solve the problem that using the conventional strong-force rotary drawing process for borehole sticking accident in comb-shaped directional borehole in floor is not ideal, and using reverse thread drill pipe or strong twist cause big time and economic loss, through the calculation and analysis of the passing capacity of casing milling and fishing pipe in the curved hole, the technical parameters of casing milling and fishing, the sticking accident of floor comb-shaped directional borehole with the depth of 344 m in a coal mine in Henan Province was successfully solved. The application results show that the maximum hole curvature for the existing casing milling and fishing pipe to pass through is large. The rotation speed was controlled at 30-50 r/min in the process of casing milling and fishing, and the drilling speed was controlled at 6-12 m/h, the borehole was washed with fluid every 12-15 m. The adoption of this set of milling and fishing technology and equipment can effectively improve the success rate of drilling sticking accident treatment in floor comb-shaped directional borehole.