For well pattern infill and large-scale comprehensive arrangement of newly drilled adjustment wells in LD oilfield of northern Bohai, 25 new wells cross with old well pattern and three-dimensional winding of borehole trajectory result in all the wells are three-dimensional designed with serious wellbores crossing problem, the typical case is C6H horizontal well which should be directional deflecting drilled in the Guantao formation basal conglomerate layer with extremely poor drillability. Aiming at the above, through the comparison and analysis on 3 kinds of trajectory scheme for C6H, the most favorable design is optimized; combined with the performance analysis on the screw motor and rotary steerable tools, new mode of DHA with screw motor hydro-oscillator micro eccentric stabilizer is adopted, C6H has been smoothly completed.