Abstract: During drilling of B2, the first two -target8 1argedeviation directional well in Yanqi basin,wel1 trajectoryand sidewall stability were not effectively controlled,downhole accidentS occurred frequent1y,and dril1ing cycleprolonged.Through ana1yzing the causes of the downholeaccidents and problems, we studied the main drillingtechno1ogical problems in dri1ling directional wells inBa`onan block in the aspects of formation characteristics,wellbore structure and operation techniques and methods.