TECHNOLOGY OF PREVENTING DEVIATION TO DRILL VERTICALLY IN WELL PUGUANG 3

The top stratum of Puguang 3 well belongs to highly steep structure, and its obliquity is big which result in borehole deviation. Drillability of the stratum is poor, and bit bouncing is severe. Preventing borehole deviation to drill vertical well of the top stratum are difficulties of constructions. During drilling, pendulum drill assembly, tower type make - up of string composed of large diameter drill collars and screw drill tool were applied in the well. Application effect showed that bit pressure was required small to prevent borehole deviation when pendulum make - up of string was used in the surface layer, which restricted drilling speed; tower type make ?up of string composed of large diameter drill collars had a better effect on preventing borehole deviation, and it could effectively improve the drilling speed when matching with suitable drilling parameters and optimizing selection drill bit type, screw torque make - up of string was a more active measurement of preventing borehole deviation which is necessary to be further explored.