Technology for increasing drilling speed in high abrasive hard formation

The formation in Ziliujin Group and Xujiahe Group in northeast of Sichuan has compact and highly abrasive rock, can lead to low mechanical drilling speed and high consumption of drill bit, so that it is the key formation which restrict the increase of drilling speed in this area. In order to increase the drilling speed, various new-type downhole tools have been applied, but the effect varies from one to another. Through calculation of rock drillabillity in rock stratum separation section, it is recommended to adopt the impregnated diamond drill bit in the areas from Ziliujin Group to Xujiahe Group, so as to improve the rock-breaking efficiency. In order to reduce the low drilling speed problem caused by failure of drill bit in hard formation and soft-hard alternating formation, the theoretical analysis on torsion and longitudinal vibration of typical drilling tool combination in Three Section has been carried out, so as to advise that, the torsional impacter should be used to help the PDC drill bit to reduce sliding effect in the formation above Dongyuemiao Section, the shock absorbing tool should be used or the drilling tool combination should be changed to reduce the longitudinal vibration in conglomerate-bearing formation in Zhenzhuchong Section, and the double-acting shock absorber or hydraulic thruster should be used to reduce the longitudinal vibration in sand slime formation. The combined drilling technology based on high-speed screw + impregnated diamond drill bit should be used to increase the orientation speed of large wellbore in areas from Ziliujin Group to Xujiahe Group. After the implementation of such technologies in 5 wells, the mechanical drilling speed has been doubled, the new degree of drill bit has been improved by 30%, and the orientation speed of ?311.2 mm wellbore in Xujiahe Group has been increased by 1.32 times.