Putaohua reservoir is the main target layer for exploration appraisal well in middle-shallow layer of periphery of Daqing oilfield, but it is a ＂three low＂ reservoir, the conventional drilling will cause high cost and low benefit; and by the characteristics of ＂three low＂ reservoir, the filtrate under differential pressure is harmful to reservoir. The formation charac- teristics and overbalance drilling result in low single well production. As a circulating medium of gas drilling in the reser- voir, nitrogen has obvious advantages in the reservoir discovery and protection. The nitrogen drilling practice was made in Putaohua reservoir in middle-shallow layer of periphery of Daqing oilfield in 2011, technological innovation was carried out in the well structure, drilling technology and completion methods, the average penetration rate reached 24.43m/h in the 4 test wells, which was more than 2 times of that of adjacent wells by conventional drilling technology. Oil flow was found at sand draining outlet in the drilling process with good reservoir protection effects.
