Application of nitrogen underbalanced drilling technology in drilling deep directional wells

The traditional underbalanced drilling technology cannot solve the problems of the low penetration rate and simple reservoir protecting measures in the west Sichuan interval of more than 3000 m.The Southwest Subsidiary Company introduces nitrogen drilling technology to better protect and discover hydrocarbon reservoirs and advance the success rate of deep well exploring.Based on large amounts of geological and engineering appraisal,application test of nitrogen drilling technology is conducted in the producing interval of 4652.26~4775.56 m during the fourth spudding in DY1 well.The test shows that the application of the new technology has brought good effect and greatly increased the drilling speed.The average rate of penetration of the interval reaches as high as 8.36 m/h,8~9 times higher than that of the offset well,meanwhile,a fractured gas reservoir is discovered.The successful application of the new technology in exploring deep wells accelerates the popularization of the gas drilling technology and can be a good reference for drilling in similar regions.