Abstract: In the Two North exploration wildcats of the Tarim Basin,serious wellhole deviation and fierce conflict between anti-deviation and fast drilling occurred during the drilling from the bottom of the Permian to Silurian strata with conventional BHA.To resolve this problem,special VTK (VertiTrak) drilling system was tested in Well 1 of Abei Oilfield.As a closed loop automatic vertical drilling system,it can automatically activate the hydraulic parts,countering deviation by exerting a certain force against the borehole wall through one to two floor plates,and keeping the well vertical.The test results showed that,using the VTK vertical drilling system in the drilling of deep inclination prone strata in Well 1 of Abei Oilfield,the deviation angle of the well was controlled between 0.14° and 2.09°,for the majority of borehole,less than 1.00°;at the same time,the ROP increased up to 2.34-1.17 m/h for most of the well section(5 331.00-5 532.00 m,5 698.82-5 965.15 m),which was 17%-21% higher than that of conventional pendulum drill assembly.This suggested that the VTK vertical drilling system could solve the problem mentioned above,but in order to give full play to anti-deviation and fast drilling speed of the VTK vertical drilling system,bit selection,drilling fluid performance optimization and dealing with the complex downhole conditions need to be studied further for the system.