Extension tool for directional well and horizontal well

The invention discloses a directional well and horizontal well extending tool which comprises a shell, an impeller is rotationally connected in the shell, a rotating disc is connected above the impeller, the rotating disc is eccentrically connected with a rack, the rack is meshed with a gear, the lower portion of the gear is connected with a steering gear through a gear shaft, and the bottom face of the steering gear is connected with a driving wheel. The axis of the driving wheel deviates from the axis of the gear; and the rear lower part of the shell is connected with a driven wheel. The driving principle is a centrifugal rule and a curve force rule, the driving wheel periodically swings, the friction force of the well bottom wall surface to the edge of the driving wheel can generate a forward pushing effect, and the alternating transverse component of the friction force enables the extension tool to have a unique form of snakelike swimming, so that the problems of high friction resistance, serious supporti