A method for extending reach of a coiled tubing string in a deviated wellbore includes vibrating the tubing string while the tubing string is injected into the wellbore at a first injection speed, finding the peak speed of lateral vibration of the tubing string, determining a second injection speed as a function of the obtained peak speed of lateral vibration, and adjusting the injection speed of the vibrating tubing string from the first injection speed to the determined second injection speed based on said function. A non-transitory computer-readable storage medium to execute the foregoing method is provided, along with a system for extending reach of a coiled tubing string in a deviated wellbore.