For modern directional drilling they use what is called a "mud motor": https://en.wikipedia.org/wiki/Mud_motor https://en.wikipedia.org/wiki/Mud_motor You bas

For modern directional drilling they use what is called a "mud motor": https://en.wikipedia.org/wiki/Mud_motor https://en.wikipedia.org/wiki/Mud_motor You basically use the drilling mud that circulates through the hole anyway (providing counter pressure, cooling, lubricataion, bringing up cuttings) to run a motor that rotates the drill bit. This way the drill string does not need to rotate & you can even change the direction by manipulating the angle of the drill attached to the mud motor.