Drilling method for enlarging a borehole using a kick sub

摘要

A drill string is fitted at the lower end with a drill string deflecting apparatus and a drill bit. The drill string deflecting apparatus is activated to deflect the drill bit from the general center line of the drill string. Drilling proceeds to enlarge a length of larger well bore. The drill bit is lifted to allow the lower end of the drill string to move, by gravity, to the low side of the enlarged well bore. The drill string deflecting apparatus is straightened and drilling bit load is applied to drill ahead along the extended center line of the lower end of the drill string.