Drilling with large-diameter tubulars eliminates the need to run convetional drillpipe, wich then must be pulled to install permanent casing. It can mitigate lost circulation, enhance well control and reduce nonproductive rig time, and also decrease the risk of unintentional sidetracks or stuck pipe. Fewer trips into and out of a well, improved wellsite safety, increased efficiency and lower cost have led to an expanding range of applications that now includes casing directional drilling.