A type of drill collar whose cross section is square instead of circular as in a more conventional collar. Square drill collars are used to prevent or minimize the chances of becoming hung up or stuck in a dogleg downhole. The square corners on the collar, which is located just above the drill bit in the string, act as a reamer and to tend to keep the hole passable for the drillpipe,Drill collars were once a few feet long and weighed 400 or 500 pounds. Today, because of increased bit pressure and rapid rotation, collars are made up in 1,000-foot lengths and weigh 50-100 tons.
