Casing drilling, a process for simultaneously drilling and casing a well, is emerging as viable technology. The concept builds upon experience gained drilling liners to bottom in troublesome holes. With the advent of dependable top-drive systems, wire-line-retrievable bottomhole assemblies (BHA's), polycrystalline diamond compact (PDC) bits, and high-torque connections, it is possible to simultaneously drill and case a complete well by use of casing as tbe drillstring.