The DOE microhole coiled tubing drilling project aims to reduce the cost of drilling and completing a well by using coiled tubing to drill a microhole. Past experience has shown that a sufficient level of action must be sustained to keep the unit operating if the cost of drilling a well with coiled tubing is to be reduced. The development of microhole completions is relatively recent and the supplier base and available tools are limited. For the purposes of this study, therefore, rather than designing a unit exclusively for the microhole completion market, a maximum completion size has been determined that will maximize the unit's potential by enabling it to be used by a greater portion of the drilling market. Based on research into current shallow well drilling areas and the types of completions involved, a theoretically ideal wellbore schematic has been developed with a maximum total measured depth (TJVID) o f 6,000 ft and a final completion size no greater than 4-1 / 2 in., bearing in mind that a surface and intermediate string might also be needed to isolate different hole coalitions. The conductor will be rotary-drilled in all completions, requiring the use of a device to rotate the drill pipe or auger. Chapter 10 of this study discusses continuous rotary devices.