K&M was engaged by US DOE to survey technologies currently being used to horizontally drill for oil or gas using air instead of mud as the drilling fluid. The study identified areas where further developments in high-angle drilling with air might be most effective. It gave an overview of the current status of research efforts and industry perception of air drilling technology. The K&M survey also included techniques based on drilling horizontal wells with muds, a brief background in conventional horizontal drilling, and studies of individual wells.