Horizontal air drilling
Drilling with air instead of mud has a strong economic advantage because of the increased rate of penetration. Since the total cost of drilling is related to the time it takes to do it, there is clear advantage to minimizing the time to finish drilling wells. Air compressors used for air drilling are still quite expensive. Nevertheless, air drilling is a cost efficient, thoroughly proven technology that may be rapidly deployed.
When it comes to using air for horizontal drilling one disadvantage is the lack of any Measurement-while-drilling (MWD) tool. There is an electromagnetic MWD tool which works in an air environment, but there are reliability issues with the device.
Another limitation with horizontal drilling is the very slow rate of penetration with downhole motors in harder rock formations. Downhole motors are far less efficient with air than they are with drilling mud.