Abstract In order to reduce water requirements for drilling on their desert concession area, Petroleum Development Oman (P.D.O.) made a 12-month trial of air-drilling techniques. By using foam as a circulating medium, top-hole sections can now be drilled with only 30 bbl/hour water-supply, where previously 500 bbl/hour were needed to drill with total losses. Cores of friable, fractured formations have also been successfully taken using foam as circulating medium, where previous attempts at coring failed. So successful were the trials, that the initial contract has now been indefinitely extended so as to include an air-drilling package as a permanent part of the drilling fleet.