Air, gas, and foam drilling has been used in specific areas in Brazil as an
alternative to the traditional drilling process. This work focuses on the
benefits and operational improvements obtained with those two-phase flow dr
illing operations. The comparison between the performance of conventional a
nd two-phase flow drilling has been showing that this technique, when appro
priately used, presents some advantages: (1) minimum or no damage to sensit
ive pay zones, (2) immediate and continuous evaluation of cuttings for hydr
ocarbon shows, (3) avoidance of lost circulation, and (4) higher penetratio
n rates in hard formations. This work shows recent on-shore two-phase flow
drilling field cases in Brazil using both, jointed pipe and coiled tubing t
echniques. The results obtained in those wells are analyzed and also the su
rface equipment design, the appropriate technique for connections, as well
as the comparison between field data and predictions from simulators are di
scussed. Future plans for two-phase flow drilling operations in Brazil are
and commented. Additionally, potential areas and concrete actions for impro
ving operational feasibility of this technology are identified. The target
is a safer and more economical air, gas, or foam drilling operation.