An overview of air/gas/foam drilling in Brazil

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.