Research and development on foam breaking and recycling technology in air-foam drilling

In recent years,air-foam combining the advantages of both liquid and air drilling has been utilized as a drilling medium. Air-foam drilling has proved its efficiency in numerous situations where serious problems were encountered,such as in fractured formations and depleted or high permeable zones. However,the major disadvantage of air-foam drilling system is that the foam can only be used once,so that an extremely large pit is required to contain the foam to allow sufficient room for cuttings and for the foam to dissipate. Moreover,it needs enormous volume prepared,consuming abundance of water and ingredient additives,which results in the high cost of foam drilling. The recycling foam fluid by using foam breaking technology is the only effective method to solve these problems associated with the known foam drilling. Various types of equipment and technique have been employed to suppress foam formation in biological and process equipment in foam drilling. The study described various methods of foam breaking technology,and the trend of the foam breaking technology for foam drilling is discussed.