Foam systems are primarily water systems with either air or nitrogen injected into the system. Mechanical equipment includes compressors, drillstring floats, a rotating control device, a separator, and a flare. The gas source (compressor, etc) is a major cost in this group.
Foam system has been used for solving problems in both drilling engineering and reservoir engineering in oil and gas fields. It can be adopted to continue gas drilling when there is too much water influx to handle by gas drilling and severe borehole collapse problems. In this case, the drilling process can continue with little sacrifice in ROP. Other drilling applications of foam drilling are found to reduce drilling complications such as loss of circulation during drilling low-pressure or naturally fractured formations. In the aspect of reservoir engineering, foam system is used to drill-in pay zones underbalanced for reducing formation damage and thus improving well productivity. Favorable conditions to drilling with foam system include (Lyons et al., 2009):
Foam systems can be used in the oil and gas industry for drilling both exploration and field development wells. Logistics issues limiting its applications include availability of chemical additives, destroy/reuse of returned foam, storage of produced oil, and technical services such as EMWD survey.
