Stable/Stiff Foam Drilling is a mixture of fresh/salt water, surfactant, and appropriate chemical additives. It acts in the manner of a drilling fluid, cleaning the hole by suspending and carrying the cuttings out of the wellbore. When properly formulated to produce an apropos liquid volume fraction, stable foam exhibits superior hole cutting carrying capabilities to that of a drilling liquid.
The significantly lower air volumes needed to implement a stable foam system, results in markedly reduced equipment requirements, particularly in large diameter holes. As well, the subsequently low annular velocities keep hole erosion in unconsolidated formations to a minimum.
Stable foam is used in wells that have relatively low reservoir pressures. Stable foam is exceptional for drilling more than one horizontal hole in the same wellbore, cased hole sand cleanouts, milling cased hole packers, and drilling out cased hole plugs. As with other air systems, stable/stiff foam drilling/workover results in penetration rates and bit footages that are superior to a corresponding direct drilling mud or reverse fluid system.
Click image to see an expanded view of the Stable/Stiff Foam Drilling Layout.