Drilling fluid foam

Foam Systems. The preparation, composition, and maintenance of foam completion and workover fluids is similar to that of foam drilling fluids. The advantage of foam is the combination of low density and high lifting capacity at moderate flow rates. The use of foam as a completion fluid can be justified by. 

The downhole turbine motor designed to be activated by the flow of incompressible drilling mud cannot operate on air, gas, unstable foam or stable foam drilling fluids. These downhole turbine motors can only be operated on drilling mud or aerated mud. 

Desirable foams Foam drilling fluid Foam fracturing fluid Foam acidizing fluid Blocking and diverting foams Gas-mobility control foams... 

The features of foam application in petroleum industry were summarised by Schramm [224], Thereafter only very few publications appeared on this subject, so that we mainly describe Schramm s concepts. First of all, these are foams which contribute to an enhanced efficiency of oil recovery foam drilling fluids, foam fracturing fluids, gas mobility control foams, and foam acidising fluids. 

Foams produced at a wellhead are usually undesirable. When a foam-drilling fluid is brought to the surface, defoaming is needed to prevent overfoaming of the pit or tank. This can be accomplished by adding a defoamer, such as a poly-dimethylsiloxane [24, 162]. In primary oil production, oil flows under its own pressure, through permeable porous rock formations, to a production well. When oil nears and enters the annulus of a production well, it experiences a decreased system pressure, dissolved gas may come out of solution, and the oil may foam. 

Gas/Liquid Systems Producing oilwell and well-head foams Oil flotation process froth Distillation and fractionation tower foams Fuel oil and jet fuel tank (truck) foams Foam drilling fluid Foam fracturing fluid Foam acidizing fluid Blocking and diverting foams Gas-mobility control foams... 

Figure 5. Schematic illustration of a foam drilling fluid system.

Well Site Safety. Containment of a foam drilling fluid into a closed loop system provides a measure of safety that open systems do not allow. Hydrocarbons, acid gases and oxygen depleted air are kept safely away from personnel. Additionally, open foam pits can create a hazard, as they are typically plastic lined pits, that could allow the unknowing person to slip in and possibly suffocate under a blanket of foam. 

Stable Foam. An oil and gas well drilling fluid foam that contains film-stabilizing additives, such as polymers or clays, and is pre-formed at the surface. See also Air Drilling Fluid, Foam Drilling Fluid, Stiff Foam. 

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