What Does Film Area Mean?
Film area is one of the areas formed by the liquid in the pipe transporting the fluid. Some pipelines transport gas and liquid together called the two-phase flow, and form different flow patterns. One flow pattern is the annular flow in which a slow-moving film of liquid moves along the pipe walls with the gas moving fast in the center of the pipe.
In the tubing, the gas forms three areas namely, gas column area, film area, and slug area.
Trenchlesspedia Explains Film Area
When liquid is present in the natural gas well, there is an increase in the pressure drop in the well due to the difference in density of the pressure head. In the annular flow pattern, the gas moves fast in the center of the pipe while a thin film of liquid slowly moves along the pipe walls. This liquid may be present as a film or as entrained droplets.
The film has two parts, a base film and a layer with wavy disturbance, the behavior of which and its interaction with the gas component determines the amount of entrained liquid. The characteristics of the liquid film and the entrained layers are affected by gravity, shear stresses, and drag forces.