Definition - What does Two-Phase Flow mean?
Two-phase flow refers to the flow in which oil and gas flow together into a wellbore. It is characterized by the presence of flow patterns representing the physical distribution of gas and liquid phases in the pipeline or conduit. The phase distribution is influenced by forces such as buoyancy, inertia, surface tension, and turbulence.
The magnitude of these forces, in turn, depends on the diameter of the pipe, the inclination of the pipe, the flow rate, and the fluid properties of the flowing phases.
Trenchlesspedia explains Two-Phase Flow
The two-phase flow forms different flow patterns such as 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. In some operating conditions, the liquid and gas are not evenly distributed but travel in pockets of liquid and gas.
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. When the flow pattern is smooth, the liquid will flow at the bottom of the pipe as gas flows over the top but the velocity of the gas is low.
In a dispersed flow pattern, the pipe is assumed to be completely filled with liquid with entrained gas in small amounts in the form of bubbles.