Definition(s)
Multiphase flow
The simultaneous flow of gas and liquid, commonly referred to as multiphase flow, occurs in almost every aspect of the oil industry. Multiphase flow is typically present in the wellbore, flowlines and topsides processing facilties and is of particular importance in subsea production systems, where the feasibility and cost of the production facilities is directly linked to the fluid flow charateristics.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards