Core-annular flow in horizontal and slightly inclined pipes: Existence, pressure drops, and hold-up

Review of oil–water through pipes

“…In a core-annular flow, when the water becomes more dominant, it will encapsulate the oil film and be in contact with the pipe wall, thus it reduces pressure drop due to decrease in shear stress. The phenomenon of core-annular flow has also been explained thoroughly by Strazza et al [84] and Brauner [51], and sees also Bannwart [109] and Hasson et al [85]. However, in an experimental study by McKibben et al [102], they found that pressure drop was greatly associated with the phenomena of water slugs whereby water encapsulated the oil in the oil-water pipe flow.…”

“…Core annular flow helps in reducing the pressure drop considerably, thus this type of flow benefits the petroleum industry when it comes to transportation and handling of the heavy crude oil or highly viscous oil. There are more comprehensive core-annular experimental studies performed by Russell and Charles [7], Hasson et al [85], Bannwart [109], Strazza et al [84], and Vuong et al [36].…”

“…The main feature of core-annular flow is that it lowers pressure drop in a two-phase flow system. The study on core-annular flow has been investigated by Oliemans and Ooms [81], Bannwart [82], Grassi et al [61], Poesio et al [60], Ghosh et al [83], and Strazza et al [84]. The choice of the mixing device is an important step in the test planning in studying a core-annular flow of oilwater mixtures in pipes.…”

Mechanistic Prediction of Oil-Water, Two-Phase Flow in Horizontal or Near-Horizontal Pipes for a Wide Range of Oil Viscosities

“…8, the shear stress from the interaction of the annular phase and the pipe wall is given by (9) and the Blasius form of the Fanning friction factor is given by (10) where D a is the hydraulic diameter of the annular phase, calculated as . The shear stress at the interface between the core fluid and annular fluid is given by (11) Brauner (2003) recommended setting c I to 2 and 1.15 for laminar and turbulent annular phases, respectively, but here c I is set to 1.17 for all cases, as in Strazza et al (2011), because the cases used for comparison are expected to have a turbulent annulus flow. The Blasius form of the Fanning friction factor is given by (12) with waviness neglected at the interface.…”

An appraisal of viscous oil–water two-phase flow through an undulated pipeline in peak configuration

“…Core annular flow among the all is more significant because of low pressure drop and hence, minimum pumping power is needed for transportation of oil. This core-annular configuration is attained when viscous oil phase is surrounded by water annulus [23][24][25][26][27][28][29][30].…”