Wax Deposition Experiment with Highly Paraffinic Crude Oil in Laminar Single-Phase Flow Unpredictable by Molecular Diffusion Mechanism

Results are presented from two-phase flow wax deposition tests using a state-of-the-art, high-pressure, multiphase flow test facility. Wax deposition was found to be flow pattern specific and dependent on the flow velocities of the two-phase fluids. Wax deposition occurs only along the pipe wall in contact with a waxy crude oil. An increase in mixture velocity results in harder deposits, but with a lower deposit thickness. The wax buildup trend at low mixture velocities is similar to that observed in laminar single-phase flow tests. The wax buildup trend at high mixture velocities is similar to that observed in turbulent single-phase flow tests. Thinner and harder deposits at the bottom than at the top of the pipe were observed in horizontal and near-horizontal intermittent flow tests. For annular flow tests, thicker and harder deposits were observed at low superficial liquid velocity than at high superficial liquid velocity. In stratified flow tests, no wax deposition was observed along the upper portion of the pipe.

Download Full-text

Multiphase Flow Wax Deposition Modeling

Part B: Offshore and Arctic Operations; Pipeline Technology; Production Technology; Tribology ◽

10.1115/etce2001-17114 ◽

2001 ◽

Cited By ~ 5

Author(s):

Ahmadbazlee Matzain ◽

Mandar S. Apte ◽

Hong-Quan Zhang ◽

Michael Volk ◽

Clifford L. Redus ◽

...

Keyword(s):

Kinetic Model ◽

Multiphase Flow ◽

Single Phase ◽

Superficial Velocity ◽

Test Facility ◽

Intermittent Flow ◽

Phase Flow ◽

Single Phase Flow ◽

Wax Deposition ◽

Semi Empirical

Abstract Results are presented from two-phase flow wax deposition tests using a state-of-the-art, high pressure, multiphase flow test facility. Wax deposition was found to be flow pattern dependent and occurs only along the pipe wall in contact with the waxy crude oil. The deposition buildup trend at low mixture velocities is similar to that observed in laminar single-phase flow tests. The buildup trend at high mixture velocities is similar to that observed in turbulent single-phase flow tests. Thinner and harder deposits at the bottom than at the top of the pipe were observed in horizontal intermittent flow tests. Thicker and harder deposits were observed at low liquid superficial velocity than at high liquid superficial velocity annular flow tests. No wax deposition was observed along the upper portion of the pipe in stratified flow tests. A semi-empirical kinetic model tailored for the wax deposition tests predicted wax thickness with an acceptable accuracy, especially at high oil superficial velocity. Deposition rate reduction due to shear stripping and rate enhancement due to entrapment of oil and other mechanisms not accounted for by the classical Fick’s mass diffusion theory were incorporated through the use of dimensionless variables and empirical constants derived from the wax deposition data. The kinetic model, although semi-empirical, provides an insight for future model development.

Download Full-text