Variation of the wax deposit properties in radial direction in crude oil
The variations of wax deposit properties in radial direction in crude
oil pipe were investigated through flow-loop experiments. It was found
that the wax content and wax appearance temperature (WAT) of the surface
deposit were lower than those at bottom. Ranked from high to low, the
mass ratio of wax molecules heavier than the critical carbon number
(CCN) is the bottom deposit, surface deposit and crude oil, while in the
range lighter than the CCN, the order is just opposite. Microscopic
observations indicated larger amount and more rod-like wax crystals
existed in the bottom layer. Moreover, the bottom deposit was stronger
in structure and presented higher yield stress than the surface deposit.
The present work revealed and verified the significant differences in
the radial properties of the wax deposits, which should be considered in
future studies, especially with regard to the force on the pig.