The presence of waxes in crude oil can lead to the formation of wax deposit
s on the walls of cold subsea pipelines, which restricts flow and can lead
to plugging of the pipelines This problem has recently become more signific
ant as the production wells move further offshore causing the oil to be coo
led below the cloud point before reaching shore. Wax deposition was studied
in the laboratory under conditions simulating the deposition in a subsea p
ipeline Wax deposition is initiated by the precipitation of wax directly on
the pipe wall and the formation of a network of wax crystals (wax-oil gel)
with significant amounts of oil trapped in it. Radial diffusion of the wax
molecules from the bulk solution to the gel deposit causes it to simultane
ously gr-ow and age with time. The, wax molecules diffusing into the gel de
posit precipitate near the interface resulting in a faster aging rate of th
e deposit near the interface than that near the wall This nonuniform aging
of the wax deposit causes the evolution of complex morphologies of the wax
deposits. The diffusion of wax molecules into the gel matrix was analyzed t
heoretically dining the growth of the wax deposit. This mathematical model
predicted the radial variation of the morphology of the wax deposit observe
d in the laboratory flow loop experiments along with The deposit thickness
as a function of time.