Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
EXPERIMENTAL INVESTIGATION OF THE TEMPORAL AND RADIAL VARIATION OF THE COMPOSITION OF WAX DEPOSITS FORMED IN AN ANNULAR TEST SECTION
Submission Author:
Alice Machado , RJ
Co-Authors:
Alice Machado, Ricardo Linhares, ivan fernney ibanez aguilar, Luis Fernando Alzuguir Azevedo, Angela Nieckele, Felipe Fleming
Presenter: ivan fernney ibanez aguilar
doi://10.26678/ABCM.ENCIT2022.CIT22-0130
Abstract
Wax deposition in subsea oil production and transportation pipelines is a relevant problem for the industry. For decades, efforts to build models capable of predicting the phenomenon have been carried out in order to minimize significant production losses, as well as costs for the the removal of wax deposits that may form on the internal surface of the pipes. When the oil from the reservoir is cooled below a critical temperature, wax crystals precipitate leading to the formation of deposits that, later, are enriched of heavier paraffin fractions. This critical temperature is called WAT – Wax Appearance Temperature. In the present work, controlled experiments were carried out in a laboratory scale test section with a test solution consisting of 20% paraffin, and 80% solvent, and a WAT of 35.6°C, to investigate the deposit aging effect for different cold wall temperatures, cooling rates, and Reynolds numbers. The experiments durations ranged from one to seven hours. A deposit sampling port allowed rapid removal of the deposits avoiding significant changes in the deposit composition during the sampling. The two cold wall temperatures investigated (WAT-23.6°C and WAT12.6°C) showed that the composition differences only begin to be significant approximately two hours after the deposit has reached its final thickness. The three Reynolds numbers investigated presented a small influence on the deposit composition. In addition, for one of the cold wall temperatures, at the high cooling rate, the radial concentration of the deposits was investigated by using a device to slice the samples precisely in half. It was found that the part closer to the hot flowing oil was enriched in heavier carbons, while the half closer to the cold wall did not present significant changes with time.
Keywords
Wax deposition, wax composition, Deposit slicing, Deposit aging, Molecular Diffusion
