Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Wax Deposition Experiment Under Cold Flow: A Transient Analysis
Submission Author:
Alexandre de Castro Martins , SP
Co-Authors:
Alexandre de Castro Martins, Ivanei Pinheiro, Letícia Bizarre, Charlie van der Geest, Vanessa Guersoni, Antonio Bannwart
Presenter: Alexandre de Castro Martins
doi://10.26678/ABCM.COBEM2021.COB2021-0822
Abstract
The Wax deposition is one of the biggest flow assurance problems when producing waxy crude oils, and because it is not completely understood, still contains several aspects that needs further investigation for better understanding of the phenomenon. When the temperature of the bulk is above the Wax Appearance Temperature (WAT), i.e. hot flow ($\bar{T}_{bulk} > WAT$), there are a lot of disagreement in the literature regarding the causation between the final thickness (steady-state) and the thermal driving force ($\bar{T}_{bulk} - T_{coolant}$), a more accurate way to correlate both is to use the fractional temperature difference $ \left( \frac{T_{int} - T_{wall_{in}}}{T_{bulk} - T_{coolant}} \right) $. However, for the cold flow ($\bar{T}_{bulk} < WAT$), the trend is better understood, the literature evidence shows that the final wax thickness is proportional to the thermal driving force. It is interesting to point out that the majority of experiments that observed those behaviours were executed with model oil. The first step of this research was to evaluate whether the same behavior occurs for Brazilian waxy crude oil under cold flow conditions. This work reports an experimental wax deposition study under cold flow conditions and varying conditions of temperature and flow rate to observe their influence on wax deposition rate. The wax deposition thickness was calculated using the pressure drop method. Another interesting analysis done in this research is the time necessary to reach steady-state by measuring the bulk temperature gradient ($T_{bulk_{in}} - T_{bulk_{out}}$), as the deposit increases, the temperature gradient between the inlet and outlet decreases, evidence that the energy being transferred from the oil to the coolant reduces as the deposit grows. Therefore, this is an easy methodology to investigate the transient time of the wax deposition, which could help the definition of PIG frequencies during production and improving both in reducing costs and stops in oil production.
Keywords
Flow assurance, Wax deposition, Waxy Crude Oil, Phase Transition Mode
