Simulação da precipitação de parafinas no escoamento bifásico unidimensional

Abstract

Wax precipitation may lead to obstruction of pipelines generating significant economic losses. Petroleum reservoirs, especially in sea areas present extreme conditions of temperature and pressure. During production, the fluid flow inside the pipeline, the temperature of the fluid tends to decrease due to the heat transfer to its neighborhood and phase change (vaporization) leading to wax precipitation and deposition of paraffins on the pipe wall. Within this context, here the Multi-Solid Model was used to calculate the WAT (wax appearance temperature) of a fluid with known composition and the Drift-Flux Model of two-phase fluid flow was used to find the point where it may precipitate inside the pipeline. A paraffinic mixture with four compounds was used in the simulations. It was observed that the effect of pressure can be considered negligible on WAT calculation, for the studied case. Analyzing the effect of the fluid compostion, the more content of light compounds (CH4 e CO2) in the mixture, the lower will be the WAT, at constant pressure. For two different cases, it was found the point inside the pipeline where the fluid began to deposit solid particles on the pipe wall. Also, it was developed an algorithm to calculate the minimum temperature at the beginning of the pipeline to avoid the wax precipiation along the pipeline.