Resumo:
Oil reservoirs containing heavy paraffinic compounds can precipitate with decreasing
temperature, forming a solid phase called wax. This wax precipitation is a problem for
the oil industry, affecting all oil production steps. The wax may be deposited as a solid
layer on pipes, and this layer may completely block the pipeline when not mechanically
removed. Part of this solid precipitated, when not deposited, becomes solid particles
through the liquid phase such as a slurry. These suspended particles increase the
apparent viscosity of oil, affecting the flow. A challenge to the petroleum industry is to
prevent the formation of this undesired solid and at the same time to reduce the costs
with methods such as heat treatment and use of chemical inhibitors, for example, which
are used to prevent the precipitation of wax. Therefore, it is necessary to specify the
conditions under which precipitation can occur as a function of pressure, temperature
and oil composition. Despite all the research efforts already made, there is not an ideal
model or method for predicting oil wax precipitation. Many of the proposed models
were used to estimate the precipitation of synthetic oils, which does not solve the real
industry problem for predicting oil wax precipitation. The main objective of this work is
to propose a simple and easily applied model to the prediction of wax precipitation in
oil through the calculation of Wax Appearance Temperature (WAT). In this context
this work proposes new simple methods for obtaining WAT, requiring few input data
and without the need for complex calculations. Through the proposed methods the
WAT can be estimated from data of molar fractions and molecular weights of the lighter
fractions. These methods have been tested with several experimental data, obtaining
good results despite its simplicity.
