INVESTIGATION OF ASPHALTENE PRECIPITATION AT ELEVATED-TEMPERATURE

In order to obtain quantitative data on the asphaltene precipitation i nduced by the addition of n-alkane (heptane) at temperatures above the normal boiling point of the precipitant, a high temperature/high pres sure filtration apparatus has been constructed. Oil and alkane are mix ed at the appropriate temperature and the pressure in closed vessels k eeping the mixture at the liquid state. The filtration is performed wi th a small differential pressure over the filter so as to avoid flashi ng the mixture. The technique requires a low dead volume in the system to minimize the content of maltenes in the extracted fraction, hence there is no room for stirring. The equipment as well as solutions to s ome of the problems are presented along with precipitation data from 4 0 to 200 degrees C. The asphaltenes separated are analyzed using FT-ir . The filtrate containing the maltenes was cooled to room temperature and the asphaltenes separating upon cooling was collected and analyzed . The oil and selected maltene fractions and extraction/cleaning solve nts were analyzed using GC.