Experimental Determination and Characterization of Wax Fractions Precipitated as a Function of Temperature

Abstract

Wax precipitation at low temperatures in petroleum mixtures is one of the most important problems in flow assurance. Experimental quantification of such processes and the further characterization of the precipitated mixtures are very difficult and extremely time-consuming, and therefore, the available experimental information is scarce and usually not very confident. In this work, wax samples were precipitated from two crude oils at different temperatures and they were characterized by optical microscopy, elemental analysis, 1H NMR spectroscopy, differential scanning calorimetry (DSC), and mass spectroscopy. The obtained results show the presence of different compounds in such mixtures regarding the chemical nature of the crude oil. The well-known presence of soaked crude oils in the precipitated fractions was experimentally estimated from 1H NMR and mass spectroscopy, and the obtained results suggest a decrease in the soaked crude oil amount as the precipitation temperature becomes lower, in agreement with the qualitative paraffinic content determined by elemental analysis. These values were used to correct the amount of solid wax precipitated experimentally and the final comparison between such corrected values and the precipitation curve calculated from DSC results shows a good agreement within the high experimental uncertainties.

Influence of wax inhibitor on fluid and deposit properties

“…The WAT measurements were performed using two different techniques: differential scanning calorimetry (DSC) (Coutinho and Ruffier-Méray, 1997;Martos et al, 2008;Rønningsen et al, 1991) and cross polarized microscopy (CPM) (Hammami and Raines, 1997;Zougari and Sopkow, 2007). Table 1 summarizes the results.…”

APCI(+)FT-ICR MS Analysis of Hydrocarbons Using Isooctane as Ionizing Reagent - A Comparison with HTGC-FID, GC×GC-MS and NMR

“…Finally, the presence of PAHs was also not detected in any of three samples in the GC×GC/q-MS data, being similar to NMR and APCI(+)FT-ICR MS results. [35][36][37][38] PAH standards and PAH/paraffin blends The ability of APCI(+) to ionize PAH standards was also evaluated. Six commercial standards were investigated, and their APCI(+)FT-ICR mass spectra are displayed in Figures S5a-S5f (SI section).…”

Badania laboratoryjne określające wzrost potencjału parafinowania wraz ze spadkiem temperatury

“…By oddzielić ciepło związane z ochładzaniem próbki od tego, które wydziela się podczas krystalizacji, należy ustalić linię odniesienia (tła). Wyznacza się ją przez połączenie punktów początkowych i końcowych na wykresie zależności wielkości strumienia cieplnego od temperatury [14].…”