The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper deals with the relation between the rheological properties and the structure of waxy crude oils cooled in quiescent conditions and under flow. In the dynamic regime, measurements were performed on gels cooled slowly in order to allow paraffin crystallisation in equilibrium. The amounts of crystalline material vs. temperature were measured independently by differential scanning calorimetry...
The gel formation in waxy crude oils is a major concern for oil production and transportation. When oil is extracted, the decrease in temperature induces a partial crystallisation of paraffins by a supersaturation mechanism, involving in the first place the longest alkane molecules. Gel formation appears for very low amounts of crystals (around 1–2%) when the oil is cooled in quiescent conditions...
The electrically induced coalescence of water-in-oil emulsions stabilized by interfacially active fractions from crude oils has been studied by means of time domain dielectric spectroscopy at high electric fields. The experiments were designed with a 2 7-3 reduced factorial design. Regression analysis clearly shows that the choice of organic solvent and the amount of asphaltenes, as well as...
This paper presents the results of an experimental study of the determination of wax appearance temperatures (WAT) of 15 crude oils by differential scanning calorimetry (d.s.c.), thermomicroscopy and viscometry. Good agreement is obtained among the three techniques for crude oils having a significant precipitation rate. Considering the great diversity of crude oils, it is concluded that d.s.c. and...
The behaviour of different types of water-in-oil emulsions in high electric fields as investigated by means of time-domain dielectric spectroscopy (TDS) is reported. The studied emulsions include true crude-oil-based ones as well as model systems stabilised by indigenous crude oil fractions or, alternatively, by commercial nonionic surfactants. It is seen that the developed TDS equipment gives a...
Using differential scanning calorimetry (d.s.c.) apparatus, an experimental procedure has been developed in order to determine the wax content of 29 crude oils from several sources. The amount of wax, which is obtained with good reproducibility, is higher than the values obtained by gas chromatography (g.c.). In fact, g.c. evaluates n-alkanes and d.s.c. evaluates the total amount of crystallized...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.