Cristina M.S. Sad

Salinidade em petróleo bruto: otimização de metodologia e proposta de um novo método para extração de sais em petróleo

The quantity of salts in the crude oils depends on the origin and of the wells production and these salts cause several problems during the transport and the process of refine as corrosions, incrustations and deactivation of the employed catalysts in the refineries. In this study were implemented changes for improvements in the execution of ASTM D 6470 method and has also developed a new methodology of extraction system of salts using process of mechanical agitation without heating. The results of the optimization produce larger efficiency and safety to the process compared to the traditional ASTM method.

Use of the Comprehensive Two-Dimensional Gas Chromatography (GC×GC-qMS) to Characterize The Classes of Saturated Compounds in Brazilian crude Oils

Brazilian oil production of pre-salt layer consists of oils with high content of saturated compounds. The identification of paraffinic and naphthenic compounds in these crude oils is key to understanding their rheological behavior. In the present study, comprehensive two-dimensional gas chromatography was performed to assess the greater separation capacity of products when compared with one-dimensional gas chromatography. Accordingly, it was possible to estimate relative the various classes existing in the saturated fraction of the crude oil. The results indicate that naphthenic compounds (53-77%) are more abundant than n-paraffins and iso-paraffins (22-46%) in nonpolar petroleum fractions from medium to low gravity, according American Petroleum Institute (API). Light oils showed high amount of iso-paraffins (37%), and the second most abundant class was the monocyclic compounds (30%). Crude oils with high pour point showed higher amount of heavy n-paraffins than oils with low pour point, suggesting a correlation between pour point and high molecular weight n-paraffins.

Study of the Corrosive Behavior of the AISI 1020 Steel in Acid Crude Oil by Microscopic Techniques (LM, AFM and SEM/EDX) and Raman Spectroscopy

Microscopic techniques were combined to study the influence of corrosion rate on the morphologic behavior of AISI 1020 steel specimens submitted to thermal degradation of a typical acid crude oil (total acid number (TAN) = 2.1390 mg KOH g and total sulfur (S) = 0.7778 wt.%). The techniques used were light microscopy (LM), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDX), atomic force microscopy (AFM) as well as Raman spectroscopy. Assays were performed in six different degradation time (t = 6, 12, 24, 36, 48 and 72 h) at 320 °C. After the exposure of the specimens to petroleum, a reduction above 37% in the TAN after t = 72 h was observed, with a maximum corrosion rate during the first periods of degradation (t = 6 and 12 h). Correlating the TAN and corrosion rate data with the microscopic data, the images of LM, AFM, and SEM/EDX showed that after 6 h of exposure to petroleum, a passivation film was formed on the surface of the steel. This film consisted of two layers, an external one, formed of FeS, and an internal one, composed of iron oxides and oxyhydroxides. However, after 48 h of thermal degradation, this morphology was altered to a single layer of FeS coating the steel surface.

Study of the Naphthenic Corrosion of AISI 316 and AISI 1020 Steels by Light, Scanning Electron and Atomic Force Microscopies (LM, SEM and AFM)

Corrosion processes were evaluated for AISI 316 and AISI 1020 steels by scanning electron microscopy (SEM), atomic force microscopy (AFM) and light microscopy. Coupons were immersed in four crude oil samples with different total acid numbers (TANs) for 48 days at room temperature. The steels were also exposed to three blends (B1-B3), produced by quaternary mixtures of the oils, with lower TANs than their respective original oils. SEM micrographs showed pitting-type corrosion in most cases. AFM imaging showed drastic changes in the peak-to-peak values, topographic profiles and phase images of the AISI 1020 coupons exposed to all oils and blend B3 as compared to the unexposed steel. Defects were produced on the surface of almost all the samples exposed to naphthenic corrosion. Exposure to the oil blends reduced the extent of the naphthenic corrosion on the coupons, especially blends B1 and B2. The oil mixtures (blends) reduced corrosion.

Improvement on Pour Point of Heavy Oils by Adding Organic Solvents

This paper describes pour point behavior of three heavy oils with the addition of kerosene, turpentine, toluene and gas condensate. The study showed a decrease in the pour point of all oils that relates with the oil chemical composition. The oil with lower API gravity (higher amount of asphaltenes and resins) showed higher pour point decay for all solvents, highlighting gas condensate and turpentine. The use of gas condensate to reduce the pour point of heavy oils is particularly advantageous, when available in the oilfield. Prevent the stoppage in the oil production, due to clogging and flow problems in the pipelines, and facilitate the logistics, reducing process operational costs