Experimental Measurements of Wax Precipitation Using a Modified Method of Simultaneous Centrifugation and High-Temperature Gas Chromatography

Wax precipitation and deposition are serious flow assurance problems. Wax precipitation is investigated simultaneously using centrifugation and high-temperature gas chromatography (C-HTGC) to obtain the amount and component distribution of precipitated wax in artificial waxy oil and diesel at different temperatures. However, the conventional C-HTGC method gives upper measurements of the amount of precipitated wax, as it ignores wax dissolved in crude oil in the centrifugal cake. A modified C-HTGC method was developed to obtain the precipitated solid fraction of crude oil, based on the mass balances of the non-crystallized fraction of the centrifuged cake. The weight, percent and carbon number distribution of precipitated solid wax crystals at different temperatures of artificial oil and 0# diesel were obtained. It was found that wax precipitation characteristics are affected by many factors, including the carbon number distribution of the oil, the sensitivity of alkane crystallization to temperature and the temperature of the waxy oil solution. The average carbon number of alkanes in precipitated wax crystals decreases with the decrease in temperature. The distribution of alkanes in solid wax crystals is roughly the same as that in 0# diesel but slightly heavier than in diesel. Alkanes with high carbon numbers precipitate simultaneously with those with low carbon numbers.

Correlation between Phase Behavior and Interfacial Tension for Mixtures of Amphoteric and Nonionic Surfactant with Waxy Oil

Phase behavior tests in the surfactant screening process for EOR applications remain one of the relatively convenient ways to design an optimum surfactant formulation. However, phase behavior studies are unable to provide quantitative data for interfacial tension, which is one of the parameters that must be considered when selecting surfactants for EOR. Several studies related to the prediction of interfacial tension through phase behavior testing have been carried out. In this paper, the Huh correlation was used to estimate the interfacial tension value based on phase behavior tests. It was found that the current form of the Huh correlation may be applied for the below-to-optimum salinity condition. Furthermore, the constants of the equation vary depending on the surfactant type and mixtures.

About the effectiveness of hydrocarbon diluents for pipeline transportation of high viscosity heavy and waxy oil

Deposits of tight high viscosity heavy and waxy oil are becoming increasingly important in the world economy. They are also of particular importance in Russia, where the fields of easy accessible oil are practically depleted, and the newly discovered ones are located mainly in the northern latitudes of the country, which complicates their delivery to places of consumption, and use of so-called "special methods" (heating, chemical reagents) leadsytanb to an increase Cost. Despite the abundance of such methods, one can distinguish one of the most accessible and understandable from the point of view of the physico-chemical effect - dilution with hydrocarbon diluents, as can be effectively used by adding ready-made motor fuels and light distillates of oil, as well as - cheaper stable gas condensate, also co-produced in oil fields.In the present work, the experience of blending high viscosity heavy and congealing waxy oil with various types of hydrocarbon diluents has been considered with the aim of improving the operational properties of hydrocarbon crude, the transport and processing of which are associated with high costs due to the peculiarities of the composition and properties of the oil. The results of laboratory experiments on dilution of heavy and congealing oils with diesel fuel and stable gas condensate are given, on the basis of which recommendations on the effective usage these special methods. Keywords: oil; rheology; effective viscosity; pour point; hydrocarbon diluent; stable gas condensate.

MODIFICATION OF COPOLYMERS BASED ON OLEFIN AND MALEIC ANHYDRIDE AS POUR POINT DEPRESSANT FOR WAXY OILS

In this work, we investigated a modification of a copolymer based on α-olefin (octadecene-1) (ODC) and maleic anhydride (MA) synthesized by the method of initiated radical polymerization. In the studies carried out, it was revealed that of all the synthesized copolymers based on maleic anhydride, the copolymer with α-octadecene was the most effective copolymer in reducing the viscosity of oil and TPT. In this work, a copolymer based on maleic anhydride and octadecene-1 (ODC – MA) was modified with primary amines – butylamine (BA), hexylamine (HA), hexadecylamine (HDA), octadecylamine (ODA), benzylamine (BzA). The copolymer was modified in a xylene solution with a Dean – Stark packing; the ratio of the ODC – MA copolymer to amines was 1:1.2 mol. Tololsulfonic acid (TSC) 0.5 wt% was used as a catalyst. Synthesis temperature 140°C, time 8 hours. The degree of completion of the reaction was evaluated by the amount of water formed in the Dean Stark packing. Modified copolymers ODC – MA with amines (ODC – MA – BA, ODC – MA – HA, ODC – MA – HDA, ODC – MA – ODA, ODC – MA – BzA) were characterized by Fourier IR spectroscopy and 1H and 13C NMR spectroscopy, which indicates the transformation of the original anhydride rings into imide ones. Modified copolymers were tested on waxy oil as depressants. Moreover, all modified copolymers exhibit the properties of depressants – they reduce the viscosity and TPT of oil relative to oil without an PPD. The morphology of waxy crystals formed in oil during a decrease in temperature was determined by microscopy; it was shown that modified waxy crystals of small sizes are formed compared to the original oil without PPDs, which indicates the dispersing effect of modified copolymers based on ODC – MA.