Monoethylene glycol (MEG) is a gas hydrate inhibitor widely applied for natural gas flow assurance. A series of density and electrical conductivity measurements of water + MEG + NaCl mixtures are reported, allowing the supervision of the MEG regeneration unit. Density (509 data points) and electrical conductivity (212 data points) measurements were performed in wide ranges of temperature, T = 278.15–363.15 K, and concentration of solvents and NaCl up to almost saturation. The theory of solutions was applied for density description using excess volume, which was correlated with the Redlich–Kister equation. The resulting absolute and relative mean deviations are 0.00127 g·cm–3 and 0.12%, indicating accurate representation. A semiempirical correlation with 15 adjustable parameters was considered for electrical conductivity of water + MEG + NaCl mixtures. The obtained absolute and relative mean deviations are 1.49 mS·cm–1 and 5.70%. The properties functions presented an approximately orthogonal behavior to each other, allowing the determination of mixture composition from experimental density and electrical conductivity data. The Matlab environment was found to be robust in solving the nonlinear system of two equations with constraints. The proposed methodology was extensively tested, and deviations less than 0.0060 and 0.0011 in solvents and NaCl mass fractions were obtained, respectively, demonstrating the required accuracy for industrial application.

Growing interest in the study of production conditions in the presalt led to the need to study complex systems at high pressures and temperatures, such as up to 70 MPa and up to 393 K. The aim of this work is to obtain vapor−liquid equilibrium data at high pressures and temperatures for hydrocarbon systems with carbon dioxide (CO 2 ). To obtain these data, an experimental setup and procedure using a synthetic cell were designed. Experimental data of the binary system CO 2 + cyclohexene (C 6 H 10 ) and CO 2 + squalane (C 30 H 62 ) over a range of temperature between 303 and 398 K and the ternary system CO 2 + C 6 H 10 + C 30 H 62 at various temperatures (318−393 K) and compositions are reported. It is noteworthy that the reported measurements in this work were not studied in the literature, and experimental data may contribute to industrial and scientific interests. The phase behavior of the system was also described using the Soave−Redlich−Kwong equation of state together with Mathias− Copeman alpha function. Interaction parameters for the attractive and repulsive terms were estimated in order to describe the experimental data within the estimated uncertainties.

The oil reservoirs are underground and have the oil and gas contained in the porous rock at high temperatures and pressures. Only 5−20% of the oil is withdrawn in primary production. Further recovery can be achieved by injecting carbon dioxide (CO 2 ) that displaces and dissolves part of the remaining oil; this process is called enhanced oil recovery. Although the characterization and fractionation of petroleum are well-known and studied, each oil sample represents a unique multicomponent system; therefore, an individual study of the sample is required. Real samples of condensate gas (CG) and light crude oil (LCO) were collected and analyzed for density, viscosity, atmospheric distillation and fractionation, and aiming characterization. Synthetic visual and non-visual methods for high pressure were successfully applied for bubble point measurements of the systems composed of supercritical CO 2 and CG or LCO. Phase envelope calculations were developed on the basis of pseudocomponents obtained by atmospheric distillation and density values using the Adachi−Lu−Sugie equation of state with van der Waals mixing rule with one interaction parameter (k ij ) from the literature. Pressure−volume−temperature (PVT) measurements are reported for the systems CG + CO 2 and LCO + CO 2 as a function of the temperature and pressure and in a wide range of CO 2 composition. Crude oil characterization using atmospheric distillation and density measurements was demonstrated to be feasible with accuracy, because the boiling points and specific mass obtained allowed us to propose a series of pseudocomponents to represent the sample phase behavior studied experimentally. Thus, results suggest that the characterization and fractioning of the samples were effective. Thermodynamic modeling and experimental data presented an average deviation of 3.1% to CG + CO 2 and 2.5% to LCO + CO 2 systems, indicating reasonable accuracy for petroleum samples.

In order to inhibit natural gas hydrate formation, monoethyleneglycol (MEG) is usually injected into producing well heads. The MEG regeneration process is continuously performed at the platform. Scaling problems usually occur due to the presence of chlorides and carbonates. This work presents salt solubility data for the aqueous system with strontium carbonate, MEG and carbon dioxide. A specific analytical method was developed. Thus, experimental data for strontium carbonate (SrCO 3) solubility at various carbon dioxide pressures are reported. Solubilities of SrCO 3 in water were measured from 760 to 1610 mmHg at 278.15. 288.15. 298.15 and 323.15 K. For the mixed solvent (ms) conditions, solubilities were measured at 298.15 K and four isobars, i.e., 760, 1210, 1410 and 1520 mmHg. Experimental data were correlated and demonstrated to be accurate for thermodynamic modeling and process simulation.

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