Search

The existence of propane (C3H8) in a CO2-oil mixture has great potential for increasing CO2 solubility and decreasing minimum miscibility pressure (MMP). In this study, the enhanced solubility, reduced viscosity, and lowered MMP of CO2-saturated crude oil in the presence of various amounts of C3H8 have been systematically examined at the reservoir conditions. Experimentally, a piston-equipped pressure/volume/temperature (PVT) cell is first validated by accurately reproducing the bubble-point pressures of the pure component of C3H8 at temperatures of 30, 40, and 50 °C with both continuous and stepwise depressurization methods. The validated cell is well utilized to measure the saturation pressures of the CO2-C3H8-oil systems by identifying the turning point on a P-V diagram at a given temperature. Accordingly, the gas solubilities of a CO2, C3H8, and CO2-C3H8 mixture in crude oil at pressures up to 1600 psi and a temperature range of 25–50 °C are measured. In addition, the viscosity of gas-saturated crude oil in a single liquid phase is measured using an in-line viscometer, where the pressure is maintained to be higher than its saturation pressure. Theoretically, a modified Peng–Robinson equation of state (PR EOS) is utilized as the primary thermodynamic model in this work. The crude oil is characterized as both a single and multiple pseudo-component(s). An exponential distribution function, together with a logarithm-type lumping method, is applied to characterize the crude oil. Two linear binary interaction parameters (BIP) correlations have been developed for CO2-oil binaries and C3H8-oil binaries to accurately reproduce the measured saturation pressures. Moreover, the MMPs of the CO2-oil mixture in the presence and absence of C3H8 have been determined with the assistance of the tie-line method. It has been found that the developed mathematical model can accurately calculate the saturation pressures of C3H8 and/or CO2-oil systems with an absolute average relative deviation (AARD) of 2.39% for 12 feed experiments. Compared to CO2, it is demonstrated that C3H8 is more soluble in the crude oil at the given pressure and temperature. The viscosity of gas-saturated crude oil can decrease from 9.50 cP to 1.89 cP and the averaged MMP from 1490 psi to 1160 psi at 50 °C with the addition of an average 16.02 mol% C3H8 in the CO2-oil mixture. [ABSTRACT FROM AUTHOR]

Cyclic Solvent Injection (CSI) has gained significant interest as a viable method among solvent injection processes to increase recovery factor of heavy oil reservoirs. The type of solvent, operating pressure, and oil viscosity markedly affect the performance of CSI. In this study, series of cyclic injection tests of pure CO 2 , CH 4 -CO 2 , and C 3 H 8 -CO 2 were conducted at various operating pressures and mixture compositions to different (in term of viscosity) heavy oil samples. Sand pack models with absolute permeability of k abs  = 6–10 D and porosity of ø  = 27–32% were used as representative of a typical heavy oil reservoir. In each cycle, the produced oil and pressured drop during soaking time were measured and CO 2 /solvent apparent solubility was calculated using the pressure decay method. Results showed that there is an optimum pressure in cyclic CO 2 injection process in heavy oil systems; the pressure beyond which the ultimate oil recovery factor ( RF ) did not notably improve (near 4.82 MPa in this study). Higher concentration of C 3 H 8 in the CO 2 stream improved the oil recovery during cyclic injection. However, ultimate RF was not noticeably increased when C 3 H 8 concentration in the mixture exceeded a certain value (near 50% in this study). Although C 3 H 8 showed effective role on the performance of CSI, it was found that the recovery factor reduces with increased CH 4 concentration in the CO 2 stream. The highest recovery factor of RF  = 73.8% was obtained by injecting mixture of 50% C 3 H 8 - 50% CO 2 under the operating pressure of P inj  = 1.72 MPa. The results of CSI tests on the heavy oil with viscosity of 6 430 mPa s were lower by almost 20% since the solvent solubility was noticeably lower. No oil production was observed after conducting the first cycle injection of optimum quantified solvents on oil with the viscosity of 22 000 mPa s. Small values of SUF, relatively high values of SOR, and low quality of the produced oil suggested that higher cycle numbers of CSI in heavy oil reservoirs is depending on the economic limits and might be conducted cautiously. [ABSTRACT FROM AUTHOR]

1,2,3,4-Butane tetracarboxylic acid (BTCA)-treated cotton fabrics were immersed in alkali for increasing time periods and the effectiveness of alkali in removing the cross-linking agent was investigated by surface (X-ray photoelectron spectroscopy, XPS) analysis, attenuated total reflectance Fourier transform infrared spectroscopy and solubility in specific solvents. The cellulose yield after the chemical ‘stripping’ processes was established and the effect of the alkali treatments on the degree of polymerization of the resultant cellulose determined. Surface analyses and solubility tests suggested that the alkali alone could successfully remove the BTCA from the crease resist-treated cotton fabric and produced a commercially viable yield of cellulose. [ABSTRACT FROM PUBLISHER]

Dimethylol dihydroxyethylene urea (DMDHEU)-treated cotton fabrics were treated with alkali or alternatively acid followed by alkali for increasing time periods, and their effectiveness in removing the crosslinking agent was investigated by surface (X-ray photoelectron spectroscopy) analysis, bulk analysis, crease recovery angle performance and solubility in specific solvents. The cellulose yield after the chemical stripping processes was established and the effect of the acid and alkali treatments on the degree of polymerisation of the resultant cellulose determined. Surface and bulk analyses and solubility tests suggested that alkali alone could not remove the DMDHEU from the crease-resist-treated cotton fabric. However, a sequential acid/alkali treatment effectively removed the easy-care finish from the cotton fabric and produced a commercially viable yield of cellulose. [ABSTRACT FROM AUTHOR]

Naphthalene tetracarboxylic acid anhydride, sulfonated diphenyl ether diamine and non-ionic aromatic diamines were successfully co-polymerized to sulfonated polyimides, and their solvent solubility and swelling behavior in organic solvents of DMSO, NMP, DMF, and m-Cresol and in aqueous solutions of chloride, sodium hydroxides, as well as pure water have been examined. The asymmetric chemical structures of non-ionic aromatic diamines and the ratios of their copolymerization strongly impact on solvent solubility. The chemical structures of non-ionic aromatic diamines and the ratios of their copolymerization also affect the solubility and swelling behavior in alkaline solutions of lithium, sodium and potassium hydroxides. Their solubility and swelling behavior in alkaline solution were explained by the Hofmeister series and electrostatic shielding effect of ionic structures on sulfonated polyimide. [ABSTRACT FROM AUTHOR]

This paper describes a systematic approach to model the phase and volumetric behavior of extra heavy oil and light solvent mixtures for a wide range of temperatures. A cubic equation of state (EOS) is first developed using crude assay data. We use a modified Jacoby correlation to describe the relationship of specific gravity and molecular weight for the heavy oil sample. A gamma molar distribution model is used to fit the crude assay data, then single-carbon-number (SCN) fractions are defined up to C 90+. The Twu correlation is used for estimating SCN critical properties, including C 90+ , resulting in an EOS with 89 components. Pure solvent-crude oil mixture PVT experimental data are analyzed and used to tune the EOS model. The resulting model reproduces accurately all phase and volumetric behavior of pure-solvent-crude mixtures. The prediction of the final EOS model provides accurate prediction against measured PVT data for mixtures of extra-heavy oil sample and synthetic combustion gas solvents made up of CO 2 , N 2 , C 1 , and C 2. For viscosity modeling, we propose a novel technique to model large variation of viscosity for a wide range of pressures, temperatures and solvent compositions. In our proposed approach, the LBC (Lorenz-Bray-Clark) correlation is used, with SCN critical volumes modified individually to ensure the LBC correlation estimates SCN viscosities as given by a modified Twu correlation. The viscosity predictions of the pure-solvent-saturated heavy oil at varying temperatures, the EOS/LBC model results in poor agreement against measured saturated viscosity data. Our solution was to split the heaviest fraction C 90+ into two sub-fractions, where only critical volumes differ, resulting in "lower-viscous" and "higher-viscous" C 90+ fractions (C 90+L into C 90+H). We find that the fraction of C 90+L (f L) correlates well against pure solvent solubility and temperature, resulting in an accurate overall viscosity fit. The final EOS/LBC model is successfully employed to predict measured PVT and viscosity data that was not used during the training process. Our new approach can provide accurate phase properties and volumetric behavior calculations and as well as good predictions of large variation of liquid viscosity. Such developed EOS technique is vital for providing an accurate estimation of phase behavior and volumetric properties, and the viscosity variations required for modeling thermal-EOR techniques. • A systematic heavy-ends characterization was made based on Athabasca crude assay data. • The EOS prediction for unseen SCG-saturated bitumen data was found to be successful. • A novel technique for estimating saturated oil viscosity is introduced. • The light-heavy splitting factor (f L) is well correlated against temperature and solvent solubility. • The proposed L&H model provides more consistent and reliable results against the available viscosity correlations. [ABSTRACT FROM AUTHOR]

In order to provide a rational basis upon which future developments in nonaqueous finishing and other processing of textile materials may be based, a basic study is being undertaken of the interactions between textile fibers and a wide spectrum of organic solvents. In this paper are reported the effects on mechanical properties of a polyester yam of 26 organic solvents differing widely in chemical and physical characteristics. The yams were conditioned in each solvent for 16 hr at 21°C and their load-extension behavior determined in the solvent. While many solvents were found to have only minor effects on the mechanical properties, several solvents caused major changes in the shape of the load- extension curve of the polyester yam. The active solvents caused a decrease in the initial modulus, a decrease in the yield stress, and an increase in extensibility. In several cases a significant plastic flow region could be noted. Dioxane, acetone, trichloroethylene, tetrachloroethane, methylene chloride, nitrobenzene, nitromethane, acetonitrile, and di methylformamide (DMF) were among the most active solvents. These solvents also caused a major irreversible longi tudinal shrinkage of the yarn, and the mechanical properties of the yarn were only partially recovered after removal of the solvent and reconditioning to a standard condition.The interactions between the solvents and the polyester yarn, as estimated by the decrease in the yarn elastic modulus, were correlated with the solubility parameter δ of the solvents. It was observed that maximum interactions take place with solvents whose solubility parameter approaches that of polyethylene terephthalate δ=10.7. There is some indica tion that these strongly interacting solvents fall into two groups: one with δ values ranging from 9 to 10, the other with δ values ranging from 11.5 to 13. It is suggested that these ranges may reflect specific solvent interactions with the aro matic and aliphatic segments of the polyester molecules. [ABSTRACT FROM PUBLISHER]