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Dissolution of cellulose is crucial for its regeneration and chemical modification, such as homogeneous transesterification, for example. The cellulose dissolution in ionic liquid (IL) media is suggested as a prospective environmentally friendly alternative to conventional solvents. In this study, novel distillable ionic liquid 5-methyl-1,5,7-triaza-bicyclo-[4.3.0]non-6-enium acetate, [mTBNH][OAc] was used for cellulose dissolution. This IL has high dissolving power towards cellulose and durability for recycling. However, the disadvantage of ILs is their high viscosity, which limits the supreme cellulose concentration in IL solutions, and their high cost, hindering their commercialization. The addition of low-viscous, low-cost, and naturally derived co-solvents can reduce the overall viscosity and cost. In this study, rheology experiments were conducted to investigate the flow behavior of cellulose in [mTBNH][OAc] ionic liquid mixed with the green co-solvents such as γ-Valerolactone (GVL), dimethyl isosorbide (DMI), and N,N′-dimethylpropyleneurea (DMPU). A study of the rheology showed that the viscosity reduces at low doses of co-solvent (≤ 50 wt%) but causes the structuring of the cellulose solution and its gelation (or phase separation) at high doses (≥ 50 wt%). The rheological study also indicated that the flow activation energy of cellulose in IL/co-solvent systems is lower than that in pure IL and decays in the order of DMPU > DMI > GVL > DMSO. [ABSTRACT FROM AUTHOR]

Currently, the pollution and clogging problems of injection wells in low-permeability reservoirs are becoming more and more serious, leading to a series of issues, such as the decline of fluid production in wells and the increase of pressure in injection wells. To cope with these challenges, SY organic polyacid solution was developed in this paper and its dissolution efficiency was thoroughly investigated. The experimental results show that SY organic polyacid solution has a high dissolution rate of 88.7%, which exhibits excellent scale dissolution effect, and the solvent's dissolution has a good slow-release performance to ensure the long-lasting action time. At the same time, the corrosion rate of the solvent on the N80 steel sheet is only 0.6291 g/m²-h, much lower than the industry standard, which effectively protects the safety of the construction pipeline and production column. In addition, the dissolution rate of SY organic polyacid on clay reaches 10.14% in five minutes, indicating that it prevents the ground collapse caused by excessive dissolution of clay and has good profound penetration ability. In summary, using SY organic polyacid solution can effectively solve multiple problems such as reservoir mud, inorganic scale, organic scale and water injection fouling oil, which provides an effective solution for the contamination and clogging of water injection wells in low permeability reservoirs.

Chelating agents' application for well stimulation is gaining more and more interest, as they can perform under harsh conditions. However, the mutual influence of surfactants and chelating agents on the wettability alteration of hydrophobic carbonate rock under conditions of high-temperature well stimulation is relatively unexplored. This paper aims to study interfacial processes on the surface of hydrophobic rock in the presence of the EDTA-based chelating agent and surfactants of different classes. Cationic (cetyltrimethylammonium bromide, CTAB, and cetylpyridinium bromide, CPB), anionic (sodium dodecyl sulfate, SDS), and amhoteric (alkyldimethyl aminooxide, AO) surfactants were studied. Wettability alteration of model hydrophobic rock was studied under conditions specific to well stimulation. It was shown that chelating agent (CA) alone and its mixture with SDS could not lead to sufficient wettability alteration. CTAB, CPB, and AO were able to change the wettability effectively. A synergistic effect between CA and these surfactants was observed and a possible mechanism was proposed. AO was selected as the most promising surfactant. The influence of surfactant on the CA's dissolution capacity towards carbonate rock was investigated; dissolution capacity strongly depends on wettability alteration. Finally, the effect of CA, AO, and their mixture on the wettability of aged reservoir rock was studied and the absence of negative effects was proven. [ABSTRACT FROM AUTHOR]

Linear and nonlinear analyses were conducted to study the onset and growth of gravitational instability in an isolated porous medium. By considering the dissolution capacity of the isolated system, base concentration profiles were obtained analytically. Based on this base concentration field, linear stability equations were derived under the linear stability theory. The present stability analysis predicts that an isolated system is more stable than the conventional open system. In addition, the dissolution capacity of the isolated system suppresses the onset of instability. Unlike the previous study, the minimum Darcy-Rayleigh number to induce gravitational instability exists and it is a strong function of the dissolution capacity. However, the critical conditions for the high Darcy-Rayleigh number system are insensitive to the dissolution capacity. Based on the results of the linear analysis and the analytically obtained base concentration profile, fully nonlinear numerical simulations were also conducted for the case of Ra=103. The vertical development of the instability motion and the dissolution flux are significantly suppressed in the high dissolution capacity systems. [ABSTRACT FROM AUTHOR]

Chelating agents’ application for well stimulation is gaining more and more interest, as they can perform under harsh conditions. However, the mutual influence of surfactants and chelating agents on the wettability alteration of hydrophobic carbonate rock under conditions of high-temperature well stimulation is relatively unexplored. This paper aims to study interfacial processes on the surface of hydrophobic rock in the presence of the EDTA-based chelating agent and surfactants of different classes. Cationic (cetyltrimethylammonium bromide, CTAB, and cetylpyridinium bromide, CPB), anionic (sodium dodecyl sulfate, SDS), and amhoteric (alkyldimethyl aminooxide, AO) surfactants were studied. Wettability alteration of model hydrophobic rock was studied under conditions specific to well stimulation. It was shown that chelating agent (CA) alone and its mixture with SDS could not lead to sufficient wettability alteration. CTAB, CPB, and AO were able to change the wettability effectively. A synergistic effect between CA and these surfactants was observed and a possible mechanism was proposed. AO was selected as the most promising surfactant. The influence of surfactant on the CA’s dissolution capacity towards carbonate rock was investigated; dissolution capacity strongly depends on wettability alteration. Finally, the effect of CA, AO, and their mixture on the wettability of aged reservoir rock was studied and the absence of negative effects was proven.

In this study, a modified dissolution apparatus was developed by equipping a USP apparatus Ⅰ with an open-loop system to discriminate the dissolution capacity in vitro and establish an in vitro and in vivo correlation (IVIVC) for mycophenolate mofetil (MMF) tablets. MMF had strong pH-dependent solubility that could influence the dissolution rate in vivo after the meal. Dissolution tests involving reference (Cellcept®) and test formulations (F1 and F2) were conducted using pH 4.5 acetate buffer to simulate gastric fluids in the fed state. The dissolution profiles of the reference and test formulations were distinguished by using the modified dissolution apparatus and compared with those determined using the USP apparatuses Ⅱ and Ⅳ, and the dissolution capacities of the formulations were discriminated at different sampling time-points. The results of human bioequivalence (BE) studies in the fed state were consistent with in vitro evaluations that the maximum concentrations (C max, in vivo) of both F1 and F2 fell below the acceptable range (80.00%). A level A IVIVC between the absorption fraction in vivo and dissolution in vitro , and a level C correlation between C max, in vivo and C max, in vitro , were established to guide the optimization of the tablet formulation containing MMF. [ABSTRACT FROM AUTHOR]

Effects of initial gas content in oil (IGC) on oil properties and interactions between oil and natural gas were firstly studied by measurements of oil viscosity, interfacial tension (IFT) between oil and gas, and continual dissolution capacity (CDC) of natural gas in oil, which were the main factors affecting oil recovery. Secondly, core flood tests using the oils with different IGC were conducted, so that effects of IGC on oil recovery could be known. Finally, reasons why IGC could influence oil recovery were mechanistically analyzed according to the breakthrough data of natural gas. The results show that, with increased IGC, oil viscosity decreased linearly and IFT was also reduced, but the CDC of natural gas in oil was weakened. Oil recovery of natural gas flood decreased obviously with increased IGC, which is mainly due to the getting-earlier breakthrough of natural gas resulting from the reduced CDC of natural gas in oil and the consequently weakened capacity of oil to dissolve the fingering gas. So for the light oils that are similar to the experimental samples, the lower the IGC was, the higher the oil recovery of natural gas flood was. [ABSTRACT FROM AUTHOR]

Abstract: The concept of Distributed Carbon Capture and Storage (DCCS) for small scale CO2 sources, such as Distributed Energy Systems (DES), is proposed, and Carbon Storage in a Shallow Aquifer (CSSA), in which CO2 is stored in shallow aquifers as aqueous solution, is also studied as a technique for the DCCS. A conceptual design for the CSSA have been performed and the fundamental calculations in this study show that the dissolution capacity, that is, the amount of CO2 which can be dissolved into unit volume of water in a shallow aquifer is 10–35kg-CO2/m3 in the range of the storage depth of 100–500m. The dissolution capacity of the CSSA is less than 10% of the possible amount of CO2 stored by the ordinary CCS technique in which CO2 is stored in the supercritical condition. However, the CSSA is estimated to allow the CO2 storage at less than ¥3000/t-CO2 of the storage cost and more than 20-years of the injection period for CO2 sources of 1800–39,000t-CO2/year, which correspond to the CO2 emissions from 0.1 to 10 MW DES. The required energy for the CSSA is estimated to be less than 10% of the energy generated by the CO2 sources. [Copyright &y& Elsevier]