Direct Gas Thickener
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Direct gas thickening technique has been developed to control the gas mobility in the miscible gas injection process for enhanced oil recovery. This technique involves increasing the viscosity of the injected gas by adding chemicals that exhibit good solubility in common gasses, such as CO2 or hydrocarbon (HC) solvents. This chapter presents a review of the latest attempts to thicken CO2 and/or hydrocarbon gases using various chemical additives, which can be broadly categorised into polymeric, conventional oligomers, and small-molecule self-interacting compounds. In an ideal situation, chemical compounds must be soluble in the dense CO2 or hydrocarbon solvents and insoluble in both crude oil and brine at reservoir conditions. However, it has been recognised that the use of additives with extraordinary molecular weights for the above purpose would be quite challenging since most of the supercritical fluids are very stable with reduced properties as solvents due to the very low dielectric constant, lack of dipole momentum, and low density. Therefore, one way to attain adequate solubility is to elevate the system pressure and temperature because such conditions give rise to the intermolecular forces between segments or introduce functional groups that undergo self-interacting or intermolecular interactions in the oligomer molecular chains to form a viscosity-enhancing supramolecular network structure in the solution. According to this review, some of the polymers tested to date, such as polydimethylsiloxane, polyfluoroacrylate styrene, and poly(1,1-dihydroperfluorooctyl acrylate), may induce a significant increase of the solvent viscosity at high concentrations. However, the cost and environmental constraints of these materials have made the field application of these thickeners unfeasible. Until now, thickeners composed of small molecules have shown little success to thicken CO2, because CO2 is a weak solvent due to its ionic and polar characteristics. However, these thickeners have resulted in promising outcomes when used in light alkane solvents.
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Al Hinai, N.; Saeedi, Ali; Wood, C.; Myers, M.; Valdez, R.; Xie, Sam; Jin, F. (2018)Direct gas thickening is a conventional mobility control method to improve volumetric sweep efficiency for miscible gas injection (MGI) projects. However, the viability of this approach with technically feasible thickeners ...
Lastari, Fonny; Pareek, Vishnu; Trebble, Mark; Tade, Moses; Chinn, D.; Tsai, N.; Chan, K. (2012)The separation of the CO2–ethane azeotrope using the hydrocarbon solvents through an extractive distillation process was simulated with the HYSYS 2004.2 software platform. The objective was to examine the optimum solvent ...
Dolzhenko, Anton; Dolzhenko, A. (2014)Use of safer solvents satisfies green chemistry practices. From the green chemistry perspective, the best solvent for reactions is no solvent. However, this ideal situation is not always achievable and choice of more ...