Research progress on supercritical CO₂ thickeners

Abstract

According to the thickening principle and molecular structure of thickeners, supercritical carbon dioxide (sc-CO2) thickeners were summarized and introduced by dividing into polymers, small molecular compounds, and surfactants. The properties...

Thickening CO2 with Direct Thickeners, CO2-in-Oil Emulsions, or Nanoparticle Dispersions: Literature Review and Experimental Validation

“…However, in 2019 a book chapter on thickening of high-pressure gas was authored by Al Hinai and colleagues that presented attempts to thicken CO 2 with polymers, oligomers, and small molecules . In mid-2021, a review of direct thickeners was presented by Zhou and colleagues . Both of these reviews presented the results of direct-thickening studies; however, both of these recent reviews were not critical in nature and presented no reviews of indirect thickeners or nanoparticle dispersion thickeners or proprietary thickeners, and neither provided the reader with specific suggestions for future research directions or a side-by-side comparison of a wide array of purported CO 2 thickeners.…”

“…12 In mid-2021, a review of direct thickeners was presented by Zhou and colleagues. 13 Both of these reviews presented the results of direct-thickening studies; however, both of these recent reviews were not critical in nature and presented no reviews of indirect thickeners or nanoparticle dispersion thickeners or proprietary thickeners, and neither provided the reader with specific suggestions for future research directions or a side-by-side comparison of a wide array of purported CO 2 thickeners. Therefore, our study was intended to present the first peerreviewed critical literature review of polymeric, associating polymers, low molecular weight polymers, oligomers, and smallmolecule associating thickeners, in addition to reviews of indirect thickening with waterless emulsions and thickening with dispersion of nanoparticles.…”

Research of CO2-Soluble Surfactants for Enhanced Oil Recovery: Review and Outlook

“…Self-assembly of surfactants can form linear or rod-like micelles, which, at a certain concentration, will intertwine to form a network structure, thereby increasing the viscosity of scCO 2 [138].…”

Evaluation of the Driving Effect of the CO2 Viscosity Enhancer Composite System in Extra-Low Permeability Sandstone Reservoirs

“…By controlling the viscosity of CO 2 , a reasonable flow ratio can be ensured. At present, the CO 2 viscosity enhancers researched at domestic and abroad mainly focus on fluorination, chain hydrocarbons, and silanes . Kilic et al prepared a series of aromatic acrylate-fluoroacrylate copolymers as CO 2 thickeners by controlling the ratio of monomer content, in which the copolymers with 71 mol % of fluoroacrylate had better solubility in CO 2 and achieved the best thickening effect, and the viscosity could be further improved with increasing pressure.…”

“…At present, the CO 2 viscosity enhancers researched at domestic and abroad mainly focus on fluorination, chain hydrocarbons, and silanes. 20 Kilic et al 21 prepared a series of aromatic acrylate-fluoroacrylate copolymers as CO 2 thickeners by controlling the ratio of monomer content, in which the copolymers with 71 mol % of fluoroacrylate had better solubility in CO 2 and achieved the best thickening effect, and the viscosity could be further improved with increasing pressure. Tapriyal 22 prepared benzoyl-vinyl acetate copolymer (polyBOVA) by grafting benzoyl chloride onto polyvinyl acetate-vinyl alcohol [P(Vac- co -VA)] based on the better pro-CO 2 property of vinyl acetate, catalyzed by 4-dimethylpyridine and was able to increase the viscosity of CO 2 at 298 K, polyBOVA mass concentration of 1 and 2, respectively, were able to increase the viscosity of CO 2 by 1.4 and 1.8 times, while the cloud point pressure of polyBOVA-CO 2 solution reached 64 MPa when the mass concentration was 3 wt %, and the dissolution conditions were more severe.…”