A Laboratory Investigation of Viscosified CO2 Process

Bae, Jae-Heum; Irani, Cyrus A.

doi:10.2118/20467-pa

Cited by 61 publications

(69 citation statements)

References 6 publications

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“…In an attempt to identify very high molecular weight polymeric thickener candidates, Chevron researchers [Harris et al, 1990;Bae and Irani, 1990;Bae 1995] selected candidates that exhibited solubility parameters less than ~7 (cal/cc) 0.5 in an apparent attempt to match the temperature-and pressure-dependent solubility parameter of CO 2 [Williams et al, 2004] at reservoir conditions, which is roughly 6 (cal/cc) 0.5 . Further, it was desired that the polymer exhibit multiple electron donor sites associated with oxygen, nitrogen, or sulfur atoms that could interact favorably with the electron acceptor site of the CO 2 molecule, which is the carbon atom.…”

Section: Polymeric Thickenersmentioning

confidence: 99%

“…It was determined that very high molecular weight silicone oil (polydimethylsiloxane (PDMS)), Mw = 197,000, kinematic viscosity = 600,000 centistokes, 7.3 (cal/cc) 0.5 , could effectively thicken CO 2 , but only if a significant amount of a co-solvent such as toluene (solubility parameter = 8.9 (cal/cc) 0.5 ) was added. For example, a 4wt% PDMS, 20wt% toluene, 76% CO 2 mixture had a viscosity of 1.2 cP, while pure CO 2 at the same condition exhibits a viscosity of only 0.04 cP [Bae and Irani, 1990]. This solution was remarkably less mobile during Berea and SACROC core floods than pure CO 2 , resulting in delayed CO 2 breakthrough and increased oil recovery.…”

Section: Polymeric Thickenersmentioning

confidence: 99%

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Development of Small Molecule CO2 Thickeners for EOR and Fracturing

et al. 2014

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The ideal carbon dioxide (CO 2 ) thickener would be an affordable, safe, water-insoluble additive that could dissolve in CO 2 at typical wellhead and reservoir conditions during CO 2 enhanced oil recovery (EOR) and elevate the viscosity of CO 2 to the same value as the oil. Further, the additive would not require heating or an organic co-solvent to achieve dissolution. A CO 2 thickener could be a transformative technology in that it would eliminate unfavorable mobility ratios during CO 2 EOR and reduce or eliminate the need for WAG. A detailed history of prior attempts to thicken CO 2 with either high molecular weight polymers or small associating compounds is presented. Our strategy for designing a novel small molecule CO 2 thickener is then detailed. Each thickener candidate contains a strongly CO 2 -philic segment (e.g. a very short polymer or oligomer of silicone oil or polyprolylene glycol), and one or more somewhat CO 2 -phobic functional groups that induces intermolecular interactions that can lead to the formation of viscosity-enhancing supramolecular structures in solution.

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Section: Polymeric Thickenersmentioning

confidence: 99%

Section: Polymeric Thickenersmentioning

confidence: 99%

Development of Small Molecule CO2 Thickeners for EOR and Fracturing

et al. 2014

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“…Silicone polymers have been previously used to thicken carbon dioxide flowing through porous media, as evidenced by decreased mobility and improved recovery. 7 Substantial amounts of an organic cosolvent were required, however, to attain a single-phase solution. 7 The fluoroacrylatestyrene copolymer is a direct thickener in that it does not require a cosolvent.…”

Section: Measurement Of Thickened Co 2 Mobility In Sandstonementioning

confidence: 99%

“…Significant contributions were also made by Irani and coworkers, who successfully thickened CO 2 using silicone-based polymers that required the addition of an organic solvent. 7 Irani and coworkers later proposed that polymers that were designed to exhibit low solubility parameters may be effective CO 2 thickeners in the presence of small amounts of an organic liquid cosolvent. 8,9 DeSimone and coworkers were the first to demonstrate that a high molecular weight polymer, poly(1,1-dihydro-perfluorooctylacrylate), PFOA, could exhibit remarkably high CO 2 solubility in the absence of a cosolvent.…”

Section: Introductionmentioning

confidence: 99%

Thickening Carbon Dioxide With the Fluoroacrylate-Styrene Copolymer

Wlaschin

Enick

2003

SPE Journal

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The fluoroacrylate-styrene copolymer is the first associative thickener that has been identified for carbon dioxide. Fluoroacrylate is highly carbon dioxide-philic, enhancing the solubility of the copolymer in carbon dioxide. Styrene is relatively carbon dioxidephobic, but promotes viscosity-enhancing, intermolecular associations. The copolymer used in this study had a composition of 29 mol% styrene-71 mol% fluoroacrylate, a number-average molecular weight of 540,000, and a polydispersity index of 1.63. The copolymer was sufficiently soluble in CO 2 at typical reservoir flooding conditions to induce a significant increase in viscosity. Falling cylinder viscometry measurements at 298 K demonstrated that the viscosity enhancement of CO 2 increased with increasing copolymer concentration, decreasing shear rate, and decreasing temperature. Mobility measurements of the fluoroacrylate-styrene copolymer-CO 2 solutions flowing through 80 to 200 md Berea sandstone cores at superficial velocities of 0.00035 to 0.028 cm/s (1-80 ft/D) at 298 K also indicated that the copolymer was an effective thickener. At a superficial velocity of 0.00035 m/s (1ft/ D), the addition of 1.5 wt% copolymer increased the CO 2 viscosity by a factor of 19 relative to neat CO 2 . Smaller increases in viscosity occurred at lower copolymer concentrations and higher velocities. These results demonstrate that it is possible to design a compound that can enhance the viscosity of dense carbon dioxide. Fluoropolymers are characterized by environmental persistence, high cost, and unavailability in bulk quantities, however. Therefore nonfluorous, inexpensive thickeners are currently being designed.

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“…A high-molecular-weight polymer and cosolvent are blended and pressurized together with CO 2 so that the CO 2 viscosity can be greatly increased before CO 2 is injected. A number of studies show that gas viscosifier chemicals can increase CO 2 viscosity by an order of one to two and can control CO 2 mobility (Heller et al 1985, Terry et al 1987, McClain et al 1996, Bae and Irani 1993, Ali and Schechter 2013. However, the main barriers of using viscosifer include the following: (1) the large volume requirement of cosolvent makes pilot-testing costs prohibitive (Enick et al 2012);…”

Section: Introductionmentioning

confidence: 99%

Polymer-Alternating-Gas Simulation—A Case Study

2014

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Carbon dioxide has been used commercially to recover oil from reservoirs for more than 40 years. Currently, CO 2 flooding is the second most applied enhanced oil recovery (EOR) process in the world behind steam flooding. Water alternating gas (WAG) injection has been a popular method to control mobility and improve volumetric sweep efficiency for CO 2 flooding. Average EOR is about 9.7% with a range between 6 and 20% for miscible WAG injection. Despite all the success of WAG injection, sweep efficiency during CO 2 flooding is a typical challenge to reach higher oil recovery.We applied polymer-alternating-gas (PAG), in which polymer flooding is combined with miscible CO 2 injection, to improve the volumetric sweep efficiency of the WAG process in TR78 of the North Burbank Unit. High heterogeneity and high permeability at the top layers are the two main challenges of the North Burbank Unit. Then, we compared PAG performance with WAG and continuous gas injection (CGI). Polymer concentration and injection slug patterns were optimized during the PAG process. Simulation results show that PAG would increase oil recovery about 14.3% compared with 7.3% for WAG in TR78.This study can not only be used to guide the development of the North Burbank Unit, but also to demonstrate that encouraging recovery can be obtained in high-heterogeneity reservoirs by using PAG.

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A Laboratory Investigation of Viscosified CO2 Process

Cited by 61 publications

References 6 publications

Development of Small Molecule CO2 Thickeners for EOR and Fracturing

Development of Small Molecule CO2 Thickeners for EOR and Fracturing

Thickening Carbon Dioxide With the Fluoroacrylate-Styrene Copolymer

Polymer-Alternating-Gas Simulation—A Case Study

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