New Insights into the Mechanism of Mobility Reduction by Associative Type Copolymers

Reichenbach-Klinke, Roland; Stavland, Arne; Langlotz, Björn K.; Wenzke, B.; Brodt, Gregor

doi:10.2118/165225-ms

Cited by 22 publications

(5 citation statements)

References 20 publications

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“…Associative polymers even show more potential for additional oil recovery than standard APAM (Wassmuth et al 2012, Reichenbach-Klinke et al 2013. Especially their ability to achieve higher resistance factors than regular APAM makes them very interesting for the application in enhanced oil recovery.…”

Section: Figure 1-sketch Of Polymer Network Formed By Associative Polmentioning

confidence: 99%

Can Associative Polymers Reduce the Residual Oil Saturation?

Reichenbach-Klinke

Stavland

Strand

et al. 2016

Day 3 Wed, March 23, 2016

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The oil recovery potential of acrylamide-based, associative thickening polymers has recently been evaluated in a coreflood study of our department. Associative polymers are anionic, water-soluble copolymers modified with varying degress of pendant hydrophobic groups. By intermolecular interactions of these hydrophobic moieties a fully reversible network of polymer coils can be formed.The oil recovery efficiency of a series of copolymers based on acrylamide, 2-acrylamidopropane sulfonic acid (ATBS) in combination with a hydrophobic comonomer has been determined in linear coreflood experiments at a temperature of 60°C. Synthetic sea water was used as brine and Bentheimer sandstone as core material. The evaluated polymers differed in molecular weight and associative groups' content.While anionic polyacrylamide (APAM) shows very similar resistance factors (RF) in coreflood experiments with and without oil, a significantly reduced RF in the presence of oil has been found for the associative polymers. The magnitude of this decrease in resistance factor was dependent on the specific type of associative polymer.The effect can be ascribed to the weakend intermolecular interaction of the hydrophobic groups in the associative polymers in the presence of oil. Even though the RF value is reduced in the presence of oil, it still remains higher than that of regular APAM.At low flow rates representing reservoir conditions a high resistance factor was observed and oil production was improved. This observation can be explained by an increase of the capillary number caused by the high RF of the polymer drive. A good correlation between oil production and capillary number was established.Permeability reduction effects explained the high mobility reduction observed with the associative polymers, as the bulk viscosity data did not correlate with the in-situ flow properties of the polymers in porous media.

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Section: Figure 1-sketch Of Polymer Network Formed By Associative Polmentioning

confidence: 99%

Can Associative Polymers Reduce the Residual Oil Saturation?

Reichenbach-Klinke

Stavland

Strand

et al. 2016

Day 3 Wed, March 23, 2016

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“…However, both the polymer exhibits similar shear viscosity of ∼0.09 Pa s corresponding to the shear rate of ∼40/s. HPAM relies on molecular weight to generate thickening viscosity whereas associative polymer characterized by the hydrophobicity generates additional resistance due to the combination of both molecular weight and intermolecular attraction . Intermolecular attraction that becomes prominent in the extensional field where the polymer molecules become fully extended to induce increased interaction volume resulted in higher elastic resistance to the filament break up (Figure ) during filament drainage as well as higher elastic extensional resistance to flow in porous media (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Capillary breakup extensional rheometry of associative and hydrolyzed polyacrylamide polymers for oil recovery applications

Azad

Dalsania

2018

J of Applied Polymer Sci

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High molecular weight polymers used for heavy oil recovery exhibit viscoelasticity that can influence the oil recovery during chemical enhanced oil recovery. Different polymers having similar molecular weight and shear rheology may have different elongation flow behavior depending on their extensional properties. Displacing slugs are more likely to stretch than shear in tortuous porous media. Therefore, it is critical to seek an analytical tool that can characterize extensional parameters to improve polymer selection criteria. This article focuses on the extensional characterization of two polymers (hydrolyzed polyacrylamide and associative polymer) having identical shear behavior using capillary breakup extensional rheometer to explain their different porous media behavior. Maximum extensional viscosity at the critical Deborah number and Deborah number in porous media classified the associative polymer as the one having high elastic-limit. Extensional characterization results were complemented by significantly higher pressure drop, marginally increased oil recovery of associative polymer in porous media.

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“…This shear-controlled behavior can be seen, as stated above, during polymer injection (at different rates) and during the subsequent water/oil injection into the treated core sample, and it is translated into an irreversible permeability reduction (residual resistance factor, RRF). More details on this associative polymer behavior can be found in Reichenbach-Klinke et al (2013), Reichenbach-Klinke et al (2016), and Dupuis et al (2010). The open-square blue data points shown in Figure 11 represent the mobility reduction that corresponds to a polymer injection flow rate as a function of shear rate in the oil-wet Berea core sample during tertiary polymer flooding.…”

Section: Figurementioning

confidence: 99%

“…Water-soluble hydrophobically modified sulfonated polyacrylamide (or associative polymers) are aqueous soluble block copolymers that contain both water-soluble (hydrophilic) and water-insoluble components (varying levels of hydrophobicity). Associative polymers have been considered as possible substitutes of HPAM polymers in IOR applications (Seright et al, 2011;Tripathi et al, 2006;Reichenbach-Klinke et al, 2011;Reichenbach-Klinke et al, 2013;Aktas et al, 2008;Dupuis et al, 2010 and. The driving force for the association process is the interaction between the hydrophobic segments that arise in order to minimize their exposure to water (Tripathi et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Associative Polymers as Enhanced Oil Recovery Agents in Oil-wet Formations - A Laboratory Approach

DrillWell¹,

Hatzignatiou²,

DrillWell³

2017

Proceedings

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Associative polymers recently tested for their EOR potential in water-wet systems displayed a good potential for reducing residual oil saturation in polymer-flooded cores. In this work, an oil-wet porous medium was used to investigate these observations. A low molecular weight associative polymer was tested as a displacing agent and its ability to increase oil recovery on chemically treated oil-wet Berea cores was evaluated. Linear coreflood experiments were performed using filtered associative polymer solution as the EOR agent at standard pressure and 60°C temperature. Results from the polymer floods conducted at an established waterflood residual oil saturation (Sorw) yielded increased oil recoveries, i.e., reduced residual oil saturations, Sor, in the formation. The observed incremental oil production was a function of the injected associative polymer treatment volume; Sor decreased with increased injected associative polymer volume. It should be noted that at laboratory conditions it is often hard to establish and also distinguish a 100% water-cut; in other words, true residual oil saturation, Sorw, is often difficult to be established during water injection. Oil production profile can be discussed based on fractional flow theory, which defines the true Sorw at 100% water-cut. Whenever the produced water-cut is not precisely 100%, oil saturation in the formation is higher than the true Sorw; polymer injection with an improved mobility ratio compared to the water injection one results in an additional oil production, which could be misinterpreted as a reduction in the residual oil saturation, i.e., enhance oil production. Although this accelerated oil production is an attractive possibility (mobility control), it is not an EOR process. Our results are in agreement with previously reported observations in water-wet media related to the EOR nature of the injected associative polymer as opposed to the traditional mobility control of other, either synthetic or organic, polymers. The same results showed that the polymer mobility reduction is highly affected by the injected polymer velocity at the lower spectrum of velocity values and a correlation for the velocity dependent mobility reduction was developed. Finally, during the injection of the associative polymer, a column of oil-polymer emulsion was formed gradually in the separator which caused some difficulties and introduced uncertainties in the separator's fluids level readings, and thus eventually in the fluids saturation evaluation. Resistivity data obtained in real time were used to correct for the overestimated values of oil production during polymer injection attributed to the formation of the oil/water emulsion.

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New Insights into the Mechanism of Mobility Reduction by Associative Type Copolymers

Cited by 22 publications

References 20 publications

Can Associative Polymers Reduce the Residual Oil Saturation?

Can Associative Polymers Reduce the Residual Oil Saturation?

Capillary breakup extensional rheometry of associative and hydrolyzed polyacrylamide polymers for oil recovery applications

Associative Polymers as Enhanced Oil Recovery Agents in Oil-wet Formations - A Laboratory Approach

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