A core-scale study of polymer retention in carbonates at different wettability and residual oil conditions

Wang, Jinxun; AlSofi, Abdulkareem M.; Boqmi, Abdullah M.

doi:10.1016/j.petrol.2020.108099

Cited by 15 publications

(4 citation statements)

References 15 publications

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“…Moreover, the wettability state of a rock is another critical factor that may affect polymer retention. Although most laboratory studies investigating polymer flooding in porous media have been conducted in the absence of crude oil, using oil-wet samples can significantly affect polymer performance 224 , 225 . In particular, polymer adsorption tends to be lower in the presence of oil than in single-phase experiments 40 , 226 – 229 .…”

Section: Challenges Faced During Viscoelastic Polymer Floodingmentioning

confidence: 99%

“…Moreover, no plugging was observed with ATBS-based polymer, even though the retention was relatively high. Wang et al 225 conducted dynamic retention experiments on carbonate reservoir cores at varied wettability conditions (in the presence and absence of oil). They utilized a sulfonated polyacrylamide polymer capable of withstanding high temperatures and salinities.…”

Section: Challenges Faced During Viscoelastic Polymer Floodingmentioning

confidence: 99%

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A comprehensive review of viscoelastic polymer flooding in sandstone and carbonate rocks

Zeynalli,

Mushtaq,

Al-Shalabi

et al. 2023

Sci Rep

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Polymer flooding is a proven chemical Enhanced Oil Recovery (cEOR) method that boosts oil production beyond waterflooding. Thorough theoretical and practical knowledge has been obtained for this technique through numerous experimental, simulation, and field works. According to the conventional belief, this technique improves macroscopic sweep efficiency due to high polymer viscosity by producing moveable oil that remains unswept after secondary recovery. However, recent studies show that in addition to viscosity, polymer viscoelasticity can be effectively utilized to increase oil recovery by mobilizing residual oil and improving microscopic displacement efficiency in addition to macroscopic sweep efficiency. The polymer flooding is frequently implemented in sandstones with limited application in carbonates. This limitation is associated with extreme reservoir conditions, such as high concentrations of monovalent and divalent ions in the formation brine and ultimate reservoir temperatures. Other complications include the high heterogeneity of tight carbonates and their mixed-to-oil wettability. To overcome the challenges related to severe reservoir conditions, novel polymers have been introduced. These new polymers have unique monomers protecting them from chemical and thermal degradations. Monomers, such as NVP (N-vinylpyrrolidone) and ATBS (2-acrylamido-2-methylpropane sulfonic acid), enhance the chemical resistance of polymers against hydrolysis, mitigating the risk of viscosity reduction or precipitation in challenging reservoir conditions. However, the viscoelasticity of these novel polymers and their corresponding impact on microscopic displacement efficiency are not well established and require further investigation in this area. In this study, we comprehensively review recent works on viscoelastic polymer flow under various reservoir conditions, including carbonates and sandstones. In addition, the paper defines various mechanisms underlying incremental oil recovery by viscoelastic polymers and extensively describes the means of controlling and improving their viscoelasticity. Furthermore, the polymer screening studies for harsh reservoir conditions are also included. Finally, the impact of viscoelastic synthetic polymers on oil mobilization, the difficulties faced during this cEOR process, and the list of field applications in carbonates and sandstones can also be found in our work. This paper may serve as a guide for commencing or performing laboratory- and field-scale projects related to viscoelastic polymer flooding.

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Section: Challenges Faced During Viscoelastic Polymer Floodingmentioning

confidence: 99%

Section: Challenges Faced During Viscoelastic Polymer Floodingmentioning

confidence: 99%

A comprehensive review of viscoelastic polymer flooding in sandstone and carbonate rocks

Zeynalli,

Mushtaq,

Al-Shalabi

et al. 2023

Sci Rep

View full text Add to dashboard Cite

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“…For polymer flooding, when the molecular weight is large, the polymer may stay at the reservoir pore throat, blocking the channel for oil and gas migration and harming the reservoir permeability [23,24]. Furthermore, the retention amount may increase in reservoirs with high salinity or in the presence of multivalent cations [24,25]. In addition, Xu et al found that the retention amount of HPAM increased with the increase in the content of clay minerals [26].…”

Section: Ji Et Al[20] Welan Gummentioning

confidence: 99%

Adsorption of Welan Gum on Montmorillonite and Its Influencing Factors

Ke-jian

et al. 2022

Polymers

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Welan gum is one of the most promising polymers used in polymer flooding for enhancing oil recovery, due to its excellent temperature resistance and salt-tolerance performance. However, welan gum, as a polymer with higher molecular weight, can be adsorbed and detained in the pore throat of the reservoir, which is characterized by a smaller size. Montmorillonite, a kind of clay mineral with high content in reservoir rocks, has strong adsorption capacity. Therefore, the adsorption behavior of welan gum on montmorillonite, as well as its influencing factors, are studied in this paper. The results show that the adsorption capacity is 2.07 mg/g. The adsorption capacity decreased with the increase in temperature. Both acidic and alkaline conditions reduced the adsorption capacity. The existence of inorganic salt affected the adsorption capacity. In addition, the higher the cation value, the lower the adsorption capacity. The characterization tests showed that the adsorption of welan gum on montmorillonite was characterized by physical adsorption and surface adsorption, indicating that there were no changes in the internal structure of montmorillonite. This study provides feasible methods to reduce the amount of welan gum adsorbed on montmorillonite, which is of great significance for reducing the permeability damage caused by welan gum adsorption and promoting the application of welan gum in polymer flooding for enhancing oil recovery.

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“…In addition, wettability is a rock surface property that strongly influences polymer retention. In the case of oil-wet rocks, polymer retention is lower than in water-wet rocks due to the low surface area available for polymer adsorption (Broseta et al 1995;Wang et al 2021). Another critical factor is the salinity condition of connate water, which significantly affects polymer retention.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Effect of Water Softening on Polymer Adsorption onto Carbonates through Single-Phase and Two-Phase Experiments

Sebastian,

Mushtaq,

Al-Shalabi

et al. 2024

SPE Journal

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Summary Polymer retention is considered a major challenge in polymer flooding applications, especially in carbonates. This is due to the prevailing conditions of low permeability (<100 md), high temperature (>85°C), and high salinity (>100,000 ppm) generally found in these formations, which limit the effectiveness of commonly used polymers such as hydrolyzed polyacrylamide (HPAM) and xanthan gum. To address these challenges, a polymer based on acrylamide tertiary butyl sulfonate (ATBS) has been used due to its tolerance to high-temperature and -salinity conditions. However, the high cost of manufacturing these polymers, combined with their anionic properties that promote adsorption onto positively charged carbonate rocks, necessitates the exploration of methods to reduce polymer retention. In this study, we aim to determine the sufficient concentration of hardness ions (Ca2+ and Mg2+) required to significantly reduce the adsorption of this polymer. The study is unique in its focus on mitigating polymer retention in carbonate formations using softened brine, as no prior research has investigated this aspect. Four different brines were investigated with a salinity of 8,000 ppm total dissolved salts (TDS) and varying ionic composition designed mainly by eliminating the hardness-causing ions, Ca2+ and Mg2+. A geochemical study was performed using the PHREEQC software to analyze the interaction between these injected brines and the rock. Furthermore, comprehensive rheological and static adsorption studies were performed at a temperature of 25°C using the potential ATBS-based polymer to evaluate the polymer performance and adsorption in these brines. Later, dynamic adsorption studies were conducted in both single-phase and two-phase conditions to further quantify polymer adsorption. The geochemical study showed an anhydrite saturation index (SI) of less than 0.5 for all the brines used when interacting with the rock, indicating a very low tendency for calcium sulfate precipitation. Furthermore, the rheological studies showed that polymer viscosity significantly increased with reduced hardness, where a polymer solution viscosity of 7.5 cp was obtained in zero hardness brine, nearly 1.5 times higher than the polymer viscosity of the base makeup brine of 8,000 ppm. Moreover, it was observed that, by carefully tuning the concentrations of the divalent cations, the polymer concentration consumption for the required target viscosity was reduced by 40–50%. For the single-phase static adsorption experiments, the polymer solution in softened brines resulted in lower adsorption in the range of 37–62 µg/g-rock as opposed to 102 µg/g-rock for the base makeup brine. On the other hand, the single-phase dynamic adsorption results showed an even lowered polymer adsorption of 33 µg/g-rock for the softened brine compared with 45 µg/g-rock for the base makeup brine. Additionally, the single-phase dynamic adsorption studies showed a remarkable improvement in polymer injectivity using softened brine. The polymer retention in wettability-altered cores was further reduced. The study highlights that water softening improves the performance of polymers, specifically in terms of lowering polymer adsorption. It concludes that a threshold hardness level (Ca2+ and Mg2+) of approximately 100 ppm is sufficient to achieve a significant reduction in polymer adsorption for the tested experimental conditions. In this paper, we show that the softened water increases the polymer viscosity and reduces polymer adsorption, which leads to an overall reduction in polymer consumption. Hence, the softened makeup water has the potential to enhance the application envelope of this potential polymer for polymer flood, especially in the case of carbonate reservoirs.

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A core-scale study of polymer retention in carbonates at different wettability and residual oil conditions

Cited by 15 publications

References 15 publications

A comprehensive review of viscoelastic polymer flooding in sandstone and carbonate rocks

A comprehensive review of viscoelastic polymer flooding in sandstone and carbonate rocks

Adsorption of Welan Gum on Montmorillonite and Its Influencing Factors

Investigating the Effect of Water Softening on Polymer Adsorption onto Carbonates through Single-Phase and Two-Phase Experiments

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