Wettability alteration in carbonates during “Smart Waterflood”: Underlying mechanisms and the effect of individual ions

Rashid, Saeed; Mousapour, M.S.; Ayatollahi, Shahab; Vossoughi, Manouchehr; Beigy, Abbas Hoseinali

doi:10.1016/j.colsurfa.2015.09.067

Cited by 98 publications

(67 citation statements)

References 39 publications

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“…The first step is to determine the wettability and zeta potential of preserved or aged samples saturated with the crude oil and formation brine of interest, and compare the zeta potential with strongly water-wet samples. Our results, along with previous studies, suggest that IOR during CSW is observed only if the initial wetting state is mixed to oil-wet1819202627.…”

Section: Discussionsupporting

confidence: 86%

See 1 more Smart Citation

Zeta potential in oil-water-carbonate systems and its impact on oil recovery during controlled salinity water-flooding

Jackson

Al-Mahrouqi

Vinogradov

2016

Sci Rep

241

193

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Laboratory experiments and field trials have shown that oil recovery from carbonate reservoirs can be increased by modifying the brine composition injected during recovery in a process termed controlled salinity water-flooding (CSW). However, CSW remains poorly understood and there is no method to predict the optimum CSW composition. This work demonstrates for the first time that improved oil recovery (IOR) during CSW is strongly correlated to changes in zeta potential at both the mineral-water and oil-water interfaces. We report experiments in which IOR during CSW occurs only when the change in brine composition induces a repulsive electrostatic force between the oil-brine and mineral-brine interfaces. The polarity of the zeta potential at both interfaces must be determined when designing the optimum CSW composition. A new experimental method is presented that allows this. Results also show for the first time that the zeta potential at the oil-water interface may be positive at conditions relevant to carbonate reservoirs. A key challenge for any model of CSW is to explain why IOR is not always observed. Here we suggest that failures using the conventional (dilution) approach to CSW may have been caused by a positively charged oil-water interface that had not been identified.

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Section: Discussionsupporting

confidence: 86%

“…The typical CSW approach in carbonates is to switch from formation brine to seawater151819 (e.g., Fig. 1a) and/or to dilute formation brine or seawater1020 (e.g., Fig.…”

mentioning

confidence: 99%

Zeta potential in oil-water-carbonate systems and its impact on oil recovery during controlled salinity water-flooding

Jackson

Al-Mahrouqi

Vinogradov

2016

Sci Rep

241

193

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“…However, there is a pressing need to develop cost-effective techniques to enhance oil recovery in the period of low oil prices. Engineering the injected water chemistry and using water wisely to enhance oil recovery is a novel and emerging research area, which is called low salinity water flooding [4][5][6][7], smart water flooding [8][9][10][11][12], designer water flooding [13][14][15][16], or ion tuning water flooding [17,18]. Many researchers found that low salinity water injection could achieve an incredible additional oil recovery in sandstone and carbonate reservoirs from both experiments and field tests [19,20].…”

Section: Introductionmentioning

confidence: 99%

Effect of multi-component ions exchange on low salinity EOR: Coupled geochemical simulation study

2016

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The mechanism(s) of Low salinity water flooding (LSWF) has been extensively investigated for 15-20 years, as a cost-effective and environmentally friendly technique for improved oil recovery. However, there is still no consensus on the dominant mechanism(s) behind low salinity effect due to the complexity of interactions in the Crude oil/Brine/Rock (COBR) system. While wettability is most agreed mechanism of low salinity EOR effect. Nevertheless, the mechanism(s) behind the wettability change is debated between multi-component ion exchange (MIE) and double layer expansion (DLE) in sandstone reservoirs. This paper aims to investigate the effectiveness of MIE with a coupled geochemical-reservoir model using published experimental data reported by Nasralla and Nasr-El-We created core-scale numerical models with parameters identical to those used in the experiments. We simulated the low salinity effect using a commercial reservoir simulator, CMG-GEM, by coupling three chemical reactions: (1) aqueous reaction, (2) multi-component ion exchange, and (3) mineral dissolution and precipitation. We modelled the adsorption of divalent cations on the surface of the clay minerals during low salinity water injection. Simulation results were compared with the experimental results.Simulation results show that the fractional adsorption of divalent cations (Ca 2+ ) increased almost 25% by injecting a 2,000 ppm NaCl solution, compared to initial 10,000 ppm NaCl. Injecting a 2,000 ppm of CaCl 2 solution, however, significantly increased the adsorbed Ca 2+ from 0.1 to 1, which implies the complete saturation of mineral surface with divalent cations. Moreover, injecting 50,000 ppm of CaCl 2 solution also demonstrated the same effect as the 2,000 ppm CaCl 2 solution but with a faster rate.Upon combining the simulation and experimental results, we concluded that the multi-component ion exchange is not the sole mechanism behind low salinity effect for two reasons. First, almost 10% additional oil recovery was observed from the experiments by injecting the 2,000 ppm CaCl 2 compared with 50,000 ppm CaCl 2 solutions. Even though in both cases the surface is expected to be fully saturated with Ca 2+ according to the geochemical modelling. Second, 6% incremental oil recovery was achieved from the experiments by injecting 2,000 ppm NaCl solution compared with that of 50,000 ppm NaCl. Although 25% incremental adsorption of divalent cations (Ca 2+ ) were presented during the flooding of the 2,000 ppm NaCl solution. Therefore, it is worth noting that the electrical double layer expansion due to the ion exchange needs to be taken into account to pinpoint the mechanism(s) of low-salinity water effect.

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“…Shehata et al (2015) concluded that existence of divalent ions in the connate water is the more effective compared to monovalent in the sandstones cores (Shehata and Nasr El-Din 2015). In addition, the effects of cations have studied in some studies (Rashid et al 2015;Al-Attar et al 2013;Romanuka et al 2012;Austad et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Impact of water saturation and cation concentrations on wettability alteration and oil recovery of carbonate rocks using low-salinity water

Zaeri

Shahverdi

Hashemi

et al. 2018

J Petrol Explor Prod Technol

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In this study, the effect of initial water saturation on the oil recovery for carbonate rocks is investigated using spontaneous imbibition experiments. The experiments are performed using 20 times diluted sea water as imbibing fluid and the sea water as initial water. In addition, the impact of pH and Ca 2+ , Mg 2+ , Na +, and K + cations concentration change of imbibing fluid are investigated during tests. These results help to identify the active cations in the wettability alteration process of carbonate rocks during the low-salinity water injection. A mechanism is proposed to describe the effect of initial water saturation on the oil recovery by low-salinity water injection. The impact of initial water saturation on the wettability alteration might be positive or negative depending on its value and the rock permeability. The comparison of divalent cations concentrations shows that the minimum adsorption of Ca 2+ and maximum desorption of Mg 2+ lead to maximum oil recovery of spontaneous imbibition. The results confirm that three cations of Ca 2+ , Mg 2+ , and Na + are active for wettability alteration of carbonate rocks in the presence of sea water as initial water and diluted sea as imbibing fluid, whilst the amounts of potassium remain constant.

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Wettability alteration in carbonates during “Smart Waterflood”: Underlying mechanisms and the effect of individual ions

Cited by 98 publications

References 39 publications

Zeta potential in oil-water-carbonate systems and its impact on oil recovery during controlled salinity water-flooding

Zeta potential in oil-water-carbonate systems and its impact on oil recovery during controlled salinity water-flooding

Effect of multi-component ions exchange on low salinity EOR: Coupled geochemical simulation study

Impact of water saturation and cation concentrations on wettability alteration and oil recovery of carbonate rocks using low-salinity water

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