Critical review of low-salinity waterflooding

Sheng, James J.

doi:10.1016/j.petrol.2014.05.026

Cited by 466 publications

(270 citation statements)

References 48 publications

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“…11 To date, studies have proposed more than 17 separate mechanisms by which low-salinity flooding can enhance oil recovery. These are explained in some detail in the recent review by Sheng (2014). 12 Nevertheless, a definitive conclusion as to which mechanism truly underpins low-salinity enhanced oil recovery has yet to be fully determined.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

et al. 2015

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Publisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Journal of physical chemistry C, copyright c 2015 American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/acs.jpcc.5b00555Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractEnhanced oil recovery is becoming commonplace in order to maximise recovery from oilfields. One of these methods, low-salinity enhanced oil recovery (EOR) has shown promise, however the fundamental underlying chemistry requires elucidating. Here, three mechanisms proposed to account for low-salinity enhanced oil recovery in sandstone reservoirs are investigated using molecular dynamic simulations. The mechanisms probed are electric double layer expansion, multicomponent ionic exchange and pH effects arising at clay mineral surfaces. Simulations of smectite basal planes interacting with uncharged non-polar decane, uncharged polar decanoic acid and charged Nadecanoate model compounds are used to this end. Various salt concentrations of NaCl are modelled: 0% , 1% , 5% and 35% to determine the role of salinity upon the three separate mechanisms. Furthermore, the initial oil/water-wetness of the clay surface is modeled. Results show that electric double layer expansion is not able to fully explain the effects of low-salinity enhanced oil recovery. The pH surrounding a clays basal plane, and hence the protonation and charge of acid molecules is determined to be one of the dominant effects driving low-salinity EOR. Further, results present that the presence of calcium cations can drastically alter the oil wettability of a clay ⇤To whom correspondence should be addressed mineral surface. Replacing all divalent cations with monovalent cations through multicomponent cation exchange dramatically increases the water wettability of a clay surface, and will increase EOR.

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Section: Introductionmentioning

confidence: 99%

“…These are explained in some detail in the recent review by Sheng (2014). 12 Nevertheless, a definitive conclusion as to which mechanism truly underpins low-salinity enhanced oil recovery has yet to be fully determined. In the present paper three of the frequently cited mechanisms are tested at the molecular level.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

et al. 2015

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“…In the case of the experiments shown here, the pH was kept constant throughout its duration, and only the concentration was changed. These conditions are also ideal to test the double layer expansion mechanism, which generally predicts an increase in the width of the double layer extending away from the surface of the mineral, when the ionic strength of the solution is reduced [3,4]. This expansion then is linked to an increase in the range of repulsion forces, and therefore to a decrease in the overall adhesion of the organic molecules to the mineral surfaces.…”

Section: Effect Of Cacl 2 Concentrationmentioning

confidence: 99%

“…Enhanced oil recovery methods include steam and CO 2 injection, chemical flooding, pH alteration, inter alia. One method that is currently highlighted is low salinity enhanced oil recovery (LSEOR) owing to its use of a low-cost, environment-friendly substance, its sustainability, and its effectiveness [3,4]. For this reason, a multitude of studies have been conducted to understand the fundamental geochemical processes driving LSEOR; nevertheless, a debate still exists on the exact nature and importance of these processes and hence whether LSEOR can be applied to any given field [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…One method that is currently highlighted is low salinity enhanced oil recovery (LSEOR) owing to its use of a low-cost, environment-friendly substance, its sustainability, and its effectiveness [3,4]. For this reason, a multitude of studies have been conducted to understand the fundamental geochemical processes driving LSEOR; nevertheless, a debate still exists on the exact nature and importance of these processes and hence whether LSEOR can be applied to any given field [3,4]. Most authors agree, however, on a series of factors or conditions that need to be met for low salinity EOR to be effective, these include: the presence of clay minerals, the presence of a saline connate water (containing multivalent ions), exposure of the rock to acidic and basic oil components, and a significant reduction of salinity in the flooding water [3].…”

Section: Introductionmentioning

confidence: 99%

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Chemical Force Microscopy Study on the Interactions of COOH Functional Groups with Kaolinite Surfaces: Implications for Enhanced Oil Recovery

et al. 2017

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Clay-oil interactions play a critical role in determining the wettability of sandstone oil reservoirs, which, in turn, governs the effectiveness of enhanced oil recovery methods. In this study, we have measured the adhesion between -COOH functional groups and the siloxane and aluminol faces of kaolinite clay minerals by means of chemical force microscopy as a function of pH, salinity (from 0.001 M to 1 M) and cation identity (Na + vs. Ca 2+ ). Results from measurements on the siloxane face show that Ca 2+ displays a reverse low-salinity effect (adhesion decreasing at higher concentrations) at pH 5.5, and a low salinity effect at pH 8. At a constant Ca 2+ concentration of 0.001 M, however, an increase in pH leads to larger adhesion. In contrast, a variation in the Na + concentration showed less effect in varying the adhesion of -COOH groups to the siloxane face. Measurements on the aluminol face showed a reverse low-salinity effect at pH 5.5 in the presence of Ca 2+ , whereas an increase in pH with constant ion concentration resulted in a decrease in adhesion for both Ca 2+ and Na + . Results are explained by looking at the kaolinite's surface complexation and the protonation state of the functional group, and highlight a more important role of the multicomponent ion exchange mechanism in controlling adhesion than the double layer expansion mechanism.

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Investigation of the kinetics of water uptake into partially saturated shales

Roshan

Andersen

Rutlidge

et al. 2016

Water Resources Research

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Several processes have been proposed to describe the low recovery of hydraulic fracturing fluid in unconventional shale reservoirs which has caused both technical and environmental concerns. This study describes novel hydraulic experiments to quantitatively investigate the kinetics of water uptake into partially saturated shale through investigating the pressure response of injecting fluids (NaCl, KCl, MgCl2, and CaCl2 with different ionic concentrations) into crushed and sieved shale fragments. The results of the study indicate that the cumulative water uptake under pressure is likely to be controlled by three processes: surface hydration, capillary hydration including advective flow, and osmotic hydration. Each of these processes is a function of the differences between the in situ pore fluid and the injection fluid (solution chemistry and concentration) and the shale physicochemical properties, in particular the contact surface area, pore diameter, and the Cation Exchange Capacity (CEC). The uptake is not instantaneous, but is diffusion limited, with the rate governed by a number of kinetic processes. Uptake proceeds in three stages, each associated with a different process: (1) predominantly surface hydration, (2) predominantly capillary hydration and finally, (3) predominantly osmotic hydration. It was also shown that shale can take up a significant amount of water compared to its available solid volume. However, contrary to the conventional understanding, the increase in salinity of the injection fluid does not necessarily lead to reduced water uptake into shales, but is dependent on the type and concentration of cations within the shale and injecting fluid.

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Critical review of low-salinity waterflooding

Cited by 466 publications

References 48 publications

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

Chemical Force Microscopy Study on the Interactions of COOH Functional Groups with Kaolinite Surfaces: Implications for Enhanced Oil Recovery

Investigation of the kinetics of water uptake into partially saturated shales

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