Response of crude oil deposited organic layers to brines of different salinity: An atomic force microscopy study on carbonate surfaces

Kumar, Saravana; Rao, Ashit; Alotaibi, Mohammed B.; Ayirala, Subhash C.; Yousef, Ali; Sîretanu, Igor; Mugele, Frieder

doi:10.1016/j.fuel.2021.121129

Cited by 5 publications

(11 citation statements)

References 64 publications

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“…On account of the surface passivation by asphaltenes, the equilibration of injected brines with the carbonate mineral is not instantaneous and entails desorption of a multicomponent and polyaromatic sorbent layer. Nanoscale observations with in situ atomic force microscopy also confirm that mineral dissolution occurs after the desorption of bound asphaltenes …”

Section: Resultsmentioning

confidence: 76%

“…Water molecules further stabilize the surface deposits of asphaltenes, evident by the broad FTIR band at 3200−3750 cm −1 (Figure 3) originating from interasphaltene and asphaltene−water hydrogen bonding interactions. 81 With the strong association of well-ordered water layers 102 and the solvation dynamics of organic deposits 103 at the water−carbonate interface, we identify water molecules as the third main constituent of the organo− ionic surface layer in addition to asphaltene and metal ion species. With the measured oil-side contact angles for crude oil droplet advancing on eqFW-aged and eqCRO-aged calcite between 138 and 50°, 26 this organo−ionic layer, established via surface reactions of aqueous and nonaqueous asphaltenes, metal ions, and associated solvation underlay the oil-wet nature of reservoir rocks.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

“…At first, the water-soluble asphaltenes are extracted by the brine enhancing the stacking interactions between residual less polar asphaltenes. This selective extraction of asphaltenes by moderate- to low-salinity brines is attributed to (i) a salting-out or dilution effect, wherein increased water activity enhances the solubility of lighter asphaltenes, , (ii) the dissociation and dissolution of organo–metal complexes/salts under low-salinity conditions (undersaturated with respect to organo–metal phases), , and (iii) relatively poor hydrophobic attraction between asphaltenes at low ionic strength. , Second, this selective extraction or fractional desorption leads to the relative enrichment of nonaqueous bulky asphaltenes at the brine–mineral interface, which undergo efficient stacking interactions and present organized alkyl terminal groups toward the brine and possibly attain high packing densities . While restructuring of asphaltenes toward more organized assemblies on the mineral surface are anticipated to yield more oil-wet conditions, the gradual depletion of aqueous or double-sided-tape asphaltenes plays a pivotal role in the overall wettability alteration.…”

Section: Resultsmentioning

confidence: 99%

“…Nanoscale observations with in situ atomic force microscopy also confirm that mineral dissolution occurs after the desorption of bound asphaltenes. 103 Our results show that the chemically heterogeneous sorbent layer indeed dissolves in low-salinity brines through a process that encompasses two stages. At first, the water-soluble asphaltenes are extracted by the brine enhancing the stacking interactions between residual less polar asphaltenes.…”

Section: Desorption and Mineral Dissolution Under Brine Flowmentioning

confidence: 99%

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Formation and Stability of Heterogeneous Organo–Ionic Surface Layers on Geological Carbonates

et al. 2022

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Many geological processes from oil recovery to underground CO2 storage are affected by natural molecules adsorbed on rock surfaces. Yet, geochemical models tend to overlook their formation and stability, let alone existence. With a suite of analytical techniques, we address this “missing-link” and describe fundamental mechanisms for (i) the deposition of surface-active molecules in complex brines and oils on underground minerals and (ii) the desorption of heterogeneous sorbents and its dependence on aqueous composition. First, we show that organic and inorganic constituents of both formation water and crude oil form an organo–ionic surface layer on calcite. Primary modifiers are revealed as aqueous and nonaqueous polyaromatic molecules with polar and metal-binding functional groups and solubility characteristics of asphaltenes. Formed via π-stacking and ionic and hydrogen bonding interactions, the heterogeneous organo–ionic layer establishes a physical barrier between the mineral and ambient atmosphere/fluid, impacting the dissolution and wettability of rocks. Second, we investigate desorption of the organo–ionic layer in various brines under flow and static conditions. With chromatographic and spectroscopic methods (including Raman and sum-frequency generation), we show that the release of adsorbed material from carbonate surfaces encompasses key coupled reactions: (i) dissolution of “brine-soluble” asphaltenes, leading to relative interfacial enrichment of bulky “brine-insoluble” asphaltenes, (ii) nanoscale orientational changes of surface asphaltene assemblies, carbonate ions, and water molecules at the brine–rock interface, and (iii) dissolution and surface reconstruction of the carbonate mineral. Through these reactions, the “low-salinity effect” is uncovered as a two-stage desorption process: the initial release or selective extraction of “water-soluble” sorbents and subsequent delamination of residual “water-insoluble” asphaltenes from the dissolving mineral surface. Illuminating the surface reactions of geological minerals, we conclude that surface passivation by heterogeneous organo–ionic matter is not only ubiquitous in nature but also a key regulator of the interfacial chemistry, reactivity and wettability of underground rocks.

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Section: Resultsmentioning

confidence: 76%

Section: ■ Results and Discussionmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Desorption and Mineral Dissolution Under Brine Flowmentioning

confidence: 99%

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Formation and Stability of Heterogeneous Organo–Ionic Surface Layers on Geological Carbonates

et al. 2022

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“…The response of crude deposited organic layers on carbonate surfaces was studied using atomic force microscopy (AFM) and reported either the swelling or stiffness of organic layers with changing salinity. 11 The swelling of organic layers is expected to provide a better access of the injection brine to the rock surface to cause either mineral dissolution or surface charge alteration, thereby changing the wetting properties of the rock surface. The thicker and more rigid/elastic oil−water interfacial layers indicate the stabilization of crude oil polar molecules at the interface, which could favor the wettability alteration toward water-wet conditions observed on carbonate surfaces, especially with brines containing sulfate ions.…”

Section: ■ Introductionmentioning

confidence: 99%

In Situ Characterization of Carbonate/Oil/Water Interfacial Layers Using Advanced EM Techniques for Enhanced Oil Recovery

et al. 2022

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The visualization and characterization of the interactions between injection brine, oil, and carbonate rock play a major role in understanding the causative mechanisms behind wettability alteration and enhanced oil recovery. However, conventional imaging methods fail to provide such important analysis due to limited resolution and visualization capabilities. To address this gap, a cryogenic electron microscope (EM) and liquid-cell holder have been utilized in this study. The results from each of these techniques are discussed and compared. The liquid-cell transmission electron microscope (TEM) holder with an encapsulation function feature successfully enabled the direct observation and analysis of the liquid sample close to its native conditions. Energy-dispersive spectroscopy (EDS) analyses have been simultaneously utilized to provide the chemical mapping of the rock–fluid interfaces. These results provide, for the first time, nanoscale images of oil droplets, calcite nanoparticles, and dissolved salt ions in their native environment. The compositional distribution of multiple elements and elemental mapping of the structures in solution are also presented. The presented novel nanoscale characterization provides a new insight into the rock–oil–brine interactions, and this understanding can be critical to optimize the salinity and injection water compositions used for enhanced oil recovery in carbonate reservoirs.

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A review on the application of nanofluids in enhanced oil recovery

Hou

Sun

2022

Front. Chem. Sci. Eng.

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Response of crude oil deposited organic layers to brines of different salinity: An atomic force microscopy study on carbonate surfaces

Cited by 5 publications

References 64 publications

Formation and Stability of Heterogeneous Organo–Ionic Surface Layers on Geological Carbonates

Formation and Stability of Heterogeneous Organo–Ionic Surface Layers on Geological Carbonates

In Situ Characterization of Carbonate/Oil/Water Interfacial Layers Using Advanced EM Techniques for Enhanced Oil Recovery

A review on the application of nanofluids in enhanced oil recovery

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