Model molecules mimicking asphaltenes

Sjöblom, Johan; Simon, Sébastien; Xu, Zhenghe

doi:10.1016/j.cis.2015.01.002

Cited by 161 publications

(143 citation statements)

References 144 publications

Supporting

Mentioning

132

Contrasting

Unclassified

Order By: Relevance

“…With a reported activation energy of 23.5 kJ/mol (Palandri and Kharaka 2004), k rxn weakly increases with temperature by a factor of four between 25 and 75 C. However, the presence of impurity metals and adsorptive organic materials significantly reduces k rxn , possibly by factors of 100 (Salem et al 1994;Eisenlohr et al 1999;Arvidson et al 2003). Because the asphaltenic component of crude oils typically contains both heavy metals and associated organic acids and bases (Peng et al 2009;Sjöblom et al 2015), we adopt a range of values for k rxn between 10 À5 and 10 À3 cm/s. Mineral dissolution occurs on exposed surface area.…”

Section: ðA-1þmentioning

confidence: 99%

Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

et al. 2017

View full text Add to dashboard Cite

SummaryLow-salinity waterflooding (LSW) is ineffective when reservoir rock is strongly water-wet or when crude oil is not asphaltenic. Success of LSW relies heavily on the ability of injected brine to alter surface chemistry of reservoir crude-oil brine/rock (COBR) interfaces. Implementation of LSW in carbonate reservoirs is especially challenging because of high reservoir-brine salinity and, more importantly, because of high reactivity of the rock minerals. Both features complicate understanding of the COBR surface chemistries pertinent to successful LSW. Here, we tackle the complex physicochemical processes in chemically active carbonates flooded with diluted brine that is saturated with atmospheric carbon dioxide (CO 2 ) and possibly supplemented with additional ionic species, such as sulfates or phosphates.When waterflooding carbonate reservoirs, rock equilibrates with the injected brine over short distances. Injected-brine ion speciation is shifted substantially in the presence of reactive carbonate rock. Our new calculations demonstrate that rock-equilibrated aqueous pH is slightly alkaline quite independent of injected-brine pH. We establish, for the first time, that CO 2 content of a carbonate reservoir, originating from CO 2 -rich crude oil and gas, plays a dominant role in setting aqueous pH and rock-surface speciation.A simple ion-complexing model predicts the calcite-surface charge as a function of composition of reservoir brine. The surface charge of calcite may be positive or negative, depending on speciation of reservoir brine in contact with the calcite. There is no single point of zero charge; all dissolved aqueous species are charge determining. Rock-equilibrated aqueous composition controls the calcitesurface ion-exchange behavior, not the injected-brine composition. At high ionic strength, the electrical double layer collapses and is no longer diffuse. All surface charges are located directly in the inner and outer Helmholtz planes.Our evaluation of calcite bulk and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration, the dissolution mechanism for releasing adhered oil is eliminated. Also, fines mobilization and concomitant oil release cannot occur because there are few loose fines and clays in a majority of carbonates. LSW cannot be a low-interfacial-tension alkaline flood because carbonate dissolution exhausts all injected base near the wellbore and lowers pH to that set by the rock and by formation CO 2 . In spite of diffuse double-layer collapse in carbonate reservoirs, surface ion-exchange oil release remains feasible, but unproved.Introduction LSW refers to improved oil recovery achieved by waterflooding a reservoir with brine of lower salinity than that of the field brine. The process is alluring because of simplicity, favorable economics, and large potential. In some applications, seawater is inj...

show abstract

Section: ðA-1þmentioning

confidence: 99%

Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The different functionalities, molecular weights, and molecular architectures make it challenging to obtain a complete understanding of their properties. Sjöblom et al 24 . indicated two main strategies that can be used to tackle this issue: fractionation of the complete asphaltene content into sub-fractions of reduced complexity (but still polydisperse 25,26 and different among reservoirs 27 ) or synthesis of model molecules of defined chemical structure that mimic aspects of the chemical structure of indigenous asphaltenes..…”

Section: Introductionmentioning

confidence: 99%

Sorption and Interfacial Rheology Study of Model Asphaltene Compounds

et al. 2016

Self Cite

View full text Add to dashboard Cite

The sorption and rheological properties of an acidic polyaromatic compound (C5PeC11), which can be used to further our understanding in the behavior of asphaltenes, are determined experimentally. The results show that C5PeC11 exhibits the type of pH-dependent surface activity and interfacial shear rheology observed in C6-asphaltenes with a decrease in the interfacial tension concomitant to the elastic modulus when the pH increases. Surface pressure-area (Π-A) isotherms show evidence of aggregation behavior and π-π stacking at both the air/water and oil/water interfaces. Similarly, interactions between adsorbed C5PeC11 compounds are evidenced through desorption experiments at the oil/water interface. Contrary to indigenous asphaltenes, adsorption is reversible, but desorption is slower than for noninteracting species. The reversibility enables us to create layers reproducibly, whereas the presence of interactions between the compounds enables us to mimic the key aspects of interfacial activity in asphaltenes. Shear and dilatational rheology show that C5PeC11 forms a predominantly elastic film both at the liquid/air and the liquid/liquid interface. Furthermore, a soft glassy rheology model (SGR) fits the data obtained at the liquid/liquid interface. Yet, it is shown that the effective noise temperature determined from the SGR model for C5PeC11 is higher than for indigenous asphaltenes measured under similar conditions. Finally, from a colloidal and rheological standpoint, the results highlight the importance of adequately addressing the distinction between the material functions and true elasticity extracted from a shear measurement and the apparent elasticity measured in dilatational-pendant drop set-ups.

show abstract

“…[1,2] Among the various crude oil constituents, asphaltenes have the highest molecular weight and are also the most polar. [3] It is now recognized that asphaltenes have a broad molecular weight distribution with an average molecular weight of around 750 g/mol with a factor of 2 in width of the molecular weight distribution.…”

Section: Introductionmentioning

confidence: 99%

Asphaltene fractionation based on adsorption onto calcium carbonate: Part 1. Characterization of sub-fractions and QCM-D measurements

Subramanian

Simon

Gao

et al. 2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

Self Cite

View full text Add to dashboard Cite

Model molecules mimicking asphaltenes

Abstract: Asphalthenes are typically defined as the fraction of petroleum insoluble in n-alkanes (typically heptane, but also hexane or pentane) but soluble in toluene. This fraction causes problems of emulsion formation and deposition/precipitation during crude oil production,

Cited by 161 publications

References 144 publications

Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

Sorption and Interfacial Rheology Study of Model Asphaltene Compounds

Asphaltene fractionation based on adsorption onto calcium carbonate: Part 1. Characterization of sub-fractions and QCM-D measurements

Contact Info

Product

Resources

About