Fluorine tracers for the identification of molecular interaction with porous asphaltene aggregates in crude oil

Stapf, Siegfried; Ordikhani-Seyedlar, Amín; Mattea, Carlos; Kausik, Ravinath; Freed, Daniel S.; Song, Yi‐Qiao; Hürlimann, Martin D.

doi:10.1016/j.micromeso.2014.07.055

Cited by 10 publications

(10 citation statements)

References 25 publications

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“…The asphaltene was provided by Schlumberger Doll Research and was extracted from oil A13 used in references [ 11 , 12 ]. It is the same as in reference [ 13 ], where its radical content was determined by EPR to (

spins per mg.…”

Section: Methodsmentioning

confidence: 99%

“…Our previous studies [ 11 , 12 ] showed a significant (factor 20) difference in the

ratios of fluorinated aromatic ring molecules (higher ratio) (benzene-f

and toluene-f

) and aliphatic chain molecules (lower ratio) (octane-f

and pentadecane-f

) in an oil containing 13

% asphaltenes, which is much smaller in an asphaltene-free resinic oil and vanishes in an asphaltene- and resin-free oil. This difference in the

ratio persists in a solution of chloroform-d and 3

% of the tracer molecule (benzene-f

and octane-f

) containing 10

% asphaltenes [ 13 ], extracted from the previous investigated asphaltenic oil.…”

Section: Introductionmentioning

confidence: 99%

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Non-Exponential 1H and 2H NMR Relaxation and Self-Diffusion in Asphaltene-Maltene Solutions

et al. 2021

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The distribution of NMR relaxation times and diffusion coefficients in crude oils results from the vast number of different chemical species. In addition, the presence of asphaltenes provides different relaxation environments for the maltenes, generated by steric hindrance in the asphaltene aggregates and possibly by the spatial distribution of radicals. Since the dynamics of the maltenes is further modified by the interactions between maltenes and asphaltenes, these interactions—either through steric hindrances or promoted by aromatic-aromatic interactions—are of particular interest. Here, we aim at investigating the interaction between individual protonic and deuterated maltene species of different molecular size and aromaticity and the asphaltene macroaggregates by comparing the maltenes’ NMR relaxation (T1 and T2) and translational diffusion (D) properties in the absence and presence of the asphaltene in model solutions. The ratio of the average transverse and longitudinal relaxation rates, describing the non-exponential relaxation of the maltenes in the presence of the asphaltene, and its variation with respect to the asphaltene-free solutions are discussed. The relaxation experiments reveal an apparent slowing down of the maltenes’ dynamics in the presence of asphaltenes, which differs between the individual maltenes. While for single-chained alkylbenzenes, a plateau of the relaxation rate ratio was found for long aliphatic chains, no impact of the maltenes’ aromaticity on the maltene–asphaltene interaction was unambiguously found. In contrast, the reduced diffusion coefficients of the maltenes in presence of the asphaltenes differ little and are attributed to the overall increased viscosity.

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spins per mg.…”

Section: Methodsmentioning

confidence: 99%

“…Our previous studies [ 11 , 12 ] showed a significant (factor 20) difference in the

ratios of fluorinated aromatic ring molecules (higher ratio) (benzene-f

and toluene-f

) and aliphatic chain molecules (lower ratio) (octane-f

and pentadecane-f

) in an oil containing 13

% asphaltenes, which is much smaller in an asphaltene-free resinic oil and vanishes in an asphaltene- and resin-free oil. This difference in the

ratio persists in a solution of chloroform-d and 3

% of the tracer molecule (benzene-f

and octane-f

) containing 10

% asphaltenes [ 13 ], extracted from the previous investigated asphaltenic oil.…”

Section: Introductionmentioning

confidence: 99%

Non-Exponential 1H and 2H NMR Relaxation and Self-Diffusion in Asphaltene-Maltene Solutions

et al. 2021

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“…The fields are relatively weak and strongly inhomogeneous; therefore, no chemical shift information is available. The characterization is based on the measurement of relaxation and diffusion, whereby CPMG in particular proved to be effective in the strongly inhomogeneous fields …”

Section: Lf‐nmr In Oil Production Formulation and Usementioning

confidence: 99%

Low‐field NMR for quality control on oils

Rudszuck

Förster

Nirschl

et al. 2019

Magnetic Reson in Chemistry

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Oil is a prominent, but multifaceted material class with a wide variety of applications. Technical oils, crude oils as well as edibles are main subclasses. In this review, the question is addressed how low-field NMR can contribute in oil characterization as an analytical tool, mainly with respect to quality control. Prerequisite in the development of a quality control application, however, is a detailed understanding of the oils and of the measurement. Low-field NMR is known as a rich methodical toolbox that was and is explored and further developed to address questions about oils, their quality, and usability as raw materials, during production and formulation as well as in use.

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“…Fast field cycling (FFC) NMR has been applied to study interactions between crude oil components by Stapf and co-workers , Relaxation time spectra T 1 (ω) (Larmor frequency-dependent longitudinal relaxation time) and T 1 / T 2 ratios of fluorinated aliphatic and aromatic tracers added to asphaltene-free and asphaltene-rich crude oils were utilized to evaluate the molecular mobility of tracers in a host liquid. The asphaltene’s presence strongly impacted the T 1 / T 2 ratio of aromatic tracers relative to aliphatic ones, indicating a stronger interaction of aromatics moieties with asphaltenes.…”

Section: Overview Of Magnetic Resonance Techniquesmentioning

confidence: 99%

“…According to the authors, the approach provides a path for an enhanced interpretation of experimental NMR data and can be extended to a case of multicomponent hydrocarbon compounds and intricate scenarios like interaction of light hydrocarbon with complex polyaromatic structures of kerogen and bitumen, which may shed a light on the role of various components of crude oil on its stability and reactivity. Fast field cycling (FFC) NMR has been applied to study interactions between crude oil components by Stapf and coworkers 46,47 Relaxation time spectra T 1 (ω) (Larmor frequencydependent longitudinal relaxation time) and T 1 /T 2 ratios of fluorinated aliphatic and aromatic tracers added to asphaltenefree and asphaltene-rich crude oils were utilized to evaluate the molecular mobility of tracers in a host liquid. The asphaltene's presence strongly impacted the T 1 /T 2 ratio of aromatic tracers relative to aliphatic ones, indicating a stronger interaction of aromatics moieties with asphaltenes.…”

Section: ■ Wettability and Asphaltenes Reactivitymentioning

confidence: 99%

On the Optimum Aging Time: Magnetic Resonance Study of Asphaltene Adsorption Dynamics in Sandstone Rock

2019

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Wettability is a key factor defining ultimate hydrocarbon recovery. Extensive experimentation is required to replicate the wetting state of reservoir rocks. This involves a rock sample wettability restoration procedure, including an aging step and a concept of an optimum aging time, in which asphaltene chemistry plays a major role. There are numerous reports on significance of various crude oil components and elements of asphaltene structure to their tendency to interact with the solid phase, though subject evidence is contradictory. We investigate a possible relationship between the composition of oil, kinetics of an aging process, and a change of sandstone rock wettability. Wettability state of the cores was monitored using low-field NMR relaxometry. The composition and key components of accumulated deposits were established by matching 1H solution-state NMR and X-band EPR spectra of deposits to the spectra of SARA (saturates-aromatics-resins-asphaltenes) fractions of aging fluids. We determined adsorption rate as a function of aging fluid type, monitored free radical and vanadyl content of deposits, and wettability state (through surface relaxivity) over extended aging time interval. EPR data suggest no correlation between the concentration of free radicals in deposits and wettability of the cores. We observe two distinctive periods in the aging process: (i) early-time adsorption best described by a pseudo-second-order kinetic model similar for all aging fluids used in this study, suggesting a common reaction-limited process; (ii) a late-time adsorption process of a faster rate proportional to a bulk diffusion coefficient of aging fluids approximated by an intraparticle diffusion kinetic model. The transition time interval between the two can be used as a definition of an “optimum aging time” in special core analysis. Results provide a link between oil chemistry and wettability phenomena in rocks and may contribute to the development of a model predicting wettability reversal and more accurate reservoir modeling.

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Fluorine tracers for the identification of molecular interaction with porous asphaltene aggregates in crude oil

Cited by 10 publications

References 25 publications

Non-Exponential 1H and 2H NMR Relaxation and Self-Diffusion in Asphaltene-Maltene Solutions

Non-Exponential 1H and 2H NMR Relaxation and Self-Diffusion in Asphaltene-Maltene Solutions

Low‐field NMR for quality control on oils

On the Optimum Aging Time: Magnetic Resonance Study of Asphaltene Adsorption Dynamics in Sandstone Rock

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