Asphaltene Precipitation and Solvent Properties of Crude Oils

Buckley, Jill S.; Hirasaki, George J.; LIU, Y.; DRASEK, S. VON; WANG, J-X.; Gill, B. S.

doi:10.1080/10916469808949783

Cited by 249 publications

(223 citation statements)

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“…Atomic force microscopy 25 has also been utilized to observe aggregates deposited onto mica surfaces. The role of solvent polarizability in the precipitation of asphaltenes has been investigated via index-of-refraction methods 26 . Photon correlation spectroscopy 27 , surface tension measurements 28 , and micro-calorimetry 29 have provided evidence of asphaltenes' self-association in organic solvents.…”

Section: The Study Of Asphaltene Aggregationmentioning

confidence: 99%

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Pietraru

Cramb

2003

Langmuir

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This work involved the study of Cold Lake asphaltenes' behavior in toluene and o-dichlorobenzene. The changes in asphaltene microenvironments with the increase in asphaltene concentration were observed using fluorescence solvatochromism. The reporter molecule chosen was the environmentally sensitive fluorophore PRODAN. This procedure represents a novel and sensitive method to study asphaltene solutions, and might bring additional information to the existent database of asphaltene properties.A pre-aggregation model was developed to explain the experimental observations, and a definition for the critical aggregation concentration was proposed. The model is valid for low asphaltene concentrations and is supported by direct measurements of refractive indices for asphaltene solutions. Atomic force microscopy was used to image asphaltene entities. The size distribution indicated that asphaltene particles do not change significantly with the increase in concentration. The appearance of larger aggregates in solutions with concentrations above CAC might support the validity of the model.

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Section: The Study Of Asphaltene Aggregationmentioning

confidence: 99%

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Pietraru

Cramb

2003

Langmuir

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“…The solvated asphaltene crystallites are the primary particles of the colloidal dispersed phase. These particles can associate and aggregate, forming various size particles depending on temperature, pressure and concentration [8,15,16,19,21,[26][27][28][29][30][31][32][33][34][35]42,43]. In fact, asphaltenes are natural surfactants stabilising water/crude oil emulsion [21,22,[44][45][46][47][48][49][50][51][52].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of asphaltenes from toluene on mineral surface

Marczewski

Szymula

2002

Colloids and Surfaces A: Physicochemical and Engineering Aspect

170

124

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Undesirable adsorption of asphaltenes on rock minerals was studied. Asphaltenes are an important component of crude oil, being also natural surfactant stabilising water/crude oil emulsions. Owing to their chemical nature, asphaltenes are able to associate, form micelles and create a surface charge at the interface. Asphaltenes may be adsorbed on rock reservoir from the organic solvents in crude oil and as an organic colloid, they can adsorb electrolyte ions from aqueous solution. In order to simulate natural conditions we used asphaltenes from local drills, toluene as solvent and several typical oxides and carbonate rock components or minerals as adsorbents. Our study included natural Brazilian quartz, dolomite, calcite and kaolin, as well as pure oxides: Fe 2 O 3 and TiO 2 . The typical shape of asphaltene adsorption isotherms was obtained for all systems studied with the characteristic 'steps' which indicate changes in the state of asphaltene molecules in the solution and at the mineral surface. Those changes are related to the asphaltene association and further formation of hemimicelles and micelles.

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“…Buckley and co-workers [60][61][62][63] proposed an alternate method for predicting the onset of asphaltene precipitation using refractive index (RI) measurements. The theory was based on the assumption that the aggregation and precipitation of asphaltenes is dominated by differences of London dispersion forces (a type of Van der Waals force) between the crude oil (maltenes) and the asphaltenes.…”

Section: Refractive Index (Ri) Measurementsmentioning

confidence: 99%

“…60 The London dispersion interactions between molecules are due to induced polarization. In systems where London dispersion forces dominate, the strength of the interactions is related to the difference in the refractive indices between the two materials (assuming that the materials have same absorption frequency).…”

Section: Refractive Index (Ri) Measurementsmentioning

confidence: 99%

Asphaltene Precipitation Models: A Review

Subramanian

Simon

Sjöblom

2015

Journal of Dispersion Science and Technology

108

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Asphaltenes are the heaviest and the most polar fraction of crude oil and are defined as a solubility class (typically soluble in toluene but insoluble in n-alkanes like n-heptane).Precipitation and deposition of asphaltenes during production, processing and transportation of oil is a major challenge faced by oil industry. Over the last thirty years, a number of different models have been proposed for predicting the onset of asphaltene precipitation and also the amount of precipitated asphaltenes. This article reviews the different models that have been proposed for predicting asphaltene precipitation either at atmospheric pressure or under depressurization. A brief summary of the different modeling approaches is presented followed by description of work done by different research groups. Our focus will be on the description of the basic assumptions underlying different models and also the ability/performance of the model to match the experimental data. Finally, a comparison of models is presented and discussed along with suggestions for improvement. Keywords:Asphaltene precipitation, Thermodynamic models, Solubility models, Equation of state models, Colloidal models INTRODUCTIONAsphaltenes are considered to represent the most polar and the heaviest components in crude oil. 1 They are a solubility class and defined as the fraction that is insoluble in n-alkane (like n-heptane) but soluble in aromatic solvents (like toluene). [2][3] The precipitation and deposition of asphaltenes during production and transport of crude oil is recognized as a serious problem in the oil industry since it can lead to formation damage, plugging of wellbores and production facilities. [4][5] Asphaltene precipitation can be encountered during primary recovery of oil as well as during enhanced oil recovery operations like miscible flooding with CO 2 or natural gas. 6The precipitation of asphaltenes occurs due to a number of reasons. These include changes in pressure, temperature, chemical composition of crude oils, acid stimulation, mixing of oil with diluents, other oil and gas components like CO 2 . 4 Heavy crudes usually have a lower tendency to give asphaltene deposition problems inspite of their higher asphaltene content.This observation is normally attributed to their higher resin content and lower saturate content. 7Asphaltenes are generally assumed to be composed of fused ring aromaticity, small aliphatic side chains and heteroatom functional groups. 8 The molecular weight of asphaltenes has been a source of controversy for a very long time. 9 It is now recognized to be close to 750 g/mol with a factor of 2 in the width of the molecular weight distribution. Solubility ApproachThe solubility models are most commonly used for predicting asphaltene precipitation. These models make use of the concept of solubility parameter and assume that petroleum crude Models based on Solution theory and Flory-Huggins theory assume that asphaltenes have homogenous structure and properties while models based on Scott-Magat theory assum...

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Asphaltene Precipitation and Solvent Properties of Crude Oils

Cited by 249 publications

References 4 publications

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Changes in Asphaltene Microenvironments Evidenced by Fluorescence Solvatochromism

Adsorption of asphaltenes from toluene on mineral surface

Asphaltene Precipitation Models: A Review

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