On the “Rag Layer” and Diluted Bitumen Froth Dewatering

Abstract

Samples of rag layer were collected using multiple bench-top, batch centrifugations with optical microslides inserted to a centrifuge cell in the last spinning. Image analysis of the samples provided data for approximate sedimentation rate analysis, based on fractal floc dimension and Smoluchowski coagulation kinetic equation. The analysis shows that, if a flocculating chemical is used as a demulsifier, overdosing will necessarily result in deterioration of the process performance. Optimization of the chemical dosage and accurate process control are thus necessary conditions to attain satisfactory dewatering process performance Des échantillons de papier chiffon ont été recueillis par des centrifugations discontinues multiples à l'échelle de la paillasse, des porte-objets optiques étant insérées dans la cellule centrifuge dans le dernier essorage. L'analyse d'images des échantillons a permis d'obtenir des données approximatives de vitesses de sédimentation, basées sur la dimension des flocons fractals et l'équation de cinétique de coagulation de Smoluchowski. L'analyse montre que, si on utilise un agent chimique floculant comme un désémulsifiant, la surdose conduira nécessairement à la détérioration de la performance des procédés. L'optimisation du dosage chimique et le contrôle précis du procédé sont ainsi nécessaires pour une performance satisfaisante du procédé d'épaississement.

Demulsification Mechanism of Asphaltene-Stabilized Water-in-Oil Emulsions by a Polymeric Ethylene Oxide–Propylene Oxide Demulsifier

“…While flocculation can promote coalescence by enhancing the contact between water droplets 7 , flocculated water droplets can also be stabilized by steric forces that resist thin liquid film drainage 8 . Although flocculants are often used to separate water from oil emulsions, the use of coalescers is preferable as it reduces oil losses to the phase-separated underflow aqueous phase 9 .…”

“…It was established that beyond an optimal dosage, the performance of a demulsifier can either plateau (type I behaviour) or degrade (type II behaviour, also known as overdose), resulting in an increase in the emulsion stability. Type I behaviour has been reported for EC 31 and for some EO-PO demulsifiers 27,[32][33][34] , while overdose was observed for octylphenylpolyethoxylates and sodium bis(2-ethylhexyl)sulfosuccinate demulsifiers 35 , commercial demulsifiers [36][37][38] , polyoxyalkylates 9 , diethanolamines 15 and some EO-PO demulsifiers 27,39 . These demulsifiers act either as flocculants or coalescers 41 .…”

Molecular Interactions between a Biodegradable Demulsifier and Asphaltenes in an Organic Solvent

“…18,19 To overcome such issues and enhance oil dewatering performance, chemical additives such as dispersants and demulsifiers are typically added at the ppm level to break particle and interfacial networks, thus promoting droplet-droplet coalescence. [20][21][22] Chemical demulsifiers are designed to actively compete at the liquid-liquid interface and disrupt the rigid networks which have formed a protective barrier around water droplets.…”

Rheological properties of highly concentrated dense packed layer emulsions (w/o) stabilized by asphaltene

“…This layer can reduce separation efficiency and upset the process. [20][21][22][23][24][25] Formation of a stable and dense packed water-in-crude oil emulsion layer (DPL), as shown in Fig. 1, is a common occurrence during the gravitational separation processes.…”

“…12, [20][21][22][23][24][25] Crude oils are complex mixtures containing millions of distinct molecular species. To simplify the study of crude oils in petroleum science, classification of indigenous components is based on SARA (refers to saturates, aromatics, resins, and asphaltenes, 4 respectively) fractionation is feasible.…”