Effect of Chemical Inhibitors on Asphaltene Precipitation and Morphology Using Ultra-Small-Angle X-ray Scattering

Abstract

This paper presents time-resolved ultra-small-angle X-ray scattering (USAXS) results of the effect of chemical inhibitors, dodecylphenol (DDPh) and nonylphenol formaldehyde resin-1600 (NPFR), on the kinetic precipitation of asphaltenes. With length scale ranges probed between 1 nm and 5 μm, USAXS provides a unique means to simultaneously characterize insoluble asphaltene clusters with length scales of >50 nm and soluble clusters with length scales of <50 nm. Both inhibitors tested were observed to reduce the insoluble asphaltene growth rate at 500 and 5000 ppm (mg/kg) inhibitor concentrations, with DDPh displaying a relatively larger reduction. Further, both of the chemical inhibitors tested modified the morphology of insoluble asphaltenes, and the most effective inhibitor, DDPh, also reduced the size of soluble asphaltene clusters. The asphaltene sample used in this study initially precipitated as a fractal cluster that transitioned to a second liquid or solid phase with a rough surface. These insoluble particles further flocculate into larger mass fractals and are commonly visualized with optical microscopy. The chemical inhibitors slowed the rate of transition to a new phase, and the fractal geometry of the insoluble particles persisted for longer times. Consequently, USAXS is a new tool that can be used to better understand the impact of chemical inhibitors on the structure and dynamic aggregation of asphaltenes over broad length scales.

Fractionation and Characterization of Petroleum Asphaltene: Focus on Metalopetroleomics

“…In addition, the size and concentration of soluble asphaltenes do not change during precipitation, whereas the structure of insoluble asphaltenes varies. Yang et al [126] also studied the effect of chemical inhibitors on asphaltene precipitation and morphology using USAXS.…”

Hydrophobic Deep Eutectic Solvent and Glycolipid Biosurfactant as Green Asphaltene Inhibitors: Experimental and Theoretical Studies

“…Many studies 4−10 have studied asphaltene precipitation remedies using various methods such as spectroscopy, 11,12 microscopy, 13,14 conductivity, 15 filtration, 16 and interfacial tension measurement. 17,18 To do so, different chemicals, including alcohols, 19 organic acids, 20 vegetable oils, 21 and amphiphiles, 22 were used as inhibitors.…”

Recent Developments on the Elucidation of Colloidal Aspects of Asphaltenes and Their Relevance to Oilfield Problems

“…The data showed that the effect of these compounds did not affect the aggregate nanostructure (first level of organization), 45 in agreement with recent USAXS data that revealed the effect only at the next level of organization. 58 In line with this observation, oil + inhibitor systems showed perturbations exclusively in submicron and micrometer size ranges through experiments conducted using a quartz crystal microbalance (QCM) and an analytical centrifuge (LUMiSizer). 21 As an example, results from the LUMiSizer showed that in case of precipitation, the inhibitor acts at the submicrometric scale, avoiding the stacking of nanoaggregates in even larger structures, thus reducing the size of objects by up to an order of magnitude.…”

“…In addition, recent results from ultra-small angle X-ray scattering (USAXS) measurements reported by Hoepfner and co-workers, 58 are capable of accessing the size range of 1 nm to 5 μm, therefore providing a full account of asphaltenes particles. Their results describe clusters of soluble and insoluble asphaltenes (following aggregation stages), abandoning the molecular description in organic medium.…”