The use of nonylphenol formaldehyde resins for preventing asphaltene precipitation in vacuum residues and hydroprocessed petroleum samples

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

“…In particular, wellbore deposition causes drops in production rates, and excessive fouling may require complete shut-in of the well, resulting in losses of up to 50 000 bbl/day. , Furthermore, the mixing of incompatible oil in a refinery can lead to asphaltene fouling of heat exchangers and other equipment . To reduce the extent of asphaltene deposition, a variety of techniques have been commercially employed, which include monitoring of thermodynamic parameters within wells to avoid conditions where asphaltene precipitations is induced and the use of chemical inhibitors. ,,, A classical mechanism of chemical inhibition is that inhibitors adsorb on asphaltene molecules/aggregates and form a steric stabilization layer that promotes asphaltene dispersion within crude oil solution; however, extensive assessment of inhibitor mechanisms of action has not been reported in the literature. Inhibitor action is also highly specific to a number of conditions: oil properties, concentration of inhibitor, temperature of operation, etc .…”

“…To reduce the extent of asphaltene deposition, a variety of techniques have been commercially employed, which include monitoring of thermodynamic parameters within wells to avoid conditions where asphaltene precipitations is induced and the use of chemical inhibitors. ,,, A classical mechanism of chemical inhibition is that inhibitors adsorb on asphaltene molecules/aggregates and form a steric stabilization layer that promotes asphaltene dispersion within crude oil solution; however, extensive assessment of inhibitor mechanisms of action has not been reported in the literature. Inhibitor action is also highly specific to a number of conditions: oil properties, concentration of inhibitor, temperature of operation, etc . Consequently, high-throughput screening tests are commonly used to evaluate inhibitor effectiveness before commercial use …”

“…Alkylphenol-derived amphiphiles are one of the most extensively researched asphaltene inhibitor classes whose results are available in the public domain. ,, The mechanism of inhibition is believed to be similar to the stabilizing mechanism of resins in crude oil, which prevents clustering by aiding in the solubilization of asphaltenes . Chang and Fogler presented extensive results on alkylbenzene-derived amphiphiles, and effective inhibition was based on the ability of the inhibitor to disperse asphaltenes in a n -alkane solvent. , The inhibition mechanism was attributed to two factors, the adsorption of amphiphiles to asphaltene surfaces based on the polarity of the amphiphilic headgroup and steric stabilization of the alkyl layer around the asphaltenes, related to the length of the amphiphile tail. , Small-angle X-ray scattering (SAXS) experiments by Chang and Fogler quantified and compared structural changes of asphaltenes mixed in n -alkane solutions in the presence of different amphiphiles: dodecylbenzenesulfonic acid (DBSA) and nonylphenol (NPh).…”

“…Inhibitor action is also highly specific to a number of conditions: oil properties, concentration of inhibitor, temperature of operation, etc. 9 Consequently, highthroughput screening tests are commonly used to evaluate inhibitor effectiveness before commercial use. 12 Inhibitor screening techniques involve measuring light transmission through a petroleum sample with inhibitors added at desired concentrations.…”

“…Alkylphenol-derived amphiphiles are one of the most extensively researched asphaltene inhibitor classes whose results are available in the public domain. 9,11,19 The mechanism of inhibition is believed to be similar to the stabilizing mechanism of resins in crude oil, which prevents clustering by aiding in the solubilization of asphaltenes. 20 Chang and Fogler presented extensive results on alkylbenzenederived amphiphiles, and effective inhibition was based on the ability of the inhibitor to disperse asphaltenes in a n-alkane solvent.…”