The asphaltene precipitation of two reservoir oil samples collected from Jinlin oil field has been studied under pressure and with/without CO2-injection conditions. No asphaltene precipitation was detected during the pressure depletion processes without CO2 injection. For the CO2-injected oil systems, the effects of operating pressure, injected CO2 concentration, and multiple-contact on the ons...

Abstract Carbonate acidization is the process of creating wormholes by injecting acid to increase reservoir permeability and oil production. Nevertheless, some oils are problematic with low asphaltene stability, which affects wormholing process. The interactions between acid, rock, lead acid-asphaltene sludge formation, reduces productivity injectivity. Neglecting this formation leads over pred...

A method to characterize crude oil including asphaltenes using the perturbed chain form of the statistical associating fluid theory (PC-SAFT) is presented. The theory accurately predicts the bubble point, density, and asphaltene precipitation onset for the oil. Examples show that the theory predicts asphaltene instability due to changes in pressure, temperature, and fluid composition. Further w...

Asphaltene precipitation occurs in petroleum fluids under certain unfavorable conditions, but can be controlled by tuning composition. Aromatic solvents in large quantities can prevent precipitation entirely and can dissolve already precipitated asphaltenes. Some polymeric surfactants can dissolve asphaltenes when added at much lower concentrations than required by aromatic solvents. Other disp...

We study the structure and phase behavior of asphaltenes comprised of large polyaromatic molecules in blends of naturally occurring crude oils using small angle neutron scattering (SANS). When two compatible oils are blended together, the asphaltenes remain dispersed as colloidal nanoparticles; however, when two incompatible oils are blended together, these asphaltene nanoparticles can aggregat...

Asphaltene precipitation is a perennial problem in producing and rejming crude oils. To avoid precipitation, it is usefid to know the solubility of asphaltenes in petroleum liquids as a function of temperature, pressure and liquid-phase composition In the novel molecular-thermodynamic flamework presented here, both asphaltenes and resins are represented by pseudo-pure components while all other...

in this work, the precipitation and re-dissolution of asphaltenes were studied for an iranian relatively heavy crude oil. a series of experiments were designed and carried out to quantitatively examine the reversibility of asphaltenes precipitation upon the change in the solvent concentration along with the temperature. n-heptane was used as the precipitant, and a temperature range of 30 to 70°...