An Investigation of Inhibitors Performance on Asphaltene Precipitation Due to CO₂Injection

Abstract

In a CO 2 gas displacement process, the injected CO 2 can disturb the reservoir fluid stability and induce flocculation and deposition of asphaltenes. Several procedures are used to remove or prevent asphaltene precipitation, but the uses of asphaltene inhibitors provide most practical and economical solution for deposits treatment. In this work, the results obtained on the inhibition effect of one commercial inhibitor namely IR95 and five non-commercial inhibitors namely benzoic acid, nonylphenol, phenanthrene, phthalic acid, and salicylic acid is presented. Static tests indicate that CO 2 concentration and temperature are the most important factors on which the asphaltene precipitation depended. Results of inhibitor tests reveal that IR95 with more than 50% precipitation reduction have best efficiency among other inhibitors.

New Molecular Insights into Aggregation of Pure and Mixed Asphaltenes in the Presence of n-Octylphenol Inhibitor

“…14 Surfactants are considered as a promising type of chemical inhibitors for asphaltenes in the literature. 14−16 Although controversial behaviors have been noticed for some ionic surfactant inhibitors such as dodecyl benzenesulfonic acid (DBSA) 15,16 and salicylic acid, 9 nonionic surfactants such as phenols are an efficient and economical category of surfactants. Octylphenol (OP), nonylphenol, and ethoxylated nonylphenol are usually considered as effective asphaltene inhibitors based on inhibitor screening.…”

“…Different physical and chemical methods are used to inhibit or mitigate the problems that originated from asphaltene precipitation and deposition. The preventive approaches are more cost effective than the treatment methods for removing the depositions because the preventative strategies allow oil production to some extent. − Although the chemical methods bring more environmental impacts (compared to the physical methods), they are commonly applied in practice as a preventive approach due to their higher performance and better economic perspectives. The chemical inhibitors are added to the crude oil before asphaltene precipitation (or deposition) to keep the asphaltenes suspended in a broad range of thermodynamic conditions.…”

“…Generally, the chemical structure of inhibitors includes polar moieties that attach to the asphaltene molecules; the nonpolar moieties cause steric repulsion, hindering the aggregation of asphaltene molecules, and suspending them in the solution . Surfactants are considered as a promising type of chemical inhibitors for asphaltenes in the literature. − Although controversial behaviors have been noticed for some ionic surfactant inhibitors such as dodecyl benzenesulfonic acid (DBSA) , and salicylic acid, nonionic surfactants such as phenols are an efficient and economical category of surfactants. Octylphenol (OP), nonylphenol, and ethoxylated nonylphenol are usually considered as effective asphaltene inhibitors based on inhibitor screening. ,,,− Although phenols are recognized as proper surfactants in terms of inhibition efficiency and economic prospect, they are not generally used as pure due to various technical and nontechnical aspects, and usually they will be mixed with asphaltene solvents and diesel to be used in industrial/field scale .…”

Behavior of Asphaltenes in Crude Oil at High-Pressure CO2 Conditions: In Situ Attenuated Total Reflection–Fourier Transform Infrared Spectroscopic Imaging Study

“…It is particularly interesting that CO 2 can induce asphaltene precipitation when it is dissolved in crude oil. This phenomenon results in severe technological problems, such as formation damage and wellbore plugging, and has been reported in many studies. ,− Thus, dissolving CO 2 in crude oil changes its chemical composition and can potentially act as an anti-solvent with respect to asphaltenes, similar to the effect of heptane . However, there have been no reported data on the possible interactions of CO 2 with asphaltene molecules, and thus, the mechanism of asphaltene destabilization is not fully understood.…”

Effects of Supercritical CO2 Treatment on the Stability of Water-in-Heavy-Oil Emulsion and Their Mechanisms

“…This equilibrium may be broken by a change of conditions like pressure, temperature, and chemical additives. When pressure is increased, the dissolved quantity of CO 2 is accordingly increased, leading to the flocculation and increased precipitation of asphaltenes. − Afterward, the precipitation mechanism of asphaltenes triggered by CO 2 was revealed. , CO 2 molecules can interact with the functional groups of asphaltene molecules, which competes with the original interactions between resin and asphaltene molecules, thus reducing the amount of resins which adsorb on the asphaltenes as peptizing agents. If the dissolved amount of CO 2 is abundant enough, the resin/asphaltene ratio will be changed to a critical value, and the asphaltenes will be destabilized.…”