Prediction of the Gas Injection Effect on the Asphaltene Phase Envelope

Abstract

and available online here Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 70, n°6, pp. 909-1132 et téléchargeable ici D o s s i e rOil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 70 (2015), No. 6, pp. 909-1132 Copyright © 2015, IFP Energies nouvelles > Editorial -Enhanced Oil Recovery (EOR), Asphaltenes and HydratesÉditorial -EOR «récupération assistée du pétrole», Asphaltènes et Hydrates D. Langevin and F. Baudin ENHANCED OIL RECOVERY (EOR) > HP-HT Drilling Mud Based on Environmently-Friendly Fluorinated ChemicalsBoues de forage HP/HT à base de composés fluorés respectueux de l'environnement Abstract -Asphaltene instability may occur when pressure, temperature and compositional variations affect the reservoir oil. Permeability reduction, wettability alteration, and plugging of wells and flow lines are the consequences of this phenomenon. Therefore, it is crucial to investigate the asphaltene behavior in different thermodynamic conditions by knowing the Asphaltene Precipitation Envelope (APE) in a preventive way rather than the costly clean-up procedures. The selected reservoir oil has faced a remarkable decline in production due to several years of extraction, and Enhanced Oil Recovery (EOR) has been considered as a solution. Therefore, in this paper, a comprehensive study was carried out to predict the effects of different injected gases on asphaltene onset and to prevent future asphaltene precipitation based on the laboratory data. The Advanced Redlich-Kwong-Soave (RKSA) equation of state was considered to develop APE using Multiflash (Infochem Co.). For the selected reservoir oil, with temperature reduction at low temperatures, asphaltene precipitation weakened and made the onset pressure decrease, so this behavior is different from the results obtained in other published reports. On the basis of this model, several sensitivity analyses were performed with different gases (i.e., methane, CO 2 , N 2 and associated gases) to compare the risk of each gas for future EOR strategies. APE tend to expand as the amount of injected gases increases, except for CO 2 gas injection, that showed another unconventional behavior for this crude oil. It was observed that for CO 2 gas injection below a certain temperature, asphaltene stability increased, which can be considered as a good inhibitor of asphaltene precipitation.Re´sume´-Pre´vision de l'effet d'injection de gaz sur l'enveloppe de phase des asphalte`nes -L'instabilite´des asphalte`nes peut se produire lorsque des variations de pression, de tempe´rature et de composition affectent les re´servoirs d'huile conduisant a`une re´duction de la perme´abilite´, a`l'alte´ration de la mouillabilite´et au blocage de l'e´coulement dans les puits et les conduites. Par conse´quent, il est crucial d'e´tudier le comportement des asphalte`nes pour diffe´rentes conditions thermodynamiques en connaissant leur domaine de pre´cipitation (APE, Asphaltene Precipitation Envelope) de manie`re pre´ventive pour limiter les ope´ra...

An improved modeling approach for asphaltene deposition in oil wells including particles size distribution

“…This event causes the solubility of asphaltene in the crude oil to increase until the lower onset point in which asphaltene dissolves again completely. The calculated solubility parameter of the oil supports this speculation (Bahrami et al, 2015). In fact, for each reservoir fluid, there is a minimum solubility point for asphaltene at fluid bubble point as mentioned by Tavakkoli (2013).…”

A theoretically modified PC-SAFT equation of state for predicting asphaltene onset pressures at low temperatures

“…For instance, Gonzalez et al [143], [158] were the first to report that O-PC-SAFT predicts a crossover temperature, where an increment in CO2 injection does not promote asphaltene precipitation, but its solubility. Recently, Baharani et al [164], using a cubic EoS with an association term, conducted predictive calculations of AOPs for 10, 25, and 50% mol of CO2 injected into a reservoir fluid, and concluded that "the CO2 injection causes asphaltene precipitation to increase at high temperatures but below at certain crossover, the asphaltene stability increases. Then the CO2 can behave like an inhibitor or a precursor of asphaltene precipitation" [164].…”

“…Recently, Baharani et al [164], using a cubic EoS with an association term, conducted predictive calculations of AOPs for 10, 25, and 50% mol of CO2 injected into a reservoir fluid, and concluded that "the CO2 injection causes asphaltene precipitation to increase at high temperatures but below at certain crossover, the asphaltene stability increases. Then the CO2 can behave like an inhibitor or a precursor of asphaltene precipitation" [164]. Thus, both O-PC-SAFT and cubic EoS predict crossover temperatures.…”

Comprehensive Water–Alternating-Gas (WAG) injection study to evaluate the most effective method based on heavy oil recovery and asphaltene precipitation tests

“…for this reservoir oil based on the solubility parameter of asphaltene [48,49]. Overall, in terms of precipitated asphaltene and APE, CO 2 miscible injection could work as a good strategy in EOR purposes as long as the pressure is high.…”