The Role of Effective Interfacial Tension in Alkaline/Surfactant/Polymer Flooding
Notice bibliographique
Résumé
Abstract Ultra-low interfacial tension (IFT) between crude oil and brine is critical for successful enhanced oil recovery by alkaline/surfactant/polymer (ASP) flooding. With the right surfactant, this can be obtained at low and economic concentrations. However, maintaining low IFT during the displacement process is a serious challenge because of dilution and adsorption effects in the reservoir. Consequently, the effective in-situ IFT will change from the static equilibrium value, and have a corresponding influence on the oil displacement efficiency. The literature does not clearly address what level of static equilibrium IFT should be used to represent the in-situ IFT in order to predict oil recovery efficiency. The effect of changing IFT on the in-situ behaviour of given oil/brine systems was studied by carrying out IFT measurements with two surfactants using pre-equilibrated oil/brine/surfactant solutions. The effective equilibrated IFTs rose markedly as the oil volume proportion increased in the systems due to surfactant partitioning between the oil and aqueous phases. Displacement studies in reservoir and Berea cores reinforced the importance of understanding the role played by changes to the IFT at the oil/brine interface in displacing oil. The parameters varied were type and concentration of injected surfactant, slug size, and chase fluid. Through the use of theeffective IFT concept, the oil displacement efficiency showed good correlation with capillary number. The coreflood results further suggest that other factors, in addition to capillary number, may affect the displacement efficiency and should be included in the design of a cost-effective ASP flood. Introduction Enhanced oil recovery (EOR) with surfactants has become a more attractive tertiary recovery processes in recent years: new surfactant systems have been developed which lower the inputcosts to a reasonable level while maintaining good oil recovery. Experiments have shown that the ultra-low interfacial tension (IFT) of less than 10−3 mN/m can be obtained with less than 0.1 wt% surfactant concentration. 1 However, the effect of dilution of surfactant solution upon injection into the reservoir should be explored. Moreover, it should be established that the IFTs obtained in oil/brine/surfactant systems after rigorous equilibration procedures in the laboratory can indeed be achieved in situ when the surfactant solution contacts the entrapped oil ganglia in porous media. 2 How can the in-situ IFT be determined? There are few works in the literature that discuss this. In surfactant flooding, in-situ IFT is governed by several factors:reservoirs conditions;phase behaviour of surfactant between trapped oil and brine;degree of surfactant dilution; andsurfactant adsorption onto the rock surface. These factors make determining the in-situ IFT extremely difficult. Consequently, it is difficult to obtain a clear consensus about how IFT changes under reservoir conditions. However, one can be sure that the effective equilibrated interfacial tension is higher than the IFT obtained from laboratory equilibrium measurements due to loss of surfactant. Laboratory and field studies on oil displacement efficiencyby ASP flooding have been reported in the literature. 3, 5 Ideally, oil displacement by surfactant flooding approaches miscibility if the interfacial tension between the trapped crude oil and its associated brine is ultra-low.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».