Field Injectivity Improvement in Heavy Oil Carbonate Reservoirs: Effective Surfactant Formulations for Lower Permeability Carbonates
Notice bibliographique
Résumé
Abstract One of the significant issues in producing heavy oil is that the higher inherent in situ oil viscosities lead to poor displacement during a waterflooding operation. Polymer flooding has been shown to be beneficial to improve overall recoveries with a modest decrease in mobility ratio compared to waterflooding. However, injecting a viscous polymer solution can reduce injectivity over time due to presence of near wellbore residual oil. The objective of this study is to identify promising surfactant formulations and test them in porous media to solubilize near wellbore oil to enhance injectivity. Previously published work has focused on sandstones and there is no comparable literature in carbonates. We focus on injectivity enhancement in carbonates. Several families of anionic and non-ionic surfactant mixtures were tested initially for phase behavior studies to understand solubilization potential at the salinity and temperature of interest. Formulations that had both aqueous stability and solubilization potential based on observed Winsor Type I to Type III windows were chosen for coreflood experiments. Initially, two basic corefloods were performed in sand packs to establish baseline performance. We then followed up with testing in surrogate carbonate cores. To understand the effect of geometry on the surfactant- oil solubilization behavior, different chemical amounts were used in 2D rock slabs to quantify displacement efficiencies. In contrast to sandstones where oil displacement was the dominant mechanism for near wellbore oil saturation reduction, we observed that solubilization was the preferred approach in carbonates. Since very high viscosity polymer cannot be injected into the lower permeability carbonates, the solubilization approach was superior as it did not require displacement by a high viscosity polymer chase. Sandpack experiments in Ottawa sand to mobilize residual oil showed greater than > 90% overall recovery when displaced with a Winsor Type III microemulsion design (shorter slug) with chase and continuous Winsor Type I microemulsion (longer slug). The residual oil saturation after chemical injection was < 5% indicating good solubilization and mobilization with an end point water relative permeability of > 0.9. Results from the surrogate rock experiments showed similar displacement characteristics with > 80% recovery and multifold improvement in relative permeability after surfactant injection. The 2D slab experiments showed that even with lower treatment amount of chemical, the overall improvement in injectivity was higher proving that robust surfactant formulations can still have good sweep efficiencies. Chemical stimulation formulations for successfully displacing near wellbore viscous crude oil in carbonates have been developed. Displacement characteristics across 1D and 2D show that such formulations can effectively improve polymer/water injectivity, especially in lower permeability carbonates. Field injection of such formulations can effectively increase processing rate and is a cheaper alternative to gain additional injectivity.
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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 | 0,000 |
| 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 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 ».