Are Field Polymer EOR Projects Reaping the Benefits of <i>Sor</i> Reduction Due to Polymer Viscoelasticity?
Notice bibliographique
Résumé
Abstract For EOR polymer solutions, viscoelasticity is a rheological phenomenon that has a strong time (therefore flux) dependency and has been tied to significant reductions in residual oil saturation (Sor) during lab core floods at high flux conditions. However, the question of whether the polymer's viscoelastic effects reduce Sor over a significant portion of a polymer-flooded reservoir remains unanswered. Two methodologies are used in this paper to examine whether polymer-flood projects conducted using vertical and horizontal wells across nine countries (Argentina, Austria, Canada, China, India, Oman, Russia, Suriname, USA) are experiencing Sor reduction due to shear thickening induced-viscoelastic effects. In Method 1, the average Darcy velocity in each field is compared with the corresponding predicted velocity for the onset of shear thickening. Then the effect of variables such as radial distance from the wellbore, well-spacing, horizontal well length, and thickness on Darcy velocity are examined. In Method 2, the Sor reduction potential of the polymer systems used in various field projects is evaluated by analyzing relevant core flood experiments conducted in various labs. The observations from the lab results are considered in view of the fluid velocity, oil viscosity, permeability, mode of flooding, and pressure gradient of the various field projects. For most polymer floods with horizontal injectors, the highest possible Darcy velocity for various combinations of thickness, injection rate, horizontal well length, and well spacing are too low (in the range of ~0.01 to 0.2 ft/day) and unlikely to reach the onset velocity for viscoelastic behavior (i.e., >1 ft/day for most field conditions). For most vertical polymer injectors in permeable reservoirs, only 2-3% of the reservoir will experience fluid velocities high enough for viscoelasticity to potentially be important. Less permeable reservoirs (<200 md) could experience the onset of viscoelasticity at low rates (e.g., ~0.17 ft/d), but even so, only a very small fraction of the reservoir is expected to achieve this onset flux. For an extreme case of a low thickness (10 ft), short horizontal well length (1210 ft), and a shorter well spacing of 656 ft, an average velocity of 1.16 ft/day and a pressure gradient of 7.65 psi/ft was estimated for the Matzen field polymer flood. At a very short well-spacing of 100 ft in the Pelican Lake polymer flood, the average velocity is 2.05 ft/day. Although both these average velocities are higher than the average onset flux rate, Sor reduction appears unlikely based on the macroscopic pressure gradients. This paper conveys the improbability of shear-thickening induced-viscoelasticity causing Sor reduction. It also discusses the potential role of other effects for Sor reduction in existing polymer floods, including wettability alteration by the polymer and secondary-versus-tertiary polymer flooding effects. EOR researchers are advised to use the realistic field-relevant fluxes during laboratory assessments while studying Sor reduction.
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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 | 0,003 | 0,003 |
| 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 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 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 ».