EOR in Tight Reservoirs, Technical and Economical Feasibility
Notice bibliographique
Résumé
Abstract Field experience indicates that primary depletion of tight oil formations, using multistage fractured horizontal wells, commonly recovers only 5 to 10% of OOIP. The impact of various EOR techniques on recovering additional oil from these formations is still not fully understood. This paper investigates the applicability of feasible EOR methods and determines their technical and economic success over the natural depletion process under different well and fracture designs. Additionally, the study investigates the minimum reservoir permeability required for success. To achieve the objectives, both black oil and compositional simulation models were generated for a Western Canadian tight reservoir containing volatile oil. In addition to primary, the EOR recovery processes that were considered include waterflooding, immiscible-N2 and miscible-CO2 gas flooding. Combinations of these techniques, coupled with the effects of various well and fracture design parameters were technically explored, and economically ranked using a comprehensive economic analysis. Furthermore, the optimal case of each process was subjected to sensitivity on matrix permeability to determine the minimum permeability at which these methods can be applicable. In the EOR scenarios evaluated, the highest cumulative oil produced was associated with the closest well and fracture spacing, and longest fracture half length. With a larger well spacing (in the order of 400 m), the wells were found to be too far apart to offer any benefit from any EOR technique. Additionally, the capital expenditure of tight-oil projects is high and therefore greatly influences the economic success. Several scenarios yielded similar NPV values, however, the IRR performances and CAPEX requirements helped further evaluate and rank the scenarios. For the reservoir model used, waterflood was found to be uneconomical at the initial permeability levels investigated (around 0.3 md) and required a minimum permeability threshold (1 mD) to become profitable. The primary recovery mechanisms in waterflooding are pressure maintenance and areal sweep, which were more pronounced in the N 2flood. This was the best recovery technique based on NPV. However, the best recovery technique based on oil recovery was the miscible-CO2 flood. It offered an increase in oil recovery factor from 11% to 23% over the best natural depletion case, which was a result of increased oil mobility by dissolution of CO2. At lower permeability values (down to 0.03 mD) immiscible-N2 flood became the most effective method via pressure maintenance within the drainage area. For even tighter reservoirs (under 0.03mD), natural depletion remained the best option for this reservoir. This paper provides an elaborate workflow for evaluating and optimizing EOR techniques in tight oil formations through an integrated modeling approach. It helps to identify the most technically and economically proficient techniques under different levels of permeability, well spacing and fracture parameters.
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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 | 0,003 | 0,003 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 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 ».