Case Histories of Solvent Use in Thermal Recovery
Notice bibliographique
Résumé
Abstract Steam injection is the most successful oil recovery method for heavy oil and oil sands exploitation. In some cases, solvents are added to steam when steam by itself fails to provide satisfactory recovery factors. In other instances, the use of solvents is justified on the basis of water usage reduction and decreasing greenhouse gas emissions. This has been done in cyclic steam stimulation (CSS), steamflooding, and steam-assisted gravity drainage (SAGD). The range of success in these instances is highly variable. Additional oil/bitumen recovery is claimed in most cases, but the commercial viability is often not discussed. The use of solvents for the recovery of viscous hydrocarbons is proposed for the obvious reason that mixing a solvent with a viscous oil reduces its viscosity, but the volumes needed are prohibitive; for example, 50% by weight of naphtha would be needed to reduce the viscosity of a one million centipoise bitumen to the level attained by a 200 °C (400 F) temperature increase. When solvents are used with steam, other phenomena are invoked to justify solvent use; for example, solvent condensation at steam temperature to promote the advance of solvent into cold heavy oil/bitumen ahead. In such postulates, the extremely low dispersivity of the solvent in the solid heavy oil/bitumen is of concern. The intent in these processes is to achieve a high mixing coefficient for solvent and heavy oil - just the opposite of what was sought in yesteryear's miscible displacement design. The feasibility of this intent is discussed, via a comparison of heat and solvent dispersion. Another line of thinking is that solvent diminishes the effect of formation heterogeneity. In this study, several case histories of solvent-addition thermal operations are discussed. A few non- thermal examples are also considered. Detailed results are not always available; the published information is tabulated. The results of the projects are discussed, and interpretations are made where possible. In recent years, solvent is being used in about 10% of the ~1500 SAGD well pairs in operation. In some cases, success is claimed. These are discussed in detail. Use of solvents in CSS is being done in Cold Lake; a new large project (Aspen) is planned there on the basis of solvent stimulation only. Solvents were used to a limited extent in some California steamfloods. None of those showed an improvement as a result of solvent addition. In a couple of cases, solvent injection was done unsuccessfully after a cold heavy oil production with sand (CHOPS) operation. This is a critical study of solvent use for the recovery of heavy oil/bitumen, showing that in most cases, solvents have not delivered the promise expected. In others, they totally failed. As such, it is hoped that the results will be of value in future planning of solvent injection.
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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 | 0,001 | 0,007 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,001 |
| Bibliométrie | 0,002 | 0,002 |
| Études des sciences et des technologies | 0,003 | 0,002 |
| Communication savante | 0,001 | 0,002 |
| Science ouverte | 0,001 | 0,002 |
| Intégrité de la recherche | 0,003 | 0,004 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,008 | 0,002 |
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 ».