The Role of Connate Water Saturation in VAPEX Process
Notice bibliographique
Résumé
Abstract A large fraction of the physical model tests of the VAPEX process reported in the literature have been conducted without any connate water in the system. The absence of connate water was rationalized by suggesting that it has little or no influence on relative permeability of oil and since the vapourized solvent does not dissolve in water, there is no effect of water on the mass transfer process. However, this ignores the possible contribution of oil spreading at the gas-water interface to the mass transfer and the contribution of film drainage to oil relative permeability at low oil saturation. We have evaluated the effect of connate water on VAPEX performance using physical model experiments carried out in a visual model with different connate water saturations. Butane was used as the solvent and Ottawa sand was used for packing the model to obtain permeability and capillary pressure values comparable to field conditions. In addition to the visual observations of the size and shape of the vapour chamber, the rates of oil and gas production were monitored during the experiments. The results show that connate water has a measurable effect on the process, both in terms of the shape of the vapour chamber and the drainage rate of the diluted oil. The presence of connate water causes faster spreading of the vapour chamber in the lateral direction and tends to increase the thickness of the mixing zone. This increase in the mixing zone thickness appears to result from capillarity driven fingering phenomenon. The mixing zone had a distinct uneven appearance that was similar to patterns generated by frontal instabilities in miscible displacements. The effect of connate water on the drainage rate was an increase in the initial rate, but a reduction in the rate, subsequently. The presence of mobile water speeds up the communication between the two wells and leads to even faster spreading of the vapour chamber. Introduction Although several successful SAGD and CSS field projects have been reported, the high cost of steam generation, considerable energy loss, need for water and water treatment(1) are some of the problems which necessitate finding a more effective and environmentally friendly recovery method. Meanwhile, solvent-based processes, like VAPEX, have drawn more attention due to their potential advantages. In this process, vapourized light hydrocarbons, like propane and butane or a mixture of these with carrier gases, are used. VAPEX is a solvent analogue of the SAGD process and uses essentially the same well configuration(1). Solvent dissolves into the bitumen and reduces its viscosity through dilution, swelling and de-asphalting mechanisms(2). It has been noted that vapourized rather than liquid solvents produce a higher driving force for gravity drainage due to a higher density difference between bitumen and solvent(3). The optimum pressure for solvent injection is near its dew point pressure where the solvent solubility in the oil is high. The role of carrier gas is to keep the injected solvent in the vapour phase at the operating pressure.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| 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 | 0,002 | 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) | 0,000 | 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 tête enseignante, 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 ».