Enhanced Numerical Simulations of IOR Processes Through Dynamic Sub-Gridding
Notice bibliographique
Résumé
Abstract Numerical simulations of IOR processes (SAGD, VAPEX,...) often require a very fine space discretization in order to follow steep fronts and to capture the physical phenomena. As a result, these simulations are mostly CPU time consuming. In this paper a new and very efficient approach is presented which allows to reduce the computational time without any loss of precision. This approach, based on a dynamic sub-gridding technique, acts as an external and independent mesh generator and does not rely on any specific simulator. To this respect, it provides an effective alternative tool for numerical performances optimization of recovery processes simulations. In addition, contrary to usual local refinement methods, this approach results in great accuracy, both in terms of fluids productivities and production rates, compared to uniform fine grids results. In the meanwhile, the simulation time is damped up to a factor 6 in the first years of production and slowly reaches a global gain of over 3.5 for long production periods. Then, after explaining the general methodology, a SAGD real field case is introduced as an example of application. For this process, where a large computational time is generally required, significant improvements of performances can be observed. Introduction Since its introduction by Roger Butler in the 80's (1)(2), Steam Assisted Gravity Drainage (SAGD) has gained a large audience among the petroleum industry (3). This is particularly true in Canada where it is one of the most promising process to recover a part of the huge reserves of extra heavy oil and bitumen. In this country, several pilots or field scale implementations of SAGD are currently underway (4)(5) in all of the three Alberta oil sands deposits and in the heavy oil deposit of Saskatchewan. While finally quite simple in its concept, SAGD requires to be modelled carefully with numerical simulators in order to be optimised because reservoirs are generally quite heterogeneous and well trajectories not exactly horizontal. A crucial aspect of SAGD modelling is that most of the fluid displacement takes place at the thin interface between the steam chamber and the cold non contacted oil zone. Therefore, fine cells or gridblocks are necessary at least in the region covered by this interface. Without dynamic sub-gridding, it means that whole the simulated domain must be discretized with fine blocks, which results in a huge number of blocks, especially in 3D, and consequently in very time consuming simulations even with actual computers. The interesting aspect of SAGD, and also of VAPEX a derived process, is precisely the thin interface which exists ahead of the steam chamber, and therefore it seems quite logical to consider dynamic sub-gridding techniques to follow this interface while it moves away from the injector, in order to have fine gridblocks in the region covered by the interface but coarser gridblocks ahead and behind of it. So, the total number of gridblocks would be reduced as well as the CPU time.
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Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| 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 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 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 ».