Impact of geochemical reactivity on desulphation requirements in a sandstone reservoir containing carbonate and sulphate minerals
Notice bibliographique
Résumé
This paper presents an investigation of the impact of in situ chemical and geochemical interactions on oil recovery efficiency and inorganic scale management. A common technique to support the reservoir pressure is water injection, but scale problems can be a major issue that develop during oil field production when there is water (especially seawater) injection. In such flooding scenarios, geochemical reactions occur between formation and injected water in terms of sulphate scales, such as barite. On the other hand, the carbonate scales may form due to a variety of reasons: changes in temperature, pressure, pH and CO 2 concentration in the aqueous or hydrocarbon phases. This paper investigates the impact of CO 2 availability, and changes in pH, ionic concentrations and temperature on carbonate and sulphate scaling risk in waterflooded reservoirs where choices may be exerted over injection water composition. In this work, the injected water does not contain CO 2 , but CO 2 is present in the oil phase, and may partition from there, or diffuse from the formation water. Also presented is the relationship between brine composition and scale precipitation and management in the production wells. There are various factors affecting the system, such as water injection well and production well flow rates and flow through the reservoir, and also compositional effects due to use of Full Sulphate Seawater (FSSW) or Low Sulphate Seawater (LSSW), and due to variations in temperature and the concentration of CO 2 in the oil phase. In this study, as preparation for addition of geochemistry to a full field 3D history matched model, we include geochemical reactions in a 1D model that has the field pressure, temperature and fluid properties, to test the impact of the various potential reactions in a simple system. This is necessary to fully understand the system before, in future work, moving on to the full field modelling, and in fact provides very valuable learnings that would be more difficult to distil if full field modelling alone had been performed. We assume the mineral reactions (anhydrite, gypsum, barite, huntite and calcite) are in equilibrium, excepting for the magnesium rich carbonate mineral reaction, which is assumed to be kinetic. The results shows that SO 4 2- , Mg 2+ , HCO 3 − and Ca 2+ are the major ions that have a very significant effect on the system, and therefore impact on precipitation (4.7E-06gmole) and dissolution (-4E-06gmole) of calcite, barite and the magnesium rich carbonate mineral. Dissolution of anhydrite (−5.1E-05gmole) present in the initial mineral assemblage is shown to have a significant impact in most scenarios, except where FSSW has been heated up to reservoir temperature, where anhydrite precipitation (5E-05gmole) in situ occurs. This has a significant impact on the levels of desulphation that should be used to prevent sulphate scales in the production wells.
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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 | 0,000 | 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 ».