Modelling of Sand Production and Wormhole Propagation in an Oil Saturated Sand Pack Using Stabilized Finite Element Methods
Notice bibliographique
Résumé
Abstract Sand production is a prevalent problem in the oil and gas industry. As sand particles are being dislodged from a sand matrix and transported into the produced fluid, they form cavities or so-called "wormholes" in the formation. The paper presents a finite element simulation of an experiment that involves sand production and wormhole propagation in a sand pack as fluid is drawn from it through a small orifice. The computations are based on a recently developed sand erosion model that describes the disaggregation of sand particles as a function of sand matrix strength and fluid flux. The writing of both particle and fluid transport equations then completes the hydrodynamics of the problem. Special numerical techniques, such as stabilized finite element methods, are developed to solve the resulting nonlinear governing equations that include coupled fields such as fluidized sand concentration, fluid pressure, and porosity. Numerical results are in close agreement with experimental datavailable for the sand pack experiment. In particular, the computed porosity field and its temporal evolution during wormhole propagation match very well with available CT scan images of the sand pack. Introduction Cold production is an economical mainstream process for heavy oil recovery in which oil and sand particles are produced together from unconsolidated formations with an abnormal higher rate (up to 20 times) than that predicted by Darcy's law based on typical reservoir parameters. However, the majority of operators report very high sand cuts that vary from 10% to 40%. As massive sand is being produced, a variety of problems arise, i.e., erosion and plugging of facilities, ground settlement, and sand disposal. Since this prevalent phenomenon is not well understood, sand production and control (management) has been a research topic for more than five decades. Extensive studies have shown that the cause of the abnormality is a combination of many factors: notably, stresses, fluid flow, thermal, solution gas drive, and reservoir heterogeneity in porosity. Even though it is well known that large amounts of sand accumulate into the wellbore, their origin is still unclear. Based on tracer and injectivity tests, a common belief is that high-permeability channels-so-called cavities or wormholes in petroleum geomechanics jargon-are formed after a period of time. In order to visualize the production process at a laboratory scale, Tremblay et al.(1–3) performed sand pack experiments to model the production of oil, gas, and sand into a perforation in a vertical well. A high-porosity channel was observed with the aid of X-ray computed tomography techniques. It was found that, besides hydro-mechanical effects, the solution gas drive enhanced the propagation of the wormhole as gas bubbles expand under a pressure decline. This in turn unlocks the sand grain structure so thatthe porosity of the skeleton increases, which in turn leads to a drop in its mechanical strength. Hence, the wormhole propagates further in regions where strength weakening takes place.
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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 | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,003 | 0,001 |
| 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 ».