Geomechanical Response of the Shale in the Colorado Group Near a Cased Wellbore Due to Heating
Notice bibliographique
Résumé
Abstract Steam-stimulation is a viable in situ thermal recovery technique for heavy oil and oil sand reservoirs. This thermal recovery process introduces many complex geomechanical problems in oil sand and overburden formations. This paper addresses the geomechanical response of Colorado shale near a cased wellbore due to heating. The temperature, pore pressure, and stress response in Colorado shale near a cased wellbore due to heating are analyzed using a coupled thermal-mechanical-hydraulic solution. The possibility of failure or fracturing of the shale due to heating is assessed. Introduction Steam-stimulation processes are currently the most viable techniques for oil recovery from oil sand reservoirs. These thermal recovery processes cause many complex geomechanical effects in the oil sand layer and the geologic overburden strata due to elevated temperatures and pressures involved in the steam injection. The study in this paper focuses on the effect of heating on shale near a cased well. Analytical solutions developed by Booker and Savvidou(1) are used to analyze the distributions of induced pore pressure, temperature, and stress near a heated wellbore. These results will be used to investigate the potential occurrence of any tensile fracture in the heated shale. Conclusions will be drawn, along with the limitations of the analysis, and recommendations made for further studies. Problem Description Figure 1 defines the problem. Steam is injected into a cased well such that the inside temperature is elevated to a constant level. Heat is continually conducted from the well to its metal casing, cement annulus, and the shale in the formation. Heating of shale causes thermal expansion of the shale structural matrix and pore fluid. Expansion of the structural matrix induces total stress changes. Expansion of the pore fluid increases the pore pressure, thereby generating pore pressure gradients and the potential for pore fluid flow. Hence, the heating process results in a thermalhydraulic-mechanical coupled process. Calculation of the changes in temperature, pore pressure, and stress changes near the heated well will require solution to this complex coupled problem. FIGURE 1: Problem description. (Available in full paper) Analytical Technique Equilibrium Equation and Constitutive Law For a saturated thermo-elastic geological medium, the equilibrium equations are: Equation (1.a) (Available In Full Paper) Equation (1.b) (Available In Full Paper) Equation (1.c) (Available In Full Paper) where σxx, σyy,..... σyz are the increase of total stress components (compressive stresses and strains are considered to be positive). In the present study, the stiffness of the solids and pore fluid are assumed to be infinite in comparison to the shale skeleton stiffness. Thus, volume changes are due to changes in temperature and effective stresses. For an isotropic thermo-linear elastic material, the stress-strain relations are given by: Equation (2.a) (Available In Full Paper) Equation (2.b) (Available In Full Paper) Equation (2.c) (Available In Full Paper) Equation (2.d) (Available In Full Paper) Equation (2.e) (Available In Full Paper) Equation (2.f) (Available In Full Paper) where the primed symbols represent effective stresses, E and ν are the drained Young's modulus and Poisson's ratio, G is the shear modulus, Ψ is the increase in temperature, and a' is the drained coefficient of volumetric thermal expansion of the geologic me
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
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 | 0,000 | 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 | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| 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 ».