Investigation on the Effect of Overburden Pressure on Vuggy Carbonate Oil Reservoir Core Properties
Notice bibliographique
Résumé
Abstract Overburden pressure in carbonate reservoirs is of great importance in understanding and improving productivity and recovery of hydrocarbons because it affects porosity, permeability, capillary pressure, particularly micro-inter-crystalline-framework and micro-fracture structures. As a result of this complexity, a Ruska Gas Permeameter was used at different pressures to measure the rock properties such as porosity and permeability of reservoir cores. The results were compared to CT-scan and NMR data. In this research over 50 core samples were prepared from AB-Teymur carbonate oil reservoir (Iran). The samples were placed in the core holder and overburden pressures of 500, 1000, 1500, 2000 and 3000psi were applied. Then Helium porosity and permeability were measured. This paper describes a systematic experimental methodology to analyze the different permeability and porosity values for reservoir characterization. The new study has shown the role of particularly micro-intercrystalline pore structure in carbonate rocks through digenesis in providing various ranges of porosity and permeability. The different hydrostatic levels in the reservoir rocks achieve a range of micro-fracture scenarios. Hence carbonate formations generally have complex porosity and permeability based on variation of overburden pressure in comparison to siliciclastic sandstones and there are not enough works published in the literature. Introduction In carbonate reservoirs, overburden pressure has significant effects on pore architecture, geometry, primary and secondary porosity and absolute permeability. As a result of complicated carbonate lithofacies and diagenesis processes, pore structure and pore sensitivity are more problematic than in siliciclastic sandstones. Overburden pressure may change the reservoir quality, capacity, producibility and recovery factors. Routine petroleum engineering reservoir parameter calculations are generally performed in the absence of the overburden pressure effect. This leads to serious errors in further development of a hydrocarbon-bearing reservoir. Thus, measurements under stress conditions become vitally important1. In the estimations of reservoir properties, the effect of overburden pressure is usually disregarded and this results in severe errors during the data processing and reservoir characterization measurements. The objective of this study is to investigate the effect of overburden pressure in vuggy carbonate oil reservoir by using real core samples. In this research the range of permeability and porosity reduction vs. increasing overburden pressure at a carbonate reservoir characterized by various facies is investigated. The results are compared to mass balance, nuclear magnetic resonance (NMR) and computerized tomography (CT scanning) data. In this investigation about forty two core samples from 3100m to 3450m depth of real carbonate reservoir in south west Iran were tested. The plugs were cored and cut to proper size. Then they were cleaned and dried. These processes were very time consuming and difficult because of the tight rock matrix. A Ruska Gas Permeameter was used for a gas expansion experiment to measure the porosity and permeability variation at different overburden pressures. In the laboratory tests, indicative different core plugs from different depths were used for each application. The bulk density and grain density of all samples were measured. Then the pore volume of each plug was established by helium gas expansion and the sample porosity and permeability were determined.
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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 | 0,000 | 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 ».