Small-Diameter Gas Lift Systems-A Potential Technical Solution for Transport of Fluids From Low-Pressure Reservoirs
Notice bibliographique
Résumé
Abstract Continuous or intermittent artificial lifting technology is competing today with electrical submersible progressive cavity (PC) pumping and sucker rod pumping for producing fluids from lowpressure reservoirs. If the shut-in fluid level is less than 45% of the depth of the well, finding a suitable and economic artificial lifting technology is a challenging task. There are thousands of dormant gas wells where bottom water accumulations of 50 m or less impede gas production. Similar conditions are often found in coalbed methane reservoirs. Due to variable (and shallow) water levels and gas presence, rod pumping cannot be used and submersible electric pumps often pose operational problems. Depending on local conditions and economics, gas lifting, alone or associated with other artificial lifting technologies, can be used for producing such reservoirs. Within a limited range of gas-liquid flow rates, depth, and reservoir pressure, the use of small-diameter pipes for gas lifting technology can become a viable technology. Laboratory investigations dedicated to small-diameter gas lifting operations have been so far limited to fluid transfer operations requiring a maximum of 10 - 20 m. This study uses mechanistic modelling approaches to respond to the industry's need for a better evaluation of depth/diameter flow rate limitations in view of assessing potential field applications of gas lifting for low reservoir pressures and relatively small liquid flow rates. Laboratory tests were conducted in a specially designed rig. Experimental results were used to evaluate the accuracy of the existing model predictions and for assessing the effect of injected gas flow rates, reservoir pressure, and liquid interfacial tension on the liquid production rates. To improve predictions of existing mechanistic models, particularly for small-diameter tubings and low pressure reservoir conditions, a new model is proposed and compared first with experimental results. The new model is then used as a scaling tool for assessing critical field depth conditions. Introduction Gas lifting or air lift has been used to remove water from flooded mines since 1782(1, 2). Today, natural gas lifting is commonly used for oil wells where gas and liquid are produced together. Conventional gas lifting uses tubing (or ducts) with a diameter greater than 2.54 cm. Vertical upward transport of gas and liquid for such conditions is well investigated and both empirical(3) and mechanistic models are available(4–6). During the last 20 years, mechanistic models are gaining more acceptance, replacing empirical models. Development of a mechanistic model involves:extensive visual observations of field and laboratory-scale models in view of assessing specific boundaries of flow patterns (e.g., bubble, slug, annular, stratified, etc.);assessment of the main gas-liquid features (e.g., bubbles, liquid film, etc.) and of the phases interface aspect (e.g., smooth, wavy, etc);estimation of local gas and liquid velocities, including the slip;estimations of local void fraction and of static and dynamic pressures;computer-assisted integration of "local" features to include the pipe pressure-volume-temperature (axial) profile; and,field validation. Flow pattern mapping and the drift-flux model(7) are essential tools used to evaluate the gas-liquid relative velocities and local void fraction.
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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 | 0,002 | 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 | 0,001 | 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 ».