Notice bibliographique
Résumé
Abstract A number of wells in western Canada have been drilled into lower pressure, lost circulation reservoirs, which has increased the use of foamed and lightweight cements. This paper compares the properties of foamed and lightweight cements and makes recommendations regarding the most appropriate situations in which each should be used. Specific emphasis is placed on the equivalent circulating density (ECD) variation between foamed and lightweight cement which demonstrates the high ECD's experienced when pumping foamed cement. A cost comparison between lightweight and foamed cements was also completed and demonstrated a 39% reduction in costs when lightweight cement was utilized. Finally, a case history in which 54 wells were switched from foamed to lightweight cement is presented along with the associated success rate and cost savings. Introduction The Western Canadian Sedimentary Basin contains a large number of low pressure and lost circulation reservoirs. As a result, there has been a strong growth in the use of lightweight and foamed cement systems. Foamed cement was introduced into the Canadian oil industry in the early 1980's. Foamed cement operations were originally plagued by operational inconsistencies which have caused the technique to fall in and out of favour over the years. In the last 10 years, however, operational, design and slurry improvements have allowed the jobs to be placed with a higher level of quality and the technique has been used to combat lost circulation and zonal isolation problems in some fields throughout western Canada. Lightweight cement has been in existence for more than 40 years. The original lightweight cements used extenders and water absorbing additives to control free water while lightening the slurry. The next generation used low density solids such as Gilsonite and ceramic spheres to reduce density and absorb water. The third generation of lightweight cements was introduced in the early 1990's and consisted primarily of adding silica fume to the slurry which had the ability to tie up large amounts of water and still maintain strength. As a result of the handling problems, health hazards, and quality control issues associated with silica fume, however, a new generation of lightweight cements has been introduced in recent years. These cements use combinations of slag, silica, zeolites, specialty cements, ceramic spheres and other chemicals to lighten slurries to densities as low as 1200 kg/m3. All foamed and lightweight cements experience similar problems of reducing density and hydrostatic pressure while still maintaining adequate compressive strengths to meet local regulatory guidelines. In Alberta, the Alberta Energy and Utilities Board requires that cement across a hydrocarbon zone achieve a minimum of 3500 kPa compressive strength in 48 hours. Meeting this requirement has resulted in innovative technology to achieve strength requirements in wells with shallow hydrocarbon zones that are near surface and may have only a 25 °C bottom hole temperature. Both foamed and lightweight cements exhibit properties which make them valuable for combating different zonal isolation issues. This paper defines the properties of each system and discusses situations where each should be applied.
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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 ».