A Device and Method of Determining the Rheological Quality of Gelled Fracturing Fluids
Notice bibliographique
Résumé
Abstract A method of determining the quality of cross-linked hydraulic fracturing gels in the field was developed at the Alberta Research Council. The method is based on the measurement of the pressure required to push the gel through an orifice. The measurement can be repeated several times in order to quantify transient changes in the rheology of the gel. The quality of the gel prepared in the field is quantified by plotting the extrusion pressure vs. shear rate at the orifice. This quality control technique was compared, for certain types of water-based and oilbased gels, to existing techniques based on shear rheometry. The comparison showed that the water-based gels we investigated could be characterized using the gel tester, but not with the existing technology. The oil-based gels we investigated could be characterized better using the existing technology. Introduction Hydraulic fracturing is a common method of enhancing formation Productivity(1). Polymer gels are often used as fracturing fluids in order to carry solid particles (proppant), such as sand, into fractures. The sand keeps the fractures open after the injection is stopped. In order to maximize the fracture width, the gel must be able to prevent the sand from settling within the well and transport it through the perforations. In addition, the gel must have the proper leak-off properties in order to keep the fracture open when the fluid is being injected. According to Ely(2), most fracture treatments fail due to the inability of a fracturing fluid to carry proppant for the duration of the treatment at in situ conditions of temperature and shear, and/or to properly degrade back to water after the treatment. The current field quality control practice is to:measure the viscosity of the ungelled polymer solution using either a Fann-35 rheometer or, more recently, a Brookfield PVS rheometer;do a lip test; andmeasure the vortex closure time. Water-based fracturing gels are commonly used worldwide since they have the following advantages according to Ely et al.(3); 1) they are economical compared to oil, condensate, and methanol; 2) they yield increased hydrostatic head compared to oil, gases, and methanol; 3) they are incombustible; and 4) they are readily available. Hydrocarbon-based gels are used where the formation may be sensitive to water injection. As described in a monograph on hydraulic fracturing(4), computerized fracturing simulators normally require the consistency and flow behaviour indices to calculate the pressure drop along injection wells and within fractures. These parameters are obtained by fitting shear stress vs. shear rate measurements to a power law. The measurements are made using shear rheometers, such as the Fann-35, Fann-50 or the Brookfield PVS rheometer. It is difficult to measure the "viscosity" of certain cross-linked gels. The problem is that the gel slips on the walls of the bob and cup of the shear rheometers, as was observed by Cameron et al.(5) invisualization experiments showing the flow of coloured tracer particles within the gap.
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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 | 0,003 | 0,003 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,003 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,001 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
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 ».