Local assessment of the risk on groundwater resources related to unconventional hydrocarbon development.
Notice bibliographique
Résumé
A study was carried out in the Haldimand sector of Gaspé, Québec, Canada, to assess the potential link between a tight sandstone petroleum reservoir, whose potential is being evaluated, and the shallow fractured rock aquifer system. Petroleum exploration operations are taking place in the forested core of a hilly 40 km2 peninsula by the sea (up to 200 m amsl). Houses located on the periphery of the peninsula use wells for their water supply. This study served as a test case for a new framework proposed specifically to regulate oil and gas exploration and production activities. Significant concerns have been voiced in Quebec about such relatively new activities in the past few years. The study thus also aimed to provide a sound scientific perspective on the actual risk to groundwater resources related to oil and gas industry upstream activities. The study was based on the compilation of existing hydrogeological, geological and petroleum exploration data and on a field characterization. The field work involved 1) the installation of 17 observation wells and their hydraulic testing, including two fully-cored wells, 2) groundwater and surface water sampling in observation wells and more than 70 residential wells within a 2 km radius of a proposed new drill pad, and 3) geophysical logging of the open-hole observation wells. On all samples, chemical analyses involved major and minor inorganics, a wide range of organics, dissolved light hydrocarbon gases and CH4 isotopes, where present. More specialized analyses were done on observation wells (stable isotopes, tritium, 13C and 14C, noble gases, CFCs and SF6, organic acids). The hydrogeological conditions were then defined on the basis of existing and newly acquired data. Fracturing was found to control groundwater flow which is more intense in the upper 15 m of the rock aquifer. Recharge occurs on topographic highs where the rock is not covered by a low permeability glacial till, as found almost everywhere. Hydrogeochemical conditions were defined on the basis of a multivariate analysis of 16 chemical parameters. Quite wide variations in geochemistry were encountered, with evolved groundwater types affected by cation exchange or mixing with sea water. Groundwater residence time can thus be quite long, which may be due to the relatively high porosity (5-10%) of the rock. Methane is of mixed origin and preferentially associated with evolved water types. SALTFLOW, a variable-density flow and mass transport simulator, was used to represent the peninsula as well as the adjacent highlands in a 2D vertical section model. The interaction of the highland and peninsula recharge leads to nested flow systems with converging-diverging flow conditions under the peninsula, with a relatively shallow active flow zone. The observed and simulated conditions support a conceptual model that can be used to infer the level of risk for groundwater quality related to oil and gas industry activities.
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 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 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 ».