Geochemical Characterization of Vaca Muerta Produced Water and Shallow Aquifers in the Neuquén Basin
Notice bibliographique
Résumé
Abstract The objective of this study is to better understand the baseline aqueous chemistry and provenance of all groundwaters from the near surface shallow aquifers to the deeper Vaca Muerta shale ~ 2000 m depth subsea in the Neuquén Basin for water disposal monitoring. The regions included in this study are Cruz de Lorena, Coiron Amargo Sur Oeste and Sierras Blancas blocks that are operated by Shell Argentina. This integrated project utilized previous work on the detailed hydrogeologic characterization of aquifers from seismic, downhole petrophysical logs and pressures measurements, and adds further water sample geochemistry data and interpretations focused on water disposal monitoring. The baseline measured water ionic and isotopic compositions from 70 downhole and produced water samples from 8 vertical wells and 3 comingled processing facilities suggests that natural geochemical compositions can be used to distinguish potential mixtures of 1) shallow fresh potable water aquifers, 2) irrigation or industrial water sources, 3) industrial water disposal zones and 4) produced Vaca Muerta Formation water. 5% to 10% mixtures of injected Vaca Muerta produced water and the Centenario Formation (disposal zone) were reliably detected, plus Vaca Muerta produced water and the Rayoso Formation (monitor zone) with confidence. Some variability in formation water baseline compositions occur geographically within each formation, especially the Rayoso Formation that is mainly low salinity water less than 5000 mg/l but may naturally mix with Centenario brines in some areas. Overall, this baseline natural geochemical variability is interpreted to result from topographic driven meteoric water influx with subsequent groundwater mixing of potentially very old brines, mineral dissolution and rock water interactions. Interestingly, the Centenario water disposal zone is very saline many times that of sea water, and more saline than Vaca Muerta produced water. This high salinity in the Centenario Formation is interpreted to result from mixtures of meteoric water, paleo sea water and evaporitic brines. Salt and evaporite mineral dissolution are possible but no known formation has been identified as the source of the salinity. The Vaca Muerta shale produced water has a unique fingerprint similar to other shale flowback waters such as from the Duvernay Formation in Canada, both interpreted as mineral and clay bound water interactions that occur quickly with the frac make up water. A Python based algorithm called Pymix was utilized to test the end member mixing model sensitivity to assess potential cross formation groundwater mixing scenarios that could notionally occur due to water injection wells. Actual samples of Vaca Muerta and Rayoso water tested with a Pymix model came within 0% to 6.9% of their actual water composition end members (i.e. percent difference Pymix versus actual). In a second Pymix model, the actual samples of Vaca Muerta and Centenario water came within 0% to 10.2% of their actual water composition end members, with a larger uncertainty due to the more similar water ion and isotopic fingerprints of these more saline, deeper sourced groundwaters. This workflow is a good example of baseline aquifer data collection and interpretation for unconventional plays. This hydrogeologic and geochemical information can be used to perform water surveillance on water disposal and monitor wells, key for the development of the Vaca Muerta shale in Argentina.
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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 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) | 0,001 | 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 ».