| Titre | Application of aromatic/aliphatic ratios analysis in revealing migration pathways in unconventional reservoirs: a case study of the Bakken Shale |
| |
| Auteur | Abarghani, A ;
Ardakani, O H; Hawthorne, S B; Smith, S A; Kurz, B A; Sorensen,
J A |
| Source | International Journal of Coal Geology vol. 260, 104070, 2022 p. 1-20, https://doi.org/10.1016/j.coal.2022.104070  Accès ouvert |
| Image |  |
| Année | 2022 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20210477 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.coal.2022.104070 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Région | North Dakota |
| Lat/Long OENS | -110.0000 -104.0000 49.0000 47.0000 |
| Sujets | schistes; pétrographie; maturation thermique; hydrocarbures aromatiques; géochimie organique; Formation de Bakken ; géochimie; pétrologie ignée et métamorphique |
| Illustrations | cartes de localisation; tableaux; photomicrographies; graphique à barres; graphiques |
| Programme | Les géosciences de l'énergie Ressources d'énergie propre - réduire les risques environnementaux |
| Diffusé | 2022 08 04 |
| Résumé | (disponible en anglais seulement)
The ratio of aromatic to aliphatic (AR/AL) hydrocarbons was used to investigate migration pathways in tight unconventional reservoirs. Analytical methods,
including organic petrography and geochemistry, programmed pyrolysis, solid bitumen reflectance, and liptinite autofluorescence, were employed to generate regional thermal maturity maps. While AR/AL ratios are known to increase with thermal maturity,
a comparison of AR/AL ratios with thermal maturity indices as well as regional thermal maturity maps shows no significant correlation to other known thermal maturity proxies (i.e., Tmax or VRo-Eq) for the Bakken Shale samples. Taking into account the
concept of “size and shape” filtration from a previous study, the observed inconsistency between AR/AL ratios and thermal maturity indicators could be explained reasonably, where, based on this concept, the aliphatics are able to migrate more easily
through the shale's tight media compared to the aromatics, which would remain in situ or migrate only very short distances because of their size and shape. This indicates that the inconsistency between AR/AL ratios and thermal maturity indicators is
related to the disproportionate rate of migration of aliphatic and aromatic hydrocarbons in the Bakken Shale. To evaluate the potential application of using AR/AL ratio chemical analyses to reveal the possible migration pathways, initial values for
total organic carbon (TOCo) and S1 (S1expelled) were calculated for the thermally immature Bakken source rock. Comparing the regional distribution maps of S1expelled and the present values of S1 could reveal the geospatial displacements of generated
hydrocarbons and, therefore, the possible pathways of hydrocarbon primary migration. Comparing the AR/AL ratio regional maps with the attained migration pathway based on S1 and S1expelled regional maps reveals an acceptable correlation in terms of
the general trend. In this regard, AR/AL ratios exhibit higher values in the locations of the higher concentrations of calculated S1expelled distribution maps and lower values in the location of the higher concentrations of programmed
pyrolysis-derived S1 distribution maps. These outcomes confirm that AR/AL ratios could be used as a potential proxy in revealing the possible migration pathways in unconventional reservoirs. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'objectif principal de cette étude est de fournir un meilleur aperçu des caractéristiques de la matière organique, d'examiner la possibilité
d'utiliser les rapports aromatiques/aliphatiques (AR/AL) comme indicateur de maturité thermique dans les réservoirs non conventionnels, et finalement l'application probable des analyses du rapport AR/AL des échantillons de carottes pour révéler les
voies de migration possibles dans la formation non conventionnelle de Bakken. |
| GEOSCAN ID | 329341 |
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