Szczegóły publikacji
Opis bibliograficzny
Molecular and isotopic compositions and origin of natural gases from Cambrian and Carboniferous-Lower Permian reservoirs of the onshore Polish Baltic region / Maciej J. KOTARBA, Keisuke Nagao // International Journal of Earth Sciences ; ISSN 1437-3254. — 2015 — vol. 104 iss. 1, s. 241–261. — Bibliogr. s. 258–261, Abstr. — Publikacja dostępna online od: 2014-08-17
Autorzy (2)
- AGHKotarba Maciej
- Nagao Keisuke
Słowa kluczowe
Dane bibliometryczne
| ID BaDAP | 96077 |
|---|---|
| Data dodania do BaDAP | 2016-02-15 |
| Tekst źródłowy | URL |
| DOI | 10.1007/s00531-014-1063-0 |
| Rok publikacji | 2015 |
| Typ publikacji | artykuł w czasopiśmie |
| Otwarty dostęp |  |
| Creative Commons | |
| Czasopismo/seria | International Journal of Earth Sciences |
Abstract
Natural gases from Middle Cambrian and Carboniferous-Lower Permian reservoirs of the onshore Polish Baltic region were studied for their molecular and stable isotope compositions. The following gas species were analysed: C-12,C-13 in CH4, C2H6, C3H8, n-C4H10, i-C4H10 and CO2, H-1,H-2 in CH4, N-14,N-15 in N-2, and stable isotopes of all noble gases. Due to significantly different geological settings and genetic types of source rocks of Eastern and Western Pomerania, the molecular and isotopic compositions of natural gases of these two regions exhibit distinct differences. Hydrocarbon gases associated with oil accumulated in the Middle Cambrian reservoir of Eastern Pomerania were generated during low-temperature thermogenic processes from a single source rock containing Type-II kerogen at one phase of petroleum generation. Non-associated hydrocarbon gases accumulated in the Carboniferous (Mississippian and Pennsylvanian)-Lower Permian (Rotliegend) reservoirs of Western Pomerania originated during at least two phases of gas generation by thermogenic processes from mainly Type-III kerogen and a small component of mixed Type-III/II kerogen. Noble gases are in general heavily enriched in radiogenic and nucleogenic isotopes such as He-4, Ar-40 and Ne-21 accumulated in the reservoirs. Weak contributions of mantle-derived He and Ne are observed. Radiogenic He-4/Ar-40 ratios are higher than the average production rate ratio of about 5 for radiogenic He-4/Ar-40 in crustal materials, which might have been caused by a selective supply of He-4 that is lighter than Ar-40 from crustal rocks, or (U + Th)/K ratio might be higher than the average in crustal block. Carbon dioxide from gases of both the Western and Eastern Pomerania were mainly generated during thermogenic processes of transformation of organic matter, although gases of Western Pomerania can contain an endogenic component. Molecular nitrogen from the Eastern Pomeranian natural gases was mainly generated during low-temperature thermal transformation of organic matter and derived from NH3 and NH4 of crustal fluid, whereas molecular nitrogen from Western Pomeranian natural gases contains a significant component from the destruction of organic matter at a higher maturity level which may have been caused by a high heat flux from the volcanic activity during late Pennsylvanian-early Rotliegend ages, and has a bigger component release from NH4-rich illites.
