Zechstein Main Dolomite oil characteristics in the Southern Permian Basin: I. Polish and German sectors

Hydrocarbon habitat in the Zielin Late Permian isolated carbonate platform, western Poland

“…Thus, the observed higher C1-C3-naphthalene alkylation 4-+ 2,3 diMN 1,5-diMN 1,2-diMN 1,3,7-triMN 1,3,6-triMN 1,3,5 + 1,4,6-triMN 2,3,6-triMN 1,2,7-+ 1,6,7-triMN 1,2,6-triMN 1,2 and lack of elevated 1,6-dimethylnaphthalene concentration in the oils of group I indicate a carbonate source rock while lower naphthalene alkylation and an elevated 1,6-dimenthylnaphthalene concentration in the oils of group II is associated with the presence of clay minerals in their source rocks; this was confirmed by the earlier findings within BMB and Cychry platforms by Kotarba and Wagner (2007) and Kosakowski and Krajewski (2015). Since the source rocks for the oils of group I (= group VI in Słowakiewicz et al 2018) have not been confirmed, and taking into account the diverse specificity in their molecular composition of selected compound classes compared to that in the oils of group II, together with the increasing maturity direction of the hydrocarbons and the known Zechstein subsidence in that NE direction (Hakenberg and Świderska 1997;Czekański et al 2010), it is postulated that the hydrocarbons which accumulated in the Zielin isolated carbonate platform migrated even further from that NE direction, from carbonates in the wider basin of the Gorzów Block, towards the SW direction. Most probably, the oils were sourced from organic-rich facies of the platform top (lagoonal-microbial-tidal flat) and they migrated laterally through the strata following subsidence and tilting of the platform in this part of the Main Dolomite basin, in a similar way to that suggested by Kotarba and Wagner (2007) for the Gorzów-Międzychód-Lubiatów area.…”

“…14). The slightly higher DBT/P ratios for analyzed oils from the Zielin isolated carbonate platform as compared to extracted bitumen from the rocks of respective wells are resulting from their slightly higher maturity (see also Słowakiewicz et al 2018 and data calculated from MPI-1 values corresponding to random mean vitrinite reflectance VR c given in Table 3) and contacting with reduced sulphur during hydrocarbon migration. The relative concentration of methyldibenzothiophene homologues was found to be sensitive to hydrocarbon maturity.…”

A new and working petroleum source rock on the UK Continental Shelf (Upper Permian, offshore Yorkshire)

“…The dominance of 17αβ-C 32 over C 31 and C homologues and 17αβ-C 34 over C 33 and C 35 homologues (Table 3b) indicates a carbonate lagoonal and evaporitic environment source (Palacas et al, 1984;Jiamo et al, 1986;Brassell et al, 1988;Waples and Machihara, 1991) or a depositional setting for oil shale (Kara-Gülbay and Korkmaz, 2008). However, elevated 17αβ-C 34 and C 35 hopanes are also characteristic for Late Permian (Zechstein) oil from south-central Germany derived from a carbonate-evaporite source rock (Słowakiewicz et al, 2018).…”

“…Kirkham Abbey Formation (KAF) carbonate rocks (Zechstein cycle 2, EZ2) in the Cleveland Basin area, which are sealed at the top and bottom by the Fordon Formation and Hayton Anhydrite evaporites, respectively, chiefly consist of ramp to slope facies (lagoonal, oolitic, turbiditic, pelagic, slump and debrite carbonate rocks), which extend landwards and interfinger with siliciclastic lagoonal-evaporitic facies of the Edlington Formation (Smith, 1989;Taylor, 1998). Clay-and microbial-rich lagoonal dolomites are, in addition to lower slope facies and chicken-wire anhydrites, regarded as source rocks for Zechstein oil in the central and eastern SPB (Słowakiewicz et al, 2018). Lagoonal carbonate facies in the Yorkshire area have TOC <2 wt.% and thickness ~25-35 m (Słowakiewicz et al, 2016).…”

“…The absence of 28,30-bisnorhopane (BNH) commonly found in KCF kerogen and oil in the North Sea (Grantham et al, 1980) argues against an Upper Jurassic source rock for Boulby oil, although this should be treated with caution because BNH decreases with increasing thermal maturity (Peters et al, 2005). However, the BNH/17αβ-C ratio (0.01-0.06) applied as a facies parameter is typical of Zechstein Main Dolomite oil in other parts of the SPB (Petersen et al, 2016;Słowakiewicz, 2016;Słowakiewicz et al, 2018), although BNH was not detected in KAF dolomite samples either. Gammacerane, commonly invoked as evidence for a stratified water column in marine and non-marine depositional environments and/or specifically for hypersalinity (Moldowan et al, 1985;Jiamo et al, 1986;Sinninghe Damsté et al, 1995), is also absent.…”