Thermal maturity, hydrocarbon potential and kerogen type of some Triassic–Lower Cretaceous sediments from the SW Barents Sea and Svalbard

Abstract

Rock-Eval and total organic carbon (TOC) analyses of 144 samples representing Triassic–Lower Cretaceous intervals from the SW Barents Sea (the Svalis Dome, the Nordkapp and Hammerfest basins, and the Bjarmeland Platform) and Svalbard demonstrate lateral variations in source rock properties. Good to excellent source rocks are present in the Lower–Middle Triassic Botneheia and Steinkobbe, and Upper Jurassic Hekkingen formations, 1 – 7 wt% and 6 – 19 wt% TOC, respectively. Hydrogen indices of 298 – 609 mg HC/g TOC in the Botneheia Formation from Svalbard, and 197 – 540 mg HC/g TOC in the Steinkobbe Formation of Svalis Dome suggest Type II (oil-prone) and Type II/III (oil/gas-prone) kerogens, respectively. The Kobbe Formation (Botneheia/Steinkobbe-equivalent) is organic-lean and generally gas-prone (Type III kerogen) on the Bjarmeland Platform and in the Nordkapp Basin, and is a good source rock with Type III/II kerogen in the Hammerfest Basin. In the investigated wells, the Hekkingen Formation is more oil-prone on the Bjarmeland Platform than in the Nordkapp Basin, while Lower Cretaceous samples have poor potential for oil. Upper Triassic samples show potential mainly for gas; however, coal/coaly-shale samples in well 7430/07-U-01 (Bjarmeland Platform) are oil/gas-prone. Most samples analysed are immature to early mature; thus, the variation in petroleum potential and kerogen type is a function of organic facies rather than maturity levels.

Thermal history of a Triassic sedimentary sequence verified by a multi‐method approach: Edgeøya, Svalbard, Norway

“…Weathering of source rocks can result in higher than expected Tmax from burial heating, therefore this will lead to erroneous thermal maturity assessments (Copard, Disnar, & Becq‐Giraudon, ). However, there was no obvious signs of weathering on source rock samples from SW Edgeøya in previous studies (Brekke et al., ; Forsberg & Bjorøy, ; Krajewski, ), and moreover in recent investigation similarities observed in most of the Rock‐Eval parameters between cores and outcrop samples strengthen this (Abay, Karlsen, Pedersen, Olaussen, & Backer‐Owe, ; Abay et al., ; Koevoets, Abay, Hammer, & Olaussen, ). The degree of weathering in outcrops is very low since the sediments have experienced arctic cold climates with low potential for weathering (Forsberg & Bjorøy, ; Littke, Klussmann, Krooss, & Leythaeuser, ).…”

Experimental nucleation and growth of smectite and chlorite coatings on clean feldspar and quartz grain surfaces

“…For that reason, there is a common consensus among academic institutions, oil companies and governmental organisations to collect more data and to increase our understanding of this petroleum exploration target region (Abay et al, 2017;Blaich et al, 2017;Gautier et al, 2009;Henriksen et al, 2011;Johansen et al, 1992;Lerch et al, 2016;NPD, 2017;Ohm et al, 2008;Worsley, 2008).…”

“…7) and hence presents an important geological risk in petroleum exploration activity (Polteau et al, 2016). The increasing shift in the focus of hydrocarbon exploration from the southwestern Barents Shelf towards the northwestern and eastern Barents Shelf demands a better understanding of the impact of this magmatic activity on the quality and distribution of source rocks rather than reservoir rocks in this area (Abay et al, 2017;Brekke et al, 2014). Therefore, an improved understanding of whether the impacts of igneous activity on both reservoir and source rocks are beneficial or detrimental is important for reducing exploration uncertainties.…”

“…The NW Barents shelf is potentially a future hydrocarbon exploration frontier, but there is evidence for past intrusive igneous activity, likely constraining the distribution and quality of both reservoir (Paper IV) and source rocks (Abay et al, 2017;Brekke et al, 2014). What is the dominant heat transfer mechanism in the highly porous Still the result from this case study is preliminary and it requires more isotope, vitrinite reflectance and fluid inclusion data to better constrain the thermal history and rigorous study regarding hot fluid flow pathways backed by field observation and more data collection.…”

Petroleum geochemical aspects of the Mandawa Basin, coastal Tanzania: the origin of migrated oil occurring today as partly biodegraded bitumen

“…The accepted upper PI limit for a source rock at the end of the oil window is less than 0.40 (Hunt 1996;Abay et al 2018). None of the samples appears to have good source rock qualities based on the TOC, where the highest one is assigned to NQ1-3-14 with 1.13 wt%.…”