Variations in Petrophysical Properties of Upper Palaeozoic Mixed Carbonate and Non‐carbonate Deposits, Spitsbergen, Svalbard Archipelago

Abstract

The Late Carboniferous – Early Permian Gipsdalen Group and the Early to Late Permian Templefjorden Group are known hydrocarbon plays in the Arctic region, e.g. on the Finnmark Platform, Loppa High and Sverdrup Basin. Time‐equivalent deposits crop out on the island of Spitsbergen and consist of mixed carbonate and non‐carbonate (primarily siliciclastic, siliceous, organic‐carbon rich and clayey) sediments deposited in continental to deep‐marine settings. In rock samples (n = 73) collected from five outcrop locations on Spitsbergen, thin‐section analysis showed the presence of ten microfacies types ranging from claystones and spiculitic cherts to rudstones and dolostones. Petrophysical and textural properties of the samples were measured to evaluate the link with the acoustic (P‐ and S‐wave) velocities of these generally tight rocks, which have an average porosity of about 2%. Variations in acoustic velocity measurements primarily depend on variations in mineralogical composition (silica versus carbonate) and, to a lesser extent, on variations in porosity and bulk density. Pore networks in the sediments are dominated by microporosity and (micro)cracks, followed by interparticle porosity. Recrystallization effects and pore shape variations show a lesser effect on the P‐wave velocity. Clay content does not exceed 12.7% and also has a secondary impact on the acoustic velocities. Defining which textural and physical parameters control the acoustic properties of these carbonate and non‐carbonate sedimentary rocks will help with the interpretation of the seismic response of equivalent deposits in the subsurface.

Migrated Petroleum in Outcropping Mesozoic Sedimentary Rocks in Spitsbergen: Organic Geochemical Characterization and Implications for Regional Exploration

“…Reservoir rocks in the Norwegian Barents Sea and Svalbard include sandstones and carbonates within the Upper Carboniferous to Paleogene succession (Nøttvedt et al, 1993;Jafarian et al, 2017). Commercial oil and gas accumulations in the Norwegian Barents Sea are found within the Middle Triassic Kobbe Formation and the Late Triassic -Middle Jurassic Realgrunnen Subgroup which are comparable to the Sassendalen Group and Wilhelmøya Subgroup, respectively, in Svalbard (Ohm et al, 2008;Nøttvedt et al, 1993).…”

Heterozoan carbonates: When, where and why? A synthesis on parameters controlling carbonate production and occurrences

“…At higher paleolatitudes, the innerramp deposits typically show terrigenous-dominated facies (Ordovician, Silurian and Permian; e.g. (Beauchamp & Desrochers, 1997;Blomeier et al, 2013;Jafarian et al, 2017a;Jafarian et al, 2017b;James et al, 2009a;James et al, 2009b;Rogala et al, 2007;Vennin et al, 1998)). The inner ramp of mid-paleolatitude case studies during the Permian shows an intermediate character with varying terrigenous deposits and biota typical of a subtropical climate (i.e.…”

“…A shift in carbonate association from photozoan to heterozoan is observed in relation with the northward drift of Permian continents that brought northern Pangea into higher paleolatitudes (cf. (Beauchamp & Desrochers, 1997;Bensing et al, 2008;Jafarian et al, 2017a;Jafarian et al, 2017b;James & Lukasik, 2010;Reid et al, 2007)). Carbonate deposits at sub-polar paleolatitudes occur within siliciclastic settings in zones where topography or currents restrict terrigenous input and where waters are highly productive (i.e.…”

Characterization of Upper Palaeozoic Organic‐rich Units in Svalbard: Implications for the Petroleum Systems of the Norwegian Barents Shelf

“…Outcropping rocks on the Svalbard archipelago are widely used as analogues for the deeply-buried equivalents in offshore areas of the western Barents Shelf (Figs 1, 2) (e.g. Abay et al, 2017;Jafarian et al, 2017). During the Late Palaeozoic, the Barents Shelf formed part of a large-scale, east-west oriented continental shelf along the northern margin of Pangea extending westwards across northern Greenland to Arctic Canada and eastwards to the Timan-Pechora Basin in Arctic Russia.…”