The Furongian to Lower Ordovician Alum Shale Formation in conventional and unconventional petroleum systems in the Baltic Basin – A review

Schulz, Hans-Martin; Yang, Shengyu; Schovsbo, Niels H.; Rybacki, E.; Ghanizadeh, Amin; Bernard, Sylvain; Mahlstedt, Nicolaj; Krüger, Martin; Amann-Hildebrandt, Alexandra; Krooß, Bernhard M.; Meier, T.; Reinicke, Andreas

doi:10.1016/j.earscirev.2021.103674

Cited by 28 publications

(9 citation statements)

References 139 publications

(201 reference statements)

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“…The Alum Shale Formation in northwestern Europe was deposited from the Middle Cambrian (Miaolingian) to the Early Ordovician (Tremadoc) in the Baltic Basin and surrounding countries. It is a conventional source of oil from Cambrian, Ordovician, and Silurian carbonates and also has potential for shale oil and biogenic or thermogenic shale gas [24] (Figure 1). ation thermal simulation experiments, and the experimental results are valuable references for the hydrocarbon generation mechanism, characteristics, and hydrocarbon generation potential of the carbonate rocks of the Majiagou Formation in the Ordos Basin.…”

Section: Geological Settingmentioning

confidence: 99%

Experimental Characteristics of Hydrocarbon Generation from Scandinavian Alum Shale Carbonate Nodules: Implications for Hydrocarbon Generation from Majiagou Formation Marine Carbonates in China’s Ordos Basin

Wang,

Xu,

Huang

et al. 2023

JMSE

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The hydrocarbon source rocks of the marine carbonates of the Ordovician Majiagou Formation in the Ordos Basin are generally in the high-overmature stage and are, therefore, not suitable for hydrocarbon thermal simulation experiments. Their hydrocarbon generation potential and hydrocarbon generation characteristics are not clearly understood. Meanwhile, Nordic Cambrian carbonates are similar in lithology, parent material type, and sedimentary age, and are in the low evolution stage, which is suitable for hydrocarbon thermal simulation experiments. Therefore, in this study, we selected the Nordic carbonates for the gold tube thermal simulation experiment to analyze the content and geochemical characteristics of the thermal simulation products. The experimental results are also compared and analyzed with the characteristics of thermal simulation products of Pingliang Formation mud shale (contemporaneous with the Majiagou Formation) and Shanxi Formation coal (in the upper part of the Majiagou Formation), which are similar to the Majiagou Formation in the Ordos Basin. The results showed that the Nordic carbonate has different hydrocarbon production characteristics from the mud shale of the Pingliang Formation of the same parent material type, and although the hydrocarbon production yields of the two are not very different, the carbonate still produces methane at 600 °C. The hydrocarbon production yield of the Nordic carbonates is almost equivalent to that of type-II2 kerogen, indicating that the hydrocarbon production yield is not related to lithology and only to the organic matter type; however, the Nordic carbonate can produce a large amount of H2S. The alkane carbon isotope changes are mainly controlled by the degree of thermal evolution, showing gradual heaviness with increasing temperature. No carbon isotope sequence reversal occurred during the thermal simulation, and its distribution range is roughly the same as that of the alkane carbon isotope composition of the mud shale of the Pingliang Formation. The ethane carbon isotope composition is as heavy as −21.2‰ at the high-temperature stage, showing similar coal-type gas characteristics. The addition of calcium sulphate (CaSO4) causes the TSR reaction to occur, which has a significant impact on the methane content under high maturity conditions, reducing its content by more than 50% at 600 °C. However, the addition of CaSO4 increases the yield of heavy hydrocarbon gases, such as ethane, and promotes the production of C6-14 hydrocarbons and C14+ hydrocarbons at high-temperature stages, and the addition of CaSO4 substantially increases the yield of H2, CO2, and H2S. The thermal simulation results have implications for the hydrocarbon formation mechanism of the early Paleozoic marine carbonate formation system in the stacked basins of the Ordos Basin and the Tarim Basin in China.

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Section: Geological Settingmentioning

confidence: 99%

Experimental Characteristics of Hydrocarbon Generation from Scandinavian Alum Shale Carbonate Nodules: Implications for Hydrocarbon Generation from Majiagou Formation Marine Carbonates in China’s Ordos Basin

Wang,

Xu,

Huang

et al. 2023

JMSE

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“…The imbibition behavior in sandstones is influenced by various factors. These include the heterogeneity of pore types and their geometric shapes [8][9][10]. Additionally, the behavior is affected by the electrochemical potential, which is induced by clay hydration and osmotic effects [11,12].…”

Section: Introductionmentioning

confidence: 99%

Impact of Osmotic Pressure on Seepage in Shale Oil Reservoirs

Mu,

Xue,

Bai

et al. 2024

FDMP

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Following large-scale volume fracturing in shale oil reservoirs, well shut-in measures are generally employed. Laboratory tests and field trials have underscored the efficacy of fracturing fluid imbibition during the shut-in phase in augmenting shale oil productivity. Unlike conventional reservoirs, shale oil reservoirs exhibit characteristics such as low porosity, low permeability, and rich content of organic matter and clay minerals. Notably, the osmotic pressure effects occurring between high-salinity formation water and low-salinity fracturing fluids are significant. The current understanding of the mobilization patterns of crude oil in micro-pores during the imbibition process remains nebulous, and the mechanisms underpinning osmotic pressure effects are not fully understood. This study introduces a theoretical approach, by which a salt ion migration control equation is derived and a mathematical model for spontaneous imbibition in shale is introduced, which is able to account for both capillary and osmotic pressures. Results indicate that during the spontaneous imbibition of low-salinity fluids, osmotic effects facilitate the migration of external fluids into shale pores, thereby complementing capillary forces in displacing shale oil. When considering both capillary and osmotic pressures, the calculated imbibition depth increases by 12% compared to the case where only capillary forces are present. The salinity difference between the reservoir and the fracturing fluids significantly influences the imbibition depth. Calculations for the shutin phase reveal that the pressure between the matrix and fractures reaches a dynamic equilibrium after 28 days of shut-in. During the production phase, the maximum seepage distance in the target block is approximately 6.02 m.

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“…Albjära-1 provides a rare, astronomically-tuned long-term (500-484 Ma), near-continuous record without major changes in lithology, depositional environment or oxygenation (Zhao et al, 2022a). The finely (sub-mm) laminated Alum Shale Formation was deposited around 60ºS paleolatitude, in a (predominantly) anoxic-euxinic shallow to deep shelf sea that covered most of present-day Scandinavia (Sørensen et al, 2020;Schulz et al, 2021;Zhao et al, 2022a) (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…1). The formation is known for its high concentrations of total organic carbon (TOC; 5-25%), high trace-element concentrations, including U, Mo, V and Zn, and astronomically modulated sulfur and aluminum (Sørensen et al, 2020;Schulz et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

No evidence for a volcanic trigger for late Cambrian carbon-cycle perturbations

Frieling,

Mather,

Fendley

et al. 2023

Geology

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The early Paleozoic was marked by several carbon-cycle perturbations and associated carbon-isotope excursions (CIEs). Whether these CIEs are connected to significant (external) triggers, as is commonly considered to be the case for CIEs in the Mesozoic and Cenozoic, or result from small carbon-cycle imbalances that became amplified through lack of efficient silicate weathering or other feedbacks remains unclear. We present concentration and isotope data for sedimentary mercury (Hg) and osmium (Os) to assess the impact of subaerial and submarine volcanism and weathering during the late Cambrian and early Ordovician. Data from the Alum Shale Formation (Sweden) cover the Steptoean positive carbon-isotope excursion (SPICE; ca. 497–494 Ma), a period marked by marine anoxia and biotic overturning, and several smaller CIEs extending into the early Ordovician. Our Hg and Os data offer no strong evidence that the CIEs present in our record were driven by (globally) elevated volcanism or continental weathering. Organic-carbon and Hg concentrations covary cyclically, providing further evidence of an unperturbed Hg cycle. Mesozoic and Cenozoic CIEs are commonly linked to enhanced volcanic activity and weathering, but similar late Cambrian–early Ordovician events cannot easily be connected to such external triggers. Our results are more consistent with reduced early Paleozoic carbon-cycle resilience that allowed small imbalances to develop into large CIEs.

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The Furongian to Lower Ordovician Alum Shale Formation in conventional and unconventional petroleum systems in the Baltic Basin – A review

Cited by 28 publications

References 139 publications

Experimental Characteristics of Hydrocarbon Generation from Scandinavian Alum Shale Carbonate Nodules: Implications for Hydrocarbon Generation from Majiagou Formation Marine Carbonates in China’s Ordos Basin

Experimental Characteristics of Hydrocarbon Generation from Scandinavian Alum Shale Carbonate Nodules: Implications for Hydrocarbon Generation from Majiagou Formation Marine Carbonates in China’s Ordos Basin

Impact of Osmotic Pressure on Seepage in Shale Oil Reservoirs

No evidence for a volcanic trigger for late Cambrian carbon-cycle perturbations

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