Evaluation of hydrocarbon generation and migration in the Molasse fold and thrust belt(Central Eastern Alps, Austria) using structural and thermal basin models

Gusterhuber, Juergen; Hinsch, Ralph; Sachsenhofer, Reinhard F.

doi:10.1306/06061312206

Cited by 24 publications

(17 citation statements)

References 47 publications

(72 reference statements)

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“…In the Sierning imbricates in the east (Fig. 1c), a detachment is present within the Rupelian (Hinsch, 2013;Gusterhuber et al, 2013;2014). However, the minimum amount of total shortening in the Chattian and Aquitanian (including overthrusting by Alpine nappes) is about 32 km (Hinsch, 2013).…”

Section: Tectonic Evolutionmentioning

confidence: 94%

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Petroleum Systems in the Austrian Sector of the North Alpine Foreland Basin: An Overview

Groß

Sachsenhofer

Bechtel

et al. 2018

Journal of Petroleum Geology

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Two separate petroleum systems have been identified in the Austrian sector of the North Alpine Foreland Basin: a lower Oligocene – Cenomanian/Eocene oil and thermogenic gas system; and an Oligocene‐Miocene microbial gas system. Recent studies by both academic and industry‐based research groups have resulted in an improved understanding of these petroleum systems, which are reviewed in this paper. Lower Oligocene organic‐rich intervals (up to 12 %TOC; HI: 400–600 mgHC/gTOC), capable of generating slightly more than 1 t of hydrocarbons/m2, are the source rocks for the thermogenic petroleum system in the Austrian sector of the North Alpine Foreland Basin. The present‐day distribution of this source rock is controlled by submarine mass movements which removed a large part of the organic‐rich interval from its depositional location during the late early Oligocene. The transported material was redeposited in locations to the south which are at the present day buried beneath Alpine thrust sheets. In addition, source rock units were incorporated into Molasse imbricates during Alpine deformation. Hydrocarbon generation began during the Miocene, and the oil kitchen was located to the south of the Alpine thrust front. Hence, lateral migration over distances of up to 50 km was required to charge the mainly Eocene and Cenomanian non‐ and shallow‐marine sandstone reservoir units. Hydrocarbons are in general trapped in structures related to east‐west trending normal faults, and differences in source rock facies resulted in the development of separate western and eastern oil families. Surprisingly, with the exception of some fields in the eastern part of the study area, associated gas contains varying (and sometimes very high) percentages of primary and secondary microbial methane. The composition of oil in some fields is influenced by both biodegradation and water washing. Post‐Miocene uplift in the Austrian sector of the basin had further effects on biodegradation and the consequent formation of secondary microbial gas, and also resulted in re‐migration. The upper Oligocene to lower Miocene succession (Puchkirchen Group, Hall Formation) provides both source and reservoir rocks for the microbial petroleum system in the Austrian sector of the North Alpine Foreland Basin. TOC contents (<1.0 %) and HI values (<140 mgHC/gTOC) of pelitic source rocks are typically low. Microbial gas was generated shortly after deposition during early diagenesis and was subsequently fixed in gas hydrates. Basin subsidence and high sedimentation rates resulted in decomposition of the hydrates below their stability zone, and reservoirs were filled during the early Miocene. Subsequent mixing of microbial gas with thermogenic gas and condensates is widespread. However, biodegradation has prevented precise determination of the fraction of thermogenic hydrocarbons present in gas samples. Reservoir sandstones were deposited within a deep‐marine channel belt along the axis of the North Alpine Foreland Basin, and reservoir quality depends on the precise posit...

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Section: Tectonic Evolutionmentioning

confidence: 94%

“…Based on 2D numeric models, Gusterhuber et al (2013Gusterhuber et al ( , 2014 reconstructed hydrocarbon generation and migration along cross-sections in the western and eastern part of the Austrian sector of the North Alpine Foreland Basin. The evolution of the basin in the eastern part is shown in Fig.…”

Section: Thermal Maturation and Hydrocarbon Generationmentioning

confidence: 99%

Petroleum Systems in the Austrian Sector of the North Alpine Foreland Basin: An Overview

Groß

Sachsenhofer

Bechtel

et al. 2018

Journal of Petroleum Geology

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“…Hydrocarbon generation started in Miocene times, when the Alpine nappes started to overthrust the southern NAFB and ended about 5 Ma ago due to uplift and cooling (Gusterhuber et al, 2013(Gusterhuber et al, , 2014. The oil window is reached at a depth of about 4 to 6 km below sea level.…”

Section: Hydrocarbon Systemmentioning

confidence: 99%

“…They experienced a complex charging history, involving minor early primary microbial gas and late thermogenic oil (Gusterhuber et al, 2013(Gusterhuber et al, , 2014. In addition, in-situ oil alteration occurs within the reservoir sandstones in shallow horizons (above -650 m; Gratzer et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Carbonate cementation in Upper Eocene clastic reservoir rocks from the North Alpine Foreland Basin (Austria)

Grundtner¹,

Groß²,

Gratzer³

et al. 2017

AJES

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A strong relationship between carbonate precipitation and microbial gas generation is evident for the Upper Eocene reservoir rocks of the North Alpine Foreland Basin. To achieve a better understanding of this relationship, 40 samples of limnic to shallow marine, gas-, oil-and water-bearing sandstones were studied to determine mineralogy and diagenetic history. The specific mineral parageneses were used to reconstruct changes in the hydrogeochemical conditions over time. Thus, authigenic mineral phases within reservoir rocks are an important archive for the reconstruction of pore fluid composition changes.The eogenetic pore space evolution of investigated Eocene sandstones is influenced by their primary mineralogy, which is strongly controlled by (i) depositional environment, (ii) detrital input and (iii) transport distances. Thus, a low compositional maturity is associated with high feldspar and high clay mineral content. Authigenic clay minerals, formed during several stages of diagenesis, play an important role for reservoir quality, due to pore space reduction.During eogenesis, authigenic micritic and sparitic carbonate phases are precipitated, which decreases the pore space. These eogenetic carbonate cements exhibit isotope values of about δ C: -5.9 to +2.2‰ and O: -8.3 to -4.3‰ [VPDB]. Some of these sam- 18ples indicate a trend towards lighter δ O values (-17.2‰), which is attributed to meteoric flush.Within the Eocene sandstones, two types of strongly cemented zones with low permeabilities can be differentiated: (i) extraordi- 13nary light δ C (-28.4‰) carbonates, which formed due to degradation of organic matter at the stage of advanced sulfate reduc- 13tion and (ii) heavy δ C (δ C: +8.7‰), which precipitated at the fermentation zone. Within the reservoir sandstones telogenesis is characterized by mineral destabilization (e.g. carbonate and feldspar corrosion) and kaolinite precipitation. The formation of authigenic kaolinite booklets resulted into a decrease in porosity.

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“…This study focusses on the thermogenic system. This petroleum system is based on Lower Oligocene source rocks which became thermally mature as a result of burial beneath the Alpine nappes in the Miocene (Gusterhuber et al, 2013, 2014. In the western part of the study area, the Lower Oligocene source rocks are incorporated in the molasse imbricates (Sachsenhofer et al, 2010).…”

Section: Petroleum Systemsmentioning

confidence: 99%

Composition of Diamondoids in Oil Samples From the Alpine Foreland Basin, Austria: Potential as Indices of Source Rock Facies, Maturity and Biodegradation

Pytlak

Kowalski

Groß

et al. 2017

Journal of Petroleum Geology

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Twenty‐seven oil samples from Cretaceous, Eocene and Rupelian reservoir rocks in the Alpine Foreland Basin (Austria) were analysed to evaluate the composition of diamondoid hydrocarbons using gas chromatography – triple quadrupole mass spectrometry. The oils were generated from marly and shaly Oligocene source rocks buried beneath the nappes of the Alpine foldbelt to the south of the study area. Diamondoid hydrocarbons were detected in the saturated fraction of all the analysed oils. A biodegraded oil sample from a shallow reservoir in the NE part of the study area showed an enrichment in diamondoids due to the molecule's high resistance to microbial degradation. Variations in the organic matter type of the source rock facies and differences in maturity are known to influence the composition of diamondoids. However in this study, biomarker‐derived maturity parameters do not show a convincing correlation with diamondoid maturity parameters. Moreover, no cracking trend based on biomarkers and diamondoid concentrations was observed. The results indicate that the composition of diamondoids in oils from the Austrian part of the Alpine Foreland Basin is mainly controlled by heterogeneities in the Lower Oligocene source rocks, including the occurrence of a redeposited source rock succession in the western part of the study area. By contrast, EAI‐1 (the ethyladamantane index) shows a good correlation with various maturity parameters and seems to be independent of source rock facies.

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Evaluation of hydrocarbon generation and migration in the Molasse fold and thrust belt(Central Eastern Alps, Austria) using structural and thermal basin models

Cited by 24 publications

References 47 publications

Petroleum Systems in the Austrian Sector of the North Alpine Foreland Basin: An Overview

Petroleum Systems in the Austrian Sector of the North Alpine Foreland Basin: An Overview

Carbonate cementation in Upper Eocene clastic reservoir rocks from the North Alpine Foreland Basin (Austria)

Composition of Diamondoids in Oil Samples From the Alpine Foreland Basin, Austria: Potential as Indices of Source Rock Facies, Maturity and Biodegradation

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