Source potential and depositional environment of Oligocene and Miocene rocks offshore Bulgaria

Mayer, J. J.; Rupprecht, Bernhard; Sachsenhofer, Reinhard F.; Tari, Gábor; Bechtel, Achim; Ćorić, Stjepan; Siedl, Wolfgang; Kosi, Walter; Floodpage, J.

doi:10.1144/sp464.2

Cited by 17 publications

(40 citation statements)

References 24 publications

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“…The architecture of the Maikop Group offshore Bulgaria is controlled by a regional erosional unconformity ("top-Eocene") and the incision of the west-east trending Kaliakra Canyon during late Solenovian time (Mayer et al, 2017;Fig. 12a).…”

Section: Western Black Seamentioning

confidence: 99%

“…The fill of the Kaliakra Canyon in well Samotino Melrose is more than 1000 m thick ( Fig. 12a) and comprises upper Solenovian to Middle Miocene rocks (Mayer et al, 2017). With the exception of the Middle Miocene, the succession is largely carbonatefree (Fig.…”

Section: Canyon Fillmentioning

confidence: 99%

“…The content of biogenic opal reaches 50 wt.% suggesting a high contribution of diatoms to the biomass. Similar sediments, but with significantly lower thickness, also occur south of the Kaliakra Canyon (Mayer et al, 2017). Based on the relationship with the shelfbreak canyon, a model implying locally enhanced upwelling of subsurface waters onto the continental shelf (e.g.…”

Section: Canyon Fillmentioning

confidence: 99%

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Paratethyan Petroleum Source Rocks: An Overview

Sachsenhofer

Popov

Ćorić

et al. 2018

Journal of Petroleum Geology

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The Paratethys area extends from Central Europe to the borders of the Caspian Sea in Central Asia and hosts a significant number of petroleum provinces, many of which have been charged by Eocene to Miocene source rocks of supra‐regional significance. These include highly oil‐prone Middle Eocene marls and limestones in the Eastern Paratethys (Kuma Formation and equivalents) which are several tens of metres thick. Estimates of the source potential index (SPI) indicate that the Kuma Formation in the northern Caucasus and the Rioni Basin (Georgia) may generate 1 to 2 tons of hydrocarbons per square metre (tHC/m2). This implies that the Kuma Formation may also be an important and additional source rock in the eastern Black Sea. Oligocene and Lower Miocene pelitic rocks (Maikop Group and equivalents) are considered to be the most important source rocks in the Paratethys. Vertical variations in source potential record different stages of basin isolation that reached a maximum during the Early Oligocene (NP23) Solenovian Event. However major variations exist between different sub‐basins in the Central and the Eastern Paratethys. In the Central Paratethys, the highest quality source rocks occur in the Carpathian Basin where the Menilite Formation, several hundreds of metres thick, can generate up to 10 tHC/m2. Locally the Menilite Formation is about 1500 m thick and continues into the Lower Miocene. In these settings, the Menilite Formation can generate approximately 70 tHC/m2. In the Alpine Foreland Basin (Schöneck and Eggerding Formations) and the Pannonian Basin (Tard Clay Formation), oil‐prone source rocks are restricted to the Lower Oligocene. In the Eastern Paratethys, the best source rock intervals of the Maikop Group are typically associated with the Early Oligocene Solenovian Event. By contrast, with the exception of the Kura Basin in Azerbaijan, the potential of Upper Oligocene and Lower Miocene rocks is often limited. In total, the Maikop Group may generate up to 2 tHC/m2 in the North Caucasus area and 4 tHC/m2 in the Rioni Basin. A particular source rock facies is found in the Western Black Sea where diatomaceous rocks with good oil potential accumulated in the Kaliakra Canyon during Early Miocene time. This facies may generate up to 8 tHC/m2, but is probably limited to shelf‐break canyons. Middle and Upper Miocene rocks are the main source for oil and thermogenic gas in the Pannonian Basin System, and also contributed to thermogenic hydrocarbons in the Moesian Platform and the South Caspian Basin. In addition, Upper Oligocene and Miocene rocks are the source for microbial gas in several basins including the Alpine and Carpathian foredeeps.

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Section: Western Black Seamentioning

confidence: 99%

Section: Canyon Fillmentioning

confidence: 99%

Section: Canyon Fillmentioning

confidence: 99%

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Paratethyan Petroleum Source Rocks: An Overview

Sachsenhofer

Popov

Ćorić

et al. 2018

Journal of Petroleum Geology

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“…Mayer et al (2017), Sachsenhofer et al (2017b) and Vincent & Kaye (2017) all demonstrate that the Maykop Suite and its equivalents may not be the high-quality source rock in the Black Sea basins that is often assumed. How important are older source rocks, such as the Kuma Suite, and, given the likely depth of burial of that unit, is gas a more likely hydrocarbon phase than oil?…”

Section: Discussionmentioning

confidence: 97%

Petroleum geology of the Black Sea: introduction

Simmons

Tari

Okay

2018

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Abstract:The exploration for petroleum in the Black Sea is still in its infancy. Notwithstanding the technical challenges in drilling in its deep-water regions, several geological risks require better understanding. These challenges include reservoir presence and quality (partly related to sediment provenance), and the timing and migration of hydrocarbons from source rocks relative to trap formation. In turn, these risks can only be better understood by an appreciation of the geological history of the Black Sea basins and the surrounding orogens. This history is not without ongoing controversy. The timing of basin formation, uplift of the margins and facies distribution remain issues for robust debate. This Special Publication presents the results of 15 studies that relate to the tectonostratigraphy and petroleum geology of the Black Sea. The methodologies of these studies encompass crustal structure, geodynamic evolution, stratigraphy and its regional correlation, petroleum systems, source to sink, hydrocarbon habitat and play concepts, and reviews of past exploration. They provide insight into the many ongoing controversies regarding the geological history of the Black Sea region and provide a better understanding of the geological risks that must be considered for future hydrocarbon exploration. The Black Sea remains one of the largest underexplored rift basins in the world. Although significant biogenic gas discoveries have been made within the last decade, thermogenic petroleum systems must be proven through the systematic exploration of a wide variety of play concepts.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.The Black Sea, located between Russia, Georgia, Turkey, Bulgaria, Romania and Ukraine, covers an area of approximately 423 000 km 2 with a maximum water depth of 2245 m. Sedimentary thickness can exceed 14 km. The Black Sea holds an abiding fascination for petroleum geologists and is a true frontier basin with very few wells drilled in its deepwater sector. Abundant seepage, outcrops of potential source rocks around its margins, large potential traps imaged on seismic data, and a variety of potential reservoir and play concepts point towards considerable potential to reward the successful explorer. This volume brings together several geoscience studies (Fig. 1) that provide additional information about the origins of the Western and Eastern Black Sea basins, their tectonostratigraphic history, sedimentary fill and petroleum potential.The Black Sea and its surrounding regions have a long history of geological research: for example, it has long been regarded as the type example of an euxinic basin in which bottom water anoxia and free hydrogen sulphide (H 2 S) result in an absence of benthonic life and the preservation of organic matter (Wignall 1994). Somewhat ironically, the term 'euxinic' is derived from an ancient Greek name for the sea, Pontus Euxinus, meaning the welcoming or hospitable sea. Another ancient Greek name (probably derived from an Iranian nam...

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“…The source rock potential of the Kuma Formation and of the Maikop Group in the Black Sea area has been described in recent studies including Mayer et al (2017), Vincent and Kaye (2017), Morton et al (2017), and Pupp et al (2018, this issue), and its regional variation within the Paratethys has been summarised by Sachsenhofer et al (2017;2018, this issue). These studies show that the Kuma Formation and the Maikop Group are thermally immature in the proximal (shelfal) parts of the Black Sea as well as in the surrounding onshore areas (see also Olaru et al, 2018, this issue).…”

Section: Introductionmentioning

confidence: 92%

Petroleum Charge and Migration in the Black Sea: Insights From Oil and Source Rock Geochemistry

Mayer

Sachsenhofer

Ungureanu

et al. 2018

Journal of Petroleum Geology

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Although a number of significant oil and gas discoveries have been made within the Western Black Sea and the surrounding area, only sparse data about migration mechanisms are available. In this paper, biomarker and isotope data from five oilfields and one oil show located offshore Bulgaria and Romania (in the western Black Sea), and from one field onshore Georgia (at the margin of the eastern Black Sea), were compared with geochemical data from potential source rock intervals from borehole samples. The source rock data came from offshore Bulgaria and outcrop samples from onshore Georgia. The biomarker data indicates that all the oils analysed were generated by source rocks of Late Cretaceous or Cenozoic age. In the Western Black Sea sub‐basin, the most likely source rocks are Oligocene to Lower Miocene shales of the Maikop Group. Compound‐specific isotope data indicate that Lower Oligocene source rocks are the most significant although a contribution by Lower Miocene diatom‐rich source rocks cannot be excluded. For an oil sample from the Shromisubani field onshore Georgia, isotope data from individual n‐alkanes together with biomarker data indicates that the oil contains a mixture of hydrocarbons generated from the Middle Eocene Kuma Formation and the Oligocene part of the Maikop Group. Oligocene and Miocene source rocks are immature at the shelfal locations where the oil samples were recovered. Charge for these hydrocarbon accumulations is interpreted to have been provided by long‐distance lateral migration from source kitchens in more central parts of the Black Sea basin, where Oligocene and (some) Miocene source rocks are within the oil and gas window. The results of this study highlight the prospectivity of recently‐discovered deep‐water plays, and significantly de‐risk future deep‐water projects within the Black Sea area.

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Source potential and depositional environment of Oligocene and Miocene rocks offshore Bulgaria

Cited by 17 publications

References 24 publications

Paratethyan Petroleum Source Rocks: An Overview

Paratethyan Petroleum Source Rocks: An Overview

Petroleum geology of the Black Sea: introduction

Petroleum Charge and Migration in the Black Sea: Insights From Oil and Source Rock Geochemistry

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