Seismic Characteristics and Development of the Upper Jurassic Carbonate Buildups from the Miechów Trough (Southern Poland)

Słonka, Łukasz; Krzywiec, Piotr

doi:10.3390/geosciences10060239

Cited by 9 publications

(10 citation statements)

References 86 publications

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“…The reef slopes show a characteristic interfingering of the reef facies with the surrounding strata, in the form of rounded pine tree shaped edges, which indicates a syn-sedimentary reef development with slightly varying build up growth rates. The same was observed by Słonka and Krzywiec (2020) for the Miechów Trough in Poland using well data and 2D seismic lines. Buildups can appear as either continuous elongate bodies oriented parallel to the shelf edge or isolated structures, where the reef geometries are affected by sea level changes and the accommodation space produced by regional subsidence (Moore 2001).…”

Section: Porosity Distributionsupporting

confidence: 80%

“…They are favoured targets for reservoir exploitation, but commonly they are very complex regarding the distribution of petrophysical parameters and facies. Often the reef core is described as a good exploitation target, but this is not always the case as demonstrated by Słonka and Krzywiec (2020) and this study. We show that the reef caps and reef slopes have increased porosities with around 7 to 14% and the reef cores have low porosities of mostly < 3%.…”

Section: Porosity Distributionmentioning

confidence: 75%

“…Besides karst structures, we also identified carbonate reef buildups in our study area, which are associated with massive facies, e.g., microbial-sponge buildups, and they often pass laterally into the surrounding bedded facies (Słonka and Krzywiec 2020). They are favoured targets for reservoir exploitation, but commonly they are very complex regarding the distribution of petrophysical parameters and facies.…”

Section: Porosity Distributionmentioning

confidence: 78%

“…In carbonate rocks, a moundshaped reflector with semi-to discontinuous reflections directly below is often associated with the upper part of a carbonate reef buildup. Transparent to chaotic reflections below these zones are expressions of the reef core (Burgess et al 2013;Słonka and Krzywiec 2020). Parallel to subparallel reflectors in the south are interpreted as a bedded carbonate facies (Burgess et al 2013;Słonka and Krzywiec 2020).…”

Section: Resultsmentioning

confidence: 99%

“…Transparent to chaotic reflections below these zones are expressions of the reef core (Burgess et al 2013;Słonka and Krzywiec 2020). Parallel to subparallel reflectors in the south are interpreted as a bedded carbonate facies (Burgess et al 2013;Słonka and Krzywiec 2020). The acoustic impedance (AI) from the inversion delivers a much more detailed image of the subsurface compared to the reflection seismic shown in Figs.…”

Section: Resultsmentioning

confidence: 99%

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Porosity estimation of a geothermal carbonate reservoir in the German Molasse Basin based on seismic amplitude inversion

Wadas

Hartmann

2022

Geotherm Energy

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The Molasse Basin is one of the most promising areas for deep geothermal exploitation in Germany and the target horizon is the aquifer in the Upper Jurassic carbonates. Carbonate deposits can be very heterogeneous even over a small area due to diagenetic processes and varying depositional environments. The preferential targets for geothermal exploitation in carbonate deposits are fault zones, reef facies and karstified areas, since they are expected to act as hydraulically permeable zones due to high porosity and high permeability. Therefore, identifying these structures and characterizing, e.g., their internal porosity distribution are of high importance. This can be accomplished using 3D reflection seismic data. Besides structural information, 3D seismic surveys provide important reservoir properties, such as acoustic impedance, from which a porosity model can be derived. In our study area in Munich we carried out a seismic amplitude inversion to get an acoustic impedance model of the Upper Jurassic carbonate reservoir using a 3D seismic data set, a corresponding structural geological model, and logging data from six wells at the ‘Schäftlarnstraße’ geothermal site. The impedance model and porosity logs were than used to calculate a porosity model. The model shows a wide porosity range from 0 to 20% for the entire reservoir zone and the lithology along the wells reveals that dolomitic limestone has the highest porosities and calcareous dolomite has the lowest porosities. The study area is cut by a large W–E striking fault, the Munich Fault, and the footwall north of it shows higher porosities and more intense karstification than the hanging wall to the south. Considering the entire study area, an increase in porosity from east to west is observed. Furthermore, we identified a complex porosity distribution in reef buildups and pinnacle reefs. The reef cores have mostly low porosities of, e.g., < 3% and the highest porosities of up to 7 to 14% are observed at the reef caps and on the reef slopes. The reef slopes show a characteristic interfingering of the reef facies with the surrounding bedded facies, which indicates a syn-sedimentary reef development with slightly varying build up growth rates. We also assessed the reservoir quality with regard to porosity distribution and determined areas with moderate to good quality for geothermal exploitation by defining porosity evaluation levels. The porosity evaluation maps show that the carbonate rocks of Berriasian to Malm $$\zeta$$ ζ 1 are preferential targets for exploitation, especially in the footwall of the Munich Fault and to the west of the hanging wall, because these areas are characterized by high porosities due to intense karstification of bedded and massive facies, although the latter is mainly restricted to reef caps and reef slopes.

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Section: Porosity Distributionsupporting

confidence: 80%

Section: Porosity Distributionmentioning

confidence: 75%

Section: Porosity Distributionmentioning

confidence: 78%