This article is the first part of an integrated study to characterize the anatomy and geometries of carbonate shoal reservoir bodies in epicontinental settings. It is based on outcrop analog data from Triassic layer-cake carbonates in the south German Basin, which were deposited along an epicontinental, very gently inclined carbonate ramp. The database of this study consists of 56 measured sections supplemented by six shallow cores and wireline logs, covering an area of 25 by 36 km (15 by 22 mi). The potential reservoir bodies consist generally of midramp shoal and shoal-fringe facies types, which are composed of skeletal and oolitic carbonate packstones and grainstones with significant amounts of porosity. The upper Muschelkalk is composed of a lower transgressive and an upper regressive interval; within these, shoal bodies show not only similarities but also major differences in character, geometry, and distribution. These reflect the conditions of an epeiric system, which reacts strongly to small changes in accommodation. The accommodation seems to be mainly triggered by the interaction of hierarchically organized large-, medium-, and small-scale relative sea level changes and a subtle paleorelief. At the level of medium-scale cycles, distinct two-dimensional cyclicity styles can be differentiated, which record the lateral facies distribution along the depositional gradient. Different styles of medium-scale cycles include different types of shoal bodies: (1) transgressive crinoidal shoal style:

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This paper represents the second part of an integrated study that is focussed on the development and distribution of reservoir bodies and properties in epeiric carbonate systems. It is based on outcrop analogue data from Triassic ‘layer-cake’ carbonates in the South German Basin, which were deposited along an epicontinental, very gently inclined carbonate ramp. The reservoir facies consists of skeletal and oolitic carbonate grainstones (Φmax 23%, Kmax 700 mD), which are organized in a pronounced hierarchy of stratigraphic cycles. Based on outcrops, cores, gamma ray (GR) logs and thin sections, a high-resolution, geocellular 3D facies model was generated, which covers the area of a Middle East giant gas field (25×36 km). The spatial distribution of reservoir properties was systematically investigated on different scales. The lateral distribution of reservoir properties remains in the same order of magnitude for hundreds of metres, within in the same stratigraphic position. However, on a kilometre scale, facies bodies, diagenetic trends and thus reservoir properties show gradual lateral changes. Vertically, in contrast, properties change commonly on a decimetre scale and are largely controlled by stratigraphic cycles. Petrophysical modelling enhanced the understanding of key factors and processes controlling both reservoir quality and quantity.

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