Use of Outcrop Analogues when Characterizing and Modelling Carbonate Reservoirs

Nardon, Sergio ¹; Aigner, Thomas ²; Blendinger, Wolfgang ⁴; Borgomano, Jean ³; Gari, Jean ³; Palermo, Denis ¹
(1)E&P, Eni S.p.A., San Donato Milanese, Italy. (2) Sedimentary Geology, University of Tuebingen, San Donato Milanese, Germany. (3) Centre de Sédimentologie-Paléontologie, Université de Provence, Marseille, France. (4) Erdölgeologie, TU-Clausthal, Clausthal-Zellerfeld, Germany.

The complexity and the spatial heterogeneity of carbonate sedimentary systems and related reservoirs result from the multiplicity and diversity of the carbonate genetic processes at all scales (biological, physical and chemical). Realizing and prioritizing these heterogeneities in a reservoir model are amongst the biggest challenges in the reservoir characterisation.

Within the GECO project, a Research group of various Universities driven by Eni e&p and focussed on the “Geometry of Carbonate Objects”, numerous studies of selected carbonate outcrops were carried out. Diverse scenarios and measurements at all heterogeneity scales within a numerical geomodel have been approached. Two major methods were developed: the acquisition of numerical outcrop data in a geo-referenced framework and the numerical geo-modelling. The first one comprises the acquisition of high resolution surface mapping (stratigraphy, sedimentology, structural geology) supplemented by Laser Scan surveyes and Ground Penetrating Radar Imaging of outcrops, high resolution seismic, well-bore coring and petrophysical logging. The second one is based on the use of reservoir modelling software that allowed 3D numerical geological realisations able to integrate all outcrop data.

The first case here shown and conducted with the University de Provence, concerns the Upper Cretaceous outcrop of the Beausset Basin (France), a mixed carbonate-siliciclastic sedimentary system with a continuous transition from the inner shelf to the basin. Surface maps, laser scanning and high resolution seismic data have been integrated within numerical models. It represents a suitable analog for rudist-bearing carbonate reservoirs in the Middle East.

The second example, studied with the Universities of Tuebingen and Clausthal, focuses on the Triassic Muschelkalk carbonates (South-German Basin) as an analog of “layer-cake” reservoir systems in the Middle East. Such carbonates were deposited in an epicontinental, very gently inclined carbonate ramp and consist of skeletal and oolitic grainstones, organised in a well-defined hierarchy of cycles. The resulting high resolution 3-D modelling of sedimentary body geometries provided new insights into very gentle clinoform geometries, with a predictable distribution of reservoir geobodies

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.