Architecture of Thick-bedded Deep Marine Sandstones of the Vocontian Basin, Southeast France

Badescu, M.O., C.A. Visser, and M.E. Donselaar, Delft University of Technology, The Netherlands

Abstract

The objective of this study is to provide facies architecture models of thick-bedded deep marine (TBDM) sandstones to improve our understanding of such sandstones in the Jurassic plays of the North Sea. Data for this study are from outcrops in the Marnes Bleues (Aptian-Albian, extensional Vocontian Basin, southeast France).

Three architectural types of TBDM sandstones have been identified in the Marnes Bleues, based on the nature of the internal bed boundaries, facies association, vertical organization, geometry, and lateral extent of the sands.

• Type 1 consists of a vertical succession of lobes at the base and channels at the top. The shales separating the lobe units are continuous. The shales separating the channels are discontinuous, because of scouring.
• Type 2 consists of stacked sheet sands, organized in thickening-upward trends. The sands are in sand-on-sand contact. Thin, discontinuous shales may locally be present.
• Type 3 consists of stacked, massive, and asymmetrical channels and Bouma-type, thin-be dded levees. The shales separating the channels are thin and discontinuous.

The study reveals that the basin topography plays an important role on the geometry and on the lateral extent of the TBDM sands. Similar facies characteristics are recognized in North Sea Jurassic TBDM sandstone reservoirs. Tartan, Petronella and Highlander fields mainly comprise Type 1 sandstones. Claymore is a combination of Type 2 and Type 3; and Miller Field partially consists of Type 3 sandstones. A comparison of the production behavior of the fields reveals that the shale types and the internal sedimentary structures significantly influence the flow dynamics of the reservoirs.