High-Resolution Analysis of a Jurassic Outcrop Analogue for Oolithic Reservoirs (Weserbergland, Germany)

Abstract

An evaluation of hydrocarbon reservoirs in carbonates shows that a series of economically relevant occurrences is in oolites. Major fields of the Middle East produce from oolithic intervals from the Permian Khuff Fm. and the Kimmeridgian Arab Fm. Additionally, the underexplored Araej and Izhara Fms. largely consist of oolithic shoal reservoirs. Oolites are the product of sedimentation under conditions of elevated hydrodynamic energy. In oolitic reservoir units, a reconstruction and interpretation of geobodies at a sub-seismic scale is therefore difficult to establish, because inter-well spacing cannot reproduce small-scale lateral facies changes that are important for the understanding of migration paths within the reservoirs. Therefore, this study aims to present facies, sediment structures and geobody dimensions of oolites based on outcrop examples of Oxfordian carbonates of the Korallenoolith Fm. in North Germany. A facies atlas is presented, which documents the relevant elements needed to distinguish distinct facies of an oolite shoal. Dimensions of structures and geobodies are documented. Furthermore, field mapping of the oolithic sedimentary system aims to visualize the extension and development of a sediment body in the Korallenoolith Fm. as an analog for carbonate reservoirs of subsurface hydrocarbon exploration. The study provides insight into an outcrop-sized sedimentary body of the key formation, representing a possible expression of reservoirs in the Upper Jurassic, located in similar rocks. The study is introduced to emphasize general geometries of the sediment body, facies architecture, bedding style, as well as features of internal sedimentary structures in a 3D environment. Thus, it enhances the understanding of subsurface reservoir characteristics within a context of sedimentary structures and facies within inter-well distances.

AAPG Datapages/Search and Discovery Article #90370 ©2020 AAPG Middle East Region Geoscience Technology Workshop, 3rd Edition Carbonate Reservoirs of the Middle East, Abu Dhabi, UAE, January 28-29, 2020