Back to the Basics, How the Interaction of Depositional Processes and Burrowers Affects the Construction of Integrated Models in Unconventional Source Rock Plays

Abstract

Middle Jurassic organic-rich carbonate mudrocks of the Middle East have been historically recognized as the source rock interval that has fed the world’s largest conventional fields. These fine grained calcareous and organic rich formations are defined by their unique sedimentological (traction vs suspension) and early post depositional processes (bioturbation intensity and style). The Middle Jurassic organic rich facies described here, were deposited in intra-shelf depocenters of what is now the Middle East. These units exhibit a high degree of large vertical variability at multiple scales (sub mm to meter scale), and have a lateral variability that can only be easily observed and captured at a scale of 10’s of kilometers. The identification of depositional packages that can be statically and dynamically modelled in 3D is difficult since most methods used to describe deposition rely on hard to discern factors relating to the nature of the depositional setting rather than the current post depositional and diagenetic characteristics. Furthermore, variation in locally measured rock properties from core and wireline logs is usually not reflected in large scale static and dynamic 3D geological models. Heterogeneity has inherent challenges when it comes to upscaling from core observations, to well logs, to seismic and finally to 3D static and dynamic models. Hence, the integration of discrete sedimentological descriptors to large data sets (e.g. logs, seismic, geomodels) has been of primary importance in the development of conventional reservoirs and has just started to evolve for unconventional reservoirs. Here we present how a holistic approach has been used for a meaningful workflow in a Middle Jurassic rock interval.

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