Constraining Reservoir Models by their Diagenetic Overprints - Impact on Reservoir Connectivity

Abstract

Dolomitic formations constitute one of the most important reservoirs in the Middle East Region. The complex diagenetic history which prevails in these reservoirs impacts on the final static and dynamic reservoir properties. Therefore in order to optimise the current production of reservoirs and future field development plans, it is mandatory to: •understand the type, impact and timing of the main diagenetic phases at all scales from regional understanding to the fine-scale reservoir heterogeneities in order to constrain geometry, •and develop approaches to effectively incorporate the most significant ones into the static reservoir model. Dolomitization is one of the most crucial diagenetic phases since it strongly constrains the permeability architecture of the field. Detailed diagenetic studies suggest that various types of genetic dolomite types exist, including evaporative, mixed evolved sea-water - freshwater and late thermobaric dolomites. The modelling approach is geologically-driven and based on the relationships between dolomite type, stratigraphic position, palaeogeographic position, depositional facies, and proximity to fault/fracture zones. The results are then quality controlled to ensure coherency with the conceptual models. The outcome of this modelling workflow is fed into a dynamic simulator to assess the potential impact on field behaviour, production profiles and well productivities.