Modeling complex reservoir architecture and connectivity in channel belt sandstones: The case study of the Rhaetian Distributive Fluvial System in the North German Basin

Fluvial geothermal reservoirs are often characterized by complex and heterogeneous reservoir geometries and sandstone-body connectivities. One particular example is the Rhaetian Distributive Fluvial System (RDFS), whose channel belt reservoirs represent key targets of medium-deep geothermal energy exploration. By combining a data- and a model-based approach, we recreate for the first time the depositional environment of Rhaetian Lower Exter Formation in the Darss area, located in Northeast Germany. In this region, high sandstone thicknesses can be found in distributary channel belt reservoirs, which consist of different morphological elements of meandering fluvial channels. The lateral and vertical distribution of channel vs. overbank facies is realistically modeled by the process-based and stochastic simulation software FLUMY™, creating a heterogeneous 3D reservoir model of the study area. Additionally, existing well data is integrated in the user-defined multi-sequence scenario to hard condition the simulation. Further, we propose a multistage workflow, featuring the pre-processing, the hard conditioned simulation and finally the post-processing. The detailed facies-classification of the wells and the consequently developed 3D reservoir model allows for a better in-depth understanding of channel belt reservoirs of the RFDS concerning lateral distribution of sand-prone facies and sandstone-body connectivity.