New Approaches of Coupled Simulation of Deep Geothermal Systems

Abstract

Determining flows, heat transfer and reactive transport processes in natural faulted and fractured geological systems receives increasing attention. Efforts are not only restricted to a better geological characterization of the complex geometry of the faulted and fractured rock reservoirs but also to describe the actual geometry and to simulate the dynamics of flow and transport processes in these natural systems. In this paper, a technical description of an improved method is presented, to represent non-planar structures of deviated wells (1D) and faults and fractures (2D) within a boundary conforming Delaunay unstructured mesh (3D). The main advantage of this approach is that these dipping structures can be integrated into a 3D volume representing the hosting porous matrix. Consequently, the interaction between the discrete flow paths through and across faults and fractures and within the rock matrix can be correctly simulated. The crucial factor that makes the approach applicable to real case geological systems is that all algorithms are parallel thus computing time increase approximately linearly with data volumes. This approach is presented in terms of a real case study of the deep geothermal reservoir of Groß Schönebeck in the North of Berlin, Germany. The model domain includes six major geological units, three major fault zones and a doublet system consisting of four induced hydraulic fractures. This domain was triangulated resulting in 6,191,564 tetrahedra and subsequently used for dynamic simulation.