Microstructural influence on reservoir integrity during variable hydromechanical pressure conditions


Porous reservoir rocks are explored as hydrocarbon reservoirs and are used as geothermal or intermediate storage. They include sedimentary and structural interfaces (bounding surfaces, disturbances, deformation bands) and structures (pressure release, deformation bands) caused by compaction within the reservoir during pressure reduction, which influence the reservoir integrity during the hydromechanical pressure change as permeability anisotropies. At the same time, a two-phase flow (injected fluid vs. formation water, oil vs. formation water) flows through the rocks, whereby the relative permeabilities depend on the wetting properties of the mineralogical microstructures. The objective of the interdisciplinary project is the modelling of the microstructural influence on two-phase flow and reservoir integrity. For this purpose, the vertical and horizontal permeabilities, which vary during the pressure changes of the fluid, are analysed and modelled experimentally and numerically in porous reservoirs. By means of coupled geomechanical and hydrodynamic models, the three-dimensional hydrodynamics of the multiphase flow, under consideration of the wetting properties, is calculated on the grain scale, and the representative volume for the reservoir scale is derived. The results are validated with the data available, and the obtained findings are quantified for reservoir integrity. Within the integrated interdisciplinary approach, grain-scale processes are applied in reservoir processes for the first time, and digital rock models are generated. The results find application in the more efficient use of deep reservoirs during exploration, and can also be applied as energy storage Systems.