Naturally Fractured Reservoirs (NFR) have typically very complex geometries from the pore scale to the field scale – discontinuities can be found at
each scale. This makes NFRs hard to accurately be modelled for flow simulations. Fractures are especially difficult to incorporate in the simulations.
The topology of a single fracture is usually simplified to a plane or disk,
and apertures are usually averaged to be implemented in the simulation
models. The fracture aperture distribution of a single fracture is already very
heterogeneous though. Contact areas in fractures can detain flow, whereas
connected fracture regions with larger apertures can result in preferred flow
paths and lead to early breakthrough.
To help understanding how well current Discrete Fracture and Matrix
(DFM) models are suitable to retain fracture influences on flow in carbonates, this research project combines the simulation of miscible single-phase
flow through fractures in carbonates with precise fracture measurements
(comprising fracture aperture distributions and 3D topologies) and the
visualization of real single and two-phase flow experiments in fractured
carbonate cores. The simulation approach employs a DFM model with a
hybrid finite element/ finite volume (FEFV) method. The fractured core
samples and the flow experiments are imaged with high-resolution X-ray
computer tomography (CT), or X-ray radiography respectively.
The main goals are to develop and optimize an image processing workflow
from the X-ray CT fracture measurement to an according mesh generation
as input for simulations, and to be able to compare simulations and flow
experiment studies qualitatively to analyse how well the DFM approach is
able to capture the true nature of fluid flow in fractures with real aperture
distributions. To obtain most relevant comparisons, we conduct numerical
simulations and flow experiments on the same fracture geometries, which
have been measured before non-destructivel