For the year of 2019, an in-depth investigation was carried out into microstructural filter cake analysis. As planned comprehensive research involving of laboratory, modelling and simulation approaches were applied to characterize the filter cakes precisely. This was done for the case of hydrophobic and hydrophilic particles, forming hydrophobic and hydrophilic filter cakes.
As applying the commercial software approach for micro-CT analysis for filter cakes, we were limited due to the predefined functionality. To implement a plug and play analysis was not satisfying us to trust the output data fully. For this reason, we validate the filter cake characteristics based on four methods. One method is the laboratory approach in which filtrations were carried out in a standard VDI nutsch filter to measure pore size distribution, porosity and capillary pressure curves. In parallel CT scans of the same filter cakes were done to study cake characteristics based on the 3D reconstructed volumes by modelling and simulation. This is the imaging analysis approach, which itself is divided into three approaches.
The first image-based approach uses commercially available software only. In our case the software VGSTUDIO MAX 3.3 (subsequently called VGSTUDIO) was used. This method is very fast but the results deviate significantly from the laboratory data. The second image- based approach uses customized algorithms applied on the raw images. This approach is called customized code within this report. Using customized code showed good agreement with laboratory data. Nevertheless, this approach is time-consuming and requires advanced knowledge in image analysis and programming. The third method is to generate a pore network of the filter cake using laboratory data such as pore size distributions. Based on the generated pore network, simulations can be run to make prediction on e.g. desaturation of the filter cake (pore network modelling). For pore network modelling the open-source tool open PNM was used. The methodology and validation of each method is discussed in the report.