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What happens during lab testing?

What’s happening during lab testing?

EPOS-eNLarge will develop new facilities to enable visualization of dynamic processes, active during laboratory rock testing. Why would that be useful? Let’s ask Amir Raoof, associate professor hydrogeology at UU and head of the Porous Media lab.

Q: Why is it so important to visualize these during tests?
A: Conventional microstructural analyses compare images of sample subjected to lab testing, to images taken from an untested, reference sample. People do that to see what (microstructural) changes occurred due to lab testing. This can be a very powerful method, but it doesn’t always reveal all processes that were active during the test. For instance: some processes, like movements between rock grains can be active while leaving little trace in a static image. In fact, it’s often difficult to prove it occurred at all, if you don’t literally see bits and pieces moving. When only studying before- and after-test images, it could then seem like nothing happened. While it did!  

Q: Why wasn’t that done before?
A: People already do imaging during lab testing, for instance using CT imaging. However, the resolution is often limited (difficult to see what you’re looking for). And some processes are too rapid to adequately capture using this technique, like transport of fluid phases and sub-micrometer particle transport. To effectively study these high-velocity events with particles, innovative approaches are essential for accurate observation and revealing the underlying mechanisms. EPOS-eNLarge includes several of these innovative, and quite exciting approaches for monitoring dynamic processes:

  • Microfluidics in porous media
  • Laser interferometry in analogue models of geological processes
  • Acoustic Tomography during High Pressure and Temperature deformation experiments
  • A nano-indenter system, for deformation testing in a microscope
  • An environmental, micro-CT system at Ghent University, for rapid, syn-testing 3D scans

The breakthroughs enabling these approaches stem from recent advancements in imaging and computational technologies, and were not as readily accessible in previous years. These techniques are state-of-the art. 

“Without imaging during testing, we can often only assume that what we can see in an image taken after testing, represents all that happened during testing.”

Q: What do you do at the Porous Media lab to visualize dynamic processes?
A: At the Porous Media Lab, we simulate rock to precisely resemble real samples, and use advanced, in-house microscopes to visualize dynamic processes like fluid flow, solute transport, biomass growth, and particle clogging. Our comprehensive facilities span from fabrication and performing experiments, to numerical simulations for accurate analysis. The integrated lab testing + modelling approach can be very useful for upscaling! 

Q: What can you do once you’ve done that?
A: Upon utilizing these facilities, we can investigate key processes vital to applications such as CO2 storage in the subsurface, geothermal energy production, and hydrogen storage. Our focus is at the pore scale on fluid phase transport, particle remobilization, clogging, and the transport and reactions of chemical species, as they dictate the efficiency of all these applications.

Without dynamic imaging, we can only assume that what we can see in a sample image taken after testing, represents all that happened in the sample during testing. With these new imaging techniques, we can directly see what happens to the sample at each stage during an experiment. And in doing so, have far more confidence in identifying the processes governing the behavior of subsurface materials. This is crucial for physics-based understanding of the impact of subsurface storage and energy production. “

Learn more about EPOS-eNLarge researchers and plans