Engineers have dispelled a 100-year-old scientific law used to describe how fluid flow through rocks. The discovery leads to a range of improvements including advances in Carbon Capture and Storage (CCS).
Miles below the surface of Earth different types of fluids are flowing through the microscopic spaces between the grains in rocks. Scientists from Imperial college, London, used the Diamond Light Source facility in the UK to make 3D videos that show how fluids move through rock.
Darcy’s Extended Law
Previously, scientists have used a formula for modelling how fluids move through rocks. It’s called Darcy’s Extended Law and the premise of it is that gases move through rock via their own separate, stable, complex, microscopic pathways. This approach used by engineers to model fluid flow for the last 100 years.
However, the Imperial scientists discovered that rather than flowing in a relatively stable pattern through rocks. The pathways that fluid flow through only in a short period of time, tens of seconds at most, before re-arranging and forming into different ones.
Researchers called this process as dynamic connectivity. The importance of the discovery of dynamic connectivity around the world now able to more accurately model how fluids flow through the rock.
Dr. Catriona Reynolds, lead author on the study, said, the model has proven a major scientific and engineering challenge. Our new observations in this study will force engineers to re-evaluate their modelling techniques, increasing their accuracy.
To create the 3D images, the researchers used the synchrotron particle at the Diamond Light Source. The synchrotron enables to take 3D images at speeds much faster than a conventional laboratory X-ray instrument around 45 seconds. This enabled them to see the dynamics, which had not observed previously.
However, an even higher time resolution would significantly enhance the observations. These fluid pathways re-arrange themselves quickly, so ideally the team would like the observations to capture every 100th of a second. This time resolution is only possible right now using optical light from microscopes combined with high-speed cameras. However, they are limited in their ability to observe the fluids moving through real rocks.
More information: [PNAS]