The setup is designed to measure permeability (gas or fluids, or supercritical fluids) of samples and in the same time to record ultrasound wave propagation within the sample. The measurements are performed at confining pressure up to 200 bar and temperature up to 100°C.
The heart of the setup is a hydrostatic cell, designed to accommodate cylindrical samples of 2.54 cm in diameter and up to 3 cm in length. The sample is placed between two stainless steel discs with interconnected circular grooves that are connected to two reservoirs: the upstream reservoir, which can be pressurized with the gas/fluid to be injected, and the downstream reservoir used to collect the gas, which leaves the sample (Figure 1). The transient step method is used to carry out the flow experiments. Sample holders contain piezoelectric transducers emitting/receiving ultrasonic waves (0.5 MHz frequency, compression and Share modes). Measuring the time of flight of the waves and knowing the length of the sample it is possible to calculate P and S wave velocities.
The rig presents at least three technical advantages, compared to standard parameters:
Recent modifications of the permeability rig enable permeability measurements and acoustic velocity measurements simultaneously. Variable pore pressures, confining pressures and temperatures are applied to the sample while ultrasonic waves travelling through the samples are recorded.
In the same laboratory together with the permeability rig, we have the possibility to measure a wide variety of physical parameters, such as density, porosity, failure under compression and tension conditions. All parameters can be measured under high confining pressure and temperature. Analytical facilities such optical and electron microscopy, XRD & XRF are easily accessible. The current users at ETH have obtained many scientific achievements based on the services offered by the infrastructures, including EU projects, National projects, and many scientific peer reviewed papers.