A CT-scanner study of foam dynamics in porous media

Abstract

We report an experimental study of N2-foam injection in a Bentheimer sandstone coupled with X-ray Computed Tomography (CT-scanner). The measurements of pressure drop and gas saturation at different flow rates and foam qualities allowed us to describe the foam dynamics under transient and steady-state flow conditions. The brine displacement by foam shows a transient piston-like displacement pattern taking place in two successive phases. Saturation profiles reveal permanent entrance effects related to the injection procedure, and transient downstream end effects related to the gradual foam build-up. Entrance effects are attenuated with a high foam quality and at low total flow rate. The rheological behavior of foam was studied in terms of apparent foam viscosity and foamed-gas mobility as a function of foam quality and gas interstitial velocity. In the low-quality regime, foam exhibits a shear-thinning behavior that can be modelled by a power function. Furthermore, for a fixed total velocity, the quasi-invariance of strong foam apparent viscosity values is shown to result from the slight increase of trapped gas saturation, within the commonly-admitted assumption of invariant foam texture in the low-quality regime. An increase in gas mobility was observed above a certain value of the foam quality. That transition between low-quality and high-quality regimes was related to a limiting capillary pressure of foam in the porous medium under consideration.

Porous Medium Typology Influence on the Scaling Laws of Confined Aquifer Characteristic Parameters

“…Although these configurations can be defined as homogeneous, as highlighted previously, an evident heterogeneity remains in the aquifer due to the different dimensions and shape of the grains, their arrangement within the porous medium and, consequently, the different interconnections of the voids, as well as to the variation of tortuosity. Especially in field investigations but also in laboratory models if there are doubts about the homogeneity of the porous medium and to better investigate some particular aspects, such as the interconnection of the pore voids, the carrying out of tracer tests and geophysical tests can be very useful [41][42][43]. The hydraulic conductivity values thus obtained are shown in Table 3, for each configuration and for all the values of the injection volume considered; Table 3 also reports the corresponding radius of influence values determined experimentally during the tests.…”

Characterization of foam flowing in a granular medium in the presence of oil by small angle neutron scattering

“…In 3D systems, the measurements are more complicated, since direct visualization is not possible. Some studies using computational tomography (CT scan) provided a good imaging of the foam generation in porous media, and a direct correlation between the pressure increase and the foam developping in the medium but the limited spatial resolution does not give access to the pore and lamellae scales 8,[21][22][23][24][25][26] .…”

Quantitative Characterization of Foam Transient Structure in Porous Media and Analysis of Its Flow Behavior Based on Fractal Theory

“…The experimental research studies were mainly carried out through the core displacement experiment using sandpacks or a plexiglass tube filled with glass beads or etched glass to represent the formation structure. − Then, the foam fluid was injected and changes of pressure and other parameters were measured; computed tomography measurement is an advanced method at present. − The foam flow mechanisms were obtained by analyzing the pressure characteristics, gas saturation, and gas–liquid distribution. It is worth mentioning that the change of foam size has started to gain attention in this kind of experiments.…”