Pore‐Scale Modeling of Drainage Displacement Patterns in Association With Geological Sequestration of CO₂

Abstract

We investigate the immiscible displacement (drainage) of a wetting fluid in a porous medium by a nonwetting fluid using multi-graphics processing unit (GPU) lattice Boltzmann simulations with the aim of better understanding the pore-scale processes involved in the geological sequestration of CO 2. Correctly resolving the dynamics involved in multiphase flow in permeable media is of paramount importance for any numerical scheme. Generally, the average fluid flow is assumed to be at low Reynolds numbers Re av. Hence, by neglecting inertial effects, this immiscible displacement should be characterized by just two dimensionless numbers, namely, the capillary number Ca av and the viscosity ratio, which quantify the ratio of the relevant forces, that is, the viscous and capillary forces. Our investigation reveals that inertial effects cannot be neglected in the range of typical capillary numbers associated with multiphase flow in permeable media. Even as the average Ca av and Re av decrease away from the injection point, inertial effects remain important over a transient amount of time during abrupt Haines jumps, when the nonwetting phase passes from a narrow restriction to a wider pore space. The local Re l at the jump sites is orders of magnitude higher than the average Re av , with the local dynamics being decoupled from the externally imposed flow rate. Therefore, a full Navier-Stokes solver should be used for investigating pore-scale displacement processes. Using the Ohnesorge number to restrict the parameter selection process is essential, as this dimensionless number links Ca av and Re av and reflects the thermophysical properties of a given system under investigation.

The Impact of Wettability on Dynamic Fluid Connectivity and Flow Transport Kinetics in Porous Media

“…Zacharoudiou et al. ( 2020 ) also reported that the presence of the surrounding wetting phase films causes snap‐off and disconnection of the invading non‐wetting phase in the narrow‐constricted pore throats.…”

“…As a result, thin films of the decane phase coated the grain surfaces and occupied crevices of the porous medium (see yellow circles in Figure 2c), while the non-wetting water phase propagated within the central regions of the narrow throats. Zacharoudiou et al (2020) also reported that the presence of the surrounding wetting phase films causes snap-off and disconnection of the invading non-wetting phase in the narrow-constricted pore throats.…”

Drainage Instabilities in Granular Materials: A New Biaxial Apparatus for Fluid Fingering and Solid Remodeling Detection

“…These pore-scale instability events are clearly driven by capillary forces and therefore happen only when capillary forces exceed the viscous force. This means, referring to the Lenormand phase diagram [9], that Haines jumps mostly occur within the capillary fingering domain [14,15]. On the other hand, the regime of viscous fingering, with viscous forces higher than capillary forces, typically implies, at the microscopic scale, a piston-type invasion, driven by high values of the NWP flow and, consequently, of the pressure gradient, this last being responsible for the absence of the stick-slip behavior previously described.…”

Dynamic CT Reconstruction With Improved Temporal Resolution for Scanning of Fluid Flow in Porous Media

“…This takes place on the millisecond time scale, achieving flow rates much higher than the injection rate, while the time between consecutive Haines jumps per unit volume is on the order of seconds to tens of seconds (Armstrong et al., 2014; S. Berg et al., 2013). The high flow rates are supplied by local fluid redistribution (S. Berg et al., 2013; Moura et al., 2020), which induces poorly understood non‐local effects (C. F. Berg et al., 2020; Zacharoudiou et al., 2020).…”