The impact of drainage displacement patterns and Haines jumps on CO2 storage efficiency

Abstract

Injection of CO2 deep underground into porous rocks, such as saline aquifers, appears to be a promising tool for reducing CO2 emissions and the consequent climate change. During this process CO2 displaces brine from individual pores and the sequence in which this happens determines the efficiency with which the rock is filled with CO2 at the large scale. At the pore scale, displacements are controlled by the balance of capillary, viscous and inertial forces. We simulate this process by a numerical technique, multi-GPU Lattice Boltzmann, using X-ray images of the rock pores. The simulations show the three types of fluid displacement patterns, at the larger scale, that have been previously observed in both experiments and simulations: viscous fingering, capillary fingering and stable displacement. Here we examine the impact of the patterns on storage efficiency and then focus on slow flows, where displacements at the pore scale typically happen by sudden jumps in the position of the interface between brine and CO2, Haines jumps. During these jumps, the fluid in surrounding pores can rearrange in a way that prevent later displacements in nearby pores, potentially reducing the efficiency with which the CO2 fills the total available volume in the rock.

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

“…Moreover, distal snap-off can potentially have a negative impact on the displacement efficiency, which is an extremely significant feature for CO 2 storage and hydrocarbon recovery, as it blocks the access to regions of the pore space that were accessible to the nonwetting phase prior the Haines jump event (Zacharoudiou et al, 2018). The average magnitude of the velocity for the wetting/nonwetting phase (dashed/solid red lines) and the inlet/outlet pressure difference for simulations with logM = 0, Oh = 1.3 × 10 −2 and varying Ca av : (a) Ca av = 3.1 × 10 −4 (u (a) in = 10 −4 ), (b) Ca av = 3.8 × 10 −5 (u (b) in = 10 −5 ), (c) Ca av = 1.0 × 10 −5 (u (c) in = 2 × 10 −6 ), and (d) Ca av = 1.0 × 10 −6 (u (d) in = 2 × 10 −7 ).…”

“…In a drainage situation, inertial effects can be also important over a transient amount of time, during Haines jump events (Armstrong & Berg, 2013; Armstrong et al, 2015; Berg et al, 2013; Zacharoudiou et al, 2018). During these sharp interfacial jumps, capillary forces accelerate the fluid interface, as it passes from a narrow restriction to a wider pore body, while initially inertial and viscous forces oppose the motion.…”

“…Another important feature of these abrupt events is the extensive fluid rearrangement taking place in the region of the jump, which contributes significantly to the draining of the pore body (Berg et al, 2013; Zacharoudiou et al, 2018). Experimentally, it has been observed that the draining of pore bodies occurs at time scales smaller than the time scales expected considering the externally imposed injection flow rate, indicating that cooperative filling dynamics takes place (Berg et al, 2013).…”

Local instabilities during capillary-dominated immiscible displacement in porous media

“…In this way, large amounts of greenhouse gases in atmosphere can be sequestrated in deep geological formations (Bandara et al, 2011). However, during oil production, the occurrence of snap-off events should be avoided to maximize The region occupied by the non-wetting phase that remains unchanged during the event is shown in yellow, while the draining pore and locations of interfacial recession are shown in light blue and red respectively (Zacharoudiou et al, 2018). Fig.…”

“…Drainage pore filling events previously observed in 2D experiments, such as Haines jump, snap-off, ganglion dynamics, cooperative pore filling and droplet fragmentation, can now be easily analyzed in a 3D system via such numerical simulation techniques. For instance, the fluid redistribution associated with Haines jumps and its effects on the displacement process in capillary fingering regimes are investigated by using multi-GPU free energy lattice Boltzmann simulations (Zacharoudiou et al, 2018). Their work demonstrated three main typical features associated with the Haines jumps: i) local (single pore) sharp increase in the non-wetting phase velocity, ii) localized sharp pressure drops and iii) extensive fluid redistribution.…”