Three-phase flow displacement dynamics and Haines jumps in a hydrophobic porous medium

Abstract

We use synchrotron X-ray micro-tomography to investigate the displacement dynamics during three-phase—oil, water and gas—flow in a hydrophobic porous medium. We observe a distinct gas invasion pattern, where gas progresses through the pore space in the form of disconnected clusters mediated by double and multiple displacement events. Gas advances in a process we name three-phase Haines jumps, during which gas re-arranges its configuration in the pore space, retracting from some regions to enable the rapid filling of multiple pores. The gas retraction leads to a permanent disconnection of gas ganglia, which do not reconnect as gas injection proceeds. We observe, in situ , the direct displacement of oil and water by gas as well as gas–oil–water double displacement. The use of local in situ measurements and an energy balance approach to determine fluid–fluid contact angles alongside the quantification of capillary pressures and pore occupancy indicate that the wettability order is oil–gas–water from most to least wetting. Furthermore, quantifying the evolution of Minkowski functionals implied well-connected oil and water, while the gas connectivity decreased as gas was broken up into discrete clusters during injection. This work can be used to design CO 2 storage, improved oil recovery and microfluidic devices.

Disconnected Gas Transport in Steady‐State Three‐Phase Flow

“…Instead, by combining pore‐scale imaging with steady‐state three‐phase flow, it has been discovered that gas, in fact, flows in disconnected clusters when injected simultaneously with oil and water in a water‐wet system. Disconnected unsteady‐state gas flow has been previously observed in a strongly oil‐wet three‐phase system, where gas was intermediate‐wet, using synchrotron X‐ray source (Alhosani, Scanziani, Lin, Selem, et al., 2020), but not over a range of fractional flows in steady‐state in a water‐wet system.…”

“…Oil and gas are immiscible at the selected experimental conditions. Water has a dynamic viscosity of μ w = 1.40 mPa·s with an interfacial tension of σ ow = 52.1 $$\text{mN}\cdot {\mathrm{m}}^{-1}$$ with oil, and σ gw = 63.7 $$\text{mN}\cdot {\mathrm{m}}^{-1}$$ with gas (Alhosani, Scanziani, Lin, Selem, et al., 2020; Jianhua, 1993; NIST, 2019).…”

Pore-Scale Imaging and Analysis of Wettability Order, Trapping and Displacement in Three-Phase Flow in Porous Media with Various Wettabilities

“…When gas is injected at immiscible conditions, it progresses through the pore space in disconnected clusters by gas-oil-water double and multiple displacements, combined with gas-water direct displacement. This was first observed by Alhosani et al (2020b), who used time-resolved synchrotron imaging to capture the connectivity of gas during gas injection in a strongly oil-wet reservoir rock at immiscible conditions. Figure 10 shows the connectivity of the gas phase during gas invasion at different time-steps-each colour represents a different gas cluster.…”

“…In a recent study (Alhosani et al 2021) the authors successfully altered the wettability of a reservoir rock towards strongly oil-wet conditions and visualized, using pore-scale imaging, the hypothesized wettability order. To further confirm the wetting order in the system, the authors quantified the in situ fluid-fluid contact angles (see Table 2), which demonstrated that oil is wetting to both water and gas, gas is non-wetting to oil and wetting to water, while water is non-wetting to both oil and gas (Alhosani et al 2021): this was the case for both the geometric and thermodynamic estimates of contact angles (Alhosani et al 2020b). Moreover, the pore occupancy statistics indicated that, on average, oil resides in the smallest pores and water the biggest, while gas occupies intermediate-sized pores (see Fig.…”

“…While this is not seen in twophase flow, the presence of double and multiple displacement mechanisms allows the gas to progress through the pore space while remaining discontinuous even under capillarycontrolled conditions. The disconnected gas ganglia reach a new position of capillary equilibrium in the pore space and can only be displaced through double/multiple displacement events (Alhosani et al 2020b).…”