Speaker
Description
Two-phase flow in porous media governs the performance of subsurface energy and storage technologies, yet flow regimes beyond capillary-dominated Darcy behaviour remain insufficiently understood. In particular, intermittent flow arising under non-equilibrium injection conditions has been observed, but its development, stabilisation, and impact on injectivity are still poorly constrained. This study investigates intermittent flow in gas–brine systems using complementary experimental approaches spanning pore-scale imaging and pressure-based characterisation.
High-resolution synchrotron X-ray micro-computed tomography was used to image supercritical CO₂–brine core-flooding experiments in a carbonate rock at 8 MPa and 50 °C, enabling direct observation of pore-scale fluid configurations as a function of capillary number (Ca). In parallel, bench-scale core-flooding experiments were conducted for hydrogen–brine co-injection in Bentheimer sandstone, where pressure gradient measurements (∇P) were employed to identify flow regime transitions in the absence of imaging.
Across both systems, a consistent intermittency framework is identified. An intermittency development regime emerges at increasing Ca, characterised by growing intermittency clusters, enhanced phase mobilisation, and a non-linear ∇P–Ca relationship, ∇P ∝ Caᵃ (0 < a < 1). This regime is followed by a stable intermittent flow regime, in which the saturation of the intermittent phase remains approximately constant and the ∇P–Ca behaviour becomes linear to pseudo-linear, analogous to Darcian flow in capillary-dominated regimes.
Analysis of the hydrogen–brine core-flooding experiments shows that the sub-linear pressure-gradient scaling in the developing intermittent regime significantly reduces the pressure gradient required to achieve a given flow rate. Consequently, when maintaining a specified injection pressure, the developing intermittent flow regime enables flow rates approximately 3 to 16 times higher than those predicted by linear ∇P–Ca scaling. These findings demonstrate that intermittent flow is a robust and repeatable regime across different gas–brine systems and experimental methodologies, with important implications for maximising injectivity in subsurface storage operations under non-equilibrium flow conditions.
| Country | United Kingdom |
|---|---|
| Acceptance of the Terms & Conditions | Click here to agree |
