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The novelty of this research lies in its original approach to controlling and suppressing viscous fingering in radial Hele–Shaw cells through time-dependent injection strategies tailored to the rheology of the fluid. Viscous fingering (also known as Saffman Taylor instability) is a hydrodynamic instability where a less viscous fluid displaces a more viscous one—leads to complex interfacial patterns that significantly reduce displacement efficiency in porous media applications. The research introduces a rheology-dependent injection flow rate, $Q(t)∼t^{-\frac{(2-n)}{(2+n)}}$, where $n$ is the power-law index of the non-Newtonian fluid, stabilizing the interface and suppressing fingering. For a Newtonian fluid, it translates to a simple relationship as $Q\sim t^{-1/3}$. The theoretical predictions are corroborated by experimental evidence showing that at specific conditions fingering can be entirely avoided even at constant injection—an unexpected and highly non-intuitive result.
This mechanism is quantified through a single dimensionless control parameter $(J)$, derived from a linear stability analysis that incorporates fluid rheology, interfacial tension, and system geometry. The connection of this parameter to the dominant instability mode is quadratic in nature (for higher modes) and also dependent on the power law rheology, $J = 3m^2 - 2m(1-n) - 1$. The Fourier Transform of the experimentally observed fingering pattern reveals the dominant mode of the instability with corroborates with the modelling outcome. The core innovation is the integration of a classical porous media flow with perturbation based methods to modal analysis, which is validated and used with real-time experimental control, establishing the prediction and dynamic suppression of interfacial instabilities. The math model plays a key role in identifying the critical thresholds of pattern growth, determining the dominant modes of instability, and guiding the design of temporally controlled displacement profiles and ensure long-term stabilization accounting for large displacements. This is especially relevant to multiphase flow engineering, where interface dynamics dictate performance outcomes.
The relevance to enhanced oil recovery (EOR) is profound: suppressing viscous fingering can significantly reduce bypassed oil and improve sweep efficiency in non-Newtonian fluid-assisted processes such as polymer flooding. In the domain of enhanced oil recovery (EOR), the findings provide a pathway to significantly improve recovery efficiency during polymer or surfactant flooding in porous reservoirs. By eliminating or controlling the onset of fingering in shear-thinning or thickening media, operators can enhance sweep uniformity, reduce chemical loss, and lower operational costs, directly translating to increased yield and economic benefit. In carbon capture and storage (CCS), particularly during the injection of liquefied CO₂ into geological formations, the ability to predict and suppress fingering in complex fluids mitigates the risk of caprock breach, improvement in storage capacity utilization, as well as CO2 based EOR.
| References | Singh, P., & Mondal, S. (2022). Control and suppression of viscous fingering displacing non-Newtonian fluid with time-dependent injection strategies. Physics of Fluids, 34(11). |
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| Country | India |
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