Researchers from the University of Manchester, including Peter Castellucci, Radha Boya, Lin Ma, Igor L. Chernyavsky, and Oliver E. Jensen, have delved into the dynamics of underground gas storage, a crucial technology for climate change mitigation and renewable energy integration. Their work, published in the Journal of Fluid Mechanics, focuses on the behavior of hydrogen gas when injected into confined porous layers, such as aquifers, and the role of gas compressibility in these processes.
Underground gas storage, particularly hydrogen storage, is vital for balancing the intermittency of renewable energy sources. However, hydrogen’s low viscosity compared to the resident brine in aquifers can lead to rapid spreading of a hydrogen bubble beneath the caprock, complicating its recovery. In long aquifers, significant pressure variations can occur, potentially causing substantial density changes in the injected gas.
The researchers used long-wave theory to derive coupled nonlinear evolution equations for gas pressure and the gas/liquid interface height. Their focus was on long domains, weak gas compressibility, and low gas/liquid viscosity ratios. Through simulations and comprehensive asymptotic analysis, they examined how gas compressibility influences spreading dynamics.
Unlike previous understanding where gas spreading rates were thought to be dictated solely by source strength and viscosity ratio, this study reveals that compression of the main gas bubble can generate dynamic pressure changes. These changes are coupled to those in the thin gas layer spreading over the liquid, with compressive effects having a sustained influence along the layer. This coupling can reduce spreading rates and gas pressures, highlighting the significant role of compressibility in the evolution of the gas layer.
The researchers characterized this behavior through a set of low-order models that reveal dominant scalings. Their findings provide a deeper understanding of the dynamics involved in underground hydrogen storage, which could inform better strategies for efficient and effective gas recovery in the energy sector. This research was published in the Journal of Fluid Mechanics.
This article is based on research available at arXiv.