Researchers Alessandro Lenci, Yves Méheust, Marco Dentz, and Vittorio Di Federico from the Institute of Environmental Assessment and Water Research (IDAEA) in Barcelona have published a study in the journal “Advances in Water Resources” that sheds light on the complex behavior of fluid flow in fractured rocks, which is crucial for understanding and optimizing carbon storage and geothermal energy production.
The team focused on the hydrodynamic transport in synthetic fractures, examining how variations in fracture aperture and correlation length affect fluid flow. They found that the flow heterogeneity persists up to the correlation length, and the ensemble-averaged velocity probability density functions (PDFs) are strongly influenced by the relative closure of the fractures. The low-velocity power-law scaling, in particular, is significantly affected by this parameter.
To model the transport processes, the researchers employed a time-domain random walk (TDRW) approach. This method allowed them to calculate plume moments and outlet breakthrough curves (BTCs). They observed that the mean longitudinal position of the plume grows linearly over time, while the variance initially shows ballistic scaling and later transitions to a regime controlled by the low-velocity power law. The exponent of this power law, denoted by alpha, depends on the relative closure of the fractures. The properties of the BTCs, including peak broadening and tail scaling, are also governed by this exponent.
Furthermore, the researchers developed a one-dimensional continuous-time random walk (CTRW) model that incorporates the velocity PDF, flow tortuosity, and correlation length. This model closely matched the results obtained from the TDRW approach and enabled analytical predictions of asymptotic transport scalings. The study provides valuable insights into the complex behavior of fluid flow in fractured rocks, which can inform the development of more efficient and effective strategies for carbon storage and geothermal energy production.
The practical applications of this research for the energy sector include improved understanding and prediction of fluid flow in fractured geological formations, which can enhance the design and management of carbon storage sites and geothermal energy systems. By accurately characterizing the transport processes, engineers can optimize the performance and safety of these energy technologies, contributing to a more sustainable and resilient energy future.
This article is based on research available at arXiv.