Numerical modeling of natural hydrogen migration from deep sources within fault zones

Abstract

On continents, H 2 -rich gas seepages have been observed along major fault zones ([1], 2], [3], [4]). Until now, there is no global consensus on the possible origins of this continental dihydrogen and several production mechanisms have been proposed, presuming that some of them may operate simultaneously (e.g. serpentinization or radiolysis of water). Moreover, the wide range of pressure, temperature, and chemical conditions H 2 encounters during its migration along the faults can modify its ultimate concentration dramatically.Considering recently revised equation of states of H 2 (e.g. density, viscosity, solubility), we have set up a 3D reactive transport model based on MRST open source software [5], to assess the conditions for which H 2 can "survive" long migration distances along a fault. The Coupled Thermo-Hydro-Mechanical-Chemical approach with Permeability Evolution provides insights about how H 2 can eventually reach the surface, accumulate in deep reservoirs, or be consumed along the way by abiotic or microbially-mediated redox reactions.