Stepwise versus direct maximum-rate brine injection

Investigate whether stepwise brine injection strategies produce greater hydrogen recovery than directly applying the maximum brine injection rate, while allowing sufficient equilibration time to account for extended imbibition dynamics.

Background

The experiments show that increasing the brine injection rate can remobilize hydrogen ganglia that remain apparently immobile during low-rate injection. Because hydrogen redistribution and recovery continue over extended timescales, short-duration tests may underestimate the ultimately recoverable hydrogen and overestimate permanent trapping.

The paper therefore identifies an unresolved operational question for subsurface hydrogen storage: whether a controlled, stepwise increase in brine injection rate is more effective for hydrogen recovery than immediately applying the maximum injection rate. Resolving this question would help determine how injection strategies should be designed and how long operators should wait before assessing residual hydrogen saturation.