Speaker
Description
For reservoir simulations which are essential to explore and optimize the feasibility for underground storage of hydrogen in saline aquifers, besides porosity and permeability also relative permeability is a required input parameter. Traditional methods to determine relative permeability suffer from various technical complications, safety risks in the laboratory, and most importantly a limited accessible mobile saturation range. Also, dissolution effects associated with ripening make the determination of the residual gas saturation very challenging. The available data is scarce (particularly for imbibition) and trends of relative permeability for similar rock types and same or different gasses are inconsistent across the literature, which is mainly attributed to inconsistencies in measurement protocols.
Here we present a new method which is a hybrid approach involving micro-CT flow / displacement experiments to obtain time lapse sequences pore scale fluid distribution on which single-phase flow simulations are conducted to obtain hydrogen relative permeability. The key novelty is that during imbibition the non-wetting gas phase very quickly disconnects into smaller clusters and inlet-outlet connectivity is lost which prevents to conduct Stokes flow simulations over the whole sample length. Instead, smaller sub-regions with more prolonged connectivity are identified and demonstrated that they belong to the same population and follow same relative permeability trends, unless they become too small.
The method is demonstrated for imbibition hydrogen relative permeability which is compared with nitrogen and methane. A much wider mobile saturation range is accessible than in traditional approaches, and the uncertainty ranges can be accessed in a more robust manner. The key finding is that no significant differences are observed. A more detailed analysis of fluid topology using Minkowski functionals supports the view that all 3 data sets belong to the same population. This is an important finding because it implies that potentially relative permeability data for nitrogen and other gasses which is more readily available/accessible for relevant rock types.
| Country | The Netherlands |
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