Impact of Hydrogen on underground reservoir properties: Laboratory characterisation @ reservoir conditions

Why are we doing this?

Cost-effective, large-scale hydrogen storage will be a game-changer to the emerging hydrogen industry, supporting a range of domestic and export applications across sectors. Being able to cheaply store hydrogen at scale opens up so called ‘seasonal scale’ applications, supporting high penetration of renewables into the grid and a range of industrial decarbonisation applications.

To lower initial capital costs/investments, and potentially reduce operating costs, two geological storage and management options are effectively considered in Australia: (i) in the short- to medium-term: blending up to 10-15% Hydrogen in existing seasonal subsurface natural gas reservoirs; and (ii) in the medium- to long-term: high purity Hydrogen storage in aquifers and depleted gas (or possibly oil) reservoirs. Despite the additional costs of post-storage Hydrogen processing to achieve industry-ready purity, the former option is seen as financially viable and could be implemented soon while global production of Hydrogen is still relatively low (e.g., Woodside or AGIG in Australia, Taranaki Hydrogen venture in New Zealand).

Hydrogen mobility through porous reservoir rocks and the impact of geochemical interactions with the rock frame in presence of formation brine are currently poorly understood, with extremely limited hard data available in the literature. Hydrogen is expected to progressively diffuse into water (2 to 5% in the long-term), while strongly reacting with iron-bearing minerals (clays, iron oxides/sulphides) and organic matter. To what extent such reactions will affect pore structure and mineral composition remains to be assessed, and the impact on rock properties (transport, storage, mechanical, seismic) needs evaluating at pressure conditions relevant for the target reservoir depths.

What are we doing?

The aim is to quantify the impact of Hydrogen on the petrophysical, geomechanical, geophysical and geochemical properties of a set of reservoir rocks (actual and analogue reservoirs). The parameters measured in the laboratory serve as input for predicting the future behaviour of an operating Hydrogen reservoir (cyclic injection and withdrawal), and are therefore pivotal for any subsurface storage project, i.e., for assessment of engineering and financial viability. They also help optimise field operational parameters (e.g., injection/withdrawal rates), and enhance reservoir monitorability through a better interpretation of field seismic and well-log data  (see Figure 1). In practice, we will look specifically at:

• Impact of static storage – Characterisation of rock samples before and after Hydrogen-ageing (exposure) at realistic reservoir PT conditions, including the effects of formation brine; and,
• Impact of dynamic injection – Estimation of relative permeability, and real-time NMR monitoring of gas mobility during injection into a brine-saturated sample.

 

Figure 1. From Hydrogen injection-withdrawal operations in the field to laboratory characterisation and testing of reservoir rocks in the laboratory. The aim is to de-risk Hydrogen Underground Storage and enhance monitorability during the project life-cycle.

What next?

The outcomes of this project will feed into the “Hydrogen underground storage in Australia” project in which a multi-phase flow simulation module for the MOOSE platform will be developed and used to model how the efficiency of a particular hydrogen storage site in Australia depends on its specific geological attributes and to explorethe  key sensitivities and uncertainties potentially impacting the operational development of the storage project at scale.

We hope that the outcomes of this research project will contribute to demonstrate CSIRO’s leadership in developing Australia’s future Hydrogen economy, reduce our GHG footprint, and help mitigate climate change.

 

For more information, contact Dr Joel Sarout