January 16, 2017

Impact of geochemical alteration on rock mechanical characteristics in geologic seals capping CO2 storage reservoirs

Impact of geochemical alteration on rock mechanical characteristics in geologic seals capping CO2 storage reservoirs 400 x 400 px

In the transition stage towards a dominant use of renewable clean energy, the emission of greenhouse gases is currently mitigated by capture and storage of carbon dioxide (CO2), one of the main greenhouse gases causing global warming.

Subsurface saline aquifers have been identified as important targets for geological storage of CO2. In these settings, containment of CO2 is mainly achieved by physical trapping, either by structural trapping of CO2 under a low permeability barrier, or by residual gas or capillary trapping.

Moreover, chemical trapping in reservoirs takes place by dissolution of CO2 in the subsurface brines, which can then trigger chemical reactions with the host rock on short term and potentially lead to mineral trapping on long term. In contrast, in coal and organic-rich shale, chemical trapping proceeds by adsorption onto organic matter.

The proposed multidisciplinary project concentrates on the integrity of containment of CO2 stored underneath geologic seals, i.e. low permeability barriers. In particular, the study aims to characterize how geochemical alteration of the seal upon interaction between CO2-rich brine and the sealing lithology impacts on the rock mechanical nature of the seal. Thereby, different types of sealing lithologies will be reacted with CO2-rich brines and the evolution of the chemical reaction with time will be evaluated. Petrophysical properties will be determined on both unreacted and reacted cores to derive relationships between stress, porosity and permeability.

Deformation experiments will be used to evaluate rock mechanical properties and the impact on those from geochemical alteration due to exposure to CO2-rich fluids. This project will apply a range of methods involving analytical chemical techniques, petrophysical methods and rock mechanical experiments. Fluid-rock chemical interaction will be characterized in both batch reactor and core-flood experiments.

Applicants should hold a minimum of a UK Honours Degree at 2:1 level or equivalent in subjects such as Environmental Science, Natural Sciences, Engineering, Geology or Chemistry.

For further details about this project, please contact Dr. Veerle Vandeginste