Sustainable CO2 storage: Assessing permeability and stability dynamics through experiments and simulations

In this exciting project, you will use novel flow through experiments, chemical analyses and numerical modelling to constrain the evolution of permeability and stability of heterogeneous sediments in response to CO2 injection. Results from your research will have direct implications for predicting and mitigating potential problems when CO2 is injected in deep reservoir rocks. Consequently, generated knowledge will support sustainable carbon capture and therefore will be of high socio-economic significance.


This project aims to shed light on how the permeability and stability of heterogeneous sandstone changes through time if used for CO2 storage (CCS). This project is unique as it aims to capitalize on the knowledge base and experimental capabilities that are available in both geoscience and mechanical engineering/materials research. In this innovative project, you will use cutting-edge analytical and experimental techniques to develop an in-depth, quantitative understanding of permeability dynamics in sedimentary formations that were former hydrocarbon reservoirs. The quantitative experimental and analytical results will be used to inform numerical simulations allowing prediction of the timescale and dynamics of permeability evolution of sandstone after CO2 injection. Outcomes promise to be of high impact in both fundamental and applied science. It will assess the injectivity impairment and potential effects on mechanical properties of the injected reservoir rock and hence storage stability.


At a time when reaching Net Zero is imperative, assessment of the sustainability and safety of CO2 storage in depleted oil and gas reservoir rocks is crucial. Currently, there are major gaps in our ability to assess the long-term sustainability of CO2 storage in impure sandstone. In particular, it remains unclear as to the rate and extent of permeability changes over the lifetime of plant operation. Permeability changes continuously during fluid and rock interactions, closing pore space and fractures through scaling, opening through dissolution and renewed fracturing. Important questions relate to the rate of mineral growth (i.e., scaling), the effects of cold water injection on permeability pathways, and the dynamics of dissolution (i.e., corrosion versus mineral growth at different locations and temperatures within the CO2 injection – storage system).

In particular, processes and parameters that we need to understand include:

  • chemistry of fluid – changing with reaction and temperature (T) /pressure (P) gradient
  • rates of mineral growth – parameters – T/P changes, surface properties, local chemistry
  • rates of dissolution of scales and/or specific phases (i.e. matrix acidization)
  • dynamic interplay between the three components mentioned above
  • effect of permeability changes on the physical stability of the host

Previous research has shown that knowledge of the kinetics of dissolution and precipitation known from quartz laboratory experiments cannot directly be transferred to sandstone with impurities of former oil/gas reservoirs. This is due to the specific nature of the impure sandstone in terms of grain size and shape, and reactivity of minor phases, as well as the impact of organic coatings that change reactive properties.

Reactions induced by injected CO2 will not only change the transport and storage capacity of the host rock in question, but may also cause changes to the substrate induced by injection of supercritical CO2, which will likely change the mechanical properties of the storage host. Potential weakening may impact the stability of the reservoir and its seals, which need to be taken into account when designing the CO2 storage site operation and ensure its safe operation over long time scales (Silva et al. 2019). Furthermore, recent work on has shown that impurities within the CO2 to be transported and sequested may significantly influence dissolution and precipitation rates (Pessu et al. 2020).

Aims and Objectives

This project aims to achieve a new level of understanding and quantification of the underlying principles governing permeability and internal integrity changes through time in reservoir sandstone as a consequence of CO2 injection. Two main areas will­ be addressed:

  • Processes and Rates: What physiochemical processes occur at different conditions? How do these physical and chemical processes interact with each other? What are their rates?
  • Effect: How do these processes effect the long term permeability of a natural rock, as well as its rheology such as resistance to fracturing?


Project plan and methods

In this project, the student will work with leading scientists in their fields at Leeds (Piazolo, Hodgson, Barker, Pessu & Fisher). The team of investigators span across material science and geoscience forming the foundation for cross-disciplinary investigations of the scaling (i.e. mineral growth) and corrosion (dissolution) behaviour of natural resources namely impure sandstone. Within this novel project, the student will utilize and modify cutting-edge equipment, unique analytical tools and numerical code to answer the questions posed above.

This project will combine three different aspects of Earth Materials research:

  1. Experiments using novel experimental designs such as autoclaves with rapid quenching (School of Earth and Environment), flow through experiments with chemical analysis at elevated temperatures and pressures (Mechanical engineering, School of Earth and Environment) (e.g. Matamoroz Veloza et al. 2020). We plan to conduct experiments where the fluid is not only supersaturated in CO2 but also spiked with Oxygen 18 allowing for post-experimental analysis identifying replacement and new growth and importantly the sequence of reactions (Spruzeniece et al. 2017). Samples to be ”flushed” with CO2 will be selected in accordance to the variance in composition expected in deep sedimentary reservoir rocks (Hansen et al. 2021).
  2. Analysis of experimental samples before and after experiments.
  3. Chemical and microstructural analysis using high end analysis: Analysis will be done with an unique Focussed Ion Beam Scanning Electron Microscope with quantitative crystallographic orientation analysis (e.g. Svahnberg & Piazolo, 2013) as well as elemental and isotopic analysis using a Time-of-Flight mass spectrometer – the particular configuration is optimized for samples produced in this project. This will allow for unprecedented analysis of the three dimensional chemical and crystallographic analysis of experimental samples (Xu et al. 2021). Other equipment needed for full sample and fluid characterization including: CT scans, Cathodolumisence analysis, microRaman, Electron Microscopy and ICPMS for fluid chemistry.
  4. Permeability tests (e.g. Fisher et al. 2017): monitor change in permeability of experimental specimen to test seal-corrosion and long term storage potential
  5. Mechanical testing: testing of specimen that have been subject to CO2 injection to assess possible changes in stability
  6. Numerical modelling to predict the permeability dynamics when injecting CO2 in a deep reservoir: The first two research areas will provide the urgently needed input parameters and knowledge of feedback mechanisms essential for reliable reactive transport models (e.g. Koehn et al. 2021).


This project is highly innovative as it brings together several fields of research. It will advance our knowledge and understanding of the physicochemical processes occurring in sedimentary reservoirs injected with CO2. Research results will markedly advancing our knowledge and understanding of gas flow and permeability dynamics in sedimentary sequences. This knowledge is urgently needed to increase our ability to assess the safety and long term sustainability of CO2 sequestration in sedimentary rocks.

Student profile

The project would suit a numerate student with a background in earth sciences, geology, or geophysics as well as mechanical engineering and chemical engineering. The student should have a strong interest in petrological challenges, a desire to undertake laboratory, and a strong background in a quantitative science. Willingness and excitement for taking up the challenge to work at the boundary of structural geology, geochemistry, geomechanics and microstructural analysis utilizing a combination of techniques (in-depth microstructural analysis, experiments and numerical modelling) is a prerequisite.

The student will be provided with training in state-of-the-art geological, petrophysical and geomechanical methods. This may include microstructural and large geological data analyses, as well as structural field mapping and numerical modelling.


Fisher Q, Lorinczi P, Grattoni C, Rybalcenko K, Crook AJ, Allshorn S, Burns AD, Shafagh I, ‘Laboratory characterization of the porosity and permeability of gas shales using the crushed shale method: Insights from experiments and numerical modelling’, Marine and Petroleum Geology, 86 (2017), 95-110

Hansen LAS, Hodgson DM, Pontén A, Thrana C, Obradors Latre A. 2021. Mixed axial and transverse deep-water systems: The Cretaceous post-rift Lysing Formation, offshore Norway. Basin Research.

Koehn D, Piazolo S, Beaudoin NE, Kelka U, Spruženiece L, Putnis CV, Toussaint R. 2021. Relative rates of fluid advection, elemental diffusion and replacement govern reaction front patterns. Earth and Planetary Science Letters. 565

Matamoros Veloza A, Barker R, Vargas S, Neville A. 2020. Iron Calcium Carbonate Instability: Structural Modification of Siderite Corrosion Films. ACS Applied Materials and Interfaces. 12(43), pp. 49237-49244

Pessu F, Barker R, Neville A, ‘CO2 Corrosion of Carbon Steel: The Synergy of Chloride Ion Concentration and Temperature on Metal Penetration’, Corrosion, 76.11 (2020)

Svahnberg H, Piazolo S. 2013. Interaction of chemical and physical processes during deformation at fluid-present conditions: A case study from an anorthosite–leucogabbro deformed at amphibolite facies conditions. Contributions to Mineralogy and Petrology. 165(3), pp. 543-562

Silva SCD, de Souza EA, Pessu F, Hua Y, Barker R, Neville A, da Cunha Ponciano Gomes JA, ‘Cracking mechanism in API 5L X65 steel in a CO-₂saturated environment’, Engineering Failure Analysis, 99 (2019), 273-291

Spruzeniece L, Piazolo S, Daczko NR, Kilburn MR, Putnis A. 2017. Symplectite formation in the presence of a reactive fluid: insights from hydrothermal experiments. Journal of Metamorphic Geology. 35(3), pp. 281-299

Xu, X., Jiao, C., Li, K., Hao, M., Moore, K., Burnett, T., & Zhou, X. (2021). Application of high-spatial-resolution secondary ion mass spectrometry for nanoscale chemical mapping of lithium in an Al-Li alloy. arXiv preprint arXiv:2102.13148.