Deformation of Unconsolidated Sediments and its Impact on CO2 Storage
To keep pace with tightening global emissions targets, increasing quantities of CO2 will need to be injected into storage aquifers in the coming decades.
An increase of CO2 injection rate from 1 to 100 Mt/y presents an enormous scale-up challenge. Although storage technology has been demonstrated for small-scale projects, building competence at a large scale of 100 Mt/y is needed. Rock deformation caused by fluid injection can result in many adverse effects, including fault reactivation, induced seismicity, and mobilization of unconsolidated sediments resulting in the formation of CO2 leakage pathways that can occasionally reach the surface and thus compromise the integrity of the caprock.
Removing or lowering the hurdles of uncertainty can accelerate the development of a CCS infrastructure in the North Sea, e.g. by avoiding investigations in critical areas and targeted site exploration focused on the acquisition of the data needed for safety assessment.
The main objective of the study is exploring flow and deformation processes of unconsolidated sediments during fluid injection and their relevance for monitoring, safety, and site selection for large scale CO2 storage. The proposed project strives to provide quantitative answers to the following principal questions:
- Are structures of sediment deformation permeable pathways that could facilitate fluid ascent in the overburden of storage sites?
- Can the injection of CO2 trigger the fluidization and mobilization of unconsolidated sediments, when critical thresholds are passed?
- What is the influence of mobilization structures on the long-term safety of injected CO2?
Combined experimental and numerical approaches will be used to achieve a better understanding of the dynamic processes of unconsolidated sediment mobilization. Experimental work will aim at reproducing flow and deformation processes in rock analogue materials during CO2 injection.
The experiments will be carried out in the transparent Helen-Shaw cell. Comparison of numerical and experimental results with natural reference cases will be used to validate the research approaches. It is intended that both experimental and numerical approaches will be used for predictive modelling of CO2 injection scenarios of relevant storage environments.