Objective and hypothesis
The aim of the project is to de-risk CO2 storage in chalk reservoirs by quantifying the magnitude of dissolution/ precipitation and predicting its sector-scale location in carbonate reservoirs during and after CO2 injection. The project will establish a sector model which can be applied to chalk fields to predict dissolution/precipitation.

Approach
The project follows a new approach based on flooding and reactor experiments designed specifically to quantify dissolution/precipitation as a result of variable pressure, temperature, lithology, and brine chemistry. The project will determine effects on porosity, permeability and injectivity, coupled to a petrographic characterisation of lithological features induced by dissolution/precipitation. These results will be geochemically modelled on the core-scale to determine the conditions leading to dissolution/precipitation, allowing us to establish a sector-scale model identifying sites of potential dissolution/precipitation at varying injection conditions. Experiments will be based on reservoir core samples and analogues if necessary. Modelling will be performed on a conceptual model based on a well-described field in the North Sea.

Expected impact/output
The most important outcome of the project is to provide the fundamental knowledge necessary to decide to further progress the TRL of CO2 storage in depleted chalk reservoirs. The project increases the potential for CO2 injection as an integral part of abandonment strategies for operators in the North Sea and increases the potential for CO2 import as a business model. In addition, the know-how created can be exported to other countries with hydrocarbon fields in chalk or other tight carbonates.