Predicting the fate of CO3 in geological reservoirs for modelling geological carbon storage

The main objective of this proposal is to determining the nature and kinetics of fluid-rock interactions between CO2-rich brines and rocks, in field settings as well as in laboratory experiments, in order to formulate and test models of the behaviour and fate of CO2 injected in geological strata. To do this we need to determine the processes which moderate the fluid-mineral reaction kinetics, particularly the nature of the processes which result in much more sluggish kinetics in field settings compared with the predictions from laboratory experiments. The ultimate objective is to creat a database and methodology that enables the results of this study to be used in risk assessments and performance modelling of geological carbon storage sites. To achieve these main objectives we will need to carry out the following: 1) Evaluate natural (CO2 natural gas reservoirs) and anthropogenic (CO2 injection EOR – Enhanced Oil Recovery) sites as analogues for geological CO2 storage. As necessary, determine the hydrology and the nature of the CO2-fluid to reservoir brine interactions in these sites and characterise the reservoir mineralogy, mineral characteristics that might control reaction rates (e.g. mineral surface areas and topologies) and fluid-mineral reactions by using a range of mineralogical, geochemical and isotopic analytical techniques. 2) Carry out laboratory experiments on reservoir materials, cap rocks and single minerals to investigate mineral-fluid reactions and reaction kinetics under controlled conditions and to test the reactions and reaction kinetics inferred from the field-scale studies. 3) Perform laboratory experiments to make detailed measurements of noble gas solubility in, and partitioning between, supercritical and liquid CO2 and brine and extend the data available for the natural analogues to include high precision noble-gas isotopic and concentration data. This data will inform modelling of the hydrology of the naturalCO2 reservoirs. 4) Utilise existing and develop improved thermodynamic modelling of both equilibrium and kinetically-rate limited mineral-fluid reactions to a) relate the results of field-based and laboratory experiments, b) enable more general application of the results from this and other studies to specific field sites and c) use the laboratory and field results to test the applicability of widely used thermodynamic models for mineral reaction rates.