Work Package B1: Pressure propagation and control
The storage of CO 2 in porous, saline formations naturally results in the displacement of ambient pore waters. In large, permeable formations this can be readily accomplished, but in smaller, or less permeable formations the pressure needed to displace the pore fluid may be significant. To improve our ability to predict the volume of CO 2 which can be safely stored, and to predict the displacement of pore fluids and the buildup of ambient pressure we are modelling the propagation of pressure throughout the reservoir. This signal, of enhanced pressure, drives small deformations which can be observed in minute ground motion detectable over large distances from satellite imagery. By constructing reduced models to explain this surface ground deformation in current storage sites we can understand something of the distribution of pressure over time within storage reservoirs.
Work Package B2: CO2 migration and storage
In planning to inject CO 2 underground it is important to be able to predict where and how quickly CO 2 will move, and where it will be trapped. These predictions are made difficult by a combination of the complexities of fluid dynamics and the unknown and heterogeneous nature of the subsurface rocks in which CO 2 will be stored. To improve our ability to design CO 2 storage projects and estimate the capacity of a formation for CO 2 storage, we are studying key problems at a range of size scales of importance to CO 2 storage. This includes questions such as: How does rock heterogeneity impact the flow pathways of injected CO 2 ? How quickly does CO 2 dissolve into water in the subsurface? What can we measure about rocks in the laboratory that would enable us to answer these questions at the larger scales associated with underground CO 2 plume movement?
Work Package B3: CO2 modelling software assessment
Numerical models for flow in the subsurface must tackle the inherent complexity of geological strata in which the CO 2 will be stored, much as weather forecasts must cope with the impact of very small-scale turbulent flows in making predictions over countries or regions. This need to parameterise geological complexity has lead to a range of models, from complex reservoir simulators commonly used in the oil and gas industry appropriate for smaller scale or shorter time frame injections, to reduced models which accurately capture the large, and long timescale migration of buoyant CO 2 . Through a process of comparing these models across length and time scales, and importantly by comparing their simulation results with the remote observations of CO 2 spreading in the field we can produce accurate and efficient methods of assessing the ultimate fate of CO 2 in the subsurface.
Work Package B4: Scoping/development of a proposed CO2GeoLab
This work package aims to examine the feasibility of developing a pilot-scale CO 2 injection test site in the UK. Many other countries have developed their own CO 2 injection test facilities (e.g. Germany, Spain, United States, Australia, Canada etc) and we believe that it would be beneficial for the UK to have its own as well. This would comprise a research facility to test typical UK storage reservoir rocks with experiments focussed on particular uncertainties in UK underground storage, and to develop a core of practical storage expertise in UK scientists. Ideally the research site would be situated in an area where CO 2 is already available from industrial sources and where the potential for future larger-scale offshore storage is present.