Effective CO₂ storage capacity in aquifers, gas fields, oil fields and coal fields

The carbon dioxide sequestration policy is often based on the volume estimation of (depleted) reservoirs or aquifers multiplied with a sweep efficiency factor. In this approach, the local processes involved in CO2 injection are not taken into account. One of the targets of European Potential for Geological Storage of Carbon Dioxide from Fossil Fuel Combustion (GESTCO) is to carry out a number of case studies in a broad spectrum of natural circumstances. So, experience could be acquired in the behavior of the local injection processes and in the resulting sequestrated CO2 volume. For this target, simulation studies of 12 real cases were carried out. The choice of these case studies was diverse in geographical as in operational respect. The cases originate from diverse geological situations—sandstone, chalk and dolomite reservoirs. Depth ranges from 1220 to 1970 m and reservoir pore fills are water, gas and oil. For each case, a numerical model study was carried out of the injection of CO2, using the well facilities available. In many cases, an existing reservoir input set was reused. In other cases, the spatial and geological characteristics, parameters, fluid presence, and properties had to be estimated. The results of these case studies in terms of injection capacity have a large range. These differences are the result of the many factors influencing the injection capacity for CO2, of which the injection pressure is the major factor.