Monitoring and Modeling Caprock Integrity at the In Salah Carbon Dioxide Storage Site, Algeria

Abstract

The In Salah gas development project, initiated in 2004, involves the long-term storage of waste carbon dioxide associated with natural gas production at several central Algerian fields. Long-term plans were to store up to 17 million tons of carbon dioxide during the life of the program. The project at In Salah was a pioneering effort in several respects. One feature that distinguishes In Salah from several other industrial-scale CO2 sequestration projects, such as Sleipner, Weyburn, Decatur, and Aquastore, is the generally smaller storage volume in terms of overall reservoir thickness and lower average porosities of around 15%. The unique features of the In Salah storage site point to the importance of wellbore, geophysical, and geochemical monitoring to ensure that the integrity of the storage complex is maintained both during and after injection. In 2005 a Joint Industry Project was set up, in an effort to use various geophysical, geochemical, and production techniques to monitor the fate of the injected carbon dioxide. Here we describe the efforts made to monitoring the fate of the injected carbon dioxide, the state of the caprock, the estimated outcome of the storage effort, and some of the uncertainties that remain.