CO2 migration and pressure evolution in deep saline aquifers

Abstract

In 2005, the IPPC Special report on carbon dioxide capture and storage (SRCCS) summarized the state of knowledge about CCS as an emerging technology for reducing CO2 emissions to the atmosphere. At the time of writing, the emphasis of the SRCCS was on understanding the fate of injected CO2 whereas less attention was paid to effects of pressure buildup associated with CO2 injection. Since then, the CCS community has significantly improved the knowledge base and addressed many of the technical gaps mentioned in 2005. A large body of research has been devoted to identify and verify the main processes that control CO2 migration, trapping, and containment in deep saline aquifers. Much work has also been conducted to better understand the magnitude and implications of reservoir pressure buildup in response to large CO2 storage projects. The aim of this paper is to provide a summary and overview of the most relevant recent (since publication of the IPCC SRCCS) literature and findings in the areas of CO2 migration and pressure evolution. The paper first summarizes recent findings related to CO2 plume migration and trapping, based on analytical and numerical modeling studies as well as several field injection tests conducted to examine the fate of injected CO2 in various subsurface settings. The paper then discusses pressure effects as a function of space and time, including the effects of confinement (boundary conditions), highlights possible unwanted pressure impacts such as pressure-driven leakage and geomechanical damage, analyzes potential capacity constraints, reviews current concepts for pressure management, and closes with a discussion about use of pressure signals for advanced monitoring.