Geological and geomechanical factors impacting loss of near-well permeability during CO2 injection. (September 2018)

• Record Type: Journal Article
• Authors: Torsæter, Malin; Cerasi, Pierre
• Is Part Of: International journal of greenhouse gas control. Volume 76(2018)
• Page Start: 193
• Page End: 199
• Publication Date: 2018-09
• Subjects: CO2 storage -- Well integrity -- Injectivity -- Geomechanics -- Permeability -- Fines migration; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2018.07.006
• Languages: English
• ISSNs: 1750-5836

Abstract

Highlights: Review of factors that affect CO2 injectivity and how problems can be mitigated. Learnings from oil & gas on how geology and geomechanics impact injectivity. Knowledge gaps and outstanding issues in injectivity research. Abstract: To maximize safety and cost-efficiency of CO2 storage, it is necessary to understand how a high permeability in the near-well region can be maintained. All the injected CO2 needs to pass through this zone before entering the reservoir, and pore clogging/closing here can cause fracturing and channelling of the formation – and will require costly mitigation measures. Recent storage pilots have reported incidents of permeability loss during injection, and these have been ascribed to salt precipitation, bacterial activity, and pressure/temperature variations caused by starts and stops in the injection pattern. As we move to larger scale CO2 storage projects (gigatonnes/year), a higher number of wells and larger quantities of CO2 will be dealt with. This means that injectivity issues will become more frequent – and thus have a greater impact on Carbon Capture and Storage (CCS) project economics. Until now, salt precipitation has completely dominated the field of injectivity – and is by far the most studied loss mechanism. In the present publication, we show that there are other important injectivity loss mechanisms that should not be overlooked. These are fines migration, geomechanical factors (e.g. borehole deformation), geochemical factors (e.g. clay content) and rock heterogeneity. We summarize laboratory and field studies of these topics, and discuss their relevance for CO2 injectivity – particularly in unconsolidated sands. The paper reviews when such injectivity problems occur in the context of CO2 injection, and how they can be prevented and mitigated.