Estimates of CO2 leakage along abandoned wells constrained by new data

Tom J.W. Postma, Karl W. Bandilla, Michael A. Celia

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


The viability of carbon capture and geological storage (CCS) projects depends in part on the risk that injected CO2 or displaced pore fluid will leak out of the target formation into surrounding formations or to the surface. Abandoned oil and gas wells, of which millions exist both throughout the United States and globally, form a potential conduit for this leakage. Recently, specific field measurements have been made to quantify the range of effective permeabilities that can be expected in abandoned wells, enabling us to, for the first time, combine field-scale numerical simulations of CO2 sequestration in deep saline aquifers with real data on effective permeabilities of leaky wells. Using a previously developed semi-analytical reservoir simulator that can accommodate an arbitrary sequence of alternating aquifers and aquicludes, as well as an arbitrary number of leaky wells, we investigated how the amount of CO2 that leaks out of the target formation depends on the spatial density of nearby abandoned wells and their effective permeability. Furthermore, we assess the influence that variations in pressure and temperature found between geological targets have on this dependency. We find that the observed differences in leakage between geological targets are controlled almost exclusively by differences in density of CO2 at the local subsurface conditions, causing the CO2 plume to contact a different number of wells when injecting at the same constant mass rate. We quantitatively assess the results obtained from our numerical experiments by combining them with the permeability data that have recently become available, typical spatial densities of abandoned wells, and performance requirements put forward in the literature. Our results indicate that leakage of CO2 through abandoned wells is unlikely to be a major limitation in storage security of CCS projects.

Original languageEnglish (US)
Pages (from-to)164-179
Number of pages16
JournalInternational Journal of Greenhouse Gas Control
StatePublished - May 2019

All Science Journal Classification (ASJC) codes

  • Pollution
  • General Energy
  • Management, Monitoring, Policy and Law
  • Industrial and Manufacturing Engineering


  • Abandoned wells
  • Field data
  • Geological storage
  • Leakage
  • Risk analysis
  • Semi-analytical solutions


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