World-class training for the modern energy industry

Seals, Containment and Risk by Richard Swarbrick

calendar March 18, 2024
Multiple tensile fractures (now filled with white cement) in Cretaceous source rock shales found in Arctic National Wildlife Refuge, North Alaska. Fractures filled with cements may be a more effective seal than the un-fractured shales

Seals are barriers to fluid flow – sometimes highly effective (such as when hydrocarbons have been trapped underground for long periods of geological time) and sometimes stopping migration for only short periods. Since evidence of leakage is commonplace, we know that many seals fail naturally allowing fluids (and gases) to escape elsewhere in the associated rock sequence or to the surface. This has been identified from both natural surface seeps and changes in remote data quality, such as on seismic records in the subsurface.  The new challenges of containing unwanted CO2 from the atmosphere and/or directly from industrial processes, as well as nuclear waste, create a new imperative to understand where seals are located in the surface and how effective they will be for long-term storage. Massive investment in long-term storage is planned globally to mitigate the long-term effects of CO2 as a greenhouse gas – seal analysis is a critical component in defining the most suitable underground repositories that meet the criteria set by regulatory authorities.


[above] Multiple tensile fractures in Marcellus Shale, a brittle source rock of Devonian age, found in the Appalachian Mountains, Upstate New York. Fractures represent a seal breach risk (photograph by Richard Swarbrick).

From a geological point of view, seals can be usefully divided into membrane seals (fluid escapes due to high buoyancy pressure) and hydraulic seals (fluid escapes along new pathways of fractures and faults) – the starting point for this is a new applied training course with GeoLogica, Seals, Containment and Risk for CCS and Hydrogen Storage (E570). What are the similarities and differences in these two groups of seals? What data are needed to assess the distribution and rock properties of seals? The course will illustrate the main processes of seal formation and the data required to diagnose those rocks that could be considered as seals. It will explore the worldwide distribution of seals, largely based on detailed characterization of rock-fluid systems from borehole data, which will also be developed as case studies and exercises to reinforce learning. Since leakage is commonplace, what are the risks of leakage (seal breach) from reservoirs injected with CO2 for long-term sequestration and storage, and/or hydrogen and compressed air repeatedly stored and released for electricity generation at peak times? How do the predicted leakage rates match regulatory requirements for storage?

The course tutor, Richard Swarbrick, has been conducting professional development courses globally for over 30 years, mainly concerning the description of rocks and fluids as they relate to sealing in the subsurface. Former participants on courses have praised his teaching style, making complex issues more easily understood and reinforced with relevant exercises for participants to work through independently or in groups.

For more information on the course and to sign up please click here.

[left] Oil seepage/leakage from sandstone along the coast of California, indicative of membrane seal failure (photograph by Richard Swarbrick).
[right] Multiple tensile fractures (now filled with white cement) in Cretaceous source rock shales found in Arctic National Wildlife Refuge, North Alaska. Fractures filled with cements may be a more effective seal than the un-fractured shales (photograph by Richard Swarbrick).