Caitlin Augustin Structural Geology

1. Evaluation of the usefulness of hydraulic fracturing sites as an analogue for geologic carbon sequestration sites Caitlin Augustin Structural Geology

2. Hydraulic fracturing for natural gas retrieval and deep geologic injection of carbon dioxide share several characteristics (NETL, 2010) • This presentation seeks to examine the similarities between the two injection fields and to analyze hydraulic fracturing sites as a potential analogue for geologic behavior and environmental risk assessment for geologic carbon sequestration. Introduction

3. Background • Process • General Structural Geology Features • Overview in the United States • Example sites • Methodology and Hypothesis • Analysis • Mineralization • Deformation • contamination • Conclusion and further work Outline

4. Hydraulic fracturing Carbon sequestration • Procedure • Injection of fracturing fluid into the wellbore at a rate sufficient to increase the pressure down hole to a value in excess of the fracture gradient of the formation rock. • Depth • 8000 ft (2666 m) • Formations • Low permeability rocks • Typically shale • Procedure • Injection of supercritical carbon dioxide at a rate maintaining reservoir pressure • Depth • 2400 ft (8000 m) • Formations • High permeability reservoir capped with low permeability shale Process

5. Systematic and Nonsystematic Natural Fractures (Joints) • Description • alteration along joints indicating fluid movement. • Systematic joints are a group of parallel to sub-parallel joints evenly spaced  to one another • Nonsystematic joints are irregularly oriented joints with no obvious spatial relationship • Site locations • Occurs in the Marcellus shale Teapot dome CCS field • (Hancock, 1986) General structural geology of injection sites

6. Fissility • Description • the property of rocks to split along planes of weakness into thin sheets. • Caused by the preferred orientation of clay minerals with their planes orientated parallel to bedding due to compaction, deformation, or new mineral growth • Site locations • Shale caprocks • (Arthur, 2008) General structural geology of injection sites

7. Folds • Description • result of compressional stress acting on rocks that behave in a ductile manner • Site locations • Weyburn injection site, Marcellus Shale • (Daniels, 2006) General structural geology of injection sites

8. Hydraulic fracturing Carbon sequestration • Approximately 400 active sites in the United States • Approximately 20 active sites in the United States Active sites

9. Hydraulic Fracturing Marcellus Shale, Pennsylvania, United States Carbon Sequestration Carbonate Reservoir, Weyburn, Canada Evaluation Sites

10. Hydraulic fracturing Carbon sequestration • Cracks in the impermeable layer to release trapped natural gas • Surface fracturing • Subsidence • Stable sequestration • Surface Fracturing • Viscous fingering Potential outcomes

11. Given the geologic similarity between the two injection fields the reactions at natural gas hydraulic fracturing sites should be a good analogue for assessment and management of carbon sequestration sites. • We anticipate similar deformation and leakage events to occur between sites. Hypothesis

12. Comparison of injection sites based on the occurrence and treatment of • Mineralization • Subsurface deformation • Subsurface contamination • Surface deformation • Surface contamination Methodology

13. Mineralization is the reaction of a compound with existing minerals to form new minerals such as siderite and dawsonite Mineralization: description

14. Hydraulic fracturing Carbon sequestration • Mineralization of precious metals • Pyrite unconformities • (Phillips,1972) suggests it commonly occurs with natural fracturing, but (Mcafferty,1999) suggests it is rare in retrieval sites • Mineralization occurs in carbonate reservoirs on a geologic timescale (Benson,2001) • Reactions occur more quickly in mafic rock formations (Matter and Kelemen,2009) Mineralization

15. Elastic Properties: ductile/brittle • Forces: compression/tension • Geomechanical changes: heating/cooling • Increased tectonic stress field Subsurface deformation: description

16. Hydraulic fracturing Carbon sequestration • Compression around borehole • effects on the prevailing tectonic stress field • Subsurface fracturing • (Van Wees,2003) shows that this deformation occurs in over 90% of injection sites • Microfractures • compression around injection well • Sediment compression • vein formation • (Lu, 2001) One of these deformations occurs in over 50% of sites Subsurface deformation

17. Fluid migration and sediment mobilization that encroaches negatively on subsurface fluid or mineral reservoirs Subsurface contamination: description

18. Hydraulic fracturing Carbon sequestration • Groundwater contamination • (EPA, 2009) occurrence prompted change in law • Coal sterilization • (Wolf, 2000) intentional sterilization in unmineable coal beds • Less than 1% pollute groundwater Subsurface contamination

19. Reaction of subsurface deformation visible on the surface such as faulting, subsidenceand uplift Surface deformation: description

20. Hydraulic fracturing Carbon sequestration • Faulting and surface fracturing • Subsidence • (Van Wees, 2009) showed that this is directly linked to subsurface deformation and occurs at a similar pace • Faulting and surface fracturing • Uplift • (CSA, 2010) surface deformation occurs but requires monitoring standards Surface deformation

21. The distribution of fluid and gaseous contaminants through currents Surface contamination: description

22. Hydraulic fracturing Carbon sequestration • Surface water contamination • (Lustgarten,2009) documented 1500 cases of water contamination between 2003 and 2008 • Carbon dioxide plumes • (DOE, 2010) reports at least two of the 17 funded injection sites have surface gas leakages Surface contamination

23. The subsurface deformation, surface deformation, and surface contamination events occurring from hydraulic fracturing and carbon sequestration are the most similar and occur most often • Recorded subsurface deformation occurs at similar depths (approximately .5-1 mile below) • Rehabilitation and education of deformation and contamination can occur in similar ways Key observations

24. The use of hydraulic fracturing sites as an analogue provides industry scale injections for carbon sequestration scientists to study for deformation and rehabilitation characteristics • It shows key assumptions, such as groundwater contamination are dissimilar between the two injection sites • Tool for disaster management protocols Study utility

25. Both hydraulic fracturing and carbon sequestration are regulated by the EPA • Hydraulic fracturing ruled by 2009 FRAC Act • Carbon sequestration by the 2010 UIC Law • Hydraulic fracturing has stricter regulation regarding contamination and rehabilitation • No industry standards exist for carbon sequestration Policy Regulations

26. Site by site comparison • Public health study • Monitoring and verification comparison and development • Adapt computer models between injection sites Recommendations and further study

27. NETL 2010 • Hancock 1986 • Arthur 2008 • Daniels 2006 • Philips 1972 • McCafferty 1999 • Benson 2001 • Matter and Kelemen 2009 • Lu 2001 • Wolf 2000 • Lustgerten 2009 Sources