Centennial Lecture Program Quantifying Risks Associated with Geologic Sequestration Ian Duncan University of Texas at Austin
What is Risk?
Risk = Likelihood x Consequences
What are Stakeholders Saying about Risk of CO2 Sequestration?
Because of the unknown risk this could perhaps be catastrophic you d have to have some sort of overlying federal layer of protection otherwise [carbon capture and storage (CCS) operators] wouldn t do it they wouldn t go forward and capture carbon and put it deep underground d unless they had some assurance that t liability issues would not come back to bite them. Tim Peckinpaugh, lawyer
My sense is that you run a risk if the government assumes too much of this liability. If you insure someone against a risk, then they re going to be less likely to take actions to reduce that risk. Richard Newell, Professor of Energy and Environmental Economics at Duke University.
"[Failure to deal with risk and liability] could delay the construction ti of billions of dollars of carbon capture and storage infrastructure." Kip Codington, lawyer Alston & Bird
Liability [and risk?] concerns are overstated David Hawkins The Natural Resources Defense Council
WHAT ARE STAKEHOLDERS READING ABOUT THE RISK OF CO2 SEQUESTRATION?
Work on Risk Assessment for CCS Stevens and van der Zwaap (2005) the most frightening scenario [related to risks associated with geologic CO2 sequestration] would be a large, sudden, catastrophic leak.
Saripalli et al (2004): acute hazards related to geologic CO2 sequestration are wellhead failure [blowouts], seismic hazard during injection, accumulation and explosion in lakes, and massive efflux in soils.
Wilson et al (2003) Catastrophic events [associated with CCS] maybe caused by slow leaks if the CO2 is temporarily confined in the near-surface environment and then suddenly released. while the specific mechanism active at Lake Nyos can occur only in tropical lakes (because they do not turn over annually), mechanisms may exist that could confine slowly leaking CO2 in the subsurface, enabling sudden releases. it is conceivable that CO2 leaking from deep underground d could infiltrate t karst caverns at shallow depths and that such CO2 could then be rapidly vented.
Damen et al (2006): there is still a lack of understanding in the physics of CO2 leakage (i.e. the processes that control leakage) through wells and faults.
CO2 PIPELINE RISK Snyder et al (2008): Transporting CO2 is the least risky aspect of CCS, both technically and economically, and it is not a barrier to CCS implementation
Doctor et al, (2005): If CO2 is transported for significant distances in densely populated regions; the number of people potentially exposed to risks from CO2 transportation facilities may be greater than the number exposed to potential risks from CO2 capture and storage facilities Public concerns about CO2 transportation may form a significant barrier to largescale use of CCS.
EXAMPLES OF INDIVUAL RISKS: North Sea offshore oil and gas production the upper limit of tolerance for risk to personnel is 1 in 1000 or 1x 10-3 per year (Avena et al, 2007). Equivalent to a rate of just above 30 fatal accidents per 10 8 exposure hours (Avena et al, 2007). Mountain climbing: risk of 10-3 per year Driving an automobile: risk of 1 x 10-4 per year Flying: risk of 5 x 10-5 per year.
EXAMPLES OF INDIVUAL RISKS: Coal Mining in Appalachia versus Staying at Home First Gulf War versus Staying at Home
BUSINESS RISKS of CO2 SEQUESTRATION Project Financing Issues Regulatory Environment Legal (pore space ownership, liability) Technology Risks Operational risks (Including Project Delays) Leakage Risks (contamination of groundwater, climate risk) Induced Earthquakes and Earthquake Rupture Contamination of Natural gas reservoirs Injectivity Decline
ASSESSING OPERATIONAL RISKS CO2 SEQUESTRATION Pipeline Accidents Well Blowouts Induced Earthquakes Seal Leakage Earthquake Rupture of Reservoir Groundwater Contamination
Other Risks Brine and/or CO 2 leakage through wells, faults, deficient seals on CO 2 atmospheric concentration (carbon credits) on ground water (contamination, displacement) on mineral resources
Risk Assessment of a Geologic CO2 Sequestration Project What can go wrong (what are the possible adverse outcomes)? What is the probability or likelihood of these outcomes? What would the consequences (or damages) be of each of the possible outcomes at this site? In view of the uncertainty in the data used, how confident are we about the answers to these first three questions?
Risk Assessment of a Geologic CO2 Sequestration Project At the present time we lack a quantitative understanding of the likelihood of leakage through the seal; up old wells or up faults. These topics are the focus of ongoing research. So what do we know?
What is the CO2- EOR Record? 0.6 Gigatons of CO2 transported since 1973 1.2 Gigatons of CO2 injected Estimated less than 1% loss of CO2 currently No deaths or significant injuries
What Can We Learn From the CO2-EOR Record? (1) The operational risks of capturing, compressing, transporting and injecting CO2 (2) The risk of blowouts or very rapid CO2 release from wells (3) The risk that t CO2 will leak into shallow aquifers and contaminate potable water (4) That sequestered CO2 (and possibly associated methane gas) will leak into the atmosphere
CO2 Pipelines Incidents From 1986 through 2006 12 leaks from CO2 pipelines No injuries or fatalities
CO2 pipelines risk of leaks: For large (50-150 mm) breaches as 3.3 10-7 per meter of pipe length per year [Reference: e e DNV]
Case Study: Denbury Pipeline Complex Five accidental releases of CO2 have occurred since the pipeline operations resumed NEJD pipeline 11.5 MMT/yr capacity, 293 km in length Jackson Dome CO2 source Built by Shell in1986
Case Study: Denbury Pipeline Complex Free State Pipeline 6.7 MMT/yr 138 Kms in length Built in 2005 Jackson Dome CO2 source two leak incidents id occurred soon after pressurizing i the line, caused by manufacturing imperfections in welds Each leak caused minimal release but a controlled release of ~75 MMCF (each) was required to depressurize the pipeline segment for repair.
Case Study: Denbury Pipeline Complex Incident on the Tinsley 8 line, occurred when an excavator accidentally cut the line
CO2 Well Blowouts Blowouts are temporary loss of control of wells 1) Blowouts of production wells drilled into natural CO2 reservoirs 2) Blowouts of CO2 injection wells 3) Blowouts of active oil production wells that are an integral part of the CO2-EOR project 4) Blowouts of inactive or plugged and abandoned wells within the area of increased pressure associated with CO2 injection wells
CO2 Well Blowouts From Skinner (2003)
Case Study One: Blowouts CO2-EOR Operations of Company A 1. CO2 production well, coiled tubing packing failed during well work. 2. CO2 injection well, caused by leaking gasket at a well head. 3. CO2 injection i well, mechanical seal blown on HP booster pump. 4. Production well, casing valve was accidentally left open during work-over over operations 5. Production well unexpectedly started to flow CO2 before it was converted to EOR producer 6. Production well, problem occurred during the installation of a Blow-Out-Preventer stack during workover operations. There were no deaths or injuries associated with any of these events.
Monitoring Data from Well Blowouts CO2 measurements were conducted during the accidental release at one of the producers was monitored by portable sensors Two hundred feet from the release maximum CO2 concentrations recorded were approximately 4750 ppm (0.475%) The elevated concentrations dissipated quickly (within 30 minutes)
Case Study Two: Blowouts CO2-EOR Operations of Company B Four of these incidents were apparently caused by the failure of mechanical components (two due to valve failures, two due to failure of nipples) The fifth failure was not related to the well itself but rather was caused by failure of a pump component related to corrosion None of the five incidents appear to have been caused by human error
Case Study Three: Blowouts CO2-EOR Operations of Company C One blowout occurred during the installation of a blowout preventer. One incident id that t was clearly l related to human error was caused by a truck ran over an injection well. Another blowout occurred when CO2 reached a planned production well before a well work over could be completed. Again one of the blowout incidents was caused by the failure of a pump component.
CONCLUSIONS The thirty seven plus years of history of CO2 injection involved in CO2 based Enhanced Oil Recovery in the US represent the most tangible evidence available for understanding the risks of CO2 sequestration in deep brine reservoirs.
In the case of both pipeline incidents and blowouts; component failure rather than corrosion or human errors have resulted in the leakage of CO2. The rarity of corrosion related incidents reflects the industries success in implementing anti-corrosion measures.
Installation of blowout preventers is the most common cause of blowouts in CO2 wells
The CO2-EOR industry has an excellent safety record. Unfortunately it is difficult to calculate probabilities from null data.
DOES CO2 INJECTION CAUSE EARTHQUAKES? estimating damages from potential seismic i events, where no liability litigation currently exists, is speculative at this point (Wilson et al, 2007)
Myth Bauer (2005) PhD dissertation, quoting Sminchak et al. (2001), asserts that of 20 seismic events caused by injection of fluids 13 were caused by the injection of CO2 for the enhancement of oil recovery.
Reality This assertion is not supported by the facts. The 13 possible induced d earthquakes (10 in Texas) in Table One of Sminchak et al (2001) were spatially related to water flooding operations at oil fields.
Thousands of injection sites within Texas are aseismic even though the injection pressures are in theory sufficiently high to induce an earthquake (Davis and Pennington,1989)
Only in a few cases have earthquakes been sufficiently monitored to demonstrate t a conclusive relationship between earthquakes and deep well injection Sminchak et al (2001)
In over 200 cases of induced earthquakes : 56% are related to mining activity (coal, potash and gold mining), 30% to water reservoirs (dams) 11% oil and gas extraction 3% are possibly related to fluid injection. (Klose, 2007)
SO DOES CO2 INJECTION CAUSE EARTHQUAKES? It could, but its highly unlikely. Site specific evaluations are needed.
COULD CO2 SEQUESTRATION BE DISRUPTED BY A MAJOR EARTHQUAKE? It could, but its even more highly unlikely. Data is available to calculate l the likelihood. lih
COULD CO2 SEQUESTRATION BE DISRUPTED BY A MAJOR EARTHQUAKE? Likelihood (in stable mid-continent) for an earthquake Magnitude 6 or greater with an epicenter within 10 km of a CO2 plume with a radius 1 km is 0.004[Pi (10 + 1)2/10 6 ] = 1.5 x 10 6 Probability is 4 times as large for a 20 km radius or 6.0 x 10 6
IS CO2-EOR A GOOD PROXY FOR CO2 SEQUESTRATION? Yes, but there are some caveats: 1) CO2 captured from power plants and industrial sources may be more impure than natural CO2 used in EOR 2) Typically CCS activities will be in more populated p areas
CONCLUSIONS Most risks associated with CCS can be quantified and are acceptable Risks that are difficult to establish probabilities for generally have manageable, bounded consequences Risk assessment ultimately is site specific
Acknowledgement SECARB Ed is supported by the U.S. Department ofenergy s (DOE) NationalEnergy Technology Laboratory as part of the American Recovery and Reinvestment Act of 2009 under DE FE0001930. www.netl.doe.gov/technologies/carbon_seq/arra/tra ining.html The Southern States Energy Board is the Principal Contractor of SECARB Ed to DOE. http://www.secarb ed.org/
Disclaimer This report was prepared as an account of work sponsored by an agency of the United dstates t Government. Neither Nith the United dstates t Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United dstates Government or any agency thereof.
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