Health, Safety and Environment Aspects of Carbon dioxide Sequestration | By: Dr. G. P. Karmakar...

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Health, Safety and Environment Aspects of Carbon dioxide Sequestration

By: Dr. G. P. KarmakarProfessor in Petroleum EngineeringSchool of Petroleum TechnologyPandit Deendayal Petroleum UniversityGandhinagar - 382007INDIA



1. What is carbon dioxide sequestration?2. Properties of carbon dioxide.3. Risks associated with carbon dioxide sequestration.4. Monitoring the risks. 5. Mitigating the risks.6. Regulatory scenario.7. Record of accidents due to release of CO2 into the

atmosphere.8. Conclusions.



Increase in the levels of CO2 has led to a global temperature rise as well as increase in the acidity of oceans. About 91% of CO2 today comes from fossil fuel combustion and around 9% because of deforestation.


Fig. 1. Graph showing ever increasing levels of CO2 in the atmosphere


Various sequestration processes

Carbon dioxide sequestration: “The process of removing carbon dioxide from the atmosphere and storing it safely for long periods of time”.

It is a mechanism to naturally or artificially trap carbon and store it permanently so as to offset the accumulation of GHGs in the atmosphere.

Sequestration can be mainly classified as: 1) Biological sequestration (Biosequestration) makes use of naturally occurring factors to trap and store carbon. Trees are a major component of the biosequestration process.

2) Physical sequestration processes are the most widely used and debated so far among all the sequestration processes where CO2 is injected into the ocean floors, or into depleted oil/gas reservoirs or into unmineable coal seams..

3) Chemical processes of sequestration mainly include converting the CO2 to carbonates via chemical reactions and thus reducing the carbon content in the atmosphere.


Hazards due to CO2 exposure for living beings

CO2 exposure for long periods of time can lead to health hazards for living beings. Headaches, nausea and chances of asphyxiation are common health hazards related to CO2 exposure. Further, CO2 being denser than air, tends to stay near the ground or the floor, making it even more susceptible for crawling infants and babies to get exposed to it, in the event of an increase in CO2 concentration.

The UK Health and Safety Executive has classified the toxicity of CO2 in the form of Dangerous Toxic Load (DTL) values which are based on the amount of CO2 in the atmosphere and the amount of time a person is exposed to it (McGillivary et al. 2009).

The hazardous threshold concentrations of CO2 have been defined as:3% Headache and restricted breathing7% Unconsciousness possible within few minutes of exposure17% Death possible within few minutes of exposure


Fig. 2: Various geologic options for CO2 storage. (Source: CO2 CRC and Global CCS

Institute)



During Enhanced Oil Recovery (EOR) method CO2 can also be injected into producing oil/gas reservoirs to store the CO2 as well as boost hydrocarbon recovery from the reservoir.

This method is by far the most important from the hydrocarbon industry point of view and much research is being conducted to improve the efficacy of combined CO2 injection-sequestration projects.

The main trapping mechanisms utilized during CO2 geo-sequestration are:Stratigraphic and structural trappingHydrodynamic trappingMineral trappingAdsorption trapping


Major problems

Major problem in sequestration projects, especially underground projects is the threat of leakage of stored CO2 that may affect the surrounding biosphere extensively.

Leaked CO2 has also been known to enter subsurface drinking water aquifers and pollute them, leading to deaths of living beings.

Hence, we realize the need for safe sequestration projects.


Properties of CO2

Carbon Dioxide is a colorless and odorless gas at standard temperature and pressure conditions.

It has a molecular weight of 44 and a specific gravity of 1.57. Density of gaseous CO2 at standard temperature and pressure conditions (60 °F and 14.7 psia) is 0.00198 g/cm3. CO2 geologic storage is preferentially done as a supercritical fluid to ensure that a greater volume of CO2 can be stored in the given same volume of the reservoir. The density of supercritical CO2 is 0.469 g/cm3. This means that to store 1 ton of gaseous CO2, the volume required will be 505 m3, whereas the same amount of supercritical CO2 would require only 2.132 m3 volume.

Thus, in the same volume, 237 times more CO2 can be stored if it is done in supercritical form, rather than gaseous form.


Fig. 3: Phase diagram of CO2.( Source: Tebodin: CO2 Liquid Logistics Shipping Concept (LLSC) - Overall Supply Chain Optimization; 27 Jul 2011, Global CCS Institute)


Fig. 4: Possible leakage pathways for CO2. Source: IPTC 15402.


Fig. 5: Simulation showing CO2 migration in an aquifer, post injection. Source: ISBN 978-1-880653-95-1.


Fig. 6: Schematic diagram showing leakage of CO2 from Lake Nyos, Cameroon. Source:URLwww.files.chem.vt.edu/confchem/1998/donnelly/LN


Fig. 7: Photo of dead cows in the village near Lake Nyos, Cameroon, following the leakage of CO2. Source: US Geological Survey.


Risks associated with Carbon Dioxide Sequestration

1. Risk occurs during transport of CO2 through pipelines.

2. Transport of CO2 under depressurized conditions, very low temperatures can result. Formation of solid CO2 can also occur at such low temperatures.

3. For injecting CO2 into sub-surface formations, injection wells should be drilled, cased, cemented and completed properly to ensure the safety of the project. Improper cement jobs are of major concern since they pose maximum risk of CO2 leakage.

4. During the injection of CO2 into the sub-surface, there is also a chance of blowouts occurring if the injection methods and pressures are improper.


Risks associated with Carbon Dioxide Sequestration

1. The long term risks are actually related to the storage of CO2 sub-surface and potentially for a long period of time.

2. Presence of a cap rock is essential to keep the CO2 trapped in the target formation. If CO2 is injected at high pressures, this cap rock can fail, or even the target formation may fracture, giving rise to a CO2 leakage pathway.

3. CO2 may also migrate to Underground Sources of Drinking Water (USDW) and cause water pollution, rendering the water unfit for human consumption.

4. In some cases, H2S may also be injected subsurface with the CO2 to sequester it too. If this H2S migrates with the CO2 into an USDW, it would surely prove fatal to the people drinking water from that USDW.


Risk Monitoring During Carbon Dioxide Sequestration

Monitoring of the risk needs to keep an eye over the following:

1. Carbon Capture and Separation technology2. CO2 compression equipment3. CO2 transport pipelines4. CO2 injection wells5. CO2 storage facilities6. Subsurface flow of the injected CO2

7. Integrity of subsurface formations affected due to CO2 injection



Hazard Identification and Hazard and Operability Analysis (HAZID and HAZOP) should be properly and regularly conducted. A disaster management plan should be frame along with provisions for escape, evacuation and rescue.



Sensitive positions should be monitored closely and usage of intelligent pigs is recommended for integrity of the monitoring.

Intelligent pigs are generally used for Gauging, Diameter Recording, Leak Detection, Curvature Monitoring, Crack Detection and Corrosion Monitoring.

They use a variety of principles including and not limited to Acoustic Methods, Ultrasonic Sensors, Strain Gauges, Magnetic Flux measurements and Mechanical Feelers.


Supervisory Control And Data Acquisition (SCADA)

SCADA is a combination of measuring instruments, Remote Telemetry Units (RTU), computers, satellites and supervisory stations. SCADA can help us detect any reductions in the pipeline integrity while also helping us frame the Emergency Response and Disaster Management Plan (ERDMP).

SCADA provides real time data and also reduces the amount of physical efforts needed to monitor the pipeline.

Thus, CO2 flow monitoring in pipelines can be conducted safely using these above mentioned time-tested and successful methods.


Monitoring the sub-surface flow of the injected CO2

1. Chemical based methods include the use of tracers and geochemical testing methods.

2. Tracers are introduced into the injected CO2 to help detect it’s migration into surrounding aquifers.

3. Natural or artificial tracers are easy to detect and can notify us of the change in chemical composition of aquifers because of the possible CO2 invasion.

4. Similarly, geochemical methods include the regular testing of soil samples and groundwater to detect any change in composition.

5. If CO2 seeps out directly through any permeable outlet, even a change in the corresponding top soil composition will be observed.

6. Combination of tilt meters, satellite technology and GPS stations are the other methods used to monitor the flow of CO2 in the subsurface


Seismic methods for sub-surface monitoring of CO2

1. Surface Seismic2. Passive Seismic3. Surface to borehole Seismic4. Cross-Well Seismic5. Single Well Seismic6. Multi-component Seismic


Various monitoring methods for CO2 geo-sequestration (Benson and Myer, 2002)

1. CO2 Plume Location2. Early Warning of Storage Reservoir Failure3. CO2 Concentrations and Flux at Ground Surface4. Pipeline Integrity, Volumetric Flow and Pressure5. Solubility and Mineral Trapping6. Leakage Through Faults and Fractures7. Groundwater Quality8. CO2 Concentrations in Vadose Zone and Soil9. Ecosystem Impacts


1. CO2 Plume Location

i. 2D and 3D time lapse seismic reflection surveysii. Vertical Seismic Profiling and cross-wellbore seismiciii. Electrical and electromagnetic surveysiv. Satellite imagery of land surface deformationv. Satellite imagery of vegetation changesvi. Gravimetric surveysvii. Reservoir pressure monitoringviii.Wellhead and formation fluid samplingix. Natural and introduced tracersx. Geochemical changes identified in observation or production wells


2. Early Warning of Storage Reservoir Failure

i. 2D and 3D time lapse seismic reflection surveysii. Vertical Seismic Profiling and cross-wellbore seismiciii. Satellite imagery of land surface deformationiv. Injection well and reservoir pressure monitoringv. Pressure and geochemical monitoring in overlying formationsvi. Microseismicity or passive seismic monitoring


3.CO2 Concentrations and Flux at Ground Surface

Real time infrared based detectorsAir sampling and analysis using gas chromatography or mass spectrometryEddy flux towersMonitoring for natural or induced tracersHyperspectral imagery to detect changes in vegetation


4. Injection Well Condition, Flow Rates and Pressures

I. Borehole logs including casing integrity logs, noise logs, temperature logs and radiotracer logs

II. Wellhead and formation pressure gaugesIII. Wellbore annulus pressure measurementsIV. Orifice or other differential flowmetersV. Well integrity testsVI. Surface CO2 concentrations near injection wells


5.Pipeline Integrity, Volumetric Flow and Pressure

I. Hydrostatic testingII. Close interval surveysIII. Ultrasonic evaluationIV. Pressure control systems and Supervisory Control and Data Acquisition

(SCADA)


6. Solubility and Mineral Trapping

I. Formation fluid sampling using wellhead or downhole samples; analysis of CO2 major ion chemistry and isotopes.

II. Monitoring for natural or induced tracers including partitioning tracers.


7.Leakage Through Faults and Fractures

I. 2D and 3D time lapse seismic reflection surveysII. Vertical Seismic Profiling and cross-wellbore seismicIII. Electrical and electromagnetic surveysIV. Satellite imagery of land surface deformationV. Reservoir and aquifer pressure monitoringVI. Microseismicity or passive seismic monitoringVII.Groundwater and vadose zone samplingVIII.Hyperspectral imagery to detect changes in vegetation


8.Groundwater Quality

I. Groundwater sampling and geochemical analysis from drinking water or monitoring wells

II. Natural and introduced tracers


9. CO2 Concentrations in Vadose Zone and Soil

I. Soil gas surveys and gas composition analysisII. Vadose zone sampling wells and gas composition analysisIII.Hyperspectral imagery to detect changes in vegetation


10.Ecosystem Impacts

I. Soil gas surveysII. Soil samplingIII. Direct observation of biotaIV. Hyperspectral imagery to detect changes in vegetation


Risk Mitigation Tools

I. HAZOP study is a combination of ‘Hazard Analysis’ and ‘Operability II. HAZID (Hazard Identification):III. SAT (Safety Analysis Table): IV. SAC (Safety Analysis Checklist): V. SAFE Chart: Safety Analysis Function Evaluation VI. Bow Tie Analysis: VII.SIMOPS: SIMOPS stands for Simultaneous Operations.VIII.MOC: Management Of ChangeIX. Management of InterfacesX. Competence


Table 1. Example of a SAT for a CO2 Transport Pipeline

Undesirable Event

Cause Detectable Abnormal Condition

Overpressure Blockage in the flow line.Possible solid CO2 formation inside the

pipeline.Inflow of CO2 exceeds outflow.

High Pressure

Leak Corrosion.Physical damage.Brittle Failure or Ductile Failure.

Low Pressure


Regulatory Scenario Pertaining to CO2 Sequestration

Intergovernmental Panel on Climate Change (IPCC)United Nations Framework Convention on Climate Change (UNFCCC) Kyoto Protocol: The Kyoto Protocol of the UNFCCC is an international agreement legally binding countries to reduce the amount of greenhouse gas emissions.London Convention: The Convention on Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 .London Protocol: The London Protocol (1996) to the London Convention entered into force in March 2006 and is important here because it clarifies issues regarding CO2 sequestration into marine environments and even promotes sequestration to a certain extent, provided it is carried out in a regulated way. OSPAR Convention: The Oslo Convention for the North East Atlantic (OSPAR 1972) is a regional agreement relating to dumping of waste matter into the North East Atlantic Ocean region.The Environmental Protection Agency (US EPA) is among the major regulators and guides for the CCS process as well as for the process of protecting the environment from the harms of greenhouse gas emissions.


Environmental Protection Agency (US EPA)I. Underground Injection Control Program: Under the UIC, in December 2010, a new class of injection wells (Class VI) was developed specifically to tailor to CO2 injection processes and to protect USDW. It ensures that CO2 injection wells are properly sited, drilled, completed, tested, monitored and finally abandoned.

II. Greenhouse Gas Reporting Program: Under the Clean Air Act, in December 2010, the GHG reporting program was finalised that requires proper reporting and monitoring of CO2 amounts to the EPA. Subpart PP deals with reporting of CO2 to the economy. Subpart RR entails agencies carrying out long term underground geologic storage of CO2 to carry out every activity of sequestration strictly based on EPA approved regulations and report the amounts of CO2 involved at each stage. Subpart UU deals with projects injecting CO2 subsurface for enhanced oil recovery methods or for R&D projects.

III. Resource Conservation and Recovery Act: Currently, the EPA is working on a regulation to classify streams of CO2 injected subsurface based on hazardous waste requirements.

IV. Vulnerability Evaluation Framework: To provide anyone in the country with a transparent framework to evaluate vulnerabilities associated with geologic sequestration sites.


The US DOE Fossil Energy Office and the National Energy Technology Laboratory (NETL) conduct and support a large number of R&D projects, in industries and universities, whose aim is to make CCS a more effective and commercially favourable process. The Department of the Interior/U.S. Geological Survey works to estimate storage potentials of sites as well as to characterise sites suitable for CO2 injection and storage.


Federal legislations relevant to CO2 sequestration processes (Vine, 2003):

I. National Environmental Policy Act (NEPA)II. Clean Water Act (CWA)III.Clean Air Act (CAA)IV.Safe Drinking Water Act (SDWA)V. Endangered Species Act (ESA)VI.The Migratory Bird Treaty Act (MBTA) and the Bald Eagle Protection Act

(BEPA)VII.Executive Order on Invasive Species (EOIS)


Table 2. Key Federal regulations in Canada relevant to different aspects of CCSRegulations and agreements related to

Name of the Regulation/Agreement

Environmental Assessment and Protection

Canadian Environmental Assessment Act (CEAA)Canadian Environmental Protection Act (CEPA)

Injection Wells and Pipelines

Canada Oil and Gas Operations Act (has no jurisdiction in the above mentioned four states)

National Energy Board ActTransportation Transportation of Dangerous Goods Act

National Energy Board Act

Storage Canada Oil and Gas Operations Act (has no jurisdiction in the above mentioned four states)

National Energy Board ActMitigation of Human

Health RisksCanadian Environmental Assessment Act (CEAA)Canadian Environmental Protection Act (CEPA)Fisheries ActCanada Labour Code


Other EU regulations relevant to CCS projects

I. EU Waste Framework DirectiveII. EU Landfill DirectiveIII. EU Water Framework DirectiveIV. EU Monitoring & Reporting GuidelinesV. EU Environmental Liability Directive


Regulation Scenario in developing nations

I. Currently, most of the emphasis for reducing emissions is being placed on developed countries under the assumption that they are the ones who have contributed the most to the climate change and global warming.

II. There are no legal bindings on developing nations to reduce such emissions, just moral obligations.

III. Moral obligations are never going to be enough as it is a well known fact that developing economies like India and China are expanding industrially at a very fast pace and hence the emissions coming from such countries are starting to become significant.

IV. The governments of both these countries are skeptical about the entire CCS process. No regulations exist in both these countries that put a burden on their industrial sector to reduce emissions and sequester CO2. Given the current financial and technological scenario, none of these countries would be themselves willing to invest huge amounts of money in a geologic sequestration project.


World Resources Institute CCS Guidelines

I. The World Resources Institute (WRI) convened a CCS stakeholder process between February 2006 and September 2008.

II. The outcome of this process is a set of guidelines that may be used for safe Carbon Dioxide Capture, Storage and Transport.

III. The set of guidelines is the result of the collective efforts of individuals from Governments, NGOs, industry as well as academia, with each person bringing in his or her own set of experiences and knowledge.


Accidents Pertaining to Release of CO2 to the Atmosphere

Storage of CO2 is currently being demonstrated at a number of Geological Storage sites. Concerns have been expressed that possible seepage from underground storage sites could have a deleterious effect on the environment. These concerns have arisen because few events over the past few decades involving rapid emissions of CO2 have resulted in serious accidents.Natural release of CO2:I. CO2 emissions from Volcanic activity: Old Faithful, one of the best known geysers releases CO2 by means of diffuse

degassing. Hot springs and other thermal features at Yellowstone National Park vent millions of tons of the greenhouse gas carbon dioxide each year, more than a typical industrial power plant.

Lake Nyos and Lake Monoun are both tropical crater lakes in Cameroon, The disaster in Lake Monoun (1984) led to the death of 37 people while a sudden outburst of CO2 in Lake Nyos (1986) asphyxiated almost 1700 people. See Fig. 14 and Fig. 15 for a better idea of the incident.

Dieng incident: This incident occurred in the Deing volcanic complex in Indonesia (1979). It was associated with the phreatic explosion which resulted in the sudden CO2 emissions from the volcanoes following a buildup of gases within them. About 2, 00, 000 tonnes of CO2 was released and flowed down to the plain causing the asphyxiation of 142 people.

:


Incidents Involving CO2 as fire suppressant:

I. Mönchengladbach, Germany (August 16, 2008).An automotive fire extinguishing system triggered by the outbreak of fire caused the leakage of CO2 .As a result of a defect in the extinguishing system the leak lasted beyond the extinction of flames. The CO2 cloud spread to the surrounding neighbourhood intoxicating 107 people, of whom 16 required emergency medical attention.II. Idaho Falls, USA (July 28, 1998).Within a large nuclear research laboratory, the automatic fire extinguishing system activated uncontrollably causing leakage of CO2. The failure of preliminary discharge alarm did not allow the evacuation of personnel working in the laboratory. Due to flooding of CO2 the visibility was reduced to zero. As a result the employees could not escape in a safe manner. All of the 16 employees required emergency medical treatment, but unfortunately 1 of them could not be saved. III. Pooler, Georgia, USA (September 7, 2001).A Florida woman died due to asphyxiation caused by the leakage of CO2 which was used to make the restaurant’s soda fizzy. About 8 other people who tried to help the women were found unconscious and were taken to the hospital by the fire fighters. As CO2 is lighter than air, it hung on to the ground and was spread to the confined space causing the lives of several at the restaurant in danger.


CO2 emissions from Sedimentary basins:

CO2 release also occurs as a result of geological processes in many sedimentary basins. CO2 is commonly trapped within the porous rocks as a supercritical phase but may also dissolve in any residual water in the reservoir. CO2 leaks from sedimentary basins can occur through permeable rocks and or along faults or fissures in the rock, although CO2 can be accidently emitted via boreholes. This is in line with the discussion presented earlier regarding leakage paths for CO2.

CO2 emission from the seabed occurs in Tyrrhenian Sea offshore from the Aeolin Islands in Italy. About 25, 000 tonnes of CO2 is released every year over an area of 15 Km2 saturating the sea water with CO2.


Incidents involving CO2 Well blowouts

I. A blowout at the Sheep Mountain Field occurred (March 17-April 3, 1982), during the drilling of a CO2 production well on the west slope of Little Sheep Mountain. A contractor called in to kill the blowout initially had problems related to the high flow rate of CO2 (estimated at 200 million standard cubic feet/day) out of the well. The well took more than a month to come under control.

II. A certain ‘Company A’ utilizes several safety and preventive measures to monitor and mitigate potential blowouts. Company A uses alarms, automatic shutdowns, and human monitoring. Even after that Company A experienced about 7 CO2 blowouts in 5 years. Most of the incidents took place during work over jobs. It is very difficult to estimate the total CO2 that was released in each of these incidents.


Conclusions

1. Developed countries around the world have started being very active in taking action against this climate change and are actively engaged in CO2 sequestration projects. Developing and underdeveloped nations too need to step up their efforts to fight climate change, with proper help from the international community.

2. CO2 geo-sequestration is still very promising because of the large potential many countries possess for this kind of sequestration to be feasible.

3. Any CCS project comes with a huge financial burden as well as the constant risk of accidentally releasing CO2 to the atmosphere. Extreme caution should be taken while handling CO2 due to its hazardous nature.

4. A variety of risk mitigating tools and technologies are available, which, if implemented properly could lead to a safe and highly efficient CO2 geo-sequestration project, capable of sequestering CO2 underground for very long periods of time.


Acknowledgements

I would like to thank two of my very bright students who collected all the literature for the preparation of this presentation and their work is finally going to be presented at the SPE Asia Pacific Oil & Gas Conference and Exhibition held in Jakarta, Indonesia, 22–24 October 2013.

Health, Safety and Environment Aspects of Carbon dioxide Sequestration | By: Dr. G. P. Karmakar...

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