Performance and risk linked to CO2 storage
At present, climate changes are threatening the planet. Four major actions may be undertaken in order to mitigate the greenhouse effects:
- Reduce usage of fossil fuel ;
- Reduce energy consumption ;
- Replace fossil fuel by clean energies ;
- Avoid releasing CO2 into the atmosphere.
The energy efficiency and the renewable energies are no doubt on the long run the most sustainable solutions for supplying security as much as for climate preservation. However, reducing by 50 % the CO2 emissions of the EU or of the world by 2050 will not be possible without resorting to other options too such as carbon capture and storage.
Geological storage of CO2 seems to be the most important source for limiting greenhouse gas emissions during the coming years.
Illustrative examples of the potential global contribution of CCS based on two alternative integrated assessment models (MiniCAM and MESSAGE)
The current activity of the European Union’s authorities highlights the future importance of the CCS process. A European directive related to CO2 geological storage is currently being written together with the actors of the field.
Copyright Image above courtesy of Schlumberger
The main Projects
Some great European projects of CO2 storage have been developed already: the Sleipner project in the North Sea (StatoilHydro) and the In Salah project in Algeria (StatoilHydro, BP and Sonatrach). These two projects consist in striping carbon dioxide from natural gas – this operation is already performed for producing the gas and being able to sell it – and in storing the gas into subsurface geological formations. The other current demonstration projects are Vattenfall in Schwartze Pumpe, Germany, which should become operational by mid-2008, and TOTAL’s CCS project in the Lacq field, France. The European Technology Platform for Zero Emission Fossil Fuel Power Plants (ETP-ZEP), joint initiative of the European Commission, has about fifteen life-size demonstration projects which are likely to be undertaken once the necessary economical framework is available.
All these projects show that C.C.S. is only starting and that its development predicts a promising future. However storage implies a risk assessment and more or less long term safety demonstrations before it is accepted by everyone.
Risks related to geological storage: OXAND’s expertise and methodology
Oxand has hence developed a risk based management methodology: P&R™ Performance & Risk, based on a model of gas leakages quantification through a well.
The various wells drilled for recovering hydrocarbons represent actually potential leakage passways on depleted hydrocarbons reservoirs, saline aquifers and coal seams, which have always contained hydrocarbons, CO2 being already part of these hydrocarbons. The integrity of a CO2 subsurface storage seems mainly related to man’s intervention.
This methodology follows the workflow presented below:
Workflow of the P&R™ methodology (developed through a partnership with Schlumberger)
Using data about the wells and their environment, the P&R™ methodology based on the SIMEO™ STOR software platform includes the uncertainties related to the various descriptive parameters of the system. It generates a risk mapping as well as concrete recommendations in order to mitigate the identified risks.
All of the well’s components (cement, casings, cavities, cement plugs…) as well as their deterioration in time are taken into account. A flow model coupled to these phenomena estimates the CO2 leakages through the whole system.
Thanks to its partnership with Schlumberger Carbon Services, Oxand is a necessary actor for controlling risks in CCS projects.
Many studies have thus started within OXAND with major oil and gas groups such as Total, Repsol and Sonatrach, StatoilHydro, Gaz de France... The P&R™ methodology can be applied to different matters, either at the beginning of a storage project (choice for injection wells) or at the end (abandoned plugged wells).
Most of these projects are for now confidential. However thanks to its prestige, OXAND participates in different networks and workgroups:
- COSMOS II : CO2 Storage MOnitoring and Safety technologies (project in the continuity of CO2SINK project http://www.co2sink.org)
- MOVECBM: Monitoring and Verification of Enhanced Coal Bed Methane : http://www.movecbm.eu
- CO2NET : Carbon Dioxide Knowledge Transfer Network : http://www.co2net.com
- CSLF : Carbon Sequestration Leadership Forum : http://www.cslforum.org
- IEAGHG : International Energy Agency GreenHouse Gas : http://www.ieagreen.org.uk
- Club CO2 : : http://www.clubco2.net